Wastegate Troubles?
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Wastegate Troubles?
I just finished up my car and put it on the dyno yesterday. But I am having trouble with the wastegate holding the boost down. First off the car is a 98 camaro 370" PT88 truck manifold kit, l92 heads with carb intake, th400, 9" etc...I am running it off the wastegate(12psi) only, right now no boost controller. While doing the dyno pull it reaches 12lb about 4200rpm and holds it there until it reaches 5000rpm. Then boost starts coming on hard from there on out by 5600 its at 18 pounds and I have to let out of it. Any recommendations on what the problem is? Wastegate is a Tial 44mm with 12pound spring. I will post a couple pics of the location of the wastegate.
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Originally Posted by alwaysinboost
Where is your boost source to the WG referenced from?
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it sounds like you're getting boost creep, which usually means the you're moving too much exhaust for the WG to evacuate. Is the path in & out of the WG smooth with no obstructions?
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i have a tial knockoff 44mm wg. I have my boost signal coming from the compressor housing...drilled/tapped a hole for a screw in barbed fitting. my turbo is around the same size as yours and i can get boost to go as low as 6psi.
One time i had a prob like yours was inside the wg. my knockoff has 4 setscrews that screw in against the valvestem that holds it in place with the diaphragm. One came all the way out and boost would bleed threw and go to 22psi....the other 3 were loose. Only help i can offer
One time i had a prob like yours was inside the wg. my knockoff has 4 setscrews that screw in against the valvestem that holds it in place with the diaphragm. One came all the way out and boost would bleed threw and go to 22psi....the other 3 were loose. Only help i can offer
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Originally Posted by alwaysinboost
it sounds like you're getting boost creep, which usually means the you're moving too much exhaust for the WG to evacuate. Is the path in & out of the WG smooth with no obstructions?
Originally Posted by cablebandit
i have a tial knockoff 44mm wg. I have my boost signal coming from the compressor housing...drilled/tapped a hole for a screw in barbed fitting. my turbo is around the same size as yours and i can get boost to go as low as 6psi.
One time i had a prob like yours was inside the wg. my knockoff has 4 setscrews that screw in against the valvestem that holds it in place with the diaphragm. One came all the way out and boost would bleed threw and go to 22psi....the other 3 were loose. Only help i can offer
One time i had a prob like yours was inside the wg. my knockoff has 4 setscrews that screw in against the valvestem that holds it in place with the diaphragm. One came all the way out and boost would bleed threw and go to 22psi....the other 3 were loose. Only help i can offer
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In your last post you stated that even with the spring out the boost would come on slow, then rocket past 15psi as the rpms climb. This is a good indicator that there is some restriction in the WG plumbing.
I see a long WG discharge tube, this could be the problem. Does it re-route into the exhaust at some point?
I suggest removing the WG discharge tube that runs down the passenger side for one run and see if you can maintain a lower boost level.
I see a long WG discharge tube, this could be the problem. Does it re-route into the exhaust at some point?
I suggest removing the WG discharge tube that runs down the passenger side for one run and see if you can maintain a lower boost level.
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Originally Posted by EGash
In your last post you stated that even with the spring out the boost would come on slow, then rocket past 15psi as the rpms climb. This is a good indicator that there is some restriction in the WG plumbing.
I see a long WG discharge tube, this could be the problem. Does it re-route into the exhaust at some point?
I suggest removing the WG discharge tube that runs down the passenger side for one run and see if you can maintain a lower boost level.
I see a long WG discharge tube, this could be the problem. Does it re-route into the exhaust at some point?
I suggest removing the WG discharge tube that runs down the passenger side for one run and see if you can maintain a lower boost level.
I tried the compressor housing for reference and no change.
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It's very possible that the wastegate is too small. I've seen this before on other setups. This is why folks buy the large racing wastegates or something similar to arrest the problems.
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Originally Posted by nutz'00 Z28
I will try this tomorrow, whats the chances of the wastegate being to small?
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If you tried the compressor housing for a boost source and it didn't help then I think your problem might be the result of two things, both related to the WG placement.
