Injection cars - SPi-TPi tuning, basic information

by Keith Calver 10. September 2005 09:16

I've been getting a lot - well even more than normal - of questions concerning tuning the injection engined-cars of late as more and more folk are looking to tune their modern Minis. Many are frustrated by the lack of product availability to achieve what they want,

some are experiencing problems with the standard ECU and others are plain hacked-off at the lacked of useful information on how to go about tuning the injected cars. In particular whether removing the Cat is a good idea, and whether there are any problems as far as the standard ECU (electronic control unit, or 'brain') is concerned when changing chunks of the standard engine - like rocker gear, cylinder head, etc. and just what can you do in the way of tuning and it's effects. It would seem other sources approached for the information are either playing their cards close to their chests, making loud sucking-air-through-teeth noises and 'hmm, well...' black-magicky sort of inferences, or simply/patently just don't know. So let's tidy that lot up for a start.

The standard injection Cat is very efficient - both from a 'cleaning up emissions' point of view and from a 'non-restrictive' one. Tests carried out by both myself and A.N.Other prominent A-series tuner have found the Cat to cost only a couple of horses right at the top end of the rpm band on modified engines developing more than 104-ish bhp (where the standard ECU has been replaced with a programmable one along with sensors, wiring harnesses, etc.). Junking the Cat is therefore pointless unless absolute maximum power is sought, and the aggro of re-fitting the Cat each MOT-time won't be an issue.

The standard ECU has a very broad operating range. I am currently doing a development program in cahoots with a learned friend and colleague to cover the whole schmooze of SPi/TPi tuning from simple add-on bits to serious add-on bits and power increases. As far as we have gone, the standard ECU copes with up to the 'GSi'-level tuning (Modified head, high lift rockers, replacement air filter element, rear exhaust section, etc.) offered by a number of the specialists.

Incidentally - this development program was instigated by the lack of available information on such stuff, and a worrying lack of information known by some who are marketing these kits. Brought to the fore by the aforementioned enquirers being worried about being flogged a heap of bits with little more than - 'nah, it'll be alright mate'…It has taken nearly a year (excluding all the time I have previously put into the injection tuning possibilities right from the start) so far to uncover all the why's and where fore's, do's and don'ts, what's possible and what isn't and source a suitable programmable ECU that doesn't cost a fortune that will integrate with the standard sensors and Rover harness (to include alarms, etc.). The standard ECU is of the very powerful and sophisticated 'MEMS' type - not the simple-by-comparison systems used on most Fords and Vauxhall's. Consequently most electronics engineering companies that develop chips and such for tuning electronic engine management systems have been defeated by the Mini's complex system. And that's one of the reasons for folks' frustrations - there's a plethora of stuff available for Ford/Vauxhall tuning but very, very little for the good old Mini!

My colleague and I have sourced the 'Holy Grail' - but the manufacturers are being very dogged about releasing the ECU before they are more than happy and confident with it - they want it to be totally reliable and fit as many MEMS-controlled engines as possible. Consequently ironing out any bugs that surface when used on any of the systems has taken time. Neither they nor us have the sort of budget and facilities the major manufacturers have to carry out such projects so patience is required. Unless someone out there wants to invest a very, very large sum on money in the project?

Anyway. The standard set-up copes, but it is getting border-line on mixture strength with the afore-mentioned 'GSi' kit fitted. The engine survives at this level because of the carefully controlled ignition timing. Addition of what would be described in the motorcycle world as an 'ignition advancer' (items like the 'Icon' boxes) really doesn't appear to do a whole lot - except perhaps push that borderline a little closer to the edge of the envelope. Also, the practice by some of crushing the fuel rail pressure regulator to increase fuel pressure in the rail in an effort to richen the mixture isn't warranted at this level. A number of piston-melting situations have also high-lighted that if you are going to advance the ignition timing by moving the reluctor ring - you need some accurate data on engine performance before you do so, and be vary careful how far you advance it.

We have tried all the combinations of parts, adding one component at a time to see where the major improvements were made. In conclusion it we decided that really the whole Gsi package is needed to give any definitive benefit. Adding just the rear exhaust section helped more than the air filter replacement. It sounded better and gave a very small on-the-road performance increase. Adding the rockers achieved a very small further increase not really detectable on the road. One of these ignition advancers was tried in conjunction with each component fitment after the test on each addition was done. At times it seemed to make the engine run smoother at idle, other times not. It certainly didn't make any discernible difference to on road performance or power output. The final addition of the modified head seemed to pull all the oddments together as there was a reasonably significant over-all performance improvement.
Power output claims don't vary a whole lot - and for good reason. The limiting factor, as stressed previously, is the ECU. Beyond the aforementioned GSi type kits, further modifications net no further power output. Well, may be the odd one or two, but not significant gains. From all the combined efforts of myself and Swiftune Racing the most we've seen is 85bhp. And that is despite going further with mods to intake manifold, throttle body and air cleaner, adjustable fuel pressure regulators, complete replacement exhaust systems, current specific camshafts and higher ratio rockers (over the 1.5s). The best average is 82-83bhp. The worst was 78.4. Standard the injection engines give a quoted 63. And this - oddly enough - is pretty consistently accurate. A couple of companies claim considerably higher outputs. I have tested a couple of cars fitted with the 'Full Monty' 90bhp kits - and found them lacking. One gave just a tad over 81bhp, the other 83bhp. Both owners were somewhat disappointed considering the comparatively large extra cost involved, and the poor mpg.


The main power increase is at the top end; only a small increase in power is gained from low, through mid range and up to the top end. There is also a marked difference in power actually achieved with some kits as opposed to that advertised. Generally though, most do make the car a much better drive.

