Alternator Grenade
Thread Starter
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
The guy I work with keeps forgetting to bring it in, but when I get it I'll give it a try. My concern is the large valve covers that I have on the engine. There is barely any room behind the CS130. My brother has another old CS130 to hold me over until I find something better.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
My brother built it and said it's good for 8000 rpm, but with my current intake and exhaust, I'm not sure if it goes all the way to 8000. My tach only goes to 7000 and it easily pins it. Engine:
Block .040 over to 385 Stroker
Scat nodular crank 3.75" stroke
Keith Black Hypereutectic pistons
Block .040 over to 385 Stroker
Scat nodular crank 3.75" stroke
Keith Black Hypereutectic pistons
KB Hyper pistons are feet per second limited. (stroke length X RPM)
KB's are intended for lower rpm 350 ci. Your longer stroke 385 will exceed their design limits at an even lower rpm. If you don't believe me call them up.
Thread Starter
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
I would probably install a milder cam and sell the motor while it is still running because of these two items.
KB Hyper pistons are feet per second limited. (stroke length X RPM)
KB's are intended for lower rpm 350 ci. Your longer stroke 385 will exceed their design limits at an even lower rpm. If you don't believe me call them up.
KB Hyper pistons are feet per second limited. (stroke length X RPM)
KB's are intended for lower rpm 350 ci. Your longer stroke 385 will exceed their design limits at an even lower rpm. If you don't believe me call them up.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Altering the output capabilities of an alternator will have nearly zero affect on the RPM limits of the unit, totally separate issue.....
if anything, you maybe want a larger alt pulley , typically they are 2" so maybe 2.5 inch would help on that high RPM stuff, maybe even 3"
then you will have output troubles at lower RPM/idle will have to be closer to 1000 rpm in order to charge,
if anything, you maybe want a larger alt pulley , typically they are 2" so maybe 2.5 inch would help on that high RPM stuff, maybe even 3"
then you will have output troubles at lower RPM/idle will have to be closer to 1000 rpm in order to charge,
Pro
Joined: Apr 2009
Posts: 650
Likes: 1
Mike80,
After looking at the photos of your engine, really nice motor btw, and seeing the small pulley on your alternator I'm convinced that your alternator failed from rpm and not heat. I feel fortunate that you started this thread because I have the same alternator and pulley as you do in your photo and the solid roller motor I just purchased will also tickle the 8000rpm limit. I never even considered an alternator failure like this one and now you can guarantee I will be adding a larger pulley to mine. I put the small pulley on when I had my last motor to keep the alternator spinning at idle to support Dewitt's fans, stereo, etc. Now with fuel injection I'm hoping that my idle will be a little more manageable. Good luck with the alternator replacement.
After looking at the photos of your engine, really nice motor btw, and seeing the small pulley on your alternator I'm convinced that your alternator failed from rpm and not heat. I feel fortunate that you started this thread because I have the same alternator and pulley as you do in your photo and the solid roller motor I just purchased will also tickle the 8000rpm limit. I never even considered an alternator failure like this one and now you can guarantee I will be adding a larger pulley to mine. I put the small pulley on when I had my last motor to keep the alternator spinning at idle to support Dewitt's fans, stereo, etc. Now with fuel injection I'm hoping that my idle will be a little more manageable. Good luck with the alternator replacement.
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Thread Starter
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
Thread Starter
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
I would probably install a milder cam and sell the motor while it is still running because of these two items.
KB Hyper pistons are feet per second limited. (stroke length X RPM)
KB's are intended for lower rpm 350 ci. Your longer stroke 385 will exceed their design limits at an even lower rpm. If you don't believe me call them up.
KB Hyper pistons are feet per second limited. (stroke length X RPM)
KB's are intended for lower rpm 350 ci. Your longer stroke 385 will exceed their design limits at an even lower rpm. If you don't believe me call them up.
Melting Slicks
Joined: Apr 2000
Posts: 3,341
Likes: 6
The other accessories are vulnerable to over-speeding, too, so don't be surprised if there are more problems down the road.
Last edited by 45ACP; Mar 22, 2012 at 01:21 PM.
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
I spoke to Marco from KB Pistons and he said that he didn't know where you got that information, but they use those pistons in many 383 engines with no issues, many have several thousand miles on them. He said if I had valve failure and something came into contact with the piston, it would shatter. He said I could switch to forged pistons, if I plan on spending a lot of time at the track, but they wear faster and do not last as long for street use which is my main use.
Le Mans Master
Joined: May 2002
Posts: 5,084
Likes: 786
From: Lebanon Township New Jersey
When you describe the crank as "nodular" I assume you mean nodular iron. If that's the case, with a hydraulic lifter cam, hypereutectic pistons and an iron crankshaft, I think you'll be pressing your luck revving to 8,000 rpm.
Le Mans Master
Joined: Jan 2006
Posts: 6,504
Likes: 139
From: Butler Pa
Thread Starter
Drifting
Joined: May 2005
Posts: 1,968
Likes: 44
From: East TN
Gkull said "Your longer stroke 385 will exceed their design limits at an even lower rpm." So, I just wanted find out from them if I should be concerned.
Last edited by MIKE80; Mar 22, 2012 at 03:30 PM.
