GT3576 - controlling boost

[FG50T]

What holds the GT3576 back from holding 20psi all the way to redline? Is it the compressor wheel, the wastegate flapper or just the way FG's can be tuned? As far as I know mine hit's 17psi mid and tapers off to redline on my FG. Reason I ask is because I'm considering taking this turbo off my FG and putting it on my VL which will run 19-20psi but need to be able to hold it. Is there a way I can get the 3576 to do this (billet wheel or external gate)? I thought this would be a good place to ask since we're the only people with this turbo!

 

[barnz]

well engine capacity has an effect on boost you will see from a given turbo. It tapers off coz it cannot flow enough air(volume) to hold the pressure when the 4.0 is spinning at 5000+ rpm. It will definitely see 20psi or more on an rb30, not sure if it will hold it to 7000 od rpm, though it stands more of a chance with 1 less litre to feed.

[MattyP]

Comp wheel size mainly hold it back

Would be a laugh turbo on the vl

A gtx3076 would suit it better but would still work

It's all about cfm

My 3540 can hold 20 to the red line

Unsure if it'll flow much more though

[Lennox]

Compressor size... remember it's a 4l engine

[FG50T]

I understand..I didn't take into account the effect capacity would have on the efficiency. It just makes sense to me to recycle this turbo and buy a GTX for the FG. Don't want to bother getting it tuned up if it's not gonna work well though and don't want to have issues with more than 20psi through the bottom end so the 3576 seems like a perfect choice for efficiency on the 3L.

[MattyP]

The turbine wheel and housing and a little to large for a 3I and with that comp wheel it's a little mismatched

You can just upgrade your front cover, wheel and back plate to a gtx3582 or even bigger but then it depends what you want of your car

[barnz]

Matty people run MUCH larger turbos on rb30's lol. Albiet with antilag, big converters, shots of gas to get on the big converters etc. I think the gt3576 will be fine on the rb30. Wont be as responsive on as on the coon but remeber the rb will turn pretty hard rpm wise particularly if its built.

[MattyP]

Of course it'll work

It's a great turbo

I just think it's mismatched for the rb

Huge turbine and housing and small compressor wheel and cover

[barnz]

Correct but in this guys case its about recycling it. It will work.

What turbo you looking at for the FG FG50T?

[MattyP]

Yup Will work well just better options imo

Gtx4202?