Spartan

Well I've decided not to go with the GT2 cams as it requires mechanical lifters. While I like the idea of being able to rev higher and the added value of the more aggressive cams of the GT2 I don't like the maintenance that is required with the mechanical lifters. Besides that I never rev past 7k anyway.

That being said I've had a couple of builders mention the RS cams which work with the hydrolic lifters. Has anyone here installed these in their build? I'm trying to do some research on the cam profile of the RS vs the stock turbo and will post up what i find. I'm assuming that these cams will further push the power band up (which i like). Haven't even inquired as to how hard its going to be to find a set of these in the States yet

Thanks for the input guys!

Geoffrey

The interesting thing about cams and the 911 series engines, particularly the turbo engines are that the intake design far more influences the powerband of the engine than the camshafts. Cams will move the peak power around 500-1000rpm, but it will rarely make power above 7k unless a change to ITBs is made. This is simply an airflow statement on these engines.

Of all the off the shelf cams I've used, I like the GT2 Evo cams the best. The RS cam profile may not be the best for a turbo engine due to their design for N/A environment.

ScottMellor

My 'old school' Andial conversion car has the RS cams.
Since it came that way, I cannot comment on before and after.
I can say the car is much more linear than my previous FVD 480 car. But it's a completly different animal as this one is a 3.8 twin plug and the old one is a 3.6 single plug.

Spartan

Thanks for the response Geoffrey. So you think that $$ better well spent would be on the intake track? From what I recall one can convet the intake to the NA but other than that what else can be done? Thanks for your help!

sfl993t4

I run the RS cams on my car and they appear to work well. I chose them as I wanted to stick with the hydraulics.
I also considered the Schrick cams, but decided to go with Porsche stuff.
Maybe one day I'll try the GT2 Evo if I convert to mechanical.
Steve

Spartan

Thanks Steve, can you shed some more light on the power increase/power band with the cams? Also did you do this mod in conjuction with other mods? Thanks!!

Geoffrey

No, I'm not suggesting upgrading the intake to ITBs and the RS Cams should work fine. The only point I was making was that the RS cam is built for an N/A engine and you might have better performance with a turbo specific camshaft that will work with the hydraulic rockers. Since I have a custom cam ground for each application, I cannot comment much on all of the off-the-shelf aftermarket ones.

911/Q45

I also have the RS cams on my Andial conversion. I have had durability problems with the hydraulic lifters, as I believe others have. If you have a twin plug engine, the turbos have to come off for a plug change anyway, so valve adjustment isn't that much more work and the interval is about the same.

Acropora

I run the GT2 evo cams with bigger turbos. At 3K there's some power but at 5K it's hold on! Not the best for a track car but fun on the long straights.

ca993twin

Does anybody know the specs on the Ruf cams as used in the Turbo R? They seem to work great, and keep the hydraulic lifters. I trust that you won't get any info from Ruf.

bb993tt

I'd love to hear an informed answer to this one! I asked this and many more questions when my car was in P'hausen ... never got much of an answer to any of them. Best was a vague answer to my turbo question. Paolo (pmf) got the same and between us we came up with a guess, but ... Not saying I'm not very happy with the results, however.

JJayB

RS cam works perfect for the street/track applications. I've run against several Ruf cars and the RS has the edge on the mid range up. I think the Ruf has a better low to medium power band. The GT2 is a race application. Ask any tech setting the lash with shims is a major pita. I wouldn't run the GT2 on the street although it does make the big power. The maintence is the reason I passed.

bb993tt

Aren't there also some California emissions problems with the mechanical lifters, Jimmy?

Geoffrey

The mechanical lifters won't cause any emissions problems, however, a camshaft with a more agressive profile and more overlap will show a higher unburned HC when tested.

JJayB

As Geoffrey said, its not the lifters, its the grind. Nevertheless the Gt2 cam doesn't pass CA emissions. The other problem is 993tt are classified as "gross polluters" due to the data base the smog huggers have developed. All those mod's when you don't pass have created a class that is scrutenized by those who's life's work is protecting citizens from the deadly 993tt.