turbo: how to choose spring for wastegate
12-17-2011, 04:28 PM
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turbo: how to choose spring for wastegate hey guys.. maybe some of your boosted guys can help me out 
my trucks vaccum is at 10..
im running the tial 38mm wg.. what spring should i drop in to get about 10lbs of boost ??
thanks guys
my trucks vaccum is at 10..
im running the tial 38mm wg.. what spring should i drop in to get about 10lbs of boost ??
thanks guys
12-18-2011, 02:06 AM
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Like Ryne said, "what size turbo?" and motor CI? My exact setup on a stock 346 held 10psi with a 10lbs spring. But when I went bigger CI, I had to upgrade my wastegate to a 46mm because the 38mm could not control boost due to higher back pressure and not being able to flow it out efficiently.
12-18-2011, 02:42 AM
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Like Ryne said, "what size turbo?" and motor CI? My exact setup on a stock 346 held 10psi with a 10lbs spring. But when I went bigger CI, I had to upgrade my wastegate to a 46mm because the 38mm could not control boost due to higher back pressure and not being able to flow it out efficiently.
12-18-2011, 03:02 AM
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generally speaking the wastegate size has no bearing on boost holding capabilties, but if the wastegate is too small or not positioned correctly you will get boost creep on the topend..... the backpressure will force the gate open prematurely resulting in receiving lower boost levels then the waste gate spring suggests.... the wastegate spring rating are a "rule of thumb" system to go by, in a perfect situation a 7 psi spring will yield 7 psi boost... but in alot of single turbo apps with v8's its not uncommon to need a 10+ spring to see 6-7 lbs of boost..... i see it all the time on the dyno.... boost controller is your friend!!
12-18-2011, 06:07 PM
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i see..
well my backpressure is staying at 10
turbo: .96 a/r and 72 cold side.
what manual boost regulator would you suggest then..
and as for the wastegate its a tial 38mm
well my backpressure is staying at 10
turbo: .96 a/r and 72 cold side.
what manual boost regulator would you suggest then..
and as for the wastegate its a tial 38mm
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12-18-2011, 06:42 PM
#8
Remember my car would get boost creep on first gear? it would creep up to 18+ psi with a 10lbs spring. I tried lowering the spring to a lower psi spring rate, but still would over boost. I even tried running no spring, still it would create boost. I finally cut out the 38mm and welded a precision 46mm waste gate with a 10lbs spring and got 10 psi with no creep. I don't know if it was a faulty 38mm waste gate, but it was recommended by someone on here with lots of turbo experience that I get rid of the 38mm and go closer to 50mm. He explained that the exhaust was not "flowing" through the smaller wastegate and causing more flow to the turbine causing the turbo to spin faster and creating the boost creep.
12-18-2011, 08:06 PM
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ima take some pics.. maybe you guys can figure it out.. it was recently rebuilt.
12-19-2011, 10:56 PM
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he said garrett !! after calling him 20x to get him to pick up..
but i still gotta look up what exact model or go get some calipers.. cause he said he cant find the paper w the build specs when he got it rebuilt
