MPI to Carbs

[Trog]

I can't seem to leave well enough alone. After tinkering on my P-Car for some time now, I'm looking to make more (and unnecessary) modifications. Santa was good to me this year, and it's burning a hole in my pocket.

I really like the looks of carburetors on our P-Car engines. What I'm wondering is are there any pitfalls with this modification?

1- Should I expect emissions to go up / down / remain the same?
2- How about fuel economy?
3- Can one expect any increase in performance? Decrease?

I aware of the general sentiment about modifying Porsches' original design intent, however I take refuge in knowing that any modifications I make are completely reversible. My only desire is to do no harm.

Anyone have experience with this mod?

Thanks,

Trog...
'84-911

[Bobboloo]

Since your car is an 84' it has EFI.

1.The emissions will go up substantially.
2.Fuel economy will go down substantially.
3.The increase in performance will be minimal. Mainly just throttle response will be improved.

4. Your car will no longer have it's excellent cold to warm running characteristics. It will not like cold mornings but once warm will run fine.

[Trog]

Well, nix that idea then.

Thanks for the feedback.

[RWebb]

As Bobby pointed out, the detriments are huge.

You might look into a Steve Wong chip + some exhaust mods. Not sure what BC will allow re emissions. There are many people who have done this before if you run searches, be aware that his chips are so common that people abbreviate his name.

[Rot 911]

What the others have said. Skip the carbs. Go with exhaust mods, a Steve W chip and if you want to spend a bit more money, change out the cams.

[frogger]

Originally Posted by Bobboloo

Since your car is an 84' it has EFI.

1.The emissions will go up substantially.
2.Fuel economy will go down substantially.
3.The increase in performance will be minimal. Mainly just throttle response will be improved.

4. Your car will no longer have it's excellent cold to warm running characteristics. It will not like cold mornings but once warm will run fine.

5. It will no longer run well over a wide range of altitudes.

[DanielDudley]

Originally Posted by Kurt V

What the others have said. Skip the carbs. Go with exhaust mods, a Steve W chip and if you want to spend a bit more money, change out the cams.

Do that. Then this.
www.springmountainmotorsports.com

Or change the steering wheel and shocks.

I personally like the fuel injection system on that engine, and have driven stock VS chipped/exhaust back to back. The difference is startling and impressive. Your gut reaction is ''Now that's an engine !''.

[tcar]

Never heard of MPI.

MFI ended in '73. Some cars prior to (and including '73) had MFI, some had carbs.

CIS went from '73.5 to '83.

EFI started in '84.

[javadog]

Originally Posted by tcar

Never heard of MPI.

MFI ended in '73. Some cars prior to (and including '73) had MFI, some had carbs.

CIS went from '73.5 to '83.

EFI started in '84.

MPI probably stands for multi-point injection. i suppose it is from the days when some American cars had single-point,or throttle body, injection.

JR

[Trog]

Thanks for all the feedback guys. As far as MPI goes...:

Multi-point fuel injection:
Multi-point fuel injection injects fuel into the intake port just upstream of the cylinder's intake valve, rather than at a central point within an intake manifold, referred to as SPFI, or single point fuel injection. MPFI (or just MPI) systems can be sequential, in which injection is timed to coincide with each cylinder's intake stroke, batched, in which fuel is injected to the cylinders in groups, without precise synchronisation to any particular cylinder's intake stroke, or Simultaneous, in which fuel is injected at the same time to all the cylinders.

All modern EFI systems utilize sequential MPFI. Some Toyotas and other Japanese cars from the 1970s to the early 1990s used an application of Bosch's multipoint L-Jetronic system manufactured under license by DENSO.

I believe I have the EFI that is "batched".

T...

[Jeff Alton]

Well, if you like the look of carbs and want all the advantages of EFI and want to gain some performance and a ton of throttle response and have some money to spend.......

Try these......



Cheers

[Danny_Ocean]

http://www.pmocarb.com/products.htm#EFI_Throttle_Bodies_for_Porsche®_911® _Engines

[Jeff Alton]

See the interesting threas on the engine rebuild forum about these....

Cheers

[TexasPete2720]

I did a few 914's back in the days when me and my pops wrenched on VW's.
The 914's responded very well to the transplants.
Carbs seemed to agree with the 914's due to the heat problems, but the cold morning starts may take some getting used too.
You will infact see a diff in throttle response and your gas gauge infact, your tires will break traction alot easier.
Not really worth the hassles in my opinion for a 911 cause the factory made it what it is, PERFECT.
If time and money is all it will cost you, then Happy Burnouts...............................

[Trog]

Originally Posted by Jeff Alton

Well, if you like the look of carbs and want all the advantages of EFI and want to gain some performance and a ton of throttle response and have some money to spend.......

Try these......



Cheers

A work of art! What "word" would I be searching on Jeff?