Instead of brutalizing the standard fuel regulator to increase fueling you can fit an up-rated pressure regulator that increases the fuel pressure in the fuel rail, which richens the mixture. Trouble is it richens the mixture through the whole engine performance band - and that means a very marked increase in fuel consumption. Down to around 22-24mpg - bit rude for a Mini! Our testing has concluded that, although there is a definite increase in power, it isn't sufficient to justify installation and running costs! Plus you must remember over-fuelling will destroy the Cat pretty quick…

Next stop is what does a cam change do, and how far can you go with it. In particular - what happens to emissions and mixture since most performance cams use an increase in overlap in the quest for more power, which will murder emissions and cause rough-running nightmares. Folk have spoken to me that have fitted cams like Kent 276 and 286 types and claim the car runs fine. I have experienced only one such engine - and that ran far from 'fine'. It had the lumpy-running attitude of an engine that promises to give a blitz of power once it comes 'on cam'. It even had that slight 'kick' when the engine components eventually got themselves to a point where the engine would run OK. Bu the bald truth was soon uncovered on the rolling road. It was 15% DOWN on power and the emissions were all over the place! Either a very special cam needs developing, or a fully programmable ECU is needed…

There is currently only one ECU on the market that has been specially developed that will run off the standard Mini sensors and basic harness. It still requires a jumper lead between ECU and standard ECU wiring plug to work since there are several versions of ECU and loom on the injection Minis to further complicate the issue. The snag is the cost - it's £750 + VAT, plus a further cost for the jumper lead. And you still need to buy the software to program the thing! For those that are desperate and have hoops of money burning a hole in their pocket - we can supply them if necessary. BUT - my advice is to be patient. The ECU we are after is currently being reliability tested on a standard MPi here in the UK right now. And we're looking at a customer purchase cost of around £350…

Useful part numbers:
C-STN20 Performance kit for SPi Mini containing; modified cylinder head with race quality valves and guides, RC40 rear exhaust box and Cat link pipe, 1.5-1 ratio roller-tip rockers, K&N replacement element air filter, set
NGK BPR7ES spark plugs, head gasket, thermostat gasket
Injection manifold gasket and rocker cover gasket.

C-STN20BUDGET As C-STN20 except head fitted with modified road- spec valves and guides and non-roller-tip 1.5-1 ratio rockers.

C-STN21 TPi performance kit - as C-STN20 but uses TPi head casting

C-STN21BUDGET As per C-STN20BUDGET but uses TPi head casting

C-STN22 Stage one kit for SPi and TPi Mini containing:
RC40 rear Exhaust box with Cat link pipe, downpipe from manifold on TBI and pipe, new downpipe studs, new downpipe nuts, new Downpipe to manifold gasket, new Cat gasket, new rubber Exhaust hangers, K&N replacement air filter element and U-clamp.

Tags:

Import

Injection Cars - Tuning up-date

by Keith Calver 10. September 2005 09:09

OK, so what's happened to the Min Tec/Mini Spares development program?

It has been a long time between my first few words on basic injection car tuning and these - for that I apologise, but business has been unbelievably fraught this year.

I did promise regular and frequent up-dates, but the best laid plans, and all that… As I said, business has been more than brisk.

OK, so what's happened to the Min Tec/Mini Spares development program? Apart from a whole lot of investigation and repetitive research into what's available currently - not that much. It is all hinging on this forthcoming ECU from this particular company. Unfortunately the company concerned is not run by businessman or automotive engineers. They are electronics whiz kids who are trying to achieve the Holy Grail. Essentially they have come up with a system that will plug into the very sophisticated and complex MEMS-type ECU system and work using all the standard sensors, for what is going to be a very comparably favourable price. The problem is they are determined to make the ECU fit as many cars as possible prior to release. Now, as is very obvious, manufacturers are turning out new cars all the time… We have tried explaining to them the merits of releasing the 'MK1' version to re-coup a great deal of their fiscal investment, then the 'MK2' when new cars are detected requiring it, and so on. So far it's fallen on stony ground. But I believe we are getting through…the first of the prototypes has been here in UK on test for several months and has performed excellently and reliably. There were a few minor hitches, but they will be straightened out quickly and easily. To try and force the time frame, the guy here in the UK that is going to be the distributor (Mini Spares will have sole distributorship for the Mini) and has been doing all the testing and assistance in development has just gone out to the country concerned to get all the kinks ironed out and try to influence the launch date.

Keeping a weather eye on what others are offering has thrown up some interesting claims. Before considering this - remember our goal is to produce an ECU that will plug into the standard wiring loom, using all the standard sensors (keeps costs down and far easier for DIY application) at an affordable price for the improvements it could make. So we are looking at about £400.

I have had a great many enquiries about some of the recent advertised claims from various quarters too. Whilst my general reply is 'contact them and ask the questions, I thought it may be useful to convey my superficial thoughts…

There have been some interesting claims on what folk are achieving. Whilst I am well aware that there are other ECUs on the market being touted for the Mini - a moments contemplation and enquiring phone calls soon bring to light the main issues; they are not cost effective and not simple to fit/use. There is one being sold at £350. Not bad. BUT, it does not use all the standard sensors at all, needs a shutter wheel and pick-up mounting on the crank pulley (not at all an easy thing to do, especially as it needs to be absolutely spot-on to have any chance of triggering the ECU properly), and will require dynoing to set the ECU data. Just the ECU and hardware necessary brings that seemingly low cost figure up to around £750. Plus dyno time for mapping… So we're looking at more like £1,000, more likely £1,200. Oops. No cheaper than the dedicated Lumenition ECU developed for Downton then… £750 plus mapping… Makes the other real alternative from Webcon look a good deal; at least is has been very extensively tried and tested - proven to be ultra-reliable - and has a wide spread dealer network and back-up capability. Still out of our target though.

By way of a superb illustration of the real cost effectiveness of one of these kits, Car and Car Conversions did an article on one company's offering…Utilising an Omex ECU and hardware, a 1380cc engine with 286 cam, modified head, and their version of an injection throttle body to replace the standard one they are claiming 135bhp and 120lb ft… That is mightily impressive horsepower from what appears to be a single intake (much along the lines of a single 1.75" SU) on a SU-ish intake manifold. I'd have to see it to believe it…and the cost? A mere £4,000-ish…Hmmm. Allowing, say, £1700 for the engine build - that's £2,300 for the other gubbins! And I'd be really surprised if 135bhp is the real output. Be far cheaper to stick a normally aspirated 1380 in from one of the more experienced A-series specialists with a good, solid 100bhp and 95lb ft torque - about all you need to have big fun in a Mini. And £2,300-ish for an extra 'claimed' 35bhp. Hmm.

