Interest in 968 or 944S2 pistons?
11-03-2008, 08:21 PM
#31
Rennlist Member
Sounds really good.
944 S2 and 968 pistons have smaller compression height than 5L or GTS pistons. There is difference between 5L and GTS also. IIRR 5L crank and 150mm stock rods would be more than 2mm below deck level at TDC and GTS more than 1mm. This would kill CR ratio also. Besided GTS rods are worst possible stock rods to use, doesn't matter if they are late '94-95 MY ...2R version.
944 S2 and 968 pistons have smaller compression height than 5L or GTS pistons. There is difference between 5L and GTS also. IIRR 5L crank and 150mm stock rods would be more than 2mm below deck level at TDC and GTS more than 1mm. This would kill CR ratio also. Besided GTS rods are worst possible stock rods to use, doesn't matter if they are late '94-95 MY ...2R version.
11-04-2008, 12:51 AM
#34
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951 and 944 S2 have very similar piston top cc numbers, 25 vs 27. S2 has even lower compression height which obviously means need for different lenght rods if deck level at TDC is the goal.
Search for ...1R rod problems if you don't recall previous talk about GTS rods being bad desgn. Later ...2R rods were attempt to fix the problem but I think they are far from perfect option also. Factory was basically trying to keep weight down as much as possible and went too far and made too weak parts. Any good quality aftermarket rod is much stronger and good investment. Especially in racing application.
Why would that be? Dropped forged vs. synther forged. Proper H-shaped lightweight rods vs. classic fat and heavy rods.... I am lost. I have always thought that contrary to expectation, the GTS engine is the one to rev due to forged everything. It just needs better breathing...
11-04-2008, 11:31 AM
#35
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Search for ...1R rod problems if you don't recall previous talk about GTS rods being bad desgn. Later ...2R rods were attempt to fix the problem but I think they are far from perfect option also. Factory was basically trying to keep weight down as much as possible and went too far and made too weak parts. Any good quality aftermarket rod is much stronger and good investment. Especially in racing application.
As with regards to the GTS rods - yet to see a bent one - drnick has 20k miles of trouble free redlininig in his early GTS, Adrian Clark had a successful season in the UK on late GTS engine and the one sitting in my garage looks as good as when it left the factory...
11-04-2008, 11:42 AM
#36
Rennlist Member
If your rules call for a limit of 6.2 liters and you are going to take an engine apart, use the GTS crank and do the stroker that way .
mk
mk
Thanks for the 968 or S2 pistons clarification. It looks like I would be stuck with a 5.4ltr engine with skimmed heads, big valves and re-ground GT cams...
As with regards to the GTS rods - yet to see a bent one - drnick has 20k miles of trouble free redlininig in his early GTS, Adrian Clark had a successful season in the UK on late GTS engine and the one sitting in my garage looks as good as when it left the factory...
As with regards to the GTS rods - yet to see a bent one - drnick has 20k miles of trouble free redlininig in his early GTS, Adrian Clark had a successful season in the UK on late GTS engine and the one sitting in my garage looks as good as when it left the factory...
11-04-2008, 11:56 AM
#37
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11-04-2008, 02:51 PM
#38
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Considering how small GTS and 968 production numbers were in '94-95 MY there must have been very serious problems with ...1R rods to cause factory to even think redesign. As other parts were not changed factory was stuck in using same rod weight in ...2R as ...1R was. This means there could not have been too much room for strenghtening them. Based on above I would use good looking used ...1R in normal street only car but no way would put them in track car. If worst happens you know who has GTS crank+rod+piston set in garage.
Hopefully the 20k miles GTS engine will make it into the GT body shell over this winter, now that I have all the parts, the dry-sump is working and the headers are installed...
