Engine - 998 Tuning, Bolt-ons

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. See bottom for useful part numbers Terminology: MSC/MM - Mini Spares Centre/Mini Mania ID - Inside Diameter OD - Outside Diameter BBU - Big Bore Unit (refers to all 1275cc-based units) SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998) BHP - Brake Horse Power LCB - Long Centre Branch Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay. The single biggest restriction on any standard Mini is the 'breathing apparatus' - anything that is connected to the induction and exhaust systems. The standard exhaust being the biggest culprit - it is desperately restrictive in the name of noise suppression and cheapness of manufacture. Oddly enough it also increases fuel consumption when tested over a better designed, fre

Engine - 998 tuning, bolt-ons (stage one)

The 998cc engine is a very robust and tunable unit. It is also the most common engine found in standard Minis. Despite the lure of the much-advertised 1380cc alternatives, many simply want to get a little more from what they have at reasonable outlay.

Terminology:
MSC/MM - Mini Spares Centre/Mini Mania
BBU - Big Bore Unit (refers to all 1275cc-based units)
SBU - Small Bore Unit (refers to all sub-1275cc units, here the 998)
BHP - Brake Horse Power
CR - Compression Ratio

To improve engine out-put, you need to increase the engine's 'breathing' ability. The stage one kit deals with all the easily bolted-on external parts, and represents the best increase for investment. From here on in the power increases will cost commensurately more money.

Exhausts - Basic information

The sheer volume and diversity of bolt on goodies available for our cherished Minis underlines the fact that a very large portion of them is modified in some way. Be it just dress up items to personalise it aesthetically, or tuning parts to improve performance.

In the latter’s case, either more power or more economy are sought - both being desired by many. Should it also enhance the looks at the same time, so much the better. Unfortunately not many components can achieve this without integrating with a number of others. The exhaust system, however, is one of the few.

Although the exhaust’s efficiency and effectiveness is reliant on a well matched system from the exhaust valve in the cylinder head to the tail pipe, the majority view it as two separate pieces - the exhaust manifold, and the ‘system’. Not entirely mis-placed, as this is how vendors present them - folk buying one or the other, though mostly both, dependent on guidance

Exhausts - RC40, Millennium and others tested

The recent rolling road re-test of the 1275 engine build I did saw an opportunity to do some exhaust systems testing.

I had noticed a few years back that the RC40 was being manufactured by a different process than the originals - giving rise to a change in the shape of the bends applied to the system. I had wondered if they would be causing a restriction at all - but hadn't had the opportunity to test it. The lack of expected power from the aforementioned engine lead me to investigate all possible angles from the tyre contact patch to the carb mouth. I found nothing that explained the 14 or so bhp I was 'missing'. After some application of the old grey cells I mentally narrowed cause down to one of two things - either the piston oil control rings were still causing excessive drag (75% of all internal friction of an engine is generated by the piston rings) or perhaps these new bends in the venerable RC40 were indeed causing a power loss.

Historical Article - Nov 1991 - Twini Mini

The front brakes are standard Cooper 'S' 71/2" variety with the standard drums on the rear, with the assistance of a servo the rear regulator valve has been left out of the system and the brakes work very well. As the weight of the second engine amounts to the equivalent of two 11 1/2 stone passengers. Rear cooling is taken care of using a 1300 radiator mounted in the standard position. The heater take offs are connected to a 19 row oil cooler.

Historical Article - Nov 1991 - Twini Mini

The front brakes are standard Cooper 'S' 71/2" variety with the standard drums on the rear, with the assistance of a servo the rear regulator valve has been left out of the system and the brakes work very well. As the weight of the second engine amounts to the equivalent of two 11 1/2 stone passengers. Rear cooling is taken care of using a 1300 radiator mounted in the standard position. The heater take offs are connected to a 19 row oil cooler.

Historical Article - October 1993 - Mini Spares Project Min

Mini Spares Project Min

Mini Spares decided to produce an up market twin headlamp grille, because so many Cooper owners needed to renew their grille or replace the front valance mounted spotlamps. Their location means that they get damaged so easily on impact. whether it be by cars reversing into them when parking or from minor accidents.

To produce this grille with stainless steel slats meant that we had to use the back plate from the current cars. which goes back to the first MK2 in 1968. Using this back plate would obviously govern the size of the lamps we could use. Originally it was hoped that a 6" lamp could be used. but because a reinforcement ring was required only a 5.75" or 5.5" lamp could be used which was not what we re...