2008 LS3 A6 twin turbo issue

[HoP]

Good afternoon all,

I'm having a strange problem with a twin turbo vette. The mods are:

STS twin turbo kit
Tial Sport wastegates with 10lbs springs (no refference lines atm just mechanical for testing)
Stock LS3 with headers and hi flow cats (cats are good i have checked them for damage visually)
Comp Turbos A/R .62 ball bearing (brand new units)

The issue is that the car is supposed to have made 525 rwhp. On the dyno it is making just 377 rwhp and is only showing peak boost of 5psi at 6200 rpm's. Really down on power. I have disconnected the charge pipe from the intercooler to T body put a NA tune in it (just the timing map and PE table) and the car laid 340rwhp. I've checked the charge pipes for any kind of restriction or loose clamps and have not found anything, the exhaust is free flowing as well. I'm not sure if I'm having an internal problem with the trans, but according to the log I'm 1:1 with no slippage. Attached is the tune and most recent log for a wot run, I'd appreciate any feedback. Thanks!

[GHuggins]

Stupid question since I know you've been doing this a while, but you are dynoing this with a load applied aren't you or are you just getting your numbers on inertia only? Inertia won't allow the turbos to build "their" maximum boost. This also throws the fueling WAY off. THIS is why I only tune with loads applied now. Infact dynojet came out with an entire set of load profiles to plug into their dyno's for this reason, but even with all that being said, your still putting down less hp with 5lbs boost than most put down stock even on inertia only testing??? SO either somethings really dragging "on dyno or car" - have seen air not just right cause the dynobrake to drag, but you should be able to tell this - or you got something really wrong with this motor. Why were turbos replaced? On diesels I've seen mice nest go through the turbos killing the compressors only to show up at the shop with brand new air filters where this supposedly "just happened", then later you find the bits of compressor and mouse nest in the intercoolers... You can typically look at your vacuum readings at idle or boost at wot to point this way. Looking for high vacuum at idle if this has occured and low boost with throttle, just to clarify... The fact that you put in a NA tune and nothing really changed has me a little worried.

[Proxses]

At 6000rpm you have just over 2psi of boost, and only 14 degrees of timing there. So that's part of it.
But I am surprised at the 50+lb/min of airflow around there. That's around 500hp if all is calibrated correctly.

Something is definitely amiss. I also don't see air/fuel. No air and lots of fuel will kill power. But that's obvious.

[Force]

Your log is showing heaps of KR even though it is not high.

[HoP]

I log the AFR through the dyno wide band and AFR is 11.3:1

I've tried loading the dyno two ways: Super flow Auto dyne allows a few different methods of loading vs other dynos

1st - I hold the dyno at 65mph through the eddy current to build the onset of boost then I release the dyno so the vehicle can accel to red line.

2nd - I load the dyno at 10% for the entire run.

What I did find is that one of the turbos had an internal failure from manufacturing and it had touched down on the housing pretty badly. Replaced the turbo and made 570 rwhp. The KR that showed up was from gaping the plugs at .025. When I changed the gap back to .035 0 KR, strange ... I know.

[GHuggins]

I log the AFR through the dyno wide band and AFR is 11.3:1

I've tried loading the dyno two ways: Super flow Auto dyne allows a few different methods of loading vs other dynos

1st - I hold the dyno at 65mph through the eddy current to build the onset of boost then I release the dyno so the vehicle can accel to red line.

2nd - I load the dyno at 10% for the entire run.

What I did find is that one of the turbos had an internal failure from manufacturing and it had touched down on the housing pretty badly. Replaced the turbo and made 570 rwhp. The KR that showed up was from gaping the plugs at .025. When I changed the gap back to .035 0 KR, strange ... I know.

On dynojets load bearing dyno's you can plug in different load values at different rpms. Load curve winds up looking like a MAF curve, increases with rpms. I've got the templates for this if you can plug that into your dyno. I just happened to meet the guy who worked with dynojet in making these curves for different wind drags and weight coefficients of the vehicles. They're supposed to "simulate" loads applied to the vehicle as if it were actually driving down the road "wind drag and vehicle weight". It's my understanding that all of the newer dynojet operating systems have these "preloaded" into them now, for anyone upgrading their dyno's electronics.

I'm glad to hear you figured it out. SO it was a base engine issue? I thought the turbos were just replaced once already? Sure they're getting oiled right?