|
|
|
|
| Author |
|
|
Registered
Join Date: Jan 2015
Posts: 1,499
|
Porsche Motorsport parts catalog
Is this available on-line? I could not find it, maybe it's not available to commoners? The specific question is what is the std high/low measurements for the yellow/red/blue Motorsport GT3 main bearings? Thanks.
|
||
02-14-2016, 09:37 AM
|
|
|
Registered
Join Date: Jan 2015
Posts: 1,499
|
Found my answer on a Rennlist thread and some other input I received. The Porsche Motorsports parts list is not available to mere mortals but I did find some good info on the Motorsports GT3 bearings. It looks like the yellow GT3 mains are the same dimension as the street GT3s, the reds are .0005" looser and the blues are a half thou. tighter.
|
||
|
02-14-2016, 06:59 PM
|
|
|
Registered
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
|
Quote:
 One should always measure crank journals before using the GT3 bearings to get proper fitment, especially with a used crankshaft.
__________________
Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
||
|
02-17-2016, 10:13 AM
|
|
|
Registered
Join Date: Jan 2015
Posts: 1,499
|
Thank you Steve. Could you answer one other question please? My manual shows a std. main bearing clearance range of .010 - .072 mm or .0004 - .0028 in. I would never consider running a main clearance of only .4 thou on non-Porsche engines, esp. using 20w-50. I usually use the traditional rule of thumb of one thou. per inch of journal diameter which would put these at 2.4-2.5 thou. Is there some reason why these engines can run a main clearance that tight? This is a '79 3.3 turbo. I know modern engines using 5w-20 or 0w-40 can run that close but I wouldn't run that in anything air cooled .
|
||
|
02-18-2016, 04:39 AM
|
|
|
Registered
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
|
GT3 engines are water-cooled so their running clearances are FAR different from the air-cooled ones.
The factory runs tighter clearances in their race engines and thin oils to allow them to make power beyond 8200 RPM.
__________________
Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
||
|
02-18-2016, 08:24 AM
|
|
|
Registered
Join Date: Jan 2015
Posts: 1,499
|
Thanks. The .4 thou mains clearance is from Wayne's book for the low end of a std. 911 bearing, not a GT3. That just seems very tight, I'm shooting for 2-2.5 thou. on my used crank that mics at a low of 3.0 thou on #2 to a high of 3.6 on #4 for clearance with the original bearings with 80k miles.
|
||
|
02-18-2016, 08:54 AM
|
|
|
