MFI pumps
 

Hi,

I have an 2.4T MFI engine wich I want to upgrade. Perhaps I''ll go for 2.2E pistons and camshafts but, as you know, I will have to fit the MFI pump.

What do you think should I do in order to have the pump matched to the pistons and camshafts?. Can I buy an E space cam or should I do something different?

Thanks,
Fernando.

That's a tough question in your half of the world. I've heard of guys in Australia and the US who rebuild the pumps and can update the space cam. Any shop that rebuilds diesel injection pumps should be able to freshen up your pump. As far as buying the right space cam, given your hemisphere, maybe you can buy one remotely. The other option which might be the best would be to send your pump to one of the rebuilders in the US or Australia with the specs of your engine and have them do it.

What I would do:

Put the T pump back on and see how the car runs. My guess is it will run fine. You may loose a little bit of power, but probably not enough to really notice and warrant a $$$$$$ pump recalibration.

Thanks John and BK911. I'll try with BK911. If the only thing is losing a little bit of power, that's ok with me.

Thanks again,
Fernando.

FYI - there is a 1973 RS MFI pump being sold on the German Ebay, current price is cheap. I emailed the man and it's the real deal.

Bavaria

Thanks for the info Bavaria.

Tyson, rebuilt his 2.4T with Solex cams (early E) and 85mm pistons. He just used his T pump and adjusted it accordingly with very good results.

Thanks Bobby. Only one question. Do you think the engine will be running short of fuel at high revs with this configuration?

Fernando.

Fernando,

I believe that the pump puts out the same amount of fuel per stroke from 4000 RPM and up. I looked into this once and decided that the pump works the same above 4000 RPM for all different space cams. So unless you have cams that don't produce power until well above 4000 RPM you shouldn't have a problem.

-Andy

That's true Andy. But your engine may have a hard time tryin to get to 4000 RPM if the pump is drastically off from the engine's tune (and specifically the cams).

I've heard the rule that a jumping 1 step is not a big issue. So using a T pump with E cams works. E pump with S cams will work acceptably too. I have yet to run across a case where this didn't yield an acceptable solution.

I built a similiar engine a few years ago and had the question regarding the MFI T pump fitness for E use. So, I went to Gus at pacific fuel injection. He happened to have an E pump that he was calibrating at the time. His test rig provides a monitor that compares each injector flow rate vs RPM and a "target" flow rate for a given pump calibation. He showed me how that T pump calibration and E pump calibration flow curves were that same up until 4500 RPM when the T pump flow rate fell off and the E pump kept rising. He went on to say that the T pump will work but you might want to run the pump a little rich under 4000 to compensate for the fall off at higher RPM's. Your basically moving the whole flow curve up by running the pump a little rich. The results? The engine ran great.

John,

I agree with you. I was refering to Fernando's worry about the engine going lean at higher RPM. My point was that as long as an engine doesn't have a large increase in volumetric efficiency above 4000 RPM the pump will supply enough fuel to keep it from going lean.

-Andy

Thanks guys. That's becoming clear to me.

Felmir, the richness of the mixture under 4.000rpm is significant enough to damage the cilynders because of washing them with the excess of fuel?

Regards,
Fernando.

Yeah....you don't want to overdue it in terms of running it rich on the lower end. You need to be juducious about this setting. I use a Gunson to check mixture. Short of that, make sure you do plug readings to make sure your not overly rich or lean. In any event, the T pump works great on my E spec motor on a car intended for the street.