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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.

You said that you may have data on a 525 ran on the same dyno? Were you able to get those?

So what Intake have you decided to go with?

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.

Quote:

Originally Posted by Wildman_grafix (Post 4679980)

You said that you may have data on a 525 ran on the same dyno? Were you able to get those?

So what Intake have you decided to go with?

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

Quote:

Originally Posted by MILD THUNDER (Post 4679998)

Yes the exhaust restriction is definitely hurting me espeially up top. I seen it the very first run and have to admit underestimated how bad it is. Figured it would hurt me but more around 6300. It starts in way sooner. Reasoning for smaller cam, which you will notice was the original way I planned on going, Is to maintain reversion free and be able to add split 10-15 degrees. In a perfect world I would be running a 235/250 114 but that cam would revert so bad I wouldnt be sble to boat. I Really dont want dry exhaust, especially on my daytona. It was cool for about an hour the first time running on sunny but hated it after that. I have two tig welders, cold saws etc so it wouldnt take crap to fab up. I know I could go mufflers but not worth the investment or hassle to me Unless they are internal. Im working on a single plane specific stroker profile now. Will update soon

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 ithttps://cimg3.ibsrv.net/gimg/www.off...f945290fe.jpeg

Seems to be close to on par with a merc 500efi

Quote:

Originally Posted by Crude Intentions (Post 4680532)

Seems to be close to on par with a merc 500efi

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.

Was the 236/236 cam in the same engine? Same cube/stroke?

Quote:

Originally Posted by MILD THUNDER (Post 4680540)

Was the 236/236 cam in the same engine? Same cube/stroke?

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.