Gradual boost creep by the end of a run

kidglok

Balls Deep
Joined
Oct 10, 2010
not a huge concern, but would like an explanation

when i start a run, the boost will peak at 21psi by the top of first, and end the run at 24.5 (there abouts)

With the ams1000, im targeting PSI at the gate (above spring pressure) so what this tells me is the pressure has remained constant throughout the run, because its electronically controlled. If the pressure at the gate rises, the controller will bleed off the excess, if it drops, it will allow more air at the top of the gate to maintain target.

so therein lies the question: How can the boost to continue to rise, even though there is a controlled amount of pressure at the top of the gate?
 

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The ex energy increases and the wastegate pressure didn't reduce at all or enough. Also if it reduced then the wastegate flow is inadequate. You have a turbo that will support 95lbs/min under ideal conditions. At 21psi with a small hyd roller you'd be lucky to see 65lbs/min on your engine. About 40% less than it could support. The energy needed to drive the compressor at it's current PR isnt much therefore the creep. The solution is to run re turbo harder or increase the wastegate bypass flow. To come close to even 80% of that turbos potential you will be around 30-32psi. If it were me I'd cam the engine to peak at 5900-6000 if I was trying to get use of that turbo. Possibly even more with those heads and smallish cam.
 
The ex energy increases and the wastegate pressure didn't reduce at all or enough. Also if it reduced then the wastegate flow is inadequate

so if the pressure at the gate is constant, then the wastegate is too small? (pw46mm)
 
Possibly but not necessarily. Its going to have to flow a lot if you are running way more turbo than you need which you are.
 
bison said:
Possibly but not necessarily. Its going to have to flow a lot if you are running way more turbo than you need which you are.

I understand what your saying, and believe me I'm not afraid to run 30psi. I am working up the boost slowly to see how she reacts first (as one should). And im not about to dial 28+ psi without knowing where the boost will end up.

So far it's made 600hp running the first half of the track at 21psi and less than 20* timing, are you saying I can do that on a ta49? :)

the thing is, id like to get an idea of where the car is at before i just throw boost at it, you know as well as anyone that can be a death sentence
 
Its making what it should. Once you get closer to the turbos mass flow potential you wont need as much wastegate. A TA49 woudlnt make the cut at the current level but a 60-1 would :). Id still consider more cam. It will help that turbo when you start to crank it up.
 
Its making what it should. Once you get closer to the turbos mass flow potential you wont need as much wastegate. A TA49 woudlnt make the cut at the current level but a 60-1 would :). Id still consider more cam. It will help that turbo when you start to crank it up.

lol i miss my 60-1 :(
 
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