Tuning The Mpi Engine
#1
Posted 17 October 2012 - 09:54 PM
I am currently restoring a late Cooper Sport, and would like to uprate the engine. I am proposing a specification along the lines of 1380cc, ported, polished and machined cylinder head, uprated camshaft, throttle body etc.
What is the best way to tune the electrical side of things ? Can the ecu be mapped ?If not, can a mappable system be obtained ? Failing all that, what sort of power figure can I expect with the standard ecu ?
Cheers guys,
Alex
#2
Posted 17 October 2012 - 09:59 PM
Founda similar thread recommending 'Calver ST' ecu's, anybody recommend anything different or have any experience with these ?
Cheers,
Alex
#3
Posted 17 October 2012 - 10:02 PM
I dont think the MPI unit can be re mapped due to its constantly changing and adapting status. It learns... for want of a better word.
As a result the best that you can get out of the standard unit is around 90bhp, which can be obtained "fairly" easily, pending money of course.
And then there are the emission woes which are apparently very hard to meet with even a lightly modified mpi.
That has to be the MPI's biggest downfall in my opinion, being so much more complicated to tune, modify.
Edited by jimmyH, 17 October 2012 - 10:02 PM.
#4
Posted 17 October 2012 - 10:39 PM
#5
Posted 18 October 2012 - 08:13 AM
Yep emissions are the problem with tuning i have an 1275 mpi with a weber and programable ECU. both cause problems
Can you program the ECU when going to the MOT so the emissions are low? I realise it may not run as good.
#6
Posted 18 October 2012 - 06:11 PM
#7
Posted 18 October 2012 - 08:45 PM
Is there a website where I can read up on the management system you mention ? Where would it be available from ?
Given all these complications, would I be better to go down the more usual carburetor route (with a different engine) ? I have one available to me.
Best regards,
Alex
#8
Posted 18 October 2012 - 10:21 PM
The MPI unit should be good for a true 80, perhaps 85 hp if you are fortunate. But, what is the intended purpose of the car? If one's driving style is to flog the motor to 5000+rpm to get into the powerband, then a carb'ed engine will have much more peak power potential. But it will hard for it to be as tractable, flexible, and economical at part-throttle.
If you're going to the drag strip, carburetors all the way.
If you're daily driving it, commuting, yet want a livelier motor, then I'd stick with the MPI. Get all 80 hp you can, and if that's not enough, then switch the final drive gearing from the super-tall 2.76:1 ratio to 3.1:1 or 3.4:1. Give that MPI motor the same final drive ratio as a carb'ed Mini, and you may be very surprised how well it goes - possibly much better on real roads than many built-up carb'ed motors.
The MPI's have a very broad powerband, developing good part at the low and mid speed ranges. This broad powerband is what helped Rover to get away with the super-tall 2:76:1 ratio to beat the sound output regulations then.
#9
Posted 19 October 2012 - 06:31 AM
#10
Posted 19 October 2012 - 02:37 PM
Also if you'really want big power then you will need to uprate your gearbox. Mpi boxes are known to be fragile. Up to 80 or 90 horses you should be ok (unless its done a lot of miles) but pushing higher could be too much for it.
#11
Posted 21 October 2012 - 08:50 AM
I am only intending to use the car on the road, and am hoping for a livelier engine with enough power to pull the 2.76 final drive, I like the way it cruises at 65-70 mph without overstretching itself, but don't like the way my brother just pulls away from me all the time ! Ha ha. I had already converted the car to ten inch wheels, which may compensate a little for this ?
I think I will stick with the MPi set up and go for a reliable 85bhp if I can !
Many thanks for your advice on this topic, much appreciated.
Cheers,
Alex
#12
Posted 21 October 2012 - 03:04 PM
It takes a bit of getting used to at first as it just feels wrong.
#13
Posted 21 October 2012 - 04:17 PM
. Bought from John Cooper and their advice was to treat 4th more like you would 5th in a modern car.
It takes a bit of getting used to at first as it just feels wrong.
very interesting
#14
Posted 21 October 2012 - 07:36 PM
She'll do 70 in third, and about 80 in 4th ! My aim is to extract enough power to pull that 2.7 final drive better.
Edited by DoubleHB176, 21 October 2012 - 07:38 PM.
#15
Posted 22 October 2012 - 09:11 AM
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