LS Build: In Progress
04-02-2019 | 06:31 AM
#191
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Posts: 3,599
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From: taxachusetts
pretty damn good,,way back when,,I had my oval port,single plane,9.3-1 comp,230/236 ls110 454 made 527hp,517tq.I love the light power plant you have.my tq curve was pretty flat to,2 tq peaks at 4100 and 5200 rpm.
04-02-2019 | 09:22 AM
#193
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Posts: 11,332
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From: chicago
FWIW, I wouldnt reduce the intake duration anymore than it already is. I would add exhaust duration, like at least a 10* split, maybe even a little more due to those heads. I agree that your lack of exhaust flow, from the port itself, and the exhaust valve duration, is hurting top end power. Sure it may lose a little down low, but I think it will more than make up for it up top. Right now, that powerband is typical of a 1990s mercury HP500 engine. By going from 5200, to 5800, youre gaining a whopping 11HP over 600RPM. The engine is dying off, and the BSFC's show the ineffiency there. I'd expect the problem to be worsened, had it been dynoed with a marine manifold like a stainless marine. One of the nice things about an LS, is its valvetrain. Seems like a waste to run it where a old big block has proven to live hundreds of happy hours without issue.
Youve got a 10.8:1 compression engine there, throw some cam at it. Worried about reversion, convert the tails to dry, drill in a couple pizzer holes at the ends, and run some mufflers or turn downs.
If youre dynoing with pump gas, and it likes the timing, to the tune of 14HP more on top, I'd run that. The engine is telling you what it likes. Its telling you that you were firing the plug at the right time in the combustion process. Im more worried about timing advance in the lower rpm range. Almost every engine i've datalogged watching things like spark knock/short term retard, has almost always happened in the lower to mid rpm. Rarely does it occur at peak hp area. Firing the plug later, on a marine engine, can be detrimental just as firing it too soon. It puts a ton of heat into the exhaust valve, and itself can cause detonation, tuliped/fatigued valves, etc. In a car, that only sees full throttle blasts for short times, the heat buildup from retarded timing isnt all that great. A boat engine, that may be held WFO for 10 minutes, I'd rather keep the combustion events going like a swiss watch.
Great build, thanks for sharing the results, looking forward to the cam swap results.
Youve got a 10.8:1 compression engine there, throw some cam at it. Worried about reversion, convert the tails to dry, drill in a couple pizzer holes at the ends, and run some mufflers or turn downs.
If youre dynoing with pump gas, and it likes the timing, to the tune of 14HP more on top, I'd run that. The engine is telling you what it likes. Its telling you that you were firing the plug at the right time in the combustion process. Im more worried about timing advance in the lower rpm range. Almost every engine i've datalogged watching things like spark knock/short term retard, has almost always happened in the lower to mid rpm. Rarely does it occur at peak hp area. Firing the plug later, on a marine engine, can be detrimental just as firing it too soon. It puts a ton of heat into the exhaust valve, and itself can cause detonation, tuliped/fatigued valves, etc. In a car, that only sees full throttle blasts for short times, the heat buildup from retarded timing isnt all that great. A boat engine, that may be held WFO for 10 minutes, I'd rather keep the combustion events going like a swiss watch.
Great build, thanks for sharing the results, looking forward to the cam swap results.
04-02-2019 | 10:17 AM
#194
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From: San Tan Valley AZ
with this current setup I would utilize the single plane. He said that he had no STOCK hp500 or 525 efi sheets as most people that go on the dyno have built engines. I do however have a sheet of a 525sc that was done recently losing its ass on the same dyno
04-02-2019 | 10:35 AM
#195
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From: San Tan Valley AZ
FWIW, I wouldnt reduce the intake duration anymore than it already is. I would add exhaust duration, like at least a 10* split, maybe even a little more due to those heads. I agree that your lack of exhaust flow, from the port itself, and the exhaust valve duration, is hurting top end power. Sure it may lose a little down low, but I think it will more than make up for it up top. Right now, that powerband is typical of a 1990s mercury HP500 engine. By going from 5200, to 5800, youre gaining a whopping 11HP over 600RPM. The engine is dying off, and the BSFC's show the ineffiency there. I'd expect the problem to be worsened, had it been dynoed with a marine manifold like a stainless marine. One of the nice things about an LS, is its valvetrain. Seems like a waste to run it where a old big block has proven to live hundreds of happy hours without issue.
