MFI questions
 

I'm going to buy the FI book from Pelican. But before it gets here, I have a couple of questions to toss out.

I guess I figured that MFI was MFI until I began to read about slide valve vs. butterflys and different space cams for different size/cammed engines.

So is an MFI setup off a say a 2.4 T not anywhere the performer of the MFI off an S? Can said T unit be made to run with something like a higher compression, bigger cam RS motor?:confused:

yes can rebuild your T MFI pump so that it will work well with a larger motor and different timing. But you will have to get it rebuild and have a new spacecam installed.
just my uninformed $0.02 others will know much more than I

As Tim pointed out a T injection pump can have the space cam swapped for an S type. Also, have you checked out all the info in the Pelican tech articles on MFI. The bible for MFI (Check Measure Adjust ) is there and you can download it.

Like others have said, you can swap the space-cam in the pump to an "S" space-cam.

But the expensive part is having the throttle bodies opened up to "S" spec. to match the pump. It's about $1000. Then you'll need "S" intake stacks. You can buy the "S" stacks, or find a set of early magnesium stacks and have them enlarged.

And then there's the port size in the heads. You'll have to enlarge them to 35mm. About $300 for a macine shop to do that if you bring them the heads.

Slide Valves and "High Butterflys" are pretty much for pure race engines. Slide Valves are cool because at WOT they don't have a shaft running through intake like a butterfly system. Barrel throttles have the same benefit. I believe that the downside of both of these systems is that they can easily jam if dirt gets into the mechanism. Not a big deal on race engines which are kept clean and often rebuilt - but definitely a big deal on a street engine.

I'm not sure what the deal is with the high butterfly systems except that I suspect that it optimises the system around a certain harmonic or something esoteric like that. Unless you have an engine engineered to be optimised for the same set of parameters as the high butterfly system, I doubt that it will do anything noticable for you compared with a properly optomised stock style MFI system.

In order to make things like high butterflys work better then a stock style system, you generally have to spend quite a bit of dyno time figuring out the correct recipe.