3.4 RUF P&C, any advice?

[vichang4]

Does anyone have any experience with the RUF 3.4 pistons and cylinders for a 87 911 turbo. The compression ratio is 7.5.
Is this just a bolt on? No case modifications?
Because of the higher compression, are other modifications necessary?
Without other modifications will the 0.1 liter and 0.5 compression make a difference?
Thanks for any feedback.

[magic930]

The 3.4L is a direct bolt on upgrade, they slip into your case without modification. The increased compression gives you a noticeable increase in torque in the low rpm range before the turbo starts spooling. The ruf pistons are slightly lighter weight so you get better throttle response (engine revs quicker with less rotational mass) so less time passes before the turbo starts to spool up, the overall increase in horsepower is nominal. No other modifications are necessary. But while your engine is apart you might want to consider SC cams or 964 cams depending on wether your car is only street or wether you take it to the track.

[vichang4]

Would it be necessary to run less boost to compensate for the higher compression pistons?

On a slightly different note, is there a knock sensor that can be installed on this engine?

[magic930]

Usually if you want to run more boost or boost for extended time then you would want to upgrade your intercooler. There's probably a formula for calculating maximum compression using boost pressure vs initial compression. For street driving where you are on boost for short periods of time... (and probably breaking the law by the time the boost is at .5 bar) it really is not an issue!

Knock sensors don't work well on porsche engines because they are aircooled and therefore noisy.