I that first pic above where you have the WG attached just below the turbine inlet, it looks as though the exhaust is going to have to make a sharp 90* turn and then travel up even further to reach the WG. That right there makes me suspect that you aren't able to vent enough exhaust to maintain the static pressure your WG is set to.
Does anyone else have a setup like this or is yours a one off? If so have they had simular issues?
Then in the second pic you have an extreamly long dump tube venting the exhaust gasses after they pass thru the WG. now, thats not nessicarly a bad thing, but if it doesn't VTA or smoothly merge into the exhaust path that could cause the kind of problems you are seeing.
I still have 2 other things you could try but I need to hear your answer to the above questions before I tell you about them.
I that first pic above where you have the WG attached just below the turbine inlet, it looks as though the exhaust is going to have to make a sharp 90* turn and then travel up even further to reach the WG. That right there makes me suspect that you aren't able to vent enough exhaust to maintain the static pressure your WG is set to.
Does anyone else have a setup like this or is yours a one off? If so have they had simular issues?
Then in the second pic you have an extreamly long dump tube venting the exhaust gasses after they pass thru the WG. now, thats not nessicarly a bad thing, but if it doesn't VTA or smoothly merge into the exhaust path that could cause the kind of problems you are seeing.
I still have 2 other things you could try but I need to hear your answer to the above questions before I tell you about them.
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Originally Posted by alwaysinboost
If you tried the compressor housing for a boost source and it didn't help then I think your problem might be the result of two things, both related to the WG placement.
I that first pic above where you have the WG attached just below the turbine inlet, it looks as though the exhaust is going to have to make a sharp 90* turn and then travel up even further to reach the WG. That right there makes me suspect that you aren't able to vent enough exhaust to maintain the static pressure your WG is set to.
Does anyone else have a setup like this or is yours a one off? If so have they had simular issues?
Then in the second pic you have an extreamly long dump tube venting the exhaust gasses after they pass thru the WG. now, thats not nessicarly a bad thing, but if it doesn't VTA or smoothly merge into the exhaust path that could cause the kind of problems you are seeing.
I still have 2 other things you could try but I need to hear your answer to the above questions before I tell you about them.
I that first pic above where you have the WG attached just below the turbine inlet, it looks as though the exhaust is going to have to make a sharp 90* turn and then travel up even further to reach the WG. That right there makes me suspect that you aren't able to vent enough exhaust to maintain the static pressure your WG is set to.
Does anyone else have a setup like this or is yours a one off? If so have they had simular issues?
Then in the second pic you have an extreamly long dump tube venting the exhaust gasses after they pass thru the WG. now, thats not nessicarly a bad thing, but if it doesn't VTA or smoothly merge into the exhaust path that could cause the kind of problems you are seeing.
I still have 2 other things you could try but I need to hear your answer to the above questions before I tell you about them.
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I disassembled my wastegate and did some clearanceing so that the valve would open all the way to the seat. Re-installed everything but I left the dump tube off and took it for a ride. First gear was fine it held 15psi pretty steady up to about 6500rpm then I shifted into second it went to 18psi and held there until I let out of it. So I guess the wastegate is to small. Has anyone ever ran 2 wastegate's on a single turbo car? It would be cheaper and easier for me to do this.
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I've seen it in a blower design but never in a single Turbo design. A larger wastgate would cost about $425.00. Then sell your wastgate for say $100.00 that'd be about $325.00. What other costs are there? Unfortunately the larger wastegate will need to find a place to live since the physical size is larger. Also changing the tubing.
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Originally Posted by chasgiv3
I've seen it in a blower design but never in a single Turbo design. A larger wastgate would cost about $425.00. Then sell your wastgate for say $100.00 that'd be about $325.00. What other costs are there? Unfortunately the larger wastegate will need to find a place to live since the physical size is larger. Also changing the tubing.
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Originally Posted by chasgiv3
I've seen it in a blower design but never in a single Turbo design. A larger wastgate would cost about $425.00. Then sell your wastgate for say $100.00 that'd be about $325.00. What other costs are there? Unfortunately the larger wastegate will need to find a place to live since the physical size is larger. Also changing the tubing.