Quote:
Originally Posted by aws
I have seen a twin turbo 993 being spun 7200 for 75 race hours making 500 HP to the rear wheels with no major problems. This engine had a stock bottom end with only Carrillo rods.
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That's not exactly a stock bottom end. I'm curious too, mine is stock except for Raceware rod hardware. I've spun it to 7200 a few times but don't make a habit of it.
Quote:
Originally Posted by aws
Porsche narrowed the rods in order to thicken the throws when they redesigned the 993 engine much like they narrowed the 3.0 rods from the 2.7. The problem with this is that there is not enough bearing area to support the forces generated by the longer stroke and higher RPM'S. The 993 crank is torsionally more rigid, but this does not outweigh the reduced bearing area. Part of this opinion was caused by Porsche going back to the 964 based crank with the earlier 3.2-3.3 rods and more rod bearing area when they developed the 4 valve water cooled GT-3 RSR engines. ( that are spinning 9200 in the Daytona Prototypes). I think 7200 with a stock engine with aftermarket rods will work because I have seen it, anything more than that and you will have to talk with someone with a lot more experience with these engines than I have.
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I've heard that same opinion from a # of different reputable sources. The M001 993 Cups, used the 964 crank/rod setup.
The guys that are spinning their 964/993 to big rpms seem to be using the GT3 crank and a custom set of rods, last one I saw was a beautiful set of Ti Pankles(they are like feathers when you pick them up), along w/ the GT3 oil pump.