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Old 01-12-2019, 01:31 PM   #76
adam99
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Originally Posted by ayau View Post
Thereís boost creep in the sense that boost is rising past 6k rpm instead of tapering down. It can still be possibly fixed by turning down the wastegate, but that may affect summer temp performance. Real boost creep is when wastegate is turned to 0, but the boost is still climbing. This is a mechanical issue.

The higher the boost and rpm, the more fuel is demanded. This is risky because if you run out of fuel, then your motor will go boom. This is where the IBR BRZ intake manifold with dual injectors would help.

I should clarify that there are compensation tables for intake temps and wastegate. Thatís why boost numbers are lower in the winter and higher in the summer. However, the rate at which the wastegate increases as rpms increases is the same, regardless of the intake temps. You can see it in the 2 logs.

It seems like Cobb doesnít allow you to have a different wastegate curve depending on intake temps, or maybe the tuner never bothered to set a different curve. For example, at 60F, wastegate could be 2/1 (rise over run). In 20F, wastegate could be set to 1/1.
Youre exactly correct, there is a WGDC Intake compensation table but you cant adjust curve as in tapering it down at higher rpms for cold weather unless you tapered down the original values (affects summer performance). The compensation targets a percentage and multiply's that to the set WGDC. Your cold weather boost curve looks normal and pretty fun. 15 psi across with a **** load of timing.
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Old 01-12-2019, 01:53 PM   #77
ayau
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Originally Posted by adam99 View Post
Youre exactly correct, there is a WGDC Intake compensation table but you cant adjust curve as in tapering it down at higher rpms for cold weather unless you tapered down the original values (affects summer performance). The compensation targets a percentage and multiply's that to the set WGDC. Your cold weather boost curve looks normal and pretty fun. 15 psi across with a **** load of timing.
Yeah it just pulls all the way to redline lol. I try not to do it too much since I worry about running out of fuel.

I asked Ron about injector duty cycle % limits this and he said:

"there really is no warning....its fine until its not

pump gas is 35-36% where most cars will start to stutter/hesitate and misfire

ethanol is around 40-42%"

Keep in mind he also said (not posted here) that these are really rough numbers and will depend on temp, altitude, humidity, etc etc. If you want to be safe, it's best to keep boost below target and tapered down.
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