SpeedJunkee

It seems to be common for people with new turbo builds to have initial issue with the waste gate springs and making boost. I have heard of others using dual wastegates.

So what is the deciding factor in weather to go single or dual here? I was thinking about going dual JGS 40mm, but it was recommended to me, and I would like to know what the criteria is.

93camaro_zzz

iTrader: (13)

Space is a consideration I suppose. Twins will most likely cost you more. I went with one single wastegate initially, but when I redo my setup, I will go with twins.

SpeedJunkee

Obviously 2 will cost more and take up more room than 1. What I am looking for is what is the determining factor on when it is necessary to go with 2? Is it a boost level? Is it a matter of better controlling to boost?

93camaro_zzz

iTrader: (13)

A lot of people choose twins if they are trying to keep the exhaust divided all the way to the turbo. There is no "point" at which you have to go to twins really. Only really when you outgrow a 60mm single. Which will take a while. lol

SpeedJunkee

What difference does it make if the exhaust is divided? Do you mean true duals? Or split at the flange back to the downpipe? What would make it so the 60mm single not enough? You say "it will take a while", but I need the details.

Looking for the "how and why" here.

93camaro_zzz

iTrader: (13)

If the turbo has a divided turbine housing like so:



than it can help spool times if you keep the exhaust divided (not merged together) all the way to that point. Here is a pretty good example of doing this in Dan Smith's thread, he does the divided exhaust with a single wastegate:

There is some good info starting at about post #60:

ls1tech.com/forums/forced-induction/1510539-turbo-firehawk-build-up-v-3-0-aes-385-s88.html

And by take a while, I mean, you have to have one HELL of a setup to need a wastegate bigger than a single 60mm.

SpeedJunkee

Gotcha. So if the turbo is divided at the flange like that, and the exhaust is split, it is a good idea to go with 2 wastegates?