is this feasable??
07 November 2002, 07:32 PM
#1
Having trouble with boost climbing at high revs
HKS system & DP fitted. The downpipe is a closed neck type.
What I'm thinking (coz i've tried all else!) is that my downpipe is causing the boost to climb.
My theory is that the gases from the turbine wheel in the exhaust housing are flowing better than the gases from the wastegate (when open)
I say this coz the actual pipe (of downpipe) is in line with the turbine wheel and the wastegate is covered by the flat surface of the plate of the downpipe where it bolts to the turbo.
Therefore all is relitively normal in boost level until 5,000rpm plus where the extra gas flow is gonna speed the turbo up and the boost is gonna 'creep' up! This I'm thinking wouldn't happen in an open neck or twin dump DP as the flow of exh gas from wastegate wont be interrupted.
How's this sound?
I'm gonna put the standard DP on this weekend and see!
James ( working it out slowly, and learning
)
HKS system & DP fitted. The downpipe is a closed neck type.
What I'm thinking (coz i've tried all else!) is that my downpipe is causing the boost to climb.
My theory is that the gases from the turbine wheel in the exhaust housing are flowing better than the gases from the wastegate (when open)
I say this coz the actual pipe (of downpipe) is in line with the turbine wheel and the wastegate is covered by the flat surface of the plate of the downpipe where it bolts to the turbo.
Therefore all is relitively normal in boost level until 5,000rpm plus where the extra gas flow is gonna speed the turbo up and the boost is gonna 'creep' up! This I'm thinking wouldn't happen in an open neck or twin dump DP as the flow of exh gas from wastegate wont be interrupted.
How's this sound?
I'm gonna put the standard DP on this weekend and see!
James ( working it out slowly, and learning
)
07 November 2002, 08:16 PM
#2
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Join Date: Nov 2001
Location: Leeds - It was 562.4bhp@28psi on Optimax, How much closer to 600 with race fuel and a bigger turbo?
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so why doesnt the std do that then??
Its something else.. (is the rest of the car std?)
Its something else.. (is the rest of the car std?)
07 November 2002, 09:04 PM
#3
Yeah ok I was having a mad train of thought
I thought it sounded goodIt's sorted now
Basically when I asked bout where to put the Dawes someone said 'put it in a pipe between compressor housing and actuator, short route, no boost solenoid'
This has been the problem, when I took the Dawes out to test without I left a single pipe between the compressor housing and actuator only. For some reason the boost climbs at the top of the revs like this, I can't see why but I'm sure I'll work it out, prob something to do with actuator opening too early and then the gas flow at high rpm raisng the boost to where it would normally come in at 4,000rpm.
Don't you 'Dawes users' out there get this problem with it between actuator and compressor??
Put the solenoid back on, no Dawes but preloaded the actuator, recorded overboost of 1.03bar (it's very cold out) and it's holding about 0.90bar
and it flies!Do I need the Dawes? I don't think so, but i've heard people not liking preloading the actuator too much but I always done it on my cossies.
Can I get an uprated actuator?
What do you 'Dawes haters' use to raise the boost?
What a prat eh? lesson learn't, at least I'm smiling again
James
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