And how 'real' are those claims likely to be? Only witnessing such an engine producing such power would be definite confirmation, so then it's down to 'scruples' I guess. How to judge? The company illustrated above claims in it's advert that they are getting this 135bhp and 122lb ft torque from their stage 3, 1380cc, Kent 276 profiled cam, injected engine - not the 286, stage 4 headed detailed above when in the CCC article the figures given for the stage 3, 276 cammed motor is only a claimed 115bhp/100lb ft torque. Some wool-pulling there or what? As this advert has been run like this for many months - I really can't see it as a genuine mis-print!

But you could have something more basic from their range - what is generally described as a 'GSi' kit (head, 1.5 rockers, exhaust system and bits), plus just the Omex ECU and hardware but retaining the standard injection set-up. Result? They claim 85bhp - entirely feasible, but then that's what is generally achieved with the better 'GSi' kits alone, but has cost an extra £750 for the ECU and bits - and it isn't clear whether this includes mapping or not…

The aforementioned 'big power' kit utilises an already available throttle body from a company called 'Jenvey'. They've been around for some time, and are generally regarded as being pretty good. However, we are looking at producing something that will hopefully be that bit better and specifically designed for our venerable A-series to squeeze the most out of it. What point is there trying to do less? Production of said items has been slow, largely because those doing the work (me included) have to earn a crust at the same time. Unlike major manufacturers we do not have a multi-million pound budget with dedicated facilities and personal…

So my findings are still pretty much unchanged - there are alternatives, but they are not at all economical or cost effective, nor possibly all that they are claimed to be. And certainly not within the realms of what we are trying to achieve. I am really hoping to have something more concrete to offer early in the New Year.

Tags:

General Tech

Induction system - Improvements, initial tasters…

by Keith Calver 10. September 2005 07:49

Modern technology has seen dramatic improvements in power outputs over very recent years. Just look at Formula One, where 3000cc engines are now putting out the sort of power not even dreamed of not so long ago at rpm levels that make motorcycle engines flinch!

At the end of every racing season the new/recurrent champions are confirmed, and the rest of the field turning their attention towards next year/season and ways of beating the crowned champ. Invariably this involves that age-old quest for the illusive extra horsepower this year's champion seemed to have over everybody else. So I thought it may be useful to have a look at some stuff that is largely over-looked by many and to further agitate those little grey cells.

Modern technology has seen dramatic improvements in power outputs over very recent years. Just look at Formula One, where 3000cc engines are now putting out the sort of power not even dreamed of not so long ago at rpm levels that make motorcycle engines flinch! The rule makers keep trying to slow them down, but they only go faster. However, the reasons for this are not purely engine size/cam types/valve gear/cylinder head proficiency. It was realised some time ago that the whole package was important, so every aspect of a racing car's anatomy received the same amount of attention to detail and development - each area demanding it's own team to investigate and control it; the 'Management' team. The technology available has distilled down over the years to the somewhat smaller budgets of the club racer, and Mini owners are among them, yet few exercise this holistic 'management' approach.

It was with this in mind that I did the recent series on going racing on the cheap in Mini Magazine - looking at the package as a whole, dealing with all those things that tend to come second for the uninformed yet are the much more affordable options for going fast initially. Now, blending a little of the 'holistic package' with budget tuning and the management aspect, here's how to add real on track performance at a modest outlay -

Thermal Management.
It has nothing to do whatsoever with keeping the driver warm. Or cool for that matter. It has EVERYTHING to do with the engine's operating conditions. Of particular importance - induction charge temperatures.

I have touched upon this subject in various articles in various media mediums in the past. Some folk have ventured trying the suggestions - and have been astonished at the results. Others have got the wrong end of the stick, or got way too complicated in their application without any real thought to what they're doing, and have been confounded by a myriad of problems. So here's a quick trip through what it's all about to set the ball rolling.

The power potential of any engine is wholly dependent on how well it fills its cylinders its volumetric efficiency; a known and accepted fact. What is not often appreciated is that it isn't just the VOLUME of fuel/air it can consume with each 'lung-full', but the MASS of that lung-full. 'Mass' can be applied to any number of subjects, but generally has one inference 'lots of'. What our engines need then is lots of fuel and air crammed into each lung-full - more commonly called the 'charge weight' in automotive circles - very ably demonstrated by what happens when strapping on a supercharger or turbo, as this is EXACTLY what they do. The result is an increase in the charge weight contained in each lung-full. But even they can be improved upon in any given situation.

The critical factor here is the induction charge temperature. It needs to be kept as low as possible commensurate with optimal fuel atomisation. In other words, every effort should be made to ensure the in-going induction charge is as cold as possible without literally freezing the fuel out. If you do this the result will be more horsepower and - more significantly - more torque.

Being pedantically repetitive to make sure you've got your minds around the idea that reducing intake temperatures are beneficial to power and torque output the crux of the deal is this - although engines may be bored and stroked, and/or fitted with more carbs, free-flowing induction systems and more efficient (modified) cylinder heads to increase its power potential by increasing its capacity, increasing the charge weight (mass/density) will greatly enhance these improvements. To do this we need to make sure the ingredients going in that form the intake charge (air and fuel) are as cold as possible without actually freezing out the fuel. Has it sunk in now? Good. So how do you achieve this?

A really good start is to isolate the intake from the exhaust manifold. A phenomenal amount of heat is emitted by the exhaust manifold - not at all helped by the fact it's trapped in a very small area between the bulkhead and a hot engine - that only exacerbates the problem. At the very least some form of heat shield should be placed between the intake manifold port runners and the exhaust. Use stainless steel in preference to mild steel, as it is a very much poorer conductor of heat. And as that subject has come up - a stainless steel exhaust manifold is not only more durable than the mild steel versions, but also retains more heat in the exhaust due to aforementioned heat conduction maladies. A further step forward is to stick heat-shield material on at least one side of your shield if not both. Polishing or chroming the outside of the intake manifold is the next step. Polishing costs little but your time.

Better than this though is using a decent thermal wrap on both exhaust and intake. I say 'decent' as there are some poor imitations of the really good stuff on the market. I always use the original 'Thermotec Cool-it' wrap and highly recommend this. An alternative to the heat wrap is to have thermal barrier coatings applied to the inside of both exhaust and intake manifolds. Even better, use it along with the wrap. Only hassle here is it's very expensive to have done if you live anywhere else in the world except America since a majority of the companies that do this are based there!

