CFM flow for a 911S head ?

[911E&26R]

Is there a source for this information ? I would specifically like to know what a Stock 2.2 S head would flow.

Thanks

G

[CamBiscuit]

Some useful info in this thread - http://www.early911sregistry.org/for...highlight=porn

[911E&26R]

Thanks Cam,

I did a search before posting and came up empty handed - by the chart it looks like a stock 2.2 S head will flow 225 CFM at .5" lift - that's pretty darn good not sure I would CNC for the extra 5% I have built other engines of the same vintage that don't flow as well relative to figures above, yet have better yields over all ...

So , being new to the engine family what are biggest challenges in making the engine produce power ? Is it CR ? combustion chamber shape ? Are you hard up against the law of diminishing returns once you go past the factory's S specification - In other words it cheaper to go faster by taking weight off the car rather then go into the motor...

Sorry for being long winded.

George

[chiroracer]

Im not a pro engine builder but I think the s is the most compromise that you would want to drive on the street.The factory full race versions have twin plugs to allow more compression ,bigger cams and bigger valves and bigger carbs/throttle bodies for circuit racing that were even too wild for rally applications.Some of the gains(minor) that my engine builder(for off road 1600vws)is getting in this old engine formula is from technology that was not available at the time ie aerospace coatings, lighter valves ,managing harmonics on a dyno.all pretty expensive stuff that is a trial and error process. Best of luck I look forward to other responses! S