Youve got a 10.8:1 compression engine there, throw some cam at it. Worried about reversion, convert the tails to dry, drill in a couple pizzer holes at the ends, and run some mufflers or turn downs.
If youre dynoing with pump gas, and it likes the timing, to the tune of 14HP more on top, I'd run that. The engine is telling you what it likes. Its telling you that you were firing the plug at the right time in the combustion process. Im more worried about timing advance in the lower rpm range. Almost every engine i've datalogged watching things like spark knock/short term retard, has almost always happened in the lower to mid rpm. Rarely does it occur at peak hp area. Firing the plug later, on a marine engine, can be detrimental just as firing it too soon. It puts a ton of heat into the exhaust valve, and itself can cause detonation, tuliped/fatigued valves, etc. In a car, that only sees full throttle blasts for short times, the heat buildup from retarded timing isnt all that great. A boat engine, that may be held WFO for 10 minutes, I'd rather keep the combustion events going like a swiss watch.
Great build, thanks for sharing the results, looking forward to the cam swap results.
Youve got a 10.8:1 compression engine there, throw some cam at it. Worried about reversion, convert the tails to dry, drill in a couple pizzer holes at the ends, and run some mufflers or turn downs.
If youre dynoing with pump gas, and it likes the timing, to the tune of 14HP more on top, I'd run that. The engine is telling you what it likes. Its telling you that you were firing the plug at the right time in the combustion process. Im more worried about timing advance in the lower rpm range. Almost every engine i've datalogged watching things like spark knock/short term retard, has almost always happened in the lower to mid rpm. Rarely does it occur at peak hp area. Firing the plug later, on a marine engine, can be detrimental just as firing it too soon. It puts a ton of heat into the exhaust valve, and itself can cause detonation, tuliped/fatigued valves, etc. In a car, that only sees full throttle blasts for short times, the heat buildup from retarded timing isnt all that great. A boat engine, that may be held WFO for 10 minutes, I'd rather keep the combustion events going like a swiss watch.
Great build, thanks for sharing the results, looking forward to the cam swap results.
Last edited by mggdoors; 04-02-2019 at 10:42 AM.
04-05-2019 | 03:35 PM
#196
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From: San Tan Valley AZ
The more and more I look at this dyno chart it makes me question the cam timing. I had a buddy install the cams and am questioning his install at this point. The way the power falls off at 5400 and hangs out tells me we are either way advanced or retarded. Comparing to a 236/236 we did (almost identical) it pulled through and peaked at 6400. Time to play doctor before we throw another cam at it
04-05-2019 | 07:43 PM
#198
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From: San Tan Valley AZ
For now yes. But nowhere close to where it should be. I firmly believe cam timing on the install is out of whack. Falling off wayyyyyy to early. Will have an answer possibly tonight. The graph tells me its advanced too much most likely Especially seeing that the dual plane and single plane are matching up on the torque curve at lower rpm. Something is definitely wrong. Definitley definitely wrong.
Last edited by mggdoors; 04-05-2019 at 07:46 PM.
04-05-2019 | 08:16 PM
#200
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From: San Tan Valley AZ
Different engine. Ls3 heads stock. 408. 10.5 comp. 950 carb. Same ignition. Vic jr intake(almost identical to tfs). Was a turbo cam but dynod initially without turbo. Ran awesome. Way more power than this. Also works good with restrictive exhaust and backpressure like my situation hence why we went this way rather than compounding the issue with overlap from the split thus creating exhaust AND intake reversion. Plus the single pattern generally give better mid range torque where my boat lives 90% of the time.
Last edited by mggdoors; 04-05-2019 at 08:23 PM.
