I THINK THAT IT IS VERY INTERESTING,JUST DON'T KNOW THE ANSWER.TEACH ME.

the type of alloy used?

I did not pose the question with the thought in mind to teach. :o It was posed with the thought of hopefully learning something new. :)

Oak,

I have heard this question about the alloy prior. I can not determine any difference. The valves are different or a better word may be lighter. I know the Cup heads use stainless steel and the R heads use titanium.

I have seen companies like TTP and Ruf use turbo heads and enlarge the valves and port the intakes and exhausts. I used Cup heads and left the valve size alone, slightly CNC ported the intakes and exhausts and had basicly Inconnel valves made and coated the valve faces and stems.

So are is the alloy different? I don't believe so. I believe the blanks are the same. Maybe someone who knows for sure could comment.

The machining of the heads (other than ports and combustion chamber) has differences. There is a groove machined into the 996tt heads that is not used on the Cup or R heads. It would be possible to have it machined in. The purpose of this curved groove is on start up to warm up gasses quicker. In other words it is smog related.

When RUF, and others, port the turbo heads do they install larger valve seats with the larger valves?

Yes. I have seen Cup and GT3R size valves installed using turbo heads. These valves are 5-7 mm wider. TTP used this approach with Elliott750's motor.

When you use this approach, you limit available cams and the GT3 uses larger cam housings. The GT3 exhaust cams will fit in a turbo cam housing, however the intake cams will not.

Here is a picture comparison between the two cam housings. The GT3 housing is not only larger, but also beefier.
Turbo Cam Housing (top) GT3 Cam Housing (bottom)
http://www.986host.com/albums/DUANEB/Viso012705_11.jpg
GT3 Cam Housing.
http://www.986host.com/albums/DUANEB/Viso012705_02.jpg
Turbo Cam Housing.
http://www.986host.com/albums/DUANEB/Viso012705_03.jpg

Chad can you finish this car already this thread is huge :)

We're peddling as fast as we can. :o

cjv, thanks for the info great stuff. the turbo heads are cast from RR350 alloy, not sure if the GT3 heads are cast from the same stuff. sorry, I haven't been able to keep upto date with your project motor. looks like it's going to be a monster. how far are you from completion? will it ever end to the point you'll be satisfied?

Oak,

Thanks for your added information. The present hold up is the exhaust valves. They were sent to us a couple of months ago in a predominately stainless steel material instead of the super alloy which is predominately Inconnel that we ordered. Manley, who is re making the valves is suppose to have them to us by July 25th. We will lose another two weeks to coating, so we should start assembling the motor in early August and be ready to run by Labor Day.

Will I be satisfied ........... probably not. :rolleyes: However, this will be as far as I'm going with this motor. :)

I highly doubt it.;)

03-turbo911,

The motor we are building should be capable of 1200 to 1500 hp. I highly doubt we will use this kind of power very often. My guess is we will dial in one of the programs for 1.1 bar which should be good for maybe 850 hp for everyday use. :D

Sorry if I'm going to disappoint you.

Everyday use, with only 850hp huh.:rolleyes:

You're a P-I-M-P Chad!;)

Everyday use for this car will be:

1) Certain mornings sometime between 12:30 AM and 2:00 AM.
2) Short Sunday drives.
3) The track.
4) The strip.

:o

They cost more! hilarious

What do I win!:D