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Discussion Starter #1
So trying to figure this out, just had the car on the dyno, and the new engine combination is off by 200 hp, at 14 psi from the old combination, and should've made more than the old combination. 383 sbc, twin vs racing 66/67 billet wheel, .84 t4 flange, air to air intercooler, Holley 4500 super sniper (efi throttle body), brodix Dragonslayer heads, 9.2:1 compression, basically the same short block and cam from the old combination. Things that the old combination had: brodix track one heads, cx racing 61 mm/.84 t3 exhaust housings, fitech 1200 pa(and also a qft blow thru 750, power output was within 20 hp between the pair). Power output with the old combination was 820 rwhp, at 15 psi. Power output with new combination, 620 hp, at 14 psi. New combination didn't see full boost until 5800 rpm, old combination was all in by 3500 rpm. Timing on both was set on the dyno starting at 26°, and final timing was 31° on both, using power output and the annealing mark on the ground strap, and using 112 octane. Old combination would gain 40 hp for every 2° put back in it, new combination didn't really see any gains (very minimal) from adding timing, but mark moved on the ground strap with addition of timing. Both engines ran 11.5 on wideband (Holley on one bank, Dyno on other bank, both within.1). Pulled all the plugs, everything is firing, all look normal, no evidence of misfiring. Ignition system is the same, msd pro billet, msd 6 digital programmable (the holley is running the timing, and the msd box has everything zeroed out), new pickup in the distributor, rotor phased, new cap and rotor and wires installed, new coil installed. So far I've also checked spring pressure on the new heads, air tested the system for leaks, verified cam timing, checked compression (160 psi cranking, same as old engine) no blowby out the valve covers, no oil burning, etc. So what gives with this? Sorry for the long post.
 

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I assume the timing was verified with a light in both cases?
How are the flow numbers of the two heads compared? Compression ratio verified with measuring?
Possible/practical to install the old turbos on the new combo to see if that is the thing?
Was a leak down also done? Perhaps a valve leaking?
Valve lash checked?
 

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Discussion Starter #6
I assume the timing was verified with a light in both cases?
How are the flow numbers of the two heads compared? Compression ratio verified with measuring?
Possible/practical to install the old turbos on the new combo to see if that is the thing?
Was a leak down also done? Perhaps a valve leaking?
Valve lash checked?
Both sets of heads cc the same, intake runner volume is 225 on both, the old track ones flow 246 @.600, Dragonslayer flow 300 @.600. timing was verified at 3 k rpm, with a timing light on the balancer vs what the ecm was showing, both match, and the annealing mark moved with the addition of timing. Valve lash has been checked before and after the dyno run. I just reringed the engine, it's got a couple of hours on it, no blowby out of the breathers on the run, or idle. Pulled a compression on one cylinder, 160 psi, which does match the old engine combination.
 

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The #8 plug looking different would be my #1 priority to chase down. Just because the plug (or wire or cap or ring seal or valves sealing etc.) is new doesn't mean it's good. I would leak down all 8 cylinders & roll all new plugs in it. Do you have O2 or EGT's in each cylinder?
 

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Discussion Starter #10
If all cylinders have spark and 160psi cranking, it should be making power.
Exactly, I don't understand why it isn't. Just pulled the timing chain cover Last night, and verified cam timing and it was spot on.
Did you try higher than 14 psi?
No, just went to 14, and that's the number im comparing from the old engine combination
 

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Discussion Starter #11
The #8 plug looking different would be my #1 priority to chase down. Just because the plug (or wire or cap or ring seal or valves sealing etc.) is new doesn't mean it's good. I would leak down all 8 cylinders & roll all new plugs in it. Do you have O2 or EGT's in each cylinder?
#8 plug just had one Dyno run on it, we were using that cylinder to set timing.
 

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Discussion Starter #12
The #8 plug looking different would be my #1 priority to chase down. Just because the plug (or wire or cap or ring seal or valves sealing etc.) is new doesn't mean it's good. I would leak down all 8 cylinders & roll all new plugs in it. Do you have O2 or EGT's in each cylinder?
I have 02 on both banks, were within.1 . I don't have egt unfortunately. If I had a ring seal issue wouldn't I have blowby coming out of the breathers?
 
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