The problem was wastegate placement due to space constants ,the turbine is the 1.22 so it is plenty big enough.

 

on the back of turbine?!?! you're gonna have to post pics man. No idea what you're talking about.

 

sounds like he made a boost cutout from a wastegate which means his "boost creep" isn't from his original wastegate it's from his exhaust backpressure.

I had that problem with the borla exhaust system. 7psi spring would run 11psi and no lower. Put a cutout so I ran straight exhaust and everything was fine. My exhaust backpressure was keeping me from lowering my boost.

 

your having issues with a 50mm gate with boost control on a 850 hp turbo. both me and binder run turbos that produce more airflow and have no issues with boost control from a 38mm gate, something is significantly wrong there, heck my turbo flows enough for 930 rated and has made 960 on supras and i have no issues going down to 15 psi.

like binder said if thats what your doing it has absolutely nothing to do with wastegate placement you simply have a crap exhaust your trying to use. my bet you wanted it quite and that dosnt work with power, everythings a compromise.

 

No the exhaust was a 4'' with one straight muffler.
What boost do u run and what sort of power
I wanted to run low boost for for wet track conditions and the 50mm gate would not let me run that, yes when it was run to 15psi it would hold it .

Like u said everything a compromise and every setup is different.
So far this engine has made 800hp at 17psi on e85 at the crank.

 

I cut a hole in the back of the turbine housing and welded a pipe to it then fitted the gate to the pipe works realy well ,will post a pic for u a bit hard to explain .

 

typically on the street i run 15-26 psi, only dynoed it at 20 psi on a slipping clutch going to redyno this week but it made 600 there. fuel consumption wise its consuming enough for 700-1000 on those boost numbersbut its wildy inaccurate since i dont know the exact bsfc only that im running 11.8 afr. how did you determine the power your making at the engine? turbo ratings by garrett precision and others are typically wheel numbers not engine. i ran the old 6765 with .96 open housing as low as 9 psi with no creep either.

i would like to see what you did with the turbine housing also, if you did what i think you did you pretty much ruined the turbo and have effectively made it a smaller turbo while still having the long delay of the larger one. since the turbo will never reach the shaft speeds it needs from exhaust pressure being leaked directly out of the volute instead of spinning the turbo and are simply better off going to a smaller turbo...............at least if you did what i think you did.


so your trying to run lower boost then 15? yes you need a smaller turbo and smaller power goals then no idea what track your trying to run but if attempting a gt style course that turbo will povide a horrible curve, if drag racing they shut down for the rain, hpde type events will have the same issue as the gt style courses.

it seems like what your trying to build and what you actually built are two completely different cars.

 

Hi the car the engine fitted to is a space framed track car it weighs just over 1000kgs we have our own engine dyno thats how i no the power we are making.
I race the car at around 750hp and if i need it i wind it up to 800hp the power curve is not problem as we run a 6 speed quiafe gearbox the lag is not that bad it has full boost by 4000 revs the e85 helps spool heaps
I have Raced this setup for 2 seasons it is a very competive car at the end of our straight i am pulling 170+ mph.
The cars that race in my class are gt3 porches, gtr skylines mazda rotors ex ex
there are no rules race what u bring just surch osca racing new zealand some very quick cars.

Fitting wastegates to the turbine housing is quite common it works well garrett even do to there turbine housings on some models just look it up.

26psi is not bad power i tuned a 3.4 supra at that boost that made 1000hp
it made the same power as the vq at 18psi that was on e85.
what engine setup u running?

 

Jerry, he essentially did this: http://www.atpturbo.com/mm5/merchant...egory_Code=GTH

 

What turbo are you running? I've easily held a steady 7psi on my setup with only a 38mm wastegate. I have friends that use their boost controller for traction control so they use .5 bar springs on gt47 turbos.

 

hi we run gt4294 a 38mm gate would control it now that we have changed the position of it where it used to be it wasent getting a good flow out of the collecter, I had a engine when i took the spring out of the gate it would still over boost due to waste gate position changed the angle and it worked fine.

 

correct

 

ok i was thinking you simply had a pipe in there openly dumping exhaust not had a second wastegate on there. like i said there was definitely something going on, changing position just shows that im guessing the angle was the issue. i run 8.0:1 wossner 96mm pistons, pauter rods, stock cams, modified revup lower plenum,6766 midmount kit with 1.32 ar t4 housing with a 60mm wastegate feeding half the turbo housing.

 

wow, I knew angle made a difference but I wouldn't think that large of a difference.