Boost creep issues please help!!
Boost creep issues please help!! First off. Stock 4.8 with 243s and 04z06 cam. Ls1 intake, truck manis with 2" crossover turbo kit. Tial 44mm wastegate.
With my eBay gt45 (68.x mm comp/77mm turbine) 1.05ar ex housing. With 10 psi spring we would see 13psi.
Last night we swapped it over to a precision 76gts with .81 exhaust housing. It measures 76mm comp/75mm turbine.
We have an issue....
With the 10psi spring we are completely uncontrollable. Letting out around 6k and 20-22 psi. Boost still climbing rapidly. So...put a 5psi spring in the gate. Car makes 5psi pretty quickly and holds for a second then starts creeping to about 22-23 psi by 7000.
Is the exhaust housing causing this? I really need a quick fix we are trying to race Saturday. We tried an air filter on the turbo and it didn't do anything for us. I would try no spring but the car is so sluggish that even if it worked it would be slow. Any suggestions or ideas. I'm pretty sure I have seen this exact turbo used without issues.
60mm single gate? Create an exhaust leak? I do not have enough time to do anything major so hopefully someone has an idea.
With my eBay gt45 (68.x mm comp/77mm turbine) 1.05ar ex housing. With 10 psi spring we would see 13psi.
Last night we swapped it over to a precision 76gts with .81 exhaust housing. It measures 76mm comp/75mm turbine.
We have an issue....
With the 10psi spring we are completely uncontrollable. Letting out around 6k and 20-22 psi. Boost still climbing rapidly. So...put a 5psi spring in the gate. Car makes 5psi pretty quickly and holds for a second then starts creeping to about 22-23 psi by 7000.
Is the exhaust housing causing this? I really need a quick fix we are trying to race Saturday. We tried an air filter on the turbo and it didn't do anything for us. I would try no spring but the car is so sluggish that even if it worked it would be slow. Any suggestions or ideas. I'm pretty sure I have seen this exact turbo used without issues.
60mm single gate? Create an exhaust leak? I do not have enough time to do anything major so hopefully someone has an idea.
Car is a 240sx. No room on the other side. The placement is as good as it can be. I think my issues are exhaust housing related. I am going to try to restrict the inlet of the turbo down to 3" and see what it does.
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TECH Fanatic
Joined: Oct 2011
Posts: 1,425
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No ****! Those welds look sick! For what it's worth. My precisions and my current ON3's do the same thing. I have my wastegates in a perfect position and I hit 5lbs for a second or so and then "BAM" it hits 20-25lbs like it's nothing. Unlike you, my dumbass can't let off the throttle. Too much damn fun. lol I am shocked I haven't blown my **** up yet.
Out of curiosity where do you have your rev limiter set to and what do you try and shift at?
Out of curiosity where do you have your rev limiter set to and what do you try and shift at?
Just for kicks to make sure it is not a faulty wastegate, pull the spring completely out and see if it makes boost. If it still does, either a serious flow issue or faulty wastegate.
I have no doubt the wastegate works. Changing springs completely changed how it came on boost and the boost level. I need to know if a different turbo with larger housing will fix my issue or if fab work is a must. I wanted to go with a 7675cea but due to this issue I am definately leaning towards the bw turbos and even considering the new turbonetics 7675 or 7875. I just need input on if the exhaust housing will or won't fix the issue.
Wicked69 I have my limiter set at 7500 and on the old set up I shifted at 7000. On this I was planning to see how it did for power up there and decide where to shift but I'll just have to feel it out.
TECH Fanatic
Joined: Oct 2011
Posts: 1,425
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Damn and that is stock? Wow. I can't get the nerve to set my higher than 6800 but feel as if I don't I don't get near enough " pull" from the turbo's before it's time to shift. Very cool car and thanks for the info. I was curious.
I have no doubt the wastegate works. Changing springs completely changed how it came on boost and the boost level. I need to know if a different turbo with larger housing will fix my issue or if fab work is a must. I wanted to go with a 7675cea but due to this issue I am definately leaning towards the bw turbos and even considering the new turbonetics 7675 or 7875. I just need input on if the exhaust housing will or won't fix the issue.
Ive had the 76gts control boost fine on a 404 cubic inch motor...your problem is wastegate placement or the wastegate itself. While running a turbo with larger exhaust side may allow it to be sufficient enough to maintain boost, the wastegate priority isnt the greatest.
Ive had the 76gts control boost fine on a 404 cubic inch motor...your problem is wastegate placement or the wastegate itself. While running a turbo with larger exhaust side may allow it to be sufficient enough to maintain boost, the wastegate priority isnt the greatest.
OP, I do however like your setup, looks awesome man. Good luck bud