8 replies to this topic

[IronmanG]

I am fortunate to have come across a brand new hif44 at not brand new prices which I am very happy about. It will be going on my 1310.
I love reading about other options and I recently read up on aftermarket efi. After researching it a bit more I cam across a post on the turbo mini forum about efi.

https://www.turbomin...p=vt&tid=395643

It's 4 pages but it's interesting reading about how aftermarket efi doesn't really do as much as it promises. Was the MPI really good? Despite 30 years of advances in tech is the MPI still as good as it can get for the 5 port.
I've only driven 1 MPI briefly and it was unbelievably smooth

[Ethel]

I think we'd be fooling ourselves if we thought we could make much in the way of improvements over what BMW could achieve with their experience & budget. Even so, if we wanted something a bit different to what they offered with the MPI we might find a different engine management system can do a better job of that.

 

It's valid to think of the ol' A series as a 2 cylinder engine wrapped round a different 2 cylinder engine because of its siamese inlet ports in particular.  A cam sensor, like the MPI has, is essential if you want to cater for the specific needs of each of those 2 cylinders. Any aftermarket system that doesn't have a cam sensor input is at an innate disadvantage. Notable that a lot over on TurboMins also went to 7 port heads when they started moving over to fuel injection.

[mab01uk]

Also interesting to read Mike Theaker's (BMW/Rover Engine Development Engineer) account of the Mini MPI development story and how it was BMW's will and John Cooper's insistence that finally got the MPI into production in 1996, extending the Mini's life by 4 more years. Mike Theaker also later worked on powertrain development for the New MINI (R50).

Mike Theaker on the Development of the Twin Point Injection system for the Mini.
Link to PDF below:-
https://www.turbomin...ts/493117-1.pdf

 

(Article in the link above is from the September 2000 issue of Miniworld magazine)

 

MPi Mini Development Story:-

https://www.theminif...elopment-story/

Edited by mab01uk, Today, 01:03 PM.

[sonscar]

The MPI system is very good because it is fully sequential,something that aftermarket was slow,or never,adopted.the drawback is you need to control large injectors to be able to fully inject the charge into the proper cylinder.this may limit fuelling.Steve..

[IronmanG]

The MPI system is very good because it is fully sequential,something that aftermarket was slow,or never,adopted.the drawback is you need to control large injectors to be able to fully inject the charge into the proper cylinder.this may limit fuelling.Steve..

Can you explain sequential as opposed to.....
Do you mean large cc injectors? I thought that was a problem as then the control at low load or low rpm was difficult?

[IronmanG]

I think we'd be fooling ourselves if we thought we could make much in the way of improvements over what BMW could achieve with their experience & budget. Even so, if we wanted something a bit different to what they offered with the MPI we might find a different engine management system can do a better job of that.

It's valid to think of the ol' A series as a 2 cylinder engine wrapped round a different 2 cylinder engine because of its siamese inlet ports in particular. A cam sensor, like the MPI has, is essential if you want to cater for the specific needs of each of those 2 cylinders. Any aftermarket system that doesn't have a cam sensor input is at an innate disadvantage. Notable that a lot over on TurboMins also went to 7 port heads when they started moving over to fuel injection.

So the cam sensor is a big advantage over a crank sensor?

[Ethel]

The crank sensor will always do the timing of the injection & sparks. The cam sensor is needed to know which cylinder to inject for because (on a 4 cylinder engine) there'll be two cylinders moving together. One pushing the piston down the bore after firing, the other drawing in the next charge through the inlet valve. You can only inject fuel in to the second one, but if you fired its spark plug along with the cylinder about to start its power stroke it wouldn't matter: as there'd only be exhaust gasses in it. That's what's called wasted spark ignition and it doesn't need a cam sensor.

[sonscar]

The MPI injects into each cylinder with the right fuel at the right time.the cam sensor is to tell it when the inlet is opening so it can fire.the injectors are large as the opening gets smaller with rpm so it can get the fuel in in a shortening time.the MPI uses two injectors to do the same job as four would normally do.when introduced it was very advanced and is still the Siamese port gold standard in my view.Steve..

[Midas Mk1]

The MPi setup is a good 26 years old at least, I got fed up of the constant failures with it and went for the sc setup. Final straw was on a third date with the iacv holding the idle at 4k with a single box exhaust, didn’t get a 4th date 😂