Turbos Wont Bulid Boost
Thread Starter
Staging Lane
Joined: Jun 2015
Posts: 57
Likes: 0
Turbos Wont Bulid Boost I Installed a eBay twin turbo kit on my 07 Silverado, Installed everything just took it to the dyno and the thing wont build boost. no turbo leaks, took turbos off flappers looked ok. Goes from 3lbs to 1lb. The weird thing is when you let off the gas it dumps through the BLOV and then like two more times sounds like through the intake on the turbos. I need some help. The tuner said maybe the turbos are too small they are MMI 56mm or the exhaust manifold is causing too much turbulence and not flowing well. I exchanged the y pipe to straight so i know its venting well.
http://www.ebay.com/itm/99-11-Tahoe-...lWca1S&vxp=mtr
thanks in advance
http://www.ebay.com/itm/99-11-Tahoe-...lWca1S&vxp=mtr
thanks in advance
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
How are the lines to the wastegates ran? How is the BOV line ran?
Does the BOV shut during a pull?
How much force does it take to open a wastegate by hand?
Double check all of your couplers.
Pics might help.
Does the BOV shut during a pull?
How much force does it take to open a wastegate by hand?
Double check all of your couplers.
Pics might help.
I Installed a eBay twin turbo kit on my 07 Silverado, Installed everything just took it to the dyno and the thing wont build boost. no turbo leaks, took turbos off flappers looked ok. Goes from 3lbs to 1lb. The weird thing is when you let off the gas it dumps through the BLOV and then like two more times sounds like through the intake on the turbos. I need some help. The tuner said maybe the turbos are too small they are MMI 56mm or the exhaust manifold is causing too much turbulence and not flowing well. I exchanged the y pipe to straight so i know its venting well.
http://www.ebay.com/itm/99-11-Tahoe-...lWca1S&vxp=mtr
thanks in advance
http://www.ebay.com/itm/99-11-Tahoe-...lWca1S&vxp=mtr
thanks in advance
Thread Starter
Staging Lane
Joined: Jun 2015
Posts: 57
Likes: 0
Thanks guys...
The waste gates are on the turbos standard actuator with rod. They take quite a bit by hand. Set at 8lbs. The flapper is closed and opens under pressure.
The blow off is on the charge pipe right before maf. Not sure if the bob shuts during a pull. The tuner said everthing looked good on stall. He felt it was turbos small or design on manifolds.
The waste gates are on the turbos standard actuator with rod. They take quite a bit by hand. Set at 8lbs. The flapper is closed and opens under pressure.
The blow off is on the charge pipe right before maf. Not sure if the bob shuts during a pull. The tuner said everthing looked good on stall. He felt it was turbos small or design on manifolds.
Thread Starter
Staging Lane
Joined: Jun 2015
Posts: 57
Likes: 0
Pulling the hoses off the waste gates or boost control was what I was going to try next. I figured if the boost was there but no power would be the turbos but if I have no boost then definetly no power
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Verdad Gallardo Ya I didn't click the link when I initially made that comment. I have worked on a care that had similar issue and wouldn't build more that a pound or two of boost. It was an external waste gate though and the fire ring wasn't installed. I'm not sure on your setup
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
What are you using the measure boost? Just a gauge? I've made a LOT of boost with smaller turbos on an LS engine, and even the stock manifolds make huge power, so that's not the issue.
Either something isn't hooked up and you're boost leaking, or you're making boost and don't know it.
Either something isn't hooked up and you're boost leaking, or you're making boost and don't know it.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Internal gates. No fire rings.
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Blowing off multiple times isn't typically an issue.
TECH Enthusiast
Joined: Jan 2012
Posts: 557
Likes: 9
From: Bowling Green KY
I normally use compressed air from my air compressor to check waste gate function. It's not bang on, but is pretty close. Maybe they are opening on very little boost, or the pressure on the exhaust side is pushing them open?. IMO there are only 3 things that could be causing this problem. 1) incorrect turbo waste gate function, 2) the turbos are damaged, and not spinning up, or 3) the intake tract from the turbos to the intake manifold is leaking somewhere, bleeding off boost, possibly the BOV leaking?
1 and 2 can be verified with compressed air on the bench. I plump a line from my air compressor onto my waste gate actuator, then begin increasing pressure on my regulator to see where it pushes the waste gate open. To check turbine function I normally just shoot a little air into the exhaust, where the t4 flange bolts up, and they should spool up. On a smaller BB turbo you can do this just by blowing in there with a big breath. Number 3 can be more difficult, but if you eliminate 1 and 2, then just focusing on 3 should be manageable.
1 and 2 can be verified with compressed air on the bench. I plump a line from my air compressor onto my waste gate actuator, then begin increasing pressure on my regulator to see where it pushes the waste gate open. To check turbine function I normally just shoot a little air into the exhaust, where the t4 flange bolts up, and they should spool up. On a smaller BB turbo you can do this just by blowing in there with a big breath. Number 3 can be more difficult, but if you eliminate 1 and 2, then just focusing on 3 should be manageable.