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Why 8v turbos?

A

Alexw

Member
Something ive been wondering about is why a lot of the turbo conversions ive seen all use 8v heads? Are 16v more trouble then the extra air is worth or is just for simplicity??
 
Its not just the conversions? - modified ones that are 8 valve ALL 944 Turbos ARE 8 valve engines!!!!!!!! as far as I am aware.
(Although I believe I saw some where of a 16valve converted Turbo but cant remember where)
Clive
8 valve Turbo and extremely contented with just the 8.
 
The 944 turbo was introduced in '85, the 16v head wasn't in production then [:)]

Actually the 924GTP (944 prototype) that ran at LeMans used a 16v turbocharged 944 engine but given the makrket the 944t was aimed at (ie performing below the 911 turbo) I guess they didn't go all-out with the spec.

4v heads do two main things - they allow more flow (larger total valve area), and allow the engine to rev higher (less valve inertia in two small valves vs one big one). Since forced induction gives more charge with a 2v head than an NA 4v head and the big pistons are probably more of a rev-limiting factor than the valve inertia I guess Porsche didn't feel the extra complexity was needed. Forced induction has come a long way in the past 20 years [:D]
 
Even the 3.0L 968 Turbo used an 8v head whereas the standard engine was 16v variocam.

944 and 968 were still the budget model for Porsche at the time so there would be no point sticking a 16v head on and making mre power than the flagship model. There have been a few 3.0L 16v turbo conversion in the US and Patrick in Oz is working on one as well as SimonP over here who built my 3.2 8v
 
what about the recent 3.2 and 3.4 engines ive seen converted recently? Theyre all still 8v arent they?
 
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