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66mm crank question
I am looking at a 66mm std/std crank that has 1 journal that's been welded. I'm planning to use it eventually to build a 2.5 liter short stroke motor on a 7R crankcase. Should I be concerned about the journal that's been welded?
Thanks!
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Michael Sans Porsche...for now 2009 Mazdaspeed 3 Grand Touring daily driver / DS autocross toy 2010 Subaru Forester X Limited - wife's daily driver |
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03-02-2006, 04:57 PM
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PRO Motorsports
Join Date: Nov 2001
Location: Burbank, CA
Posts: 4,580
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Yes, especially in a SS-2.5, where it should be a very high-revving engine.
You may develop cracks near the welded journal. The higher it's revved, the greater the harmonics acting on the crank, and the greater potential for failure. If it's just going to be a street motor, it may be O.K., but I wouldn't risk it. Never go cheap on major internal parts that could potentially destroy the entire engine.
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'69 911E coupe' RSR clone-in-progress (retired 911-Spec racer) '72 911T Targa MFI 2.4E spec(Formerly "Scruffy") 2004 GT3 |
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03-03-2006, 08:58 AM
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I would rather be driving
Join Date: Apr 2000
Location: Austin, TX
Posts: 9,108
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Tyson, What is your opinion on the CW vs non-CW 66mm crank for a 2.5 motor? I have seen some that say the CW is stronger and that the non-CW spins up faster. This would be for a non-full race motor but one that would see multiple track events/year.
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Jamie - I can explain it to you. But I can not understand it for you. 71 911T SWT - Sun and Fun Mobile 72 911T project car. "Minne" - A tangy version of tangerine #projectminne classicautowerks.com - EFI conversion parts and suspension setups. IG Classicautowerks |
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03-03-2006, 09:02 AM
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Registered
Join Date: Jul 2001
Location: Thunder Bay, ON
Posts: 4,551
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I have a 66mm CW crank that is 1st undersized (.25mm) on both rods and mains if you need one.
I also have a 3.0 crank 1st undersized on rods and mains if anyone needs that as well. Regards, Andrew M
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1970 911E - track / weekend car 1970 911S - under restoration 1986 930 Slant Nose - fun car |
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03-03-2006, 09:21 AM
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Thanks for the input Tyson!
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Michael Sans Porsche...for now 2009 Mazdaspeed 3 Grand Touring daily driver / DS autocross toy 2010 Subaru Forester X Limited - wife's daily driver |
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03-03-2006, 09:41 AM
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PRO Motorsports
Join Date: Nov 2001
Location: Burbank, CA
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Quote:
It's true that the non-counterweighted crank will spin up faster. The advantage of the counterweighted crank is bearing longevity, and reliability long-term. If you run the non-counterweighted crank, you need to rebuild more often, and be very dutiful on your inspections.
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'69 911E coupe' RSR clone-in-progress (retired 911-Spec racer) '72 911T Targa MFI 2.4E spec(Formerly "Scruffy") 2004 GT3 |
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03-03-2006, 11:09 AM
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Quote:
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John '69 911E "It's a poor craftsman who blames their tools" -- Unknown "Any suspension -- no matter how poorly designed -- can be made to work reasonably well if you just stop it from moving." -- Colin Chapman |
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03-03-2006, 01:39 PM
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Registered
Join Date: Jul 2001
Location: Thunder Bay, ON
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No, I don't have the bearings, but they are available new from our host as well as others.
AM
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1970 911E - track / weekend car 1970 911S - under restoration 1986 930 Slant Nose - fun car |
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03-03-2006, 02:38 PM
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Try not, Do or Do not
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1st over bearings for a 2.2 crank are easy to find.
If done properly a first under crank should be no problem.
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Henry Schmidt SUPERTEC PERFORMANCE Ph: 760-728-3062 Email: supertec1@earthlink.net |
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03-06-2006, 07:57 PM
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1969 Porsche 911E 2.0 E
Porsche
Retor 911
Scarab
Riley
