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Tom W Tom W is offline
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Join Date: Jan 2004
Location: Half Moon Bay, CA
Posts: 987
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Didn't Porsche, at one point, step down from a forged rocker set up to a cast rocker, so that in the event of an over-rev or missed shift, the rocker would bend/break rather than the valve?
Hopefully preventing catastrophic valve/engine failure.
I can't speak to what Porsche has done, but Jerry Woods designed and built my engine components so the rockers would break before the valve springs would allow the valves to float and hit the piston. Cheap and easy to replace rockers. My engine is designed to rev to 8000k without a problem, it simply stops making much power at about 7200 and I have the rev limiter set to 7400. With my gearing, shifting at 7000-7200 is best.

When I miss a shift (e.g. 3-2 instead of 3-4) I usually hit ~8100 rpm. My worst was at Laguna a year or so ago when I went 2-1 instead of 2-3 and hit 8500 or so. That was a problem.

My engine also has small screens installed so a piece of the rocker can't get sucked into the internal oiling area. That happened once and meant the engine had to be removed and spun around on the stand to get the damn piece to fall out. It won't happen again.
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Tom

SL63 AMG Daily Driver
'92 964 now a GT3R/GTL toy for track fun (Tom's Turtle)
Old 07-14-2017, 02:43 PM
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