hi guys
i have 20 pounds of boost untill abt 6k or so, by 7200rpm i have 17 pounds....
i cant figure out why....i have no boost leaks, i have a manual boost controller mounted by the radiator......
basically my setup is a buschur stage 4 on pump gas.....
any suggestions?
thanks

 

wastsgate, even Buschur can't hold boost. spike to 24 then levels at 21-22psi on pump gas

 

I experience around the same thing.. though its around 18psi.. I think it may be a limitation of the stock turbo or the wastegate. In my case, I'm still running a stock blowoff valve so I was convinced it was what was leaking boost.

 

if you run the HKS EBC EVC setup you will maintain boost better. most everyone has some boost drop. usually just turn the MBC up to 21 then peaks for a second but drops to 19.5 to 20 pretty well. most vary by 1-2 pounds of boost. also i wonder how accurate some gauges are when your talking about 1 lb of boost out of 20.

 

With an E-01 you can maintain it flat as you can do an RPM based boost offset. YOu can do the same thing with an AVCR. I do not think any other boost controllers do that.

 

I think he's running more into the bottleneck of the stock cast manifold than the actual turbo itself. With an equal length header on my car (stock turbo), I still get 21psi at 7800rpm. The tubular 02 housing may also help a bit.

 

interesting......so from what i gather, with my current setup, it is normal to lose 2-3 pounds of boost by redline??
i dont have the funds right now, nor really the desire to sink too much more into this car...
well, at least not for now...

 

just curious to see if you have a VTA or recirculating BOV (1g)? I have a 1g and I'm loosing boost at redline like you and still looking to see why. with the 1g the turbo does not spool as fast and the car does not pull as hard compare to the turbo RFL VTA bov.

 

Yes, it's normal with a stock manifold to lose a few psi up top. Don't worry about that too much. It's all hot air after 7k anyway.

As for different BOV's holding boost better, my 1G works fine to 21psi at redline.

 

I just upgraded to Turbo XS waste gate. On the stocker I was losing about 3 lbs. of boost, now only about 1lb. I did also swap out my boost gauge from factory to autometer so that my be reading better also?.