911 sc 3.0 performance upgrades

[DoninDEN]

Originally Posted by fred cook

If I were to do it all over again, the only thing I would change would be to use the 105mm cylinders and pistons for a 3.7SS !

Would the CIS system work with 105s and a 3.7 build? What would have to be done differently, if anything?

[fred cook]

Originally Posted by WP0ZZZ

Interesting. What machining was done on the heads to increase the compression ratio?

Normally, machining the head gasket surface will reduce the combustion chamber volume, thus increasing compression. I got the heads from a track engine that had been rebuilt a couple of times. I don't know for a fact, but it is fair to presume that they (the heads) had been "cleaned up" at least once during their life on the racing engine. Also, the heads had been cut for twin plug use. That probably offset some of the volume loss.

[fred cook]

Originally Posted by DoninDEN

Would the CIS system work with 105s and a 3.7 build? What would have to be done differently, if anything?

In Wayne's 911 book, in the section on recommended engine mods, there is reference to a 3.7SS using CIS injection. Apparently, it made about 300 hp at the rear wheels! I imagine that the torque that engine produced was "significant" also! So, it sounds like it worked to me!

[mikedsilva]

I am running a 3.0 with the big ported heads.. engine is stock with low compression 8.5 pistons and cam is totally stock.
At this stage exhaust is totally stock too.. but am using efi, itbs and coil on plug for ignition with aem infinity.
Power is 194 at wheels (apparently).. but peak torque is produced around 4500rpm.
Would like to bring that lower.. would a cam change to 964 be the way to go? At this stage, I do not want the expense of changing pistons/cylinders.
Is there a more suitable profile cam?

Mike

[trond]

mikedsilva; no, 964 cam will bring the torque peak higher than stock cam. Timing your stock cams earlier, to small port spec 1.55 mm lift at Z1 should lower peak slightly. I find the stock cam to make a lot of sense in traffic on street with good power from before 4000. I rarely reach 4500. But I have to admit it is slightly boring and I would have preferred your engine with higher CR pistons