To those running 1 bar

[G20_GTI-R]

Does your boost taper off in high rpm's? I hold 1 bar (14.7 psi) then it starts to slowly drop to about 11 psi in high rpm's. Is this just because the standard turbo is small?

 

[neil240z]

the T28 is strong enough to hold 1 bar throughout the rev range, the drop in boost could be due to a faulty actuator or cracked wastegate housing.

regards

Neil

 

[gtir bean]

mine drops off at high rpm with a stage 1 hybrid too.probably safar that way anyway.drops from 1.2 to about 1 near the red line.

 

[dan-hipgrave]

Yes mine does exactly the same. I put it down to having done the 1 bar loop, nut using a boost controller but maybe its not that afterall...

 

[stumo]

DanDuds' R holds 17psi all the way to the redline...

 

[neil240z]

you dont need a boost controller to maintain any decent amount of boost, a logical theory is that at high rpm, the gases flowing into the turbine housing from the manifold are putting such pressures on the wastegate that its closing the wastegate slightly reducing boost pressure, a stronger spring/uprated actuator should solve this problem.

regards

Neil

 

[G20_GTI-R]

Thanks guys, i'll have to look into that. I thought it might be my cheap manual boost controller but i guess not. Where can i score an uprated actuator for the t28?

 

[Rage]

HKS makes one that could fit. With an adjustable acturator bracket, so you can adjust the basic pressure on the turbo.

 

[neil240z]

yes rage is correct, HKS do do a like for like replacement and i think it is set to one bar, which means you dont have to run nasty bleed valves, if your running a bleed valve at the moment then when fitting an uprated actuator make sure you remove it and replace the hose.

Neil

 

[gtirx2]

Forge motorsport make a aculator for the R also.

 

[CruiseGTi-R]

Dropping to 0.7ish bar at high rpms from 1bar means something isn't quite right.

Don't need to run an HKS actuator for just 1 bar, spend your money on solving your problem.

 

[neil240z]

Dropping to 0.7ish bar at high rpms from 1bar means something isn't quite right.

Don't need to run an HKS actuator for just 1 bar, spend your money on solving your problem.

if you have a better idea on why the boost is dropping i would like to hear it, he could take his car to a garage and spend money and still not solve the problem, you are right that you dont need a HKS actuator to run 1 bar you can do it with a stock one and a bleed valve or boost controller but you can get spikes due to the weak (and weakend over the years) spring in the stock actuator, look into the forge ones as gtirx2 suggests, they will do the same job and likely to be cheaper.

on another note, test whether it only does this when hot and not cold (its not advisable to drive your car hard from cold) but it could also be hairline cracks around the wastegate housing, it happened on my 5 turbo, it ran 1 bar then one day i lost loads of power, so i checked the turbo found the cracks and swapped it for another one and it was flying along again, but if it holds boost up to 5-6k it wont be this.

regards

Neil