From everything I've been able to dig up, it seems that a stock G37 coupe on a mustang dyno should run somewhere between 260-270hp. I recently had a few dyno runs conducted last week just to determine where the car is currently sitting and to compare to additional runs once I have my remote tune completed. I have a video of the runs and results that I'll post in my build thread.

All in all, the final numbers came out to 272hp and 208tq, which seems extremely low with all the mods I have installed even without a tune. So, unless there is something catastrophically wrong with my car, (which they said they everything seemed healthy, no knock, no misfire, etc.), or the excuse they gave me is the factory tune on the ECU is fighting to keep everything within OEM parameters is a true statement. Just wanted to see if anyone else had experienced this, if I'm being paranoid, or the shop is joshing me around. Thanks!

 

Did they datalog anything? I'd like to know your long term fuel trims and how far the ECU is advancing timing. The stock ECU can compensate for a lot, but that doesn't give it a lot of overhead for mods performance increases.

Also depends on your transmission - if you search on here there's a few threads early on of baseline dyno pulls.

For reference - my car, 75k miles, 6MT trans, VQ37 with G35 upper manifold, long tube cold air intakes, FI resonated cats and resonated 2.25 catback and a Z1 ECUTek tune = 314 RWHP. Baseline with those mods was like 290 something.

 

No datalogs, I asked if they could tell me how the A/F ratio was looking and they said they couldn't "see" any of that, only power and torque. Also a 6MT here with only 55k miles and mods are Z1 race filters, Stillen G3 CAI, aFe TB spacers, Ported Upper Plenum, Ported Lower Manifold, ISR LTHs, Z1 y-pipe, Z1 Cat-back. Were your numbers also from a Mustang Dyno?

 

Not sure what the Z1 garage uses - I think so since they do AWD cars. I couldn't do an e-tune since I have larger AFM housings - those need to be calibrated on a dyno specifically.

With headers and your other mods you should see more power than that IMHO, even without a tune, unless the ported manifolds are too much for the ECU to handle in terms of adjustment.

I'd get an OBD2 dongle appropriate for your phone, the right app (I use OBD Fusion on iPhone) and do some normal driving datalogs and then spirited/highway high speed run datalogs. Something is up there.

When's the last time you had your injectors cleaned? What about the evap canister valve recall?

Edited to add: From my post way way ago, with the mods described 314 HP and 273 TQ. From my post: From looking on the web, it seems like the driveline loss is between 13 and 16% so that means 355-364 HP and 308-316 ft.lbs. Not too far off the Z1 400 HP package that also includes headers and test pipes.

I've since moved to a 2.75ID intake setup that is the same diameter filter to manifold. No idea if that helps (would only help if the smaller intake was starving the engine a bit).

 

I'd imagine your numbers are from a Mustang Dyno as my car put down 298 on a DynoJet with only the CAI installed. I cleaned the injectors less than 1000 miles ago when I had them out to install the lower manifold. I don't ever recall doing anything with the evap canister valve, though I haven't had any CEL or other codes until after I installed the LTHs.

All the stuff I need for the remote tune should be on the way, so hopefully when I talk to the tuner (who is not from this shop), they should be able to see what's going on.

 

Wanted to add: Since I have the VQ35 manifold, my HP peak will be lower than otherwise (trade off is higher torque in the middle of the curve). IMHO you should be at like 375-380 flywheel (adjusted for drivetrain loss) since you're at 95% of the Z1 400-HP kit in terms of mods.