C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Back from the dyno

Old Sep 18, 2005 | 05:33 PM
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Default Back from the dyno

Well, it was a good day overall, but not perfect. The bad news is that it looks like I need to replace the Opti (yay), I have a very bad missfire, so bad that the dyno graph cuts out 4300-5000rpm.

But there was some decent news...even with the huge miss, and only revving it up to 5800 it still put down 415RWHP and 390 RWTQ, so I'm not overly disappointed. The engine was built to rev to about 7000 and it really wants to get there!

So I'll replace the opti and go from there!

I have to hook my scanner up to get the graph scanned in, not sure if I'll have time to do it tonight or not, not really much to see though in terms of a problem as it's very apparent!!
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Old Sep 18, 2005 | 06:38 PM
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Very nice! It sounds like once the missfire is cleaned up the beast will really make you happy.
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Old Sep 18, 2005 | 07:13 PM
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Congrats
Sounds as if you had a similar problem as me the first time I tried to dyno tune my car. I had a dead miss at 3600 RPMs. It ws so bad the Dyno operator made me do the pulls because he didn't want to be responsile. It was crazy the thing would pull good backfire at 3600 then pull fine for the rest of the pull. I replaced the opti and it corrected the problem. Those are some good numbers, how was the A/F just to make shure it is a spark problem and not a lean missfire.
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Old Sep 18, 2005 | 07:41 PM
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415rwhp..... nice.....please tell us what mods you have done
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Old Sep 18, 2005 | 08:23 PM
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Very nice! It sounds like once the missfire is cleaned up the beast will really make you happy.
That's what I'm hoping for! If I'm lucky it's just the opti and nothing else

Congrats
Sounds as if you had a similar problem as me the first time I tried to dyno tune my car. I had a dead miss at 3600 RPMs. It ws so bad the Dyno operator made me do the pulls because he didn't want to be responsile. It was crazy the thing would pull good backfire at 3600 then pull fine for the rest of the pull. I replaced the opti and it corrected the problem. Those are some good numbers, how was the A/F just to make shure it is a spark problem and not a lean missfire.
The air-fuel during the runs was right at about 13.0:1-13.3:1 a little on the lean side but not by much. We pretty much figured that we should get the opti issue fixed and then work on the last bit of tuning. It sucks trying to tune a car that misfires this much!

415rwhp..... nice.....please tell us what mods you have done
I am happy with the results so far, the tuner thinks we can get another 25-35 HP out of it when it's running as it should, maybe more. Here's a quick breakdown of the engine;

All forged 383 LT4
11.2:1 compression
Heavily ported and worked LT4 heads and intake
242/252 duration .55x/.56x lift 110LSA cam
Electric water pump
TPIS long tubes
Corsa cat-back
LTCC LS1 coil kit
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Old Sep 18, 2005 | 10:28 PM
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Here's a scan of one of the dyno sheets, this was the second run we made. My tuner has the final run, but this one is pretty close, just a couple HP an TQ off...but it gives you a good look at the miss!


Last edited by Zix; Sep 18, 2005 at 10:38 PM.
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