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Boost Creep Fixed!


240hoke

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Sooo.....

 

I dunno if any of you remember but i was having trouble getting my Greddy Profec-SpecII to work properly. It really had me stumped lol. I was getting different boost levels in different gears, and unlimited boost under roll on throttle or 4th and 5th gear. NO matter what i did with the programming i couldnt figure it out.

 

I hooked my Manual controller back up and had similar results at the higher boost pressures., 12+.

 

So i took my actuator completly off the turbo and took it for a drive. I was able to build 10+ psi with the flapper completely open!!!! So I figured out i needed to port out the wastegate hole a bit. I used a die grinder with a carbide bit (this was a lotta fun!, i almost got carried away!) I enlarged it from 7/8" to 1.25" Ity was quite a big increase, but i had room as i am using the Ford 3 bolt wastegate housing with a 1.5" puck. Heres are the pictures:

normal_DSCN0994%20%28Small%29.JPG

normal_DSCN1335.JPG

 

This turned out working very very good. I have absolutly zero ceep. I did run into one problem though, and that was there was alot more pressure on the door and it would blow open the actuator. I had to tighen it all the way and add a spring. But anyhow everything is jiffy now. And yes i said jiffy.

 

16psi is FUNN!!!!

 

-Austin

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Austin, Thanks for the great post. I did the same as you and extensively modified the factory wastegate. My wastegate hole is also roughly at 1.25 inches.

 

My problem is that I can't get more than about 15psi of boost. I've tried everything from adjusting my Blitz boost controller to changing out my wastegate actuator. All with no success.

 

After reading your post I think I probably have the same problem as you with the wastegate door blowing open. I'm going to try and preload the actuator then try it again. Maybe I'll get better boost response.

 

Does anyone know if a large diaphram has any advantage over a small diaphram wastegate actuator? The reason I ask is I have the choice of either one.

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jgkurz - My actuatator is adjustable so i screwed the shaft as short as it could go. Then i made a little plate and put it between the locking nut and the end piece so i could hook a spring on it and then made a plate to hook the spring on to the top where the diaphram is, effectivly pulling the actuator rod in. I am also running a dual port wastegate actuator which puts pressure on both sides of the diaphram.

 

Bernardd - Im running a .82 stage 5 exhuast wheel. There was sufficient room for a 1.5" flapper as you can see. I also am using a ford 3-bolt wastegate from turbonetics. I did have to port it out a bit to match the turbine opening, but nothing major. I ordered my turbo and wastegate from Top end performance, who recommended this wasegate, they said it would allow for much more flow then the nissan unit. Heres a picture of the wastegate housing, before it was ported:

normal_DSCN0990%20%28Small%29.JPG

 

ill get some pics up of the spring later

 

-Austin

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Bernardd - Im running a .82 stage 5 exhuast wheel. There was sufficient room for a 1.5" flapper as you can see. I also am using a ford 3-bolt wastegate from turbonetics. I did have to port it out a bit to match the turbine opening, but nothing major. I ordered my turbo and wastegate from Top end performance, who recommended this wasegate, they said it would allow for much more flow then the nissan unit.

 

Thanks Austin. That's the info I was looking for.

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Well replacing the stock wastegate with the ford housing will help, since it will give you better flow and allow you to get the bigger puck. I personally wouldnt do it because it has a different bolt pattern and is larger, this means you would have to redesign the downpipes.

 

But just swapping the wastegate housing wont get you anywhere, you still need to port out the actual hole in the turbine housing. If it was me i would try getting a larger puck for the stock housing first, and port hte turbo, adn see how that turns out.

 

-Austin

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