On to cold air induction. Having trunking picking up cold air from behind the grill and dumping it at the carb mouth performs wonders in the intake temperature reduction stakes. Refrain from connecting this directly to the carb mouth though. Use a decent, high-flowing air cleaner and dump the cold air on that. Too much air disturbance at the carb mouth will cause excessive turbulence, reducing power output by messing up airflow and fuel metering.

That lot is all pretty straightforward and can be seen in varying amounts, and occasionally all together, on a number of racecars in club racing but very rarely on the road. Now for a very little used method of reducing intake charge temperature at club level - fuel cooling.

Yessiree - reducing fuel temperature contributes handsomely to reducing intake charge temperature and dramatically increases charge weight. All that's needed is to run the fuel through what the racing fraternity call a 'cool can'. Simply a container with a removable sealing lid through which a length of coiled copper fuel line runs round/through it and into which is put a mixture of pure alcohol and ice or dry ice. To maximise its effect it needs to be as near the carb as possible without being in the engine bay. Definitely an inexpensive way to more power and especially torque, but needs combining with all the other options to reduce induction temperature, otherwise the cooled fuel will be heated up again by the time it gets into the cylinders and much of the possible advantage will be lost.

NOTE - the engine will need to have its fueling re-set when any of these methods are used. Cooling the fuel and intake air will increase fuel droplet size.

Now, before the aforementioned tasters on reducing induction charge temperatures agitates folk into beating me over the head with the benefits of ram-charging using cold air picked up from behind the grille and 'forced' into the carb/induction system/engine by means of a sealed section of trunking linking a large panel filter at the grille end to a purpose built plenum bolted to the back of the carb/intake body. Sorry guys and gals - nice thought, but it ain't so. Let me explain a few things…

There seems to be two main sources for the reason why many folk rush out and slap a pressure ram-charging system onto their Minis - the 'stick-your-hand-out-the-car-window-and-feel-the-pressure' one, and the 'look-what-they're-doing-with-motorcycle-engines-these-days' ones. Both are fairly plausible when considered briefly, but a little investigation proves otherwise.

Anybody that has stuck his or her hand out the window of a moving car has felt the seemingly immense pressure it creates against your hand. Essentially there are two factors that affect this 'ram-air' pressure - air speed and density. The pressure changes in proportion to density, but changes at the SQUARE of speed. This means that when a ram-induction equipped car doubles it's speed, the ram-pressure generated increase by a factor of four. Intense! Now the downer. There is a formula to illustrate/assess this, but take it from me - a vehicle traveling at 100mph under ideal conditions only generates 0.177psi of ram effect pressure. That's 1.22% more than normal atmospheric pressure. You therefore need to be doing well in excess of 200mph to achieve 1psi of pressure. Not the territory of your common or garden Mini. Nor even your super-tuned one, come to that (as, brick, a, aero-dynamic - re-arrange to form a common phrase associated with Minis). So that's the 'hand-out-the-window' syndrome explained.

Pressurised air boxes create havoc with fuelling and air/fuel mixtures. Not so much of a problem on fuel injected cars where the programming can be sorted to deal with it. Carbs, on the other hand, tend to do weird things. A carb is little more than a self-powered, low-pressure fuel injection system. Where a pukka injection system works on typically 40-ish psi, a carb uses around 1psi. Quite a difference. To achieve maximum power under most instances, the air/fuel ratio needs to operate within fairly tight limits - say 5 to 6 percent. Outside this, power will drop off quite a lot. Without getting into major carb 'modus operandi', carbs generally have two stages of venturi. The secondary venturi is there to amplify the pressure drop across the main venturi. This creates a stronger draw on the fuel main jet hole. This system is very susceptible to outside influences - and why running a decent, high-flow air filter will improve fuel metering and therefore power output by stabilizing the air around the carb entry.

Then there's the problem of what it does to the carb itself. Increasing the pressure at the carb mouth may not automatically cause a suitable rise in pressure within the crab's float bowl. If an imbalance occurs, it will lean out the carb mixture - and that can have potentially disastrous results. What is required to circumvent this problem is to make sure the area in the float bowl and above the fuel level is linked to the ram-air sealed box. Fortunately, Webers have just such a facility - those holes just above the intake mouths. These obviously must be sealed off from the out-side air, within the pressurized air box to enable them to work. It's worth noting that if you go this route, the jet access cover should be sealed too.

By way of a comparison of how much gain can be had by either cooling the incoming charge or from ram charging, consider this -

Density increases as temperature drops - roughly speaking 3.3 deg C will see a change of around 1% in density. Production engine intake charge temperatures are regulated to about 80-85 deg C for maximum all round efficiency. Feeding cooler air in from outside the under-bonnet environment can see that dropped to around half that. That's an increase of air density in excess of 10%, which gives a similar effect to around nearly 2psi of super-charging pressure.

I largely suspect that the gains achieved by using sealed air intake systems such as seen on Mini Miglias and the like are made through reduced induction temperatures, not ram-charging. Ram-charging is a real science. Consider the ram induction hoods/snorkels used on those monster V8 motors, and indeed the design of those air boxes used on motorcycles. Notice anything similar? They both have much smaller intake mouths/nozzles than the plenum area. Want to know why? It has to do with causing a pressure drop across the intake area - not feasible unless there is a precisely calculated, designed and manufactured intake air box/plenum used that follows the basic details above. And then they will only work when exhaustive dyno and on-track/road tuning has been carried out. Not the sort of thing I'd recommend a club racer to get into unless a very serious budget was involved!

Have a think about this lot. My experiences have shown considerable on-track gains can be made with limited budget but a bit of careful thought and planning.

Tags:

Engine

Ignition - What's needed

by Keith Calver 10. September 2005 07:42

Firstly - re-runs or re-hashes of technical literary prose always brings to light either new, or old forgotten subjects for close scrutiny/re-examination. The arrival of 'A Well Known A-Series Tuning Bible' is no exception. Good news as far as I'm concerned as it keeps me gainfully employed!

