High Rpm Boost taper?
High Rpm Boost taper?
Hey guys...I am having boost starting to taper from 21 psi down to like 16 or 17 Psi near or after 6000 rpm. With that being said I have an Xede computer, turbo back exhaust (no cat)...stock fuel pump, and a greddy Type S recirc valve.
I don't remember it tapering like this. I just recently ran an autocross (which i won my class and came in 3rd out of 70 overall) and don't know if anything could have changed there. I have found that my Greddy valve has a vacuum leak, but does not leak boost when its closed (unless it could somehow leak out of the vacuum line to the bov). I replaced a couple hose clamps and check the IC hoses and what not and haven;t found anything definite.
What I don;t understand is why the turbo would lose pressure at only high RPMS, but hold 21 psi solid all the way to 6000 rpm or so and then dip off so quickly. I know that there is some natural boost taper, and that stock cars do this on purpose, but the Xede is supposed to not allow that to happen.....anyone have any thoughts? thanks!
I don't remember it tapering like this. I just recently ran an autocross (which i won my class and came in 3rd out of 70 overall) and don't know if anything could have changed there. I have found that my Greddy valve has a vacuum leak, but does not leak boost when its closed (unless it could somehow leak out of the vacuum line to the bov). I replaced a couple hose clamps and check the IC hoses and what not and haven;t found anything definite.
What I don;t understand is why the turbo would lose pressure at only high RPMS, but hold 21 psi solid all the way to 6000 rpm or so and then dip off so quickly. I know that there is some natural boost taper, and that stock cars do this on purpose, but the Xede is supposed to not allow that to happen.....anyone have any thoughts? thanks!
yeah the more i think about it...it seems like even a little leak at higher rpms could have a pretty severe taper....from what I;ve read the turbo isn;t very efficient at high rpms...so i guess a small leak would have a more dramatic effect maybe?
Remember, depending on which map is installed in your Evolution, peak boost pressures should be between 20-22psi. Due to limitations of the factory turbocharger, boost pressure will taper noticeably towards redline. This means that, at 7000RPM, boost pressures may have fallen to 17-19psi. This is normal.
ahh...well that makes me feel a little better. I do have a small leak within the BOV so maybe one I fix that it will make the taper a little less. I'm trying to make a pressure tester, but I don't see any way that this thing is going to fit onto the intake side of the turbo. What is the size of the inlet that i would be attaching this too? I followed a guide on these forums saying 2.5" OD radiator hose with a 1.5 ID pvc end on one side. The 1.5" pvc barely fit...i actually have to cut a relief cut to get it to fit. Any ideas?
