carbs or MFI??

[Porschekid962]

I am buying parts to rebuild my 78 3.0 to a 3.2 this summer and was wondering since the prices are nearly identical what would you do?? Get a set of 46 PMO's or go with a custom MFI setup? I am leaning towards the MFI for it's greater fuel pressure and better atomization but the ease of carbs is also a arguing factor.

Plans are 3.2, around 10.75 CR from custom JE's, refurbed 3.2 cylinders, possible twin plug, not sure yet.

[Shuie]

Im in the same boat, kinda. Ive got a 3.0 based motor that has a set of 40mm Webers on it already that Im thinking of changing to MFI.

Carbs are pretty much a bolt on. MFI is not. Going to MFI is going to require machine work for the injectors and cams that have the drive sproket for the pump. MFI also needs a different (not cheap) fuel pump than the carbs will.

You may want to give Henry Schmidt a call at Supertec to talk about the custom MFI setups if you are thinking of going down this path. His shop does a lot of big displacement MFI setups in house.

Good luck!

[911pcars]

I would go with custom EFI unless you're into early nostalgia.

Sherwood

[Shuie]

I wasnt real nostalgic about MFI until I got my stock T motor up to 6000RPM for the first time

Custom EFI would be awesome and probably the bestest thing out there, but setups really seem expensive. I'm eagerly awaiting Noah's dyno results from the t-bitz system.

[Porschekid962]

i have contemplated EFI but unless TWM has a 60% off sale along with Motec and/or Clewett I think I will be staying with a non electronic system. I had talked to Tyson about some other options and an interesting one would be to fit the 3.2 intake system to my engine and have a custom chip burned for it, EFI for less. Or I can jet out a set of cheap carbs and weld in some bungs for the fuel injectors and put a EFI brain on the motor. Unless I was going twin plug for sure or going with a higher CR I dont plan on needing EFI.

I have spoken with Henry and I have to say that he is one of the nicest guys around, sat on the phone with me for at least half an hour and we discussed many different ideas, cranks, rods, pistons, cylinders, heads, intakes, EFI, MFI, carbs, CR, cams, exhaust, the whole gambit. I know feel a little bit more knowledgeable on the topic of Porsche engines.

[Henry Schmidt]

Carbs ? EFI ? You're kidding right ?
Porsche never ran carbs on an engine bigger that 2.5 and those were 46 mm Webers. EFI, expensive to say the least and huge reliability issues. (sensor failure)
What could be cooler than this ?
3.5, 10.5 to 1, single plug, MFI = 369 rwhp

[Henry Schmidt]

"WHAT COULD BE COOLER THAN THIS ?"

MAYBE THIS ? Click for the link to what's better.

(Moderator's edit, because of complaints.)

[W Scott Shores]

Henry,
I've been admiring that 3.5 MFI motor since you first mentioned it on another thread
(as well as that 2.8 MFI motor on your website).
Can you give us a ballpark figure of how much one would pay for such motors?

Thanks!
William

[724doorE]

Gee, I'm kinda thirsty now

Ok Henry,

How about a 66mm crank, 2.4 E pistons a 7R case MFI and a couple a Garrett TO3's with ported heads and E cams to start with....

[Henry Schmidt]

350 HP 2.2 liter Twin turbo. Sounds cool. MFI turbos have their own problems but HP is not one of the. The hard part of this engine will be keeping the heads on.
As for the MFI system I have it.
Lets do it !!

[724doorE]

How bout dowel pinning the case and adding case savers for all head studs. I have most of the pieces, thats how I got the idea.... what to do with the left over pieces! What is the most you can bore out stock mfi throttle bodies? The butterfly is 38mm. I can get undrilled 1 11/16 butterflies for cheap, but the wall of the tb would be very thin if they were bored out that much. Whats the practical limit with stock tb's?

[billwagnon]

Best idea I saw was using a Chevy six EFI setup - don't remember who did it, but it sounds like a great and inexpensive solution. I've got Webers anyway, so I'm already on the slippery slope!

[billwagnon]

maybe Joe can tell us more!


stlrj
Senior Member

Registered: Dec 1999
Location: Novato, CA
Posts: 1265
Some time back I adapted an 85 Chevy 2.8 V6 EFI into my 78 3.0. Results were amazing considering the time an work it took adapting all the wiring, sensors etc., including all the functions of the on board diagnostics.

You might consider this because it simplifies the ignition signal source since it uses the same input from your 3.0 distributor, no knock sensor to worry about, no cam or crank sensor to adapt, and best of all, parts are available dirt cheap from almost any junk yard.

Cheers,

Joe


Last edited by stlrj on 05-28-2004 at 11:34 AM

[svandamme]

Originally posted by Henry Schmidt

What could be cooler than this ?
3.5, 10.5 to 1, single plug, MFI = 369 rwhp

me wants

[Henry Schmidt]

724doorE
"How bout dowel pinning the case and adding case savers for all head studs."

Dowel pins and case savers, Oh yeh.
Don't forget the SUPERTEC head stud kit.

"What is the most you can bore out stock mfi throttle bodies? The butterfly is 38mm Whats the practical limit with stock tb's?"

41.5 mm is where we stop when we bore out the housings and rebush.

svandamme "me wants"

Call, place your order, send the deposit and 30 days later you're flyingl

[svandamme]

Originally posted by Henry Schmidt

Call, place your order, send the deposit and 30 days later you're flyingl

me got no money