Can a 2.4T-MFI induction modified to 2.7MFI?
 

Hi to all, might be buying a 1972 2.4T-MFI... and guess whats in my garage? A 2.7RS-spec to be reassembled, but less the MFI.

Can the 2.4T-MFi whole induction system can be modified - stacks, pump, manifold, etc - to be used on the 2.7RS engine? Making it a true 2.7RS?

Thanks for replying.

what type type of MFI do you have? Any of them can be modified to run on the 2.7RS. If they're not the S type then you have to have your pump rebuilt and possibly the stacks bored out. It's entirely possible. I'm thinking of doing the same thing.

It's something I'm dreaming about, too. Someday.

Contact Pacific Fuel Injection in San Francisco, Calif. They are considered one of the best and most knowledgeable (sp). 650 588-8880 ask for Gus Pfister.

Your T plastic stacks are not going to be capable of being expanded. You have find some S or RS stacks. The pump needs a space cam swap and the throttle bodies need expansion. HTH

Zotman's right. Your plastic T stacks are too small and can't be bored out. It's easier to find earlier magnesium stacks and open those up. The throttle bodies can be enlarged, but it's about $1,000. The pump needs the S/RS space cam, and recalibration.
It can all be done, but it's pricey. Probably close to $2500 all tolled.

To elaborate on what Bill said. The T stacks won't do it but the T throttle bodies and injection pump can be modified. The throttles can be bored out from 30mm to 36mm where they meet the cylinder head. The tops of all the T,E & S throttles are all 38mm so nothing is needed there. The hardest thing to round up are the S stacks. (S and RS stacks are the same in 73') You can find them but they are not cheap. Usually in the $1000 range. I know of a set for $900 if your interested.

Another alternative is an E setup. This is something I'm in the process of building right now. A 2.7MFI E motor. Sort of a detuned RS motor if you will. You can get the E stuff much cheaper. I see stacks go for $100 every now and then. (Just bought a set.)

I'm also curious to see how a 2.7 would run with E stacks, throttles and S cams and injection pump. I would think it would move the torque curve lower at the cost of some top end HP. But might be a blast on the street. Kind of a large rally motor if you will.

One other possibilty would be to bore out some E stacks. S stacks measure 42mm> at the top and taper down to >38mm. E stacks measure 38mm> at the top and taper down to >35mm. If you can take out 1.5mm from the inside of the E stack you would have a stack that would measure 41mm>38mm. Pretty dang close.

By the way there is a complete E setup in the want ads for $850 I think.

But like I say You can get E stacks for $100 and a complete T setup for about $500. The only thing is you have to spend the money changing the pump and boring the throttles so you'd still be looking atleast another $1500 or so and we still haven't talked about cams yet which need to match the MFI setup. (another $350)

But to have a true RS motor you need the S stacks.

Bobby,

I thought the plastic S/RS stacks from '73' were still available to buy from Porsche. Based on your info. I must be mistaken. You are certainly correct about the difficulty finding 'S' stacks. I finally found a set for our '71' and they were expensive.

Brian,

To be honest. I haven't even checked with Porsche as a source for the 72'/73' plastic S stacks. That's an interesting thought though.

Bobby