how much backpressure is too much?
04-22-2009, 12:11 PM
#2
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there are a few opinions.
I do exactly that, I just put a port in and run it to a boost gauge. Since its temporary (in my case) I dont worry about a metal line etc. So far for limited testing,rubber line works fine.
If your in the 1 to 1 area thats usually pretty ideal. If you make 20 psi of boost, some systems will be as low as 20 psi in the exhuast. Some are 2 to 1...and higher. I think its really mostly theory, but by testing , if you have an issue, it might lead to a better set up.
Like if your changing turbos, you might improve things by testing back pressure first to choose a better exhuast housing.
I do exactly that, I just put a port in and run it to a boost gauge. Since its temporary (in my case) I dont worry about a metal line etc. So far for limited testing,rubber line works fine.
If your in the 1 to 1 area thats usually pretty ideal. If you make 20 psi of boost, some systems will be as low as 20 psi in the exhuast. Some are 2 to 1...and higher. I think its really mostly theory, but by testing , if you have an issue, it might lead to a better set up.
Like if your changing turbos, you might improve things by testing back pressure first to choose a better exhuast housing.
04-23-2009, 10:45 AM
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1:1 pressure ratio is a good target to shoot for. It all depends on what you are doing with the car.
If you want a fast spooling responsive set-up you may want more backpressure to light the turbo up faster but there will be a trade off in top end power.
For making power you ideally want to have less exhaust back pressure than intake pressure.
If you want a fast spooling responsive set-up you may want more backpressure to light the turbo up faster but there will be a trade off in top end power.
For making power you ideally want to have less exhaust back pressure than intake pressure.
04-23-2009, 12:49 PM
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this is exactly where the quick spool valve comes in. Run a turbo large enough to have minimal back pressure , and use the valve to increase pressure below a certain boost, to get the turbo going. Best of both .
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04-23-2009, 05:41 PM
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Just a housing probably....but yea, I know, its all $$$. On the upside, I wont buy a turbo now unless its divided. LOL
The other problem is small spacing changes on existing set ups. Most will require alittle refabrication for fit, pipe lenght etc.
The other problem is small spacing changes on existing set ups. Most will require alittle refabrication for fit, pipe lenght etc.
04-23-2009, 07:53 PM
#10
yeah i really like how the divided housing stuff is working out..maybe one day.One thing i got to thinking about: on a divided turbo, how is it divided at the impeller?I am just wondering if you are using one side a majority of the time , is it only pushing on one side of the impeller until the other side opens?If thats the case it seems like all that side load would kill the bearings pretty quick.But dont know if this is the case or not.
04-23-2009, 07:55 PM
#11
The lower the backpressure, the more power you will make. Folks say 1:1 is a good target, but a very limited few actually get there. Most reasonably quick spooling street setups are around 2:1. I really think that the ones achieving 1:1 are really sluggish to spool and not very good for street use, but they do make a lot of power.
Mike
Mike
