SC Veterans- Engine Out - Suggestions for HP?

[Lindy]

The engine came out last weekend, and is now with the local rebuilder who specializes in SC's and vintage racing. Ollie's will be doing the machining work.

I have searched previous threads and have read and re-read the "911 Performance Handbook". The following are current plans for the rebuild, which will start next week. The goal is reliability, while also (hopefully) getting as much HP/$ as possible:

- Go from the 3.0 P/C's to euro (Mahle) 3.2 P/C's (will not require twin plugging)
- Rebuild heads, valvtrain, etc.
- R&R CIS (would prefer not to go to carbs)
- 964 cams
- BB headers (dual in/out) - Already purchased
- Complete lower end R&R
- Raceware fasteners
- 7:31 ring and pinion (car has factory limited slip)
- Sachs sport clutch
- Lighter front/rear bumpers and tail
- Based upon similar projects, we are targetting 240-260 HP

I would really appreciate opininions regarding the above. (would 3.0 euro P/C's be better, etc.?). If there is anything that is missing or blatently wrong with these plans I would rather know now then when the engine is back in the car.

Thank You,

Lindy

[kstylianos]

Lindy,

I'm doing the same with my 3.0 but keeping the keeping the 3.0 P/C's only beacuse of $$$. Head and manifold port, custom cam from Elgin (TBD), SSI's with sport muffler and Sachs lightweight clutch.

There are modification you can make to the CIS to bring it to ROW spec. Good for another 15 HP. HP difference between US and ROW SC's were 180 and 192 (I believe). The engines mechanicals were identical, the additional HP came from different CIS components. Intake runners, fuel distrib, etc. There are many topics here regarding differences between US and ROW CIS differences. Might be able to source ROW parts from Ebay Germany. Late 70's and early 80's CIS specs were different, so depending on which year you have, part sourcing will be different.

MSD ignition will allow you to run bigger spark gaps, reduce the chance of detonation, and give crisper lower end throttle response due to the multiple sparks up to 3K RPM. MSD may also allow you to run a higher compression ratio as well, worth some research if you are not dual plugging. Advance your timing a bit more, max 35-37 degrees. Unplug your O2 sensor and set your CO to 3.5.

Thats all I can think of for now......

[Schuey]

what about going with clewitt engineering upgrade to MFI on it and getting rid of the CIS?

[JonT]

I've got a B & B muffler that works with those headers if you are interested. Dual in/ Dual out 3" outlets. Great condition. email me at Jon.Theobald@bp.com Make me an offer.

[ChrisBennet]

Originally posted by Lindy

- Based upon similar projects, we are targetting 240-260 HP

I think those figures are are pretty optimistic for a CIS car.
Are you using P&C from a Euro 3.2 to make a higher compression 3.0L or are you bumping the displacement to make a short stroke 3.2L?
-Chris

[Lindy]

Chris,

The 3.2 P/C's would be new from Mahle motorsport that would be 98mm with the higher euro compression as well. The engine will not be stroked.

Lindy

[CamB]

- Based upon similar projects, we are targetting 240-260 HP

Yeah, I don't think you'll get to the top end of that. Maybe the lower end (sorry).

For reference, I've got 270hp from a similar 3.2 but with early S cams, MoTeC efi, 10.5:1 c/r and twin plug. I do only have SSIs and a single in and out exhaust though.

[emcon5]

What type of fuel is available where you are? Some people think California's piss-water 91 octane "premium" is marginal for 9.8:1 911 engines.

Any reason you want to stick with CIS?

Tom

[Bill Douglas]

How about 20/21 cams instead of the 964? And match the manifolds to the heads for better flow. I'd save money and avoid the Raveware - others will dissagree with this.

Edit: Maybe boatail the insides of the crankcase.

[Lindy]

Tom,

We can purchase 100 and 110 octane racing gas from the local Texaco for street use here. I am not doing the rebuild with the intention of selling the car, however I am interested in retaining the CIS primarily due to (eventual) resale value. I have heard that it is difficult to sell an SC with PMO's etc. (I could certainly be wrong.)

Lindy

[Kemo]

Originally posted by emcon5
Any reason you want to stick with CIS?

Would a set of PMO carbs be any better than CIS, for the street I mean? I have read mixed reviews of CIS, some love it, some hate it. In any event, I'm sure you would have to fiddle with the carbs alot more than the CIS to keep the car in tune...or maybe im wrong.

[ErVikingo]

a 3.2

[jmz]

don't think you wil get to those hp goals unless you change the cis out wich most importantly will allow for a more aggressive cam.

[fred cook]

Since you will have the engine all apart and are planning on doing a rebuild on the cylinder heads, one of the best "bangs for the buck" will be to go ahead and port/polish the cylinder heads. Also, make sure that the intake runners, gaskets and ports all are matched for size. If you can spend the $$ maybe even go for larger valves. A little money spent here will go a long way towards making extra horsepower.

Good Luck!

Fred Cook
'80 911SC coupe (stock for now, but soon ........)

[emcon5]

Originally posted by Kemo
Would a set of PMO carbs be any better than CIS, for the street I mean?

As jmz mentioned, the big reason for going to carbs is that it allows use of more agressive cams. The CIS sensor plate can't tolerate cams with a lot of overlap, so web 20/21 is as far as you can go.

If he goes with carbs and an hot cam, he may need to rethink the piston choices though, as I don't believe the Mahle 9.8:1 98mm pistons will allow enough valve clearance for a high lift cam.

My opinion is 240HP is overly optomistic, as the late euro 3.2 with 10.3:1 only made 231HP.

There was a good SC engine mod thread on Rennlist last year. Check it out:
http://forums.rennlist.com/cgi-bin/rennforums/ultimatebb.cgi?ubb=get_topic;f=1;t=004403

Tom

[JonT]

spend a little more and do a 3.6 swap. you won't regret it.

[ruf-porsche]

Wait until rfng has his turbo kit for 80-83 SC out. See postings on this development

[Wayne 962]

Keeping CIS is a losing proposition - it's a fuel delivery system designed to meet emissions - not for power. You really need to go with carbs, or the best, which would be a Tec-3 system...

240 HP with your config will be questionable...

-Wayne