[rhjames]

the problems with high rpms are pretty basic.

above 6500 with hydraulic lifters/buckets you will get valve/lifter float.

above 6500 you will need to go to a solid lifter/bucket or a roller.

above 7000 you will need to go to a stiffer valve spring package.

above 7000, to make power you will need a cam profile with more overlap than you would want to drive on the street (rough idle, very low vacuum, peaky power band, etc). Cost? Billet cams= $3500 and up for 16V. Custom buckets for up to 9000 rpms= $300 per bucket. Ask me how I know.....

if you're running a slushbox, a cam profile that produces power above 7000 will require a high stall torque converter for the car to even be drive-able, much less work. Where are you going to get one of those for a 928? Sure, you can get anything for a GM, Ford, or Chrysler, but for a Porsche? Try having ATI or TurboAction build you a converter that will stall 3500 and up...... good luck with that. Cost? Try $1K and up.

I understand your concerns about the smog cops and their issue with adding pieces that weren't offered by the factory.....but why bother with this endeavor? How do you think you'll pass the sniffer test as well?

You are not going to drive the 928 to it's fullest potential on the street, so what's the goal by twisting it to the moon?

Build your engine to produce torque and HP down low, use it from stop light to stop light, and you'll come out better for it.


--Russ