9 replies to this topic

[DoubleHB176]

Hi all,

Considering doing a high performance type rebuild on my MPi Mini.

Are there any big complications with overboring this type of engine ?
I understand the Cooper 'S' type cylinder heads do not fit without big mods, so can bugger valves be fitted, with appropriate enlargements, again without to much hassle ?
I'm not converting to carbs, I'm too fond of the economy
Which give better road performance, roller tip rockers whith increased lift or camshafts ?
Any other issues I should be aware of before setting out ?!

Many thanks in advance,

Best regards,

Alex

[Cooper1999]

Others may know better, but....

Why should there be any 'overboring' problems with the MPi?
The standard injectors can cope to around 90bhp, so if you're happy with this kind of bhp limit, no need to go carbs anyway!
There are only a few injection cams around for the MPi (with cam position sensor) so your choice is limited - you can fit 1.5 roller rockers to the standard of replacement cam, so perhaps see if the replacement cam is satisfactory, if not fit the 1.5 rockers to make it a bit 'hotter'?
Just be careful you don't end up running too lean with the standard ecu. You can fit a different fuel pressure regulator, but is this the best way to control the fuelling?!? Don't know....

[Jay3178]

from my experiance and some talking to engine builder when i was looking to get mine done you dont need to go straght to 1380, 1340mpi is just as good as a 1380mpi this is maily due to the limitations of the ecu and its restriction on the fueling to meet the preset emmisions the ecu is programed for. if you could get a ecu to to make use of the extra cc then yeah 1380 would be worth it but currently that is a bit tricky and expensive. plus if you experiance engine trouble at 1340 you can bore out to 1380, but if already at 1380 the block has nothing left in it and could end up scrap! but dont just take my opinion there are many 1380 mpis out there

here is my 1340mpi Link to my TMF garage

[mykweb]

I think what ever you do you will need to factor in an aftermarket ecu.

The standard ECU will more than likely give you issues when you aproch the 80-90BHP mark with the engine.

The sw5i cam is a good choice for the MPi, allows a good range of driving both normal, and when you want a bit of fun.

mIKE

[DoubleHB176]

Thanks all, very kind and very helpful.

From my own research and taken from what you say here, I gather that the standard ECU is the most troublesome part of the job..........

Can they be re-mapped with any success, or is a whole new ECU required for 90bhp+ ? What else would be sensible upgrades to the system for this kind of power ?

Where can an aftermarket ECU be obtained from ?

Thanks again,

Alex

[mykweb]

The standard ecu is locked and can't be altered in any way. Or not that anyone knows off.

There are some ecu options all start around £400+ for the hardware then you need a few hours on the rolling road for setup.

Mods for the engine. You are looking at rockers, camshaft. Block bore, larger head, large throttle body, ported inlet manifold, lcb manifold, dual core radiator, fuel pressure regulator, center oil pickup and possible change of the final drive ratio

Mike

[benpopham]

Am I right in thinking that the Mpi block is linered and you cant over bore it that high?

[DoubleHB176]

Cheers Mike, very helpful ! Now to find a donor MPi engine.....

As far as I know, blocks are not linered, I have seen 1380's before.

Best regards,

Alex

[Capt_S-R2]

Hi guys I'm new hear but this topic caught my eye. I bought my MPi brand new in 1997 and have done daft amounts to it including the Swift Tune Road Rocket, 1380cc, includes the SW5i which is great, also pickyback ecu, 103bhp.

definately possible just depends how deep your pockets are, when I did mine about 7 years ago now it was hard to try and find a Mini tuner hapy who could deal with the perceived limitations of the ECU so had to go outside the mini scene.

very pleased with it.

Regards

Capt S

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[DoubleHB176]

Thanks very much !
I like the sound of 100+ bhp ! Very nice car also.
I'm currently aiming for 90, which is stretching the very fabric of my pockets as it is ! Will aim for something like yours as they get deeper methinks.

Cheers !