Engine rebuild advice pls
Joined: Sep 2003
Posts: 3,361
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From: las vegas
Compression has to match the cam profile.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
Joined: Sep 2004
Posts: 4,894
Likes: 9
From: Tampa, FL
Originally Posted by S2oooNvegas,Sep 4 2009, 08:45 PM
Compression has to match the cam profile.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
For your power goals lowered compression is not a necessity. I'd leave the bottom end alone as well. Don't fix what isn't broken.
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Joined: Apr 2008
Posts: 227
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From: AZ
Originally Posted by spectacle,Sep 4 2009, 06:25 PM
For your power goals lowered compression is not a necessity. I'd leave the bottom end alone as well. Don't fix what isn't broken.
Leongalt, please solve the mystery as we have seen no numbers on your cylinder compression and HP numbers provided to you by your tuner. This information would be most useful to make a determination of block issues versus tune issues. On that note, have you contacted Chris @ SOS to get his thoughts on the proper CR for your kit?
B
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Joined: Jun 2007
Posts: 1,004
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Originally Posted by OKSTWOK,Sep 5 2009, 05:43 AM
Spectacle, I always enjoy your input in the FI forum but he has mentioned he is having issues with his compression readings on teh 100k+ block he is running.
Leongalt, please solve the mystery as we have seen no numbers on your cylinder compression and HP numbers provided to you by your tuner. This information would be most useful to make a determination of block issues versus tune issues. On that note, have you contacted Chris @ SOS to get his thoughts on the proper CR for your kit?
B
Leongalt, please solve the mystery as we have seen no numbers on your cylinder compression and HP numbers provided to you by your tuner. This information would be most useful to make a determination of block issues versus tune issues. On that note, have you contacted Chris @ SOS to get his thoughts on the proper CR for your kit?
B
We need more Info. As far Is this board goes there Is a ton of good info but when It comes down to It call a professional.
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Registered User
Joined: Jan 2005
Posts: 363
Likes: 0
From: Atlanta
Originally Posted by S2oooNvegas,Sep 4 2009, 04:45 PM
Compression has to match the cam profile.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
All those boosted cars referenced here mean nothing. They have cams specific to boost. This car has huge cams, and remember that drops the dynamic compression considerably, leaving no reason to drop compression at all.
hence all the s2ks hitting over 700 on unopened motor.
Leon your bottom end is likely perfect. Pull the head and inspect for scoring in the bore. if none, verify that it is the valve guides that have gone bad, which trashed the valve seats. Which is what will cause your high leakdown on several cylinders.
i say toss on the proflow head, use stock head gasket and bolts, add good management and boost up a storm.
Compression
1: 230
2: 230
3: 225
4: 232
Leak Down
1: 4%
2: 9%
3: 12%
4: 5%
Mods on car
Stock AP1 motor, Kpro, J's header, test pipe, 60RS exhaust, SoS throttle body, 3.4" pulley, Injector Dynamics 725cc.
Made 360 whp, 214 torque, perfectly flat 12.2 AFR. Boost was varying between 11psi and 13psi.
The car also eats about 1 quart of oil every 1000 miles. Any time I get on the throttle at all, huge clouds of black smoke out the tail.
It is very tempting to put the head on and go with it as is. If the bottom end is fine, I am not interested in touching it.
Thanks,
J
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