Thread: 8mm valves
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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
 
Join Date: Jun 2008
Location: Detroit
Posts: 883
Well, the 993 EVO intake valve can be had with a 2.5mm bigger intake diameter (51.5 vs 49) but that is hard to fit in a 97mm bore. It can support a 46mm intake port, the biggest ever on an air cooled 911 motor! So, probably overkill without some port work.

The regular 993 turbo intake valve is 49mm, the same as the 930, with the thinner 8mm stem.

The secret here is that it is sodium filled, unlike the 930, which has only the exhaust sodium filled. The sodium cools the intake valve, which is the hot spot in the whole chamber at WOT. Much more resistant to detonation. I always use them. Definitely worth it IMHO. Slightly pricey though.
Old 12-30-2017, 08:26 AM
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