Dynamometer Results & Comparisons - Not making the power I want/expected - check my setup, anything wrong?

I was expecting this to make AT LEAST in the 450-465whp ballpark or even a little more and it didn't, was wondering if people can look over my mods and see what's missing if anything...

The car is a 99 Corvette 6MT with 4.10s. I will check the compression today and see if its ok, but the bottom end was freshly built (I crushed a valve spring, dropped a valve on my last motor and it crack the block, etc) so I don't think that's the issue.

Bottom End...
-stock 346 with new gaskets, all new bearings, etc.
-2.5cc reliefs fly cut in pistons
-Magic stick 4 camshaft
-Ported oil pump
-Powerbond 25% reduction pulley


Top End...
-TEA Stage 2 heads with PAC 1521s, stock lifters, rocker trunion upgrade with stock rockers - .040 milled = 60.9 cc chamber size = should give approx SCR of 11.1-11.2 to 1
-.040 headgaskets
-FAST 102mm intake mani ported by Vengeance Racing
-LS2 OEM fuel rails
-Cobra 39lb injectors with EV6 pig-tails wired in
-LS2 90mm T-body ported with tb harness adaptor
-Breathless intake and airbridge
-Truck MAF - Tuned with MAF only - MAP is shut off after 400rpm
-1 3/4 headers of unknown origin, got em with the car - has an x-pipe replacing where the cats would be, but its cut short and the factory h-pipe is welded to it with the factory cat-back


The car made 411whp with 26 degrees of timing in it up top, no knock at all with that, but it knocked with 27 degrees and didn't make any more power so we put it at 26 and left it. A/F was a smooth 12.5 throughout. We thought it might be the exhaust being a bit restrictive so we unbolted the X-pipe and made 431whp with the headers dumped open. Like I said I was expecting more and was wondering if there's something I'm missing.

*edited*

Data log the pulls??

Data log the pulls??

Data logged every pull, looked fine. No knock, nothing out of the ordinary.

Your mod list says just "TEA Stage 2 heads" ...how about a little more info? 241s? 243s? 317s? Leaving us in the dark there...also, what type of dyno. Mustang?

Your mod list says just "TEA Stage 2 heads" ...how about a little more info? 241s? 243s? 317s? Leaving us in the dark there...also, what type of dyno. Mustang?
TEA Stage 2 243s
Dyno isn't a factor

TEA Stage 2 243s
Dyno isn't a factor

The type of dyno does IS a factor. With no changes, a local guy went and dynoed on 2, made 40hp more on one than the other.

Sounds like the exhaust is holding it back, since it gained 20hp from it. Might be a little left on the table since it has less timing than usual and the AFR is on the safe side.

Go make a pass at the track, see what it traps. Stuffing a big cam with some nice heads isn't always a recipe for success.

The type of dyno does IS a factor. With no changes, a local guy went and dynoed on 2, made 40hp more on one than the other.

Sounds like the exhaust is holding it back, since it gained 20hp from it. Might be a little left on the table since it has less timing than usual and the AFR is on the safe side.

Go make a pass at the track, see what it traps. Stuffing a big cam with some nice heads isn't always a recipe for success.

The dyno I made 398 on the other setup is within 5hp of the dyno I used yesterday... 3 other cars all made within the same power (5hp) between the 2 dynos.

AFR is on the safer side, 27 degrees started getting 1/4 to 1/2 degree of knock and added no power - so we put it back to 26. if the exhaust is restrictive, that could possibly explain it a little - same with poor header design.

I'd expect more than 430whp with this setup even with open headers tho, can't imagine header design is THAT poor that it stifles the motor THAT much.

What kind of dyno?? Dynojet vs. Mustang vs. Dynocom...all makes a difference: especially Dynojet vs. Mustang.

You dont need two crossovers in your exhaust...pick the X or the H and ditch the other...get a 102mm TB to match the intake...That should help some...

have you checked the valvetrain? Pushrods correct length?

This is crazy. I have a 383 with patriot heads and the ms4 cam. I am only making 411 as well. My rear end is a 3.90. this is in a 1975 280z. I have ls6 intake and 3/4 headers. My baby cammed 346 made 405 hp/tq on the same dyno and same car. no with the bigger engine and cam im only making 6 more hp/tq. I have been looking everywhere to try to find a similar incident for a solution. Did you ever find out what was going on?

I really hope you aren't using injectors made for a DOHC engine... Could be a huge issue there...

http://www.youtube.com/watch?v=BdQeA77skuk

Just saying

Also gearing kills some hp because your doing the same amount of work in less time. The more time you have to the work (power) it will usually be about 10 to 15hp higher with a taller gear. So don't worry about the dyno too much. Run it at the track.

Like posted above I would be worried the injectors are spraying too far off center and not atomizing the fuel correctly.

What did you spin the motor too? Was the top of the graph rough? Can you post the graph?