964RS_NGT

Got a high milage 997.1 GT3 that will get a top end rebuild and the coolant pipes fixed. What options for more power are there re pistons and cyl heads? Any Cup car parts that would add some HP? Any high(er) comp pistons available from Mahle motorsport etc?

Right or wrong i don’t know, but I’m not too much into big bore conversions due to everything that’s been written about harmonic vibrations etc in the 3.8/4.0. Besides, I actually like the caracter of the 3.6 with a LWFW.

Engine mods so far: a Cargraphic ”kit6” exhaust with their ECU tune (headders & 200 cell cats + valved side delete’s). Also a dual intet Porsche MS airbox with a .2 RS declid (replica).

Tom@TPC Racing

Lots of good options from OEM and aftermarket. Depending on how much you want to spend... One option is OEM 3.8 (102.7mm) pistons & cylinders from 997.2 GT3/Cup is direct bolt on, have cylinder heads build/prepare by a good machine shop, add .2 RS or 4.0 intake manifold assembly and ECU tune, 400hp at the wheels. I have a set of pistons, PM me if interested.

misterwaterfall

Correct me if I'm wrong, but only the 3.8 RS has the vibration issues right?

Tom@TPC Racing

Some .2 GT3's and some RS's have bolts came loose, some of these cars don't. There are measures that can be taken to prevent possible issues such as Harmonic damper from Dundon Motorsports, and/or get updated OEM cam actuators(with I think they applied thread locker and assign a different part #) or Loctite the actuator bolts and crank pulley bolt, or modify the actuator to accept larger bolts(for higher clamping force) and Loctite them.

misterwaterfall

I hadn't heard about any non RS cars having issues.

Tom@TPC Racing

Oh I have. Some are RL members.

964RS_NGT

Tom,
Thanks for the offer. I've pretty much decided to not go down the big bore route though. This is more a refresh of a stock motor then a big budget build. But, since the motor is out and partially opened anyway, I'd like to understand if there are any gains to be had by using other parts vs OEM.

Reason for asking about Cup heads is that I might be able to buy recently rebuilt ones of a -09 3.6L cup car (#997.104.016.92). Don't know the cost yet though. I also know that the 04/05 996 RSR used higher comp pistons (same stroke and rod length) but they might not be durable enough for street use. Any other 100mm options?

Tom@TPC Racing

Understood.

Aftermarket pistons can be custom made, even standards ones have more choices on compression ratio, dome type, material, ring config, wrist pin options...requires the builder to do calculation to create a formula including filing ring gap for expansion. Some builders and shops offers a proven formula/package, which is great. With all done right the output can be higher than OEM.

IMO, OEM parts is a known quantity for those who doesn't have the desire to creating their own formula and feel that the OEM quantity is adequate. This is how I feel lately because I am occupied by many things. LOL

Don't know about where you are but 997 Cup heads are expensive here! Have seen some used 996-series heads at decent prices.

grrrmonster

Don't assume the rods are ok. I've seen several gt3 motors with rods that had elliptical holes on the ends

Texas RS

...most of the issues I have heard of were non RS going to lwfw