This dissertation is centred upon that old chestnut 'ignition systems'. Technological advances running through the entire automotive world hasn't ignored the system that supplies life-giving sparks to bring your engine alive. It's true - no spark, no power. Much of the technology applied has been about making bigger, fatter, longer lasting, and more consistent sparks. The plethora of Mini spares suppliers have embraced this whole-heartedly as it's another string to their bows of profit generation. And it's this that's causing the problem - again Mini owners are being sold stuff that they don't need, or more pointedly will NOT increase power out-puts one iota. It's not necessarily the vendor's fault - ignorance is generally the reason they are trying to force the 'latest and graetest' upon you. So here's some enlightenment for you.

The Mini combustion chamber is very efficient. Consequently the standard coil-generated, distributor - well - distributed, points triggered ignition systems works very effectively - when new and properly serviced. When in good order, properly serviced and accurately set-up it's very hard to beat by any meaningful margin. However, the effectiveness starts to wane after only a very short period of time when degradation sets in. Much of the problem is centred on the distributor. Short term, the points wear/burn out, condensers break down, points heal cam wears, and eventually the distributor spindle bushes wear because of the relentless hammering of the points operation - particularly where poor quality aftermarket products are used. Without covering the more technical aspects of ignition system operation, the sum total of this degradation is reduced spark performance and consistency - and therefore power and economy.

From this, the solution seams eminently simple - replace the points with a more reliable trigger. But no, uninformed or greedy vendors would have you believe you need a system that will create what amounts to 'artificial lightening' within the confines of your combustion chambers to develop nuclear-fusion type mixture burns. And this, they assure you, will give you more power. Absolute rubbish. Oh, I've spoken to folk who swear by this or that system who are certain they got an immense power increase after replacing the 'old system' with it. I'll bet 'old' is the determining factor here. Anything replacing a poorly serviced and set-up ignition system will improve things no end. And the performance gains so carelessly tossed about that influenced them to part with their hard-earned cash were generated on other engine types with particularly poor 'burn' characteristics. The absolute best you're likely to get on a truly well sorted ignition system in a Mini will be 4%-ish, but more likely 2%.

The point is you don't need to invest fortunes in mega-spark producing systems in the good old A-series to get consistent, capable, and more than adequate sparks. If you can't be bothered/don't want the hassle of maintaining a standard points set-up all you need is one of the decent, reliable electronic ignition trigger systems readily available - such as Aldon Ignitor (Petronix), Piranha (Newtronic), or Lumenition. These eliminate all the points-generated problems with no maintenance required and can compensate for a certain amount of wear in the distributor. Lashing out more money than these systems cost will be a waste.

And the rest of the system? Lightening-bolt producing coils are just as unnecessary. A good 'sports' coil (Lucas Gold, Bosch Blue) is fine for the points-triggered system. A decent quality standard coil is all that's generally needed with electronic-triggered systems because the stable, consistent performance of these triggers maximises the sparking-power availability. Watch out here though - it's essential to use a coil suitable for your system. Late Minis have ballast-resisted ignition systems (See 'Ignition - Ballast-resisted). A standard 12v coil is no good on these.

HT (High-Tension) leads are another bone of contention. Seems like everybody's obsessed with 6mm/8mm and even 10mm 'silicone' plug leads. Sounds impressive but all it means is they've got lots and lots of expensive silicone-based insulation wrapped around the conductor to protect it from extremely hostile turbo-induced under-bonnet temperatures. Complete waste of time on a Mini where the HT leads are kept nice and cool behind the grille…And the conductor used is generally carbon-impregnated string - just like the standard, factory fitted leads so should be replaced yearly too. To maximise spark-production, you can't beat good old copper-cored leads with suppressed plug caps (NGK's are highly recommended) or a really decent aftermarket set like the Lucas 'Speedleads' range.

All that's left are the spark plugs. Again we are bludgeoned with 'power increasing' plugs such as these 'Splitfire' items sold at over twice, may be three times the price of a 'standard' plug. And again - in a Mini; worthless for all the same reasons artificial lightening isn't needed - the very efficient combustion characteristics possessed by the A-series engine. A decent, standard-style plug will suffice - and once more NGK give consistently better results than any other in the A-series I have experienced so get my vote.

Tags:

Engine

Ignition - Possible pre-ignition/pinking cause

by Keith Calver 10. September 2005 07:41

It's one of those things that, once ingested, lurks in the dark corners of the mind until a pertinent situation comes along. Such a situation reared its head a couple of weeks back - so now's the time to spread the word before it disappears back into obscurity.

Engine's that run on or pink (detonate) for some seemingly illusive reason may well be suffering from a problem that causes an apparently correctly chosen heat range spark plug to run too hot. The problem is worn spark plug threads in the head. This reduces the heat-path required to cool the plug, consequently it over-heats and causes the aforementioned problems. So if you come across this one, check the plugs for fit in their threads. If they're loose, try the next heat range up!

Tags:

Engine

Ignition - Pertronix Ignitor issues

by Keith Calver 10. September 2005 07:38

I have been using the Ignitor ignition systems for some 8 years or so, as long as they have available in the UK, and have never found fault with them nor had any reliability issues. Until the beginning of this year…

A new customer for this year, racing an MG Midget here in UK under a limited mods category, was doing splendidly for the first couple of races, then started experiencing a misfire. Initially it was believed to be a fuel starvation/vaporization issue. All fuel pipes were checked and re-routed where it was considered necessary. Those still considered in danger of getting too warm were heat shielded. The misfire persisted. On to the ignition system. All was checked, but then a loose alternator wire was found and blamed for the fault. It wasn't. Back to the ignition system then.

Since the engine would run, it wasn't considered to be the Ignitor ignition, since we are advised that these things either work or they don't. The car isn't close to me, and therefore I couldn't be on hand to physically carry out checks myself, so it was down to advise by phone and e-mail. We ran the gambit of all the usual suspects - plugs, leads, dizzy cap, rotor arm, coil and so on. After some time I popped the question about coil temperature, the reply was that it was so hot you couldn't comfortably hold it - A-ha!! But this was the second new Lucas Gold Sports coil tried… hmm. But it, too, was getting excessively hot - so it must be the coil right? Since the engine would still run, but the coil got hot after a short time. As the electronic ignitions don't really require a high-power coil, it was suggested a bog-standard 12-volt coil was tried. And there I left it as Mini Meet east was beckoning, so off I went…

…to discover another couple of folk having the same problem. One was cured pretty quickly - miraculously seemingly as nothing was changed except the rotor arm. The other person's problem, however, was a harder nut to crack. Despite changing everything from the plugs to the coil and everything in between, the misfire persisted. Not at all helped by an occasional loss of power to the coil once the 'start' position of the ignition key was released… So there was more than one issue to cure - but it didn't explain the persistent misfire and red-hot coil. The coil type and suitability was checked - no problem there (using a coil made for ballast-resisted systems will not work properly and will cause the symptoms experienced here). One other problem I'd known in the UK was a misfire caused by the rivets holding the Ignitor pick-up together had become loose - so these were replaced and the unit worked fine. So I checked this, but all was OK here.

