3 replies to this topic

[extreammini]

Hello all,

I hope that everyone is all well and keeping safe during these difficult times.

Apologies for bothering you with this again, as I know that there are alot of threads covering the options for an aftermarket injectors and ECU's however I have looked all over and I can't seem to find a thread where there is an answer as to what the best all round aftermarket set up is for the MPi minis ?

I only ask as I have a 1340 cc tuned MPi with all the usual internal upgrades but it isn't developing anywhere near as much power as it would with twin carbs - I may be wrong, but I put this down to the lack of fuel available as the engine is hindered by the standard ECU and injectors. So what are you running and which is the best for a 'racing' road car ?

Thank you for your time people and I look forward to hearing from you all ?.

Take care and best wishes,
Mark

[Avtovaz]

i dont know much about the mpi manifold at all, but id imagine that could be a massive restriction. To keep it you need to get a ecu that not only can cope with Siamese port code, but you need to know how to tune it or find someone who can.

 

So that narrows things down a bit i would imagine. I have a lot of love for the microsquirt ecu, but i believe its only the megasquirt that can do the Siamese port code. [im looking from not a mini point of view though]

[Alice Dooper]

The stock MPI ECU is a real big block if you go past 90 BHP.  It's unmapable too.  I've a friend who fitted the SC kit and had it mapped at a rolling road - excellent job.  I'm almost tempted myself except its way above my project budget, suppose I've a spare kidney I could sell though.

[bluedragon]

Search on "MPi" and "Megasquirt" and you should pull up many of the threads that discuss the technical issues with uprating the MPi.

 

Basically it's the problem of having true port fuel injection into a head that only has two ports for four cylinders. This means some tricky programming is needed to get more fuel into the port in the limited time window that exists before another cylinder starts to "rob" and grab the fuel intended for the first.

 

Unless they have an all new product, the SC kit is just a glorified SPi unit - it does not attempt to inject fuel specifically for one cylinder but is more like an electronic carburetor. The only commercial port fuel injection product I know of (and I'd be happy to be ignorant of new developments and be wrong) was the injection setup by Canems a few years ago. All others were DIY, using the MegaSquirt system and custom programming developed by some Mini luminaries (who may still be active on Turbominis.uk.)

 

I don't know if the Canems setup was based on the Megasquirt MPi code - being proprietary I don't think they ever detailed that. Some fellows from Germany were going to productionize the Megasquirt MPi code, but as far as I know never did. (maybe Keith Calver knows what happened to that project.)

 

If you're going racing, then probably the best bet is to dump the MPi and go with something like SC's setup - the advantages of port injection are best realized at part throttle and lower RPM, where it can fatten up the torque curve with more optimal fuel delivery at lower RPMs and be more economical. But it hits its ceiling around 80-90 hp unless you can use the Megasquirt type solution to run larger (or additional) injectors to get more fuel in during the limited timeframe available in the intake cycle.

 

 

Dave

Edited by bluedragon, 23 April 2020 - 09:51 AM.