So I recently installed the ewg wires and had the stinger tuned professionally. Currently I'm hitting in the neighborhood of 25 to 27 lbs of boost in comfort mode. Curious what others are seeing. Mods are cold air intakes, turbo back exhaust, meth injection, jb4 with fuel wires and ewg.
If you dont have head studs you are going to experience head lift if you havent already. I dont know what professional tuner you used but they may have already grenaded your engine.
Hopefully not. I turned the tune back down after initial post. Car seems to be running strong. Planning on going to a different tuner at some point with a boost limit in mind.
Does anyone have specifics on head lift? I've seen plenty of references to it, with people claiming 22, 24, 25psi as limits, but haven't seen any firsthand accounts or shops weighing in and would like to find them, if only for peace of mind.
I'm assuming that if legit outfits like @Terry@BMS are selling CPI, WMI, and HPFP kits good for say 550 lbs-ft without a warning that you need head studs means they haven't seen issues (on properly running cars etc), but I'm curious how much breathing room we have. @AWDGT2 anything you could point to?
I'm definitely not the SME but lifting heads is getting popular. As we push these cars harder and harder, and as they age, it's bound to happen. From experience, anything over 22.5 to 23 psi all the turbos do is blow hot air, they are not efficient past that point. Hundreds of guys have hit that with no issues and yet some weren't so lucky. Tolerances in head bolt torque at factory? Tolerances on the actual bolt? I've seen sketchy ECU tunes that spike and have caused a stretched bolt too. Also, don't confuse torque/HP of the motor with how much boost the car can take. While one car can hit 500hp on 20 psi, another may only hit 475. Factors like timing, fuel, inlet air temps, even weight of the rims on the dyno will affect the final numbers.
Thanks @AWDGT2. I was using peak torque at shorthand for the cylinder pressure that actually lifts heads...I know turbo psi is a couple steps removed, but with the same turbos and all else equal it seems like a reasonable proxy.
Do you have any examples you can point to, to see what combinations of factors were at play? IE is it just guys cranking more boost from piggybacks without other mods, knock from turbos blowing hot air, guys running E60 via CPI, etc.
The max I see on Map 5 is 20 psi, running E30 with no signs of timing pull or fuel crash, so I'm assuming there are enough guys with 50-75 more hp (via CPI, WMI, or more aggressive piggybacks) that I don't need to be concerned, but don't want to make a bad assumption if (for example) sudden unexpected knock is the bigger threat.
Running CPI or higher E contents is actually safer than guys running 91/93 due to higher octane levels. Knock can come from two things, and at times they are directly related. One is not enough octane and the fuel pre-detonates as the piston is coming up. The other is the flash the ecu is running has aggressive timing. The second sets the conditions for early detonation and the need for octane is even higher to protect the motor.
There are lots of guys that have stretched heads. Some won't talk about it, some will. They all have their own story, their own theory, their own excuse, ect. I will tell you none of them did it with 22 PSI. Almost all had a flash of some sort, and if they had the JB they were running a Map6.
If you set your boost safety for 24, run either Meth or CPI with a safe 22 PSI (Max) you should be just fine. If you have a high timing flash like 20 deg (instead of the 17ish stock), I would keep it at 20 PSI max. Both combos have the potential to run very low 11's or even 10's with weight reduction.
I'm sorry I don't have a "don't do this or this will happen" for you. Best to post logs and get advice from your log, with your mods and go from there. I hope that makes sense.
Ok thanks again -- I understand cars vary and there's no bright line where you go from safe to catastrophe, but it's good to have some additional color on the conditions where things get risky.
I think I've seen 18 degrees before, but my saved logs on map 4/5 max out at 20psi and 15-17 degrees (piggybacks don't alter this right?), on E30-35 with no cyl2-6 corrections, and that was at 75-80 degrees. Guess I should run a few in the winter weather to see if boost changes, but knock shouldn't be a worry.
Correct, the piggy back can't change timing. The thing that gets even more fuzzy is our adaptive ECU's. Several factors determine what that ECU will do. Ambient temps, barometric pressure, inlet air temps, ect. None of which we can control. That's why a good log scrub helps a ton.
