Yes, I am a bit of noob. My last high performance car was a 69 GTO Judge that I owned way back in the '80's. But here goes. I was hoping someone might have a clue as to why I'm missing about 30 hp by all accounts.
My 04 V sedan had long tube headers, 3" duals, and a K&N cold air intake installed. I took it to a tuner (Doc at EFI Alchemy in Green Cove Springs, FL...great LS rep) and when tuned it dyno'd at 374. I wanted to to go over 400, but stay below 450 until I could address the apparently questionable rear diff in these cars.
I spoke to GP Tuning about my hp desires and they hooked me up with a cam (intake .616/227 exhaust .616/234) and the associated BTR cam kit (platinum LS springs, titanium retainers, one piece chromoly push rods, etc). My tuner did the install and also added a trunion kit, GM high performance wire set, copper plugs (so he could gap them he said), Hypertech 180 thermostat, high volume oil pump, larger oil filter, new fuel filter and I had the clutch upgraded to the LS7. When tuned it dyno'd at 394 (93 octane gas). Only a 20 hp gain I've spoken to GP Tuning and was insured I got the right cam that should dyno (with a healthy engine and the other add-ons) at about 425. My tuner agrees that the car should be in the 425 range as well. My tuner mentioned low compression could be an issue, so I had that checked and the dry numbers are as follows;#1 225 #2 220 #3 220 #4 220 #5 223 #6 210 #7 220 #8 215. From my forum searches they seem a little high, but they are fairly consistent.
I'm sure it's near impossible to diagnose in the forums, but any thoughts/ideas would be appreciated. I'm taking the car to a Chin Track Days event at Sebring at the end of March (I CAN NOT FLIPPIN' WAIT!!!) and would like the hp Thanks in advance anybody/everybody!

 

I'd figure an LS6 motor with your cam would be 415-425rwhp on a dynojet so I agree the numbers seem a bit low (if they were produced on a dynojet). So the car was tuned on the same dyno both times? There are many variables when it comes to dyno readings even when using the same dyno at two different points in time so it could potentially be related to that. Do you know if the installer degreed the cam to spec? and measured for correct pushrod length to ensure proper lifter preload?

 

Yes, it was a dynojet.
I do not know that specifically, but he did have the cam spec sheet and swears the install was correct. I've attached the dyno sheets if that's beneficial.
Sweet Formula man!

 

Pushrods are BTR chromoly one piece, 7.4" long

 

Tuner did mention A/F ratio at 12.8/1 at 27 degrees timing.
"With air fuel at 12.8 to 1 and 27 degrees timing going up and down just to find the peak torque and horsepower I can't do anything else in the tune to "make" any more power. "

 

That happen to be a tick cam? Doesn't make sense that even after a cam swap your still pulling the same rpm you were before. i mean it obviously peaks more and higher and more tq sooner.. I mean Dyno's are Dynos I would see what it is doing at the track as well to really tell the difference. I would go with msd wires, not saying its going to get you where you want but those have been proven to perform, also get a 160 t-stat instead of 180.. 1 more thing, get an under drive pulley, that'll free up some power. I know your AFR is good but i would think you are getting really close to running out of injector. Good luck!

 

Thanks for the input!

 

yessir! Stock throttle body? a good ported one will help a decent amount due to mods and also the size of your maf.