The decision was taken to re-fit the standard points set-up in an effort to go back to basics - still believing, as advised, that electronic ignitions either work or they don't - since something was causing the coil to over-heat and therefore produce an inadequate spark. The engine ran like a Swiss watch! No misfire. No over-heating coil. And no cut-out when releasing the ignition switch from the 'start' position - although this was still considered a second issue. So why? The coil over-heating is generally caused by insufficient dwell period between each spark or insufficient voltage 'damping' (like when a condenser breaks down). Over-charging or under-charging by the charging system can be an issue, too much charge will cook the coil, too little will not allow the electronic ignition to function properly - but these didn't show in testing the relevant circuits… so where was the problem? It had my brain buzzing, and a determination to seek the solution once I'd returned to the UK.

I called Aldon Automotive since they were the original importers and distributors of the Pertronix Ignitor kits and asked them their opinion. Their input was thus…

They confirmed the previous statement about the charging system - make sure it wasn't over or under charging. Make sure the coil is suitable - they suggested a standard oil-filled coil with 3-ohms resistance for road use and a resin-filled coil with 1.5-ohms resistance for race use (quoting Lucas numbers 40511 - possibly 40501 - for road use and 40111 for race use). Make sure there is a good and proper earth between the Ignitor pick-up and the block - so that includes no dirt/grease between the pick-up and base plate, no thread-lock compound on the pick-up to base plate screw, a good earth between the sliding plates where a vacuum advance is used, a proper fixing where a vacuum unit is removed to fix the two plates together, clean base plate to dizzy body screws, clean dizzy clamp to retaining bolts fixing, and clean retaining bolts to block fixings. Apparently these units are very sensitive to poor earthing. They say 99.9% of problems experienced by Ignitor users are down to one of the above - otherwise they are a very reliable unit.

So if you are having problems with an Ignitor set-up, make sure all the aforementioned are checked before returning the kit for testing.

Tags:

Engine

Ignition - Establishing a TDC reference point

by Keith Calver 10. September 2005 07:35

Establishing an accurate TDC reference point is of paramount importance when developing and monitoring ignition timing (and cam timing come to that).

Terminology -
TDC - Top Dead Centre
BTDC - Before Top Dead Centre

Establishing an accurate TDC reference point is of paramount importance when developing and monitoring ignition timing (and cam timing come to that). When an experienced engine builder assembles an engine - no matter whether for road or race - he will establish an accurate TDC indicator that can be used for ignition purposes. Usually contrived as a rigid pointer aligning to a corresponding mark on the crank pulley in a position easy to see with the engine installed. Unfortunately, many of us have to deal with engines that haven't had such attention to detail - so either have to make do with the standard ignition timing graduated scale if it's there or sort something else out.

If it's purely a reference point you're after without needing to be desperately accurate, the easiest way is to either use the standard markers, check timing with a strobe once established with whichever pointer you decide on at a specific rpm, and use that same point each time the ignition timing is checked. Or make a pointer, fix it so it's adjacent to the crank pulley, get number one piston rough at TDC position and make a corresponding mark on the crank pulley/damper. This, of course, will mean nothing when applied to another engine as there was no consistent accurate point established. There are a number of methods to establish this all-important reference where the engine is already completely assembled and no implicit information on the engine is known. Some are more complex than others. Following is the 'easy' method I use that doesn't involve any fancy equipment - just general toolbox stuff.

Jack the car up under the bottom suspension arm on the left side of the car until the tyre is off the ground so it can be rotated easily. Select third gear; remove spark plugs, rocker cover, grill and alternator/dynamo. Rotate wheel/tyre anti-clockwise until you get numbers one and four pistons at TDC. Doesn't matter if it's number one or number four on it's firing stroke - they both reach TDC at the same time! Check the piston is as near TDC as you can get it by sticking something through the spark plug hole to act as a 'rise and fall' indicator. When indicator 'peaks' that's near enough TDC for now.

If there are no pointers/markers at all, you need to fashion one. I generally use a strip of steel plate 3/4"/19mm wide, 1/16"/1.5mm thick, and long enough to reach the edge of the crank pulley/damper from the front plate, plus enough to act as a 'foot' through which a 5/16"/8mm hole can be drilled to mount it to the front plate. Cut the pulley end to a point. On A+ engines or those using the timing chain tensioner, the length will have to be increased again as the pointer blade will have a kink in it to get it around and across the wider timing cover. I usually use the lowest timing cover to engine block bolt as the securing point. When making this pointer for the tensioner cover type set-up, make a template out of cardboard first - saves a lot of anguish and scrapped metal! Alternatively you can use 1/16"/1.5mm welding rod bent to the relevant shape. It's not as stable as the plate one, but is better than nothing at all.

Before finally fitting your pointer in place, clean the edge of the crank pulley thoroughly as you're going to need to mark it. As there's no room for hacksaws, and we're supposed to be doing this without fancy equipment, that means using a white or bright coloured paint of some sort. I use metal marking paint coz I have it. Now fit your pointer.

Next up is establishing the TDC point. To do this we're going to use a 'positive stop' method. This is where an object is used to stop the piston in a required position either side of TDC. I use my 3/8"-drive 'T' handle, but anything reasonably resilient and longer than around five inches that will fit through the spark plug hole will do. Using tape or marker pen, make a reference line 1 1/2" to 1 5/8" from one end. This is the end you're going to stick through the plug hole, the reference line indicates 'by how much'.

