How many engine upgrades can the MFI handle?

jsoderbe · 07-04-2009, 10:42 AM

Hi guys,

I have a '72 E 2,4 liter engine I'm going to put into my '72 T Coupé. Since I have no idea about the condition of the engine, I'm at least rebuilding the heads. While in there I figured I can change the pistons & cylinders at the same time, especially if they are worn. I'm thinking about a set of 95 mm cylinders with high comp pistons, like the 9.8:1 JE Pistons.

My question is: Can my original 165 hp E MFI system handle the increase in displacement? I'm pretty sure the pump can't handle a different cam, but maybe it is different with the changes I'm thinking of?

Any ideas, or anyone out there that have tried?

Thanks,

Johan

Raceboy · Raceboy's Garage

You'll need to retune the MFI at least when engine VE is changing by such amount.
Not sure if the MFI itself can or can't cope with the increase in fueling needs after retune but such increase (2.2 -> 3.0) is not itself too much.
Get at least a decent WBo2 kit after starting the engine with new configuration to monitor mixture.

longhornchris04 · longhornchris04's Garage

You should try running a search in the Engine Building forum. I believe there are several threads about MFI in there, as its a popular alternative to carbs in the early cars.

I'd definitely make sure you have the tuning checked w/ WBO2 to make sure you don't end up lean with the high compression P&Cs.

jsoderbe · 07-04-2009, 12:26 PM

Just to clarify, I'm going from 2,4 to 2,7 liters.

Should have posted in the engine section, sorry about that!

Thanks,

Johan

RSTarga · 07-04-2009, 03:52 PM

you need different spacers on the cam of the MFI but it can be upgraded

Flieger · Flieger's Garage

He means a different space cam. I would say you can retain your current one, however.

The space cams are really more specific to the T/E/S profile rather than the displacement. You can get very close by just richening the entire rev range provided your valve timing cams are matched to your MFI pump space cam profile.

Search for Jeff Higgins' thread about MFI pump open heart surgery. He made a small motor's MFI pump feed his big 3.0 liter. It has all the details for turning the fuel screws.

The best course of action is to send it to Gus or someone else like Supertech for a full tune-up and re-map to your individual specifications.

Flieger · Flieger's Garage

Here is that thread: MFI Pump - Open Heart Surgery