Interesting find on my new project car! Questions...

[scottrx7tt]

I just bought a 79 911 widebody. I already knew it had a 1980 "3.1" block, but the rest was unknown. It had a Holley Pro-jection TBI kit on it with a custom intake manifold. The TBI kit was not operational, so I went ahead and removed it, along with the engine shroud. As I was doing some clean up on the engine I noticed that it has 3.2 heads on it with the date code 2/86!

I was already going to do a 3.2 intake with a Bitz EFI kit on it anyways, which will make things a bit easier, but my question is, how will this effect performance? I know the 3.1 had the 3.3 turbo cylinders with some kind of high compression pistons from the factory. I have verified that the engine still has the larger cylinders.
So, what can I expect?

[EPorsche]

Do you have pics of the engine and engine bay?

[scottrx7tt]

Anyone??

[scottrx7tt]

[scottrx7tt]

[RWebb]

3.2L heads flow real well, bone stock

OTOH, you can expect that a PO who would eff up by using that manifold and carb may have effed up elsewhere too

I assume you will do a full teardown anyway...

[scottrx7tt]

I did a compression test, and all cylinders were 178-180, and no broken studs, so it does not make any sense to tear it down.

[Nostril Cheese]

You need to do a leak down test. I'm sure that the motor was not getting the same amounts of fuel to each cylinder with that manifold setup.

Based on what I see in those pics, yes, tear it down and check everything. That manifold is a serious WTF?

[Dan J]

I would check the cam timing also in addition to checking that it's correct you may
also find the cams have been changed
I agree on not tearing it down if the leakdown/comp is good and it's not leaking oil

[MBAtarga]

What is a "3.1" ? I've never heard of that displacement.

[scottrx7tt]

Excellence :: Point One : The Forgotten 911 SC-L 3.1

[rattlsnak]

I have to say in all my years of P ownership I have never seen or even heard of a TBI setup on a 911! WTH?

[911nut]

Big ports on a 3 L engine will make for sluggish response at low engine speed. This can be overcome with a higher compression ratio. I suggest getting it running as you planned, drive it and decide if you can live with it. The compression ratio might have been bumped already.

[tonizzos]

if it's a real SC 3,1 ... i would not modifie it.... my 2 c

[scottrx7tt]

Originally Posted by 911nut

Big ports on a 3 L engine will make for sluggish response at low engine speed. This can be overcome with a higher compression ratio. I suggest getting it running as you planned, drive it and decide if you can live with it. The compression ratio might have been bumped already.

the porsche 3.1 engine is 9.5:1 with 3122cc's
the porsche 3.2 engine is 9.5:1 with 3164cc's

so there is a 42cc difference, and the compression is the same, so i might be 5hp down from the 3.2, or atleast thats what i think.

[scottrx7tt]

Originally Posted by tonizzos

if it's a real SC 3,1 ... i would not modifie it.... my 2 c

its already been modified with the 3.2 heads, so its definitely not original. Besides, the original CIS is long gone.