6 replies to this topic

[E23TFD]

As the title says really does it make it breath better and release any torque or does the ECU just cancel it all out?

[FlyingScot]

ECU won’t “cancel out” any improvements but due to the set up it’s quite tricky to get any decent gains. 

 

I know several of our club members who have spent a lot of money and gained very little.....

 

FS
 

[Steve220]

As the title says really does it make it breath better and release any torque or does the ECU just cancel it all out?

The only real step up with an MPi is if you have a stage 1 with head work with a matching cam, then lower the final drive. I cut my losses and turbod it lol

[E23TFD]

Well aware of your build Steve, your not a million miles from me so I’m hopeful I get to see your wow factor Mini at some point.

[Rusty Nut]

For older A series, David Vizard’s book Tuning the A-series is the bible and explains each and every gain to be had. But many/almost all  of these improvements have either been dealt with in the development of the MPI or would be negated by the ECU which would need to be re-somethinged to adjust any timing changes, mixture settings and the rest. You could spend a lot of money before any noticeable gain imho.

What did they do to the MPI to get 62 bhp out of the factory up to 90bhp for the works version ?

Edited by Rusty Nut, 06 October 2020 - 08:11 AM.

[bluedragon]

As already stated, the ECU doesn't "negate" or "cancel" improvements. In fact, it is capable to responding to some changes without requiring re-tuning on a carbureted motor.

 

But it is strictly capped as to the maximum power obtainable, due to the limits of port fuel injection on a 2 port shared intake 4 cylinder motor. This limit is reckoned by most to be ~80 hp, and the "90 hp" Works models are, shall we say, overrated.

 

Again, as already mentioned, the one major factor to improve power is a freer flowing head. With that in place, other items like exhaust and intake can contribute minor improvements, but the head upgrade is the only one you'll really be able to "feel."

 

Note that while peak power may be limited to 80-85 hp at best, the upgrade packs with a well-done head will fatten the powerband and improve power considerably below the peak RPM curve. This can make the car feel considerably stronger in day-to-day driving, where you are not revving the motor to peak power RPM constantly like a madman. This is especially valuable in a tall geared MPI, where a fat torque curve helps pull the tall final drive.

 

If you are of the sportier rev-happy crowd, switching to a lower final drive (higher numerically) like a 3.2 would make the car feel more energetic, at the cost of noisier highway cruising. Combine the head and the lower final drive and one might be very happy if they don't mind higher revs on the motorways.

 

 

Dave

[sonscar]

Confess,I have no experience of MEMS but how can it respond to improvements as it only has a narrowband lambda?at best it can aim for stoich which is too lean for max power and it must itself go out of closed loop for accelelation and max power.As I understand it the target map of MAP and RPM set the fuelling(with minor temp etc adjustments)so does the porting etc alter the MAP for the same load?Interested to know,Steve..