22 replies to this topic

[minicooper1.3i]

Hi

Was thinking about doing some performance tweaks to my standard 1275 MPi engine. But istead of just slapping a big head on top and big exhaust out the back, I want to be a bit more thorough and subtle, and this is where I need some assistance. Because of the nature of the beast, with it all being sensor controlled etc, I'm not sure what is practical. I've already got a performance boost valve to fit and I'd like to have a Burlen throttle body with a K&N cone on top. But I need some recommendations on the rest. Ideally I'd like to exceed the Cooper S conversion spec of 90bhp, say, 100bhp as a nice round number

May I please have your comments on the following?

Bore size?
Stroke length?
Rockers?
Cams?
Pistons (dished, flat)?
Lightening / Balancing?
Cylinder Heads?
Exhausts?
Clutch?
ECU?
and anything I've missed

Cheers!

[the.stroker]

get yourself a nice gold seal vauxhall 2ltr 16v lump out of a mk2 astra gte,or a nice r1 bike engine,nicely mounted where the rear seats used to be!

[Rodders]

I cut this from a web site who also stated there was not much that could be done in the way of tuning, because the ecu controls the car too much.



"The one upgrade that appears to be a very cost effective one is to exchange the throttle body. The stock throttle body has a bore size of 48mm and is made of some sort of high tech plastic. The upgrade path provides 2 options. A simply direct swap to the metal version now available will yield gains in simply allowing the system to regain it’s performance as new. The original plastic version is prone to heat distortion and cracking. The second option is to upgrade to a big bore throttle body. The 52mm version has been used successfully even with the ECU limitation to yield an almost 10% performance increase."

[CooperTrooper]

Get a nice cylinder head (st 3 or 4) because this will make alot of difference to torque and get some 1:5's or if you want to be different why dont you cam it with a SW5i? Iv heard this makes MPi ridiculously smooth and torquey!

I have to warn you though mate it starts getting expensive if you buy a new head...

[liam_italian]

Sprocket is the guy to speak to! He knows loads about the Mpi!

[Sprocket]

get yourself a nice gold seal vauxhall 2ltr 16v lump out of a mk2 astra gte,or a nice r1 bike engine,nicely mounted where the rear seats used to be!

HMM Thats nice and subtle






You will be hard pushed to get 100bhp with the MPI as its nothing to do with the engine, its down to the way the fuueling is controlled on the MPi. The port injection on the MPi is the problem Its more commonly called the siamese port injection problem. Have a search around on turbominis.co.uk and you will see that its not so easy to overcome

With the Standard ECU (which you are restricted to, unless you consider CANEMS(not the same)) you are looking more at the 90bhp on the outer limits.

To get this and still be able to pass MOTs and it to be driveble, you need to add CC, fit a big bore LCB, modify the inlet manifold, use a Kent 274 cam, 1.5 rockers, use the power boost valve, fit the best 35/29mm valved head you can find. A 2" exhaust sytem is required as well.

Fitting lightweight cranks rods and flywheels will also help things

You can suposedly get 90 bhp from a 1275 MPi, but this is some what subjective.

After all that im not sure what you mean about being subtle

[Sprocket]

oh yeh, and i will gaurantee you that the 52mm throttle body will not do anything for overall performance, other than increase throttle response. For the money, the 48mm one is more than adequate!!!

[minicooper1.3i]

Thanks all

Sprocket: I was just after people opinions on doing all those little mods 'inside' the engine, that all add up to making a big difference.

Isn't it possible to get the ECU re-programmed, or a custom one made?

[liam_italian]

get yourself a nice gold seal vauxhall 2ltr 16v lump out of a mk2 astra gte,or a nice r1 bike engine,nicely mounted where the rear seats used to be!

HMM Thats nice and subtle






You will be hard pushed to get 100bhp with the MPI as its nothing to do with the engine, its down to the way the fuueling is controlled on the MPi. The port injection on the MPi is the problem Its more commonly called the siamese port injection problem. Have a search around on turbominis.co.uk and you will see that its not so easy to overcome

With the Standard ECU (which you are restricted to, unless you consider CANEMS(not the same)) you are looking more at the 90bhp on the outer limits.

To get this and still be able to pass MOTs and it to be driveble, you need to add CC, fit a big bore LCB, modify the inlet manifold, use a Kent 274 cam, 1.5 rockers, use the power boost valve, fit the best 35/29mm valved head you can find. A 2" exhaust sytem is required as well.

Fitting lightweight cranks rods and flywheels will also help things

You can suposedly get 90 bhp from a 1275 MPi, but this is some what subjective.

After all that im not sure what you mean about being subtle

See, told you!

[Racer_Pete]

I agree with Trooper, it can get seriously expensive.

This is a little insite to tuning a Mini clicky
Id would probley start as Trooper said, ST3 Head, 1.5 Rockers, RC40/Maniflow ect.. A 1275i would already have around 45ish bhp, so you wouldent be 'too far' off yout 90bhp target when you have fitted thoses mods. Id then get it set up on a Rolling Road.

Edited by Racer_Pete, 08 April 2008 - 01:32 PM.

[Mini_Magic]

A word of advice, the 90bhp kit fron places like Minisport very rarely actually give 90bhp. I believe it is the same kit that came in the late Cooper S conversion.

[liam_italian]

Am I right in saying that the 90BHP figure normally refers to the BHP at the flywheel and not the wheels?

[CooperTrooper]

Just remembered pal, i went in Dev's last mini which was cammed with a swiftune cam and it really did shift up the revs! Cam it first

Edited by CooperTrooper, 08 April 2008 - 01:59 PM.

[minicooper1.3i]

So am I right in thinking that the ECU is the limiter on performance increases? Are there not any after market ones available, or 'chipping' for the standard?

There must be thousands of MPi's out there. Somebody must have found a way, surely!

[liam_italian]

I dont see why not! Ive you ever seen the video on youtube of L33 EJb the mini cooper that was entered into the 1994 monte carlo when you will have heard Paddy Hopkirk mention that it was an injection type running at 100BHP and you see a guy with playingwith the setting on the engine management system through the use of a console.!

Watch and see http://www.youtube.c...feature=related