boost creep vs turbine housing AR

[DaveH]

My experience.... I have 11 psi wastegates. With a 1.08 a/r I could run as low as ~17 psi. I changed to a 1.39 a/r and now I can run as low as 15 psi. So, I would say the larger a/r helps with boost creep.

[integra_gsr98]

increase in AR.

[PSI2HI]

Where's the neither option? Both have decreasing benefits in their perspective applications.

Smaller AR creating backpressure it going to kill poweroutput/powerband and lower the effiency, thus creating heat, and large AR is is also going to midrange poweroutput/spool.

I vote C. Make the wastegate work correctly in its current application.

[SPANISH-RICE]

psi2hi;286299 wrote:
where's the neither option? Both have decreasing benefits in their perspective applications.

Smaller ar creating backpressure it going to kill poweroutput/powerband and lower the effiency, thus creating heat, and large ar is is also going to midrange poweroutput/spool.

I vote c. Make the wastegate work correctly in its current application.

for a lack of better words i agree with this. Get a properly matched waste gate and solve boost creep with that. If you're having issues with boost creep instead of swapping housings get a bigger waste gate/dump tube that can flow enough.

I think argument a is very incorrect tho. Increasing back pressure before the turbo isn't making the waste gate more efficient its just making it work harder and have to flow more.

[weshole]

If I had to choose, it would be to increase the Ar. But I do agree with Tufte. Making extra backpreesure at the turbo is <u>never</u> good for efficiency and of course the turbo itself.

[zbrown]

PSI2HI;286299 wrote:
Where's the neither option? Both have decreasing benefits in their perspective applications.

Smaller AR creating backpressure it going to kill poweroutput/powerband and lower the effiency, thus creating heat, and large AR is is also going to midrange poweroutput/spool.

I vote C. Make the wastegate work correctly in its current application.

SPANISH-RICE;286302 wrote:
for a lack of better words i agree with this. Get a properly matched waste gate and solve boost creep with that. If you're having issues with boost creep instead of swapping housings get a bigger waste gate/dump tube that can flow enough.

I think argument a is very incorrect tho. Increasing back pressure before the turbo isn't making the waste gate more efficient its just making it work harder and have to flow more.

Obviously i know that other changes would be more beneficial.... This was strictly a philosophical question of if you could only change the turbine housing AR; NOTHING else.

which change by either going bigger or smaller would help with the problem

[funky_monkey58]

+1 on a properly suited waste gate,and if need be run two or more.

[SPANISH-RICE]

zbrown;286315 wrote:
obviously i know that other changes would be more beneficial.... This was strictly a philosophical question of if you could only change the turbine housing ar; nothing else.

Which change by either going bigger or smaller would help with the problem

bigger

[Parker]

Some people need to learn how to read..... Wow.....

[TsiTom]

Based on the question, I say increase it

[Grr]

wow, what a dumbass, increase of course

[Bookem]

Bigger is always better, no matter what...................

[zbrown]

Ok gone on long enough

I had argued that increasing would, for the above reasoning

the other FS member argued decreasing it would for the above reasoning

not gonna say who it was unless he wants to say something or argue his logic here in this thread

[DrifterExtreme]

haha, i will say i was wrong based on your response's. but i still think for the car me and zac talked about. it would have fixed the problem. but might be bad if generalized for every situation.

[Parker]

so, what car?

[DrifterExtreme]

it was a civic with a ls motor. running a afi turbo kit, 57 trim 60/63, v-band 38mm gate.

guy was trying to run 7 lbs and was creeping to 10-11 lbs. Also he is running stock redline 7200 and map sensor.

So i had mentioned switching to the small a/r as it will spool sooner and help wastegate flow. all the larger housing will do in this case is slow down the turbine and increase lag.

So there might be 2 ways to go about solving the problem. but in this case i think the smaller a/r is the way to go.

still think it is crazy it makes 4 psi without the wastegate on at all.

[DelSlow]

What car was that? Honda-Tech?

[DrifterExtreme]

yes it was on honda-tech

[SPANISH-RICE]

drifterextreme;286402 wrote:
still think it is crazy it makes 4 psi without the wastegate on at all.

that has some serious flow issues through that wastegate elbow then. Thats nuts

[DrifterExtreme]

funny thing is it is a afi ramhorn. pretty standard manifold. so i think this guy is smoking crack, or something is up