Millhaus

I am rebuilding my 930 motor. I was planning on the SC cam upgrade but others have mentioned the stock 964 cam upgrade instead.

Opinions and suggestions?

(stock 1980, 930 motor with euro fuel system, K27-7200, 1 bar spring, GHL muffler and stock IC)

stahwille

Hey there mill, Can only speak from experience building , testing , and owning 78 or later 930 engines. The SC camshafts are exciting performence enhancment , and work well with CIS injection. No flat spots, no cold stumble , just improved torque from 1500 - 6000 rpm. However , you must have SC or aftermarket exhaust to match. check this and confirm what exhaust / header system you have or will use. ALSO Turbo cylinder heads as most 911 heads may be flycut when rebuilding up to 1mm. This will increase compression , so be mindfull; every things a trade off but if done correctly .... priceless fun!

dt930

I have hade both 964 an sc cams in mine, the 964 cams seem to have more high rpm power than the sc cams. I guess it depends on what you want and where you use the car, mine is track only and operates from around 5 to 7K rpm most of the time. The 964 cams don't run out of breath on top.

JFairman

All depends where you want the powerband, more down low and in the middle rpms or up high from 4500- 7000rpms.
964 cams will move the powerband around 1000rpms higher than SC cams.

SC cam powerband is better for city and all around driving, while the 964 cams powerband is dull at lower rpms and then they come alive around 4000rpm and make more power during highway and track driving.

If that is confusing it's best you drive a car with each setup to decide for yourself, and you would have to have the same turbocharger in each car to feel the difference in cams alone because some people put in a turbo with a larger hot side or turbine housing and wheel with less exhaust back pressure like a k27 7006 to match the higher rpm 964 cam's powerband.

If you like low end torque getting away from stoplights during city driving more than highway driving with a top end speed rush to redline, or thats more practical on the roads you drive on... than you will probably be happier with SC cams and a k27 7200 turbo to match them.

With all that said 930 ignition timing is extremely_retarded and conservative at idle and low speeds below 3000rpm before the turbo starts spooling up.
There is an amazing amount of low end torque that was left untapped by retarding the timing so much at low speeds in the interest of higher exhaust temps to heat up the catalytic converter faster and pass emission testing... but thats another topic that hasn't been discussed much on rennlist.

There's a long thread on this over on pelican.

Metal Guru

I wouldn't do this.
Screws up cam chain lengths.
Better to buy new pistons if a bump in compression is required.

pdqcarrera

How about a custom hybrid of the two (which I understand Web Cam can do)...?
http://www.webcamshafts.com/pages/au..._sohc_12v.html

stahwille

Good point metle guru , all the more reason to rebuild with new chains and chain sprockets, to minimize chain tension interferience issues.. Also if flycutting heads one should flycut timing chain housing boxes accordingly for correct fit. I still stand by flycutting when done correctly as it greatly improves lowend torque / compression , something all 3.3l turbo enginges lack.

Metal Guru

To clarify, I have no first hand experience with this but there are a few over on Pelicanparts that have fly cut heads and wouldn't do it again.
For my part, I wouldn't be happy to crack into an engine only to find that this had been done to it; just a pain in the butt to deal with.

ZX3tuning

we just installed the 964s on our 930 and while the power isn't as neck snapping down low, it more than makes up for it up top. i'm more than happy with the outcome despite some suggesting it's powerband is laggy, it still feels much stronger even off boost!

Turtletime

What are Group B camshafts? Where do they optimize power band?

Geoffrey

Group B camshafts were from the 935 era and are designed to work with individual throttle body mechanical injected engines. They are old technology and I'd look to something else.

Turtletime

How well would these work with EFI and twin plugs?

juans930

Any one knows what is the best cam timing for SC cams on the 3.3 turbo engine, for street driving??
The engine has JE 7.5 CR pistons with SC cams gt35 garret turbo and fabspeed exhaust and long neck intercooler, I have them at 1.4mm, but haven't run the engine.

9Eleven

So SC Cams produce more power/torque at a lower rpm?

Yargk

How do SC330 cams compare to SC and 964?

I'm with pdqcarrera, a hybrid seems optimal (just by looking at some dyno plots).

Also, at what rpm do you need to worry about the valves? On a track car?