Rotate wheel/tyre clockwise to drop number one piston away from TDC a ways. Insert your 'positive stop' tool until the reference line is in line with the top of the plug hole, then VERY CAREFULLY rotate wheel/tyre anti-clockwise again until the piston just traps the 'stop' tool. Obviously extreme care and a certain amount of 'feel' are needed here. Any heavy-handedness will cause damage to both piston and plug hole/thread. Using a fine point of some sort (cocktail stick, scribe, very small screwdriver, etc.) dip it in the paint and mark the crank pulley exactly adjacent the pointer. The smaller you make this mark the better. Now rotate wheel/tyre clockwise a little way to release 'stop', and remove it. Then continue clock-wise rotation to turn engine backwards, bringing pistons 1 and 4 back to TDC. Before they get to TDC, insert your 'stop' again to the relevant reference point, and again trap it with the same pressure you used before. Now marl the pulley adjacent to the pointer again. Rotate wheel/tyre anti-clockwise a little to release 'stop' and remove it.

Rotate wheel/tyre until you have the two marks on the crank pulley clearly visible and accessible. Using a rule or tape, measure as accurately as possible the mid-point between these two points. Take your time. Once satisfied, mark this with paint. And there you have your TDC reference point. To get really carried away, make second and third markers below the TDC point at 5/32" (metric doesn't work here!) intervals. This represents 4 and 8 degrees BTDC.

Tags:

Engine

Ignition - Ballast ignition systems

by Keith Calver 10. September 2005 07:32

I'd like a pound coin for every time I've been asked about what these are all about and why they are used. Folk seem to hold them in some kind of awe - but they are very simple.

The ballast resisted ignition system was - I believe - developed by Ford when they were experiencing poor starting on a certain prodigiously-used 4-cylinder engine. To get round the issue of the massive current drain caused by the starter motor functioning, the ballast-resisted system was designed. When you hit the starter button/key, a massive drop in available current to the coil occurs as the starter motor does its thing. The colder the weather or the more worn the starter motor, the more current it draws, the less there is passed to the coil to instigate ignition.

The ballast-resisted system utilises a 6 (commonly called the 'cold start' system) or 9-volt coil instead of the older style 12-volt item. When you hit the starter button/key, the coil is still seeing maximum current so produces a nice, big, fat, 12-volt induced spark to start the engine. Kind of 'super-charging' the coil by increasing the voltage to way above it's normal supply - by some 30%+. When the key is released, the ballast resister ensures the voltage passed to the coil stays at 6 or 9 volts. It also significantly increases points life by massively reducing the EMF contained in the system when the points trigger the ignition system (the spark you see at the points when the open) and therefore the intensity of the 'arc' across the points.

Running a 12-volt coil on a ballast-resisted system will produce a very weak spark - consequently the engine won't run too well. Running a 6 or 9-volt coil on a 12-volt system will produce a healthier spark but will burn the coil out real quick. I messed about with this years ago on my Miglia motor and found a few extra horses when using a 9-volt coil on a 12-volt system, but coil failure was way too rapid to make it economically viable and coil failure time was not pre-determinable so could leave you high and dry in the middle of a race!

Identifying which system your car has is pretty straightforward - I believe generally all Minis from 1984 onwards were fitted with ballast-resisted ignition systems. Identifying if it is ballasted resisted became very much easier on later post-1990 cars as the system used a resisted wire rather than an actual resistor electronic component. The ballasted resisted wire is coloured pink with a green tracer in it and is connected to the coil in place of the old, original white wire. However, the ballast-resistor component equipped models still used the white ignition feed wire to the coil that actually ran the 6-volt coil system. The only truly definite way of discovering which your car has is by testing the voltage at the coil lead feed with the ignition on. 12-volt says it's the old system, 9-volt identifies it as ballast-resisted, 6-volt as the older 'cold start' set-up.

And you must use the correct electronic ignition system to suit your wiring system - otherwise it'll get real expensive to keep replacing blown electronic ignition kits!


Useful parts list:
GCL110 Original 12-volt pre-1984 coil
GCL111 Cold-start coil, 1984-1990 approx
GCL143 Electronic ignition coil - 1989-0n (ERA/Cooper, etc.)
GCL132 9-volt ballast-resisted coil, 1990 onwards
DLB105 Lucas 'Gold' hi-power sports coil for 12-volt systems only

Tags: , , , ,

Engine

Gearbox - Formulae for FD/tyre size/car speed and gear ratio calculation

by Keith Calver 10. September 2005 07:26

Calculation for gear ratios and transmitted engine rpm
Basic rule to remember is ratio is established by dividing tooth count on driven gear by the tooth count on its driver.

Basic rule to remember is ratio is established by dividing tooth count ondriven gear by the tooth count on its driver. To work out overall gearbox ratios you also have to establish the constant ratio.

Terminology -
FD - Final Drive (diff ratio)

Calculation for establishing vehicle speed for different final drives.
Formula :                               60,000 
                    FD (Final drive/diff ratio) x  wheel rev per mile.

Wheel/tyre combinations revolutions per mile:
145/70/10 1176.78
165/70/10 1078.47
145/70/12 1059.06
155/70/12 1030.71
165/60/12 1047.27
175/50/13 1058.82

These are for common tyre types, and accurate enough for assessment - a combination of using industry standard for theoretical calculation, actually measured assortment of wheels/tyres, and calculated averages! Applying the formula to a modern Mini with 12” wheels gives the following -

                                60,000              =      60,000    =   18.25 mph per 1,000 rpm.
                         3.105 x 1059.06             3,288.38
So 70 mph is achieved at a whisker over 3,800rpm. (I just know a bunch of you are going to check this out next time you’re driving around! But remember the speedos are grossly inaccurate, whereas the rev counters are fairly good).

Calculation for gear ratios and transmitted engine rpm
Basic rule to remember is ratio is established by dividing tooth count on driven gear by the tooth count on its driver. To work out overall gearbox ratios you also have to establish the constant ratio.

Constant ratio =       tooth count on laygear input gear
                                     tooth count on input shaft

This is NOT the fourth gear ratio assumed by many. Fourth gear doesn’t actually exist, as once in top gear the first motion shaft directly engages the mainshaft. Consequently it’s always a 1 to 1 ratio.

