Backpressure question
Backpressure question This question may be too vague but here goes.... All else being equal, which turbo will have less backpressure: Precision 6262 w/t3 .82 open exh housing or Precision 6765 w/t3 .82 divided exh housing? This is for my twin rear mount setup.... It is a daily driver. Thanks guys
TECH Addict
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Not sure about open vs divided, but the one that puts the compressor in a more efficient place on the map will have lower backpressure. This is because it takes less energy to drive the compressor when it's running more efficiently.
Remember, if you kept it 6265, drive pressure would be lower. Now that you have increased compressor as well, drive pressure may be the same in relation to boost pressure, but total power output will be greater.
I should have bought 6265's but i bought 6262's instead. So instead of going with 6265's as an upgrade, my thought is to go with a larger compressor side just in case i go larger cubes later.... I would think it would spool pretty close to the 6265's plus i will add a spool valve. thanks
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Last edited by TracyRR; Feb 3, 2011 at 08:36 PM.
FormerVendor
Joined: Dec 2001
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From: WWW.SPEEDINC.COM
You seem to put a lot of energy into chasing efficiency. Have you considered switching to a -proper- front mount turbo system? I think if you ran something with say, TTIX manifolds you would be pleased with the improvements in transient response and overall efficiency.
i thought about building a front mount but the only reason i didn't is because i daily drive the car and it would have to be down for more than a weekend..... i built my twin rear mount over a couple weekends and thankfully always able to drive it to work on the monday..... it can be a pain to break up projects to have it running for monday but i much prefer to drive the car everyday because it is a freaking blast!! You have helped me on several occasions so thanks a bunch!! tracy
hey mike, i have not dyno'd it yet but i really hope to be around 900rwhp now at 22 - 23 pounds. It totally transformed the car! Before i was near 700rwhp at 14 pounds and it is now a different car at 14 pounds. Thanks
The big jump is from eliminating the back pressure? My motor used to fall on it's face about 5k with the TC76 .96a/r now with the ST80 1.1a/r the car is night and day different. Back pressure is a killer.
hey mike, when i fabbed the new hot side, i tested backpressure/blasted the car... it did make less backpressure and responded well to the change but the largest improvement was when i fabbed the new cold side. The sts cold side (imho) was just too restrictive and long.... the car absolutely woke up. Under 600rwhp or so, the sts performed real well for a rear mount but phil (phil99vette) calculated the intake air speed with the sts pipe (1.75") and at my hp level and it was way too fast so it became an issue. When i went to the 2" pipe and shortened the length it completed the package i guess. Thanks
I custom built a rearmount for my F body, I went with 3" oval intake piping under the car. On the hotside I went 2.5" Ypipe and 3" I pipe to the turbo, I wrapped it in 300ft of header wrap to keep it nice and hot. The turbo is a ST80, it's a 83mm turbine with a 1.1a/r housing, tried the 1.25 and it's sluggish, if I go front mount I'll use the bigger housing.
I put it on the dyno and blew thru the converter, only made 445rwhp, boost climbed to 16lbs but didn't make anymore power it was loosing over 800rpm thru the converter. It's supposed to be a 4000 stall but all the extra power it's not holding. I know it must be making good power because my 60lb injectors boost reference to 74-76psi at that boost level was see 80% duty cycle running a fairly large amount of meth.
I put it on the dyno and blew thru the converter, only made 445rwhp, boost climbed to 16lbs but didn't make anymore power it was loosing over 800rpm thru the converter. It's supposed to be a 4000 stall but all the extra power it's not holding. I know it must be making good power because my 60lb injectors boost reference to 74-76psi at that boost level was see 80% duty cycle running a fairly large amount of meth.
hey mike, yes, i followed that last thread you had. Did you get a converter yet? It is going to make great power when you are done.
I custom built a rearmount for my F body, I went with 3" oval intake piping under the car. On the hotside I went 2.5" Ypipe and 3" I pipe to the turbo, I wrapped it in 300ft of header wrap to keep it nice and hot. The turbo is a ST80, it's a 83mm turbine with a 1.1a/r housing, tried the 1.25 and it's sluggish, if I go front mount I'll use the bigger housing.
I put it on the dyno and blew thru the converter, only made 445rwhp, boost climbed to 16lbs but didn't make anymore power it was loosing over 800rpm thru the converter. It's supposed to be a 4000 stall but all the extra power it's not holding. I know it must be making good power because my 60lb injectors boost reference to 74-76psi at that boost level was see 80% duty cycle running a fairly large amount of meth.
I put it on the dyno and blew thru the converter, only made 445rwhp, boost climbed to 16lbs but didn't make anymore power it was loosing over 800rpm thru the converter. It's supposed to be a 4000 stall but all the extra power it's not holding. I know it must be making good power because my 60lb injectors boost reference to 74-76psi at that boost level was see 80% duty cycle running a fairly large amount of meth.