Gear ratio       =       tooth count on driven mainshaft gear    X   constant ratio.
                                   tooth count on driver on laygear

Example:     1st gear of A+ standard gearbox
Constant ratio =     30  =  1.765
                              17
Gear ratio       =     31  x 1.765  =  2.066  x  1.765  =  3.647
                              15

Calculation for transmitted engine rpm at output shaft
Input gear speed in rpm  =          engine rpm
                                           transfer (drop) gear ratio

Pinion speed in rpm       =  input gear speed (rpm)
                                               actual gear ratio

Out put shaft speed in rpm =  pinion speed (rpm)
                                                 final drive ratio

Tags:

Gearbox

Fuel - Leaded/unleaded fuel and the alternatives

by Keith Calver 10. September 2005 07:21

The fuel situation seems to be worsening at a great pace these days. And as is exhibited by the questions that appear on the message board many folk are confused by what they can and can't do, and what is best to do as far as race engines go.

Many have posted (particularly from the States) that nothing need be done - just run on unleaded. They've been doing this for years and never had any problems. I have trouble believing that in the face of what I know and have investigated - so here's what the score really is.

Years ago this stuff called Tetraethyl lead was originally conceived as an octane enhancer. It was soon discovered, however, that the metallic oxides produced by the combustion process formed a protective coating on the valves and seats. This coating prevented micro welding of the valve seat to the corresponding seat in the head under high temperature operation.

Micro welding causes removal of material on the softer head seat material, causing subsequent recession of the valve into the head. The debris produced by this process is flung into the airflow, causing premature wear of valve stems and valve guides. In particularly excessive cases to piston rings and bores too. Valve recession means that the valve no longer seats properly, causing poor sealing during the compression stroke. The end result being reduced power output, loss of fuel economy, and ultimately replacement of the cylinder head. Reconditioning of a badly recessed head is often not possible as the seats are so damaged they cannot be reclaimed. Some cheap engineering places will do it, but it leaves the valves so far down in the head that little improvement is made once refitted.

In the early eighties, the toxicity of lead produced by petrol burning vehicles was seen to be a massive health threat and environmentally damaging. After much hue and cry from the 'greens', lead levels in petrol were to be gradually reduced to a proposed 'safe' level. A bit stupid really because it is either dangerous or not. The average level of lead in petrol at this point was generally around 3.0GPG (grams per gallon), and provided the protection levels needed for a vast majority of the engines it found its way in to. The environmentalists wanted it to be eliminated altogether of course, but not all old type engines would work on this, so the 'safe' level of 0.1GPG was set. A huge drop, and was it going to be enough to provide the required protection.

This whole 'levels' thing was of some concern. As usual, not enough information was available to the general public. 'Help lines' were far and few between and those written pamphlets available were sketchy to say the least. Was 0.1GPG really sufficient? Could you safely run a previously leaded engine (4-star) on unleaded or super unleaded fuel? It has become common knowledge that many petrol stations put unleaded fuel in supposedly leaded tanks. This appears to be legal providing that the fuel meets the relevant octane rating - hardly the same thing!! Not many (if any) petrol stations advertise the lead content of the fuel they supply. So, many of you have probably been running unleaded fuel unknowingly.

The main differences to the car are a fall in performance and possible detonation ('pinking' - heard as a rattling noise on acceleration under load). Little initial damage is caused if the engine has covered a fair amount of mileage on proper 4-star fuel. This builds up a protective barrier that will last over a comparatively small period - the so-called 'lead memory'. Hence the advice from some 'specialists' that you can use unleaded fuel in your car providing four-star is used every other tank full. Others say it is not a problem as long as you 'back the timing off' (retard it) a couple of degrees.

After much testing by specialist laboratories and engine manufacturers, it was generally concluded that 0.1GPG was nowhere near enough. But the agents supplying data to governments gilded the lily slightly, showing that 0.1GPG would be OK. Just how much lead is needed is determined by a number of things. The major point being the valve seat temperatures. This can be strongly influenced by speed, load, and perhaps most importantly - fuel mixture.

Lean mixtures were needed to pass emission tests on later vehicles and give good fuel economy produce exhaust gas temperatures several hundred degrees hotter than a rich mixture. Consequently, rich mixtures allow the seats to run much cooler. Tests were conducted under arduous conditions by the independents, and favourable by the 'informers'. Running an engine under part load (light throttle) for hours on end achieves nothing. We already know that it is under load that the damage will occur (i.e. heavily laden car or when accelerating uphill in top gear). The cynics found 0.5GPG to be a minimum happy level for good protection.

Even the briefest investigation into what the fuel companies and more particularly aftermarket additive manufacturers were using to replace Tetraethyl lead was mind-bending. Some of the information supplied read like a who's who of the chemical table world. Others were much simpler. Many merely had supposedly special oils in them to help 'upper cylinder lubrication ', but the temperatures in the combustion process are far too high for these to work. They would probably simply burn off, having no effect at all. Others used race fuel in a bid to attain the 0.1GPG recommended.

Then there were those that professed to have certain chemicals that at combustion temperatures would phosphide or nitride the relevant surfaces. Extremely difficult to do as both these processes usually command careful temperature control over a specific time period to achieve correct application. Potassium type concoctions are also used, appearing to offer a reasonable chance of success. In reality though, this kind of chemistry causes fairly heavy deposits to build up on the backs of the exhaust valves - decreasing efficiency and seizing valves in guides in some instances.

The very best option is to use very special sodium based chemistry, which forms sodium oxides upon combustion. This gives the same physical protection from micro welding as lead oxides. This is definitely the stuff to use if you want to run unleaded fuel in an engine originally built to run on leaded. My own personal and extensive testing of additives has proven Red Line Lead Substitute to be far superior to anything else, allowing even race engines to suffer no seat recession when run on unleaded fuel without seat inserts. And no - I'm not on a retainer.

I've completely ignored the 'drop in the tank' pellets/briquettes or 'in line' filters/ionisers/de-ionisers as they simply don't work at all. Fact.

Possibly the best high-mileage, long-term option for road cars is to convert the cylinder head to run unleaded fuel. Basically special exhaust valve seat inserts are pressed into the head, new seats cut, and new, later specification exhaust valves put in. The later A+ series heads use valves with triple-groove collets that allow the valve to rotate to reduce micro welding further.

Tags:

Fuel Systems