What can I expect from a GT4088 journal bearing turbo.

I am deciding between this and a T-04R.

Here are the specs for both:

GT4088:
Turbine Wheel: 77mm w/ 84 trim
Turbine Housing: 0.81A/R
Compressor Wheel: 88mm w/ 54trim
Compressor Housing: .72A/R

T04R:
Compressor Wheel: 50 Trim - 65.5 Inducer / 92.0 Major.
Compressor Housing: 105mm(4.0") Inlet / 65mm(2.5") Outlet -51mm(2.0") A/R.
Turbine Wheel: -76 Trim - 68.0 Major / 78.0 Exducer.
Turbine Housing: -T04 inlet / 92.0 V-outlet -71mm(2.75") 1.01 A/R.

How do these spool relative to each other? How much whp should I expect at 14-15psi and at 20-22psi from each?

I drive the car on the street. Looking for mid 400-low 500 whp with the quickest spool possible on E-85. I know people have accomplished this on a GT35R but this is what I have available to me at the moment. The car is slightly ported.

I know the GT4088 is a newer wheel design so I wanted to know how this plays a role when compared to an older design like the T04R

I just want to know people's opinion on what they would choose if they were choosing between these two, both new and for the same price.


Thanks.

Chris

 

Anyone?

 

I'd go GT series.

My experience with a T04-R vs. a GT3574 have shown me the slight improvements (most notably transient response) They're not a great pair to compare though I'll admit.

Either one will be a riot though, differences will be minimal.

 

Both of them are good turbos. Depending on the A/R size you will see similar response and both of them will do 500 RWHP depending on boost.

 

Well, the gt4088 was never mounted and has a .81A/R.

The T04R is also new/never mounted and has a 1.01A/R

How do you think they will compare? I am looking at 450-500whp on E85 but I want to stay around or under 20psi.

Thanks.

Chris

 

Chris,
The 4088 with a .81 wont do 500 RWHP at 20lbs. It will spool pretty quick and make mid 400HP.
The T04R should make around 500 RWHP at around 21-22lbs with a 1.01 A/R.

 

Oh wow, I though the GT4088 would be able to do 500whp no problem....how did those guys with the GT35R make 500+ on E85 at 20-22psi on a T3 inlet housing? Did they have a huge housing A/R?

So far its pointing towards a T04R, It just bugs me knowing that the GT series have better wheel design.

Anyone else?Jason?

Thanks,

Chris

 

If they're the same price, buy the 4088 and just pick up a larger turbine housing.

Really, to me also, the .81 seems small for "high" boost, but I bet it would still rock some socks at 20lbs with that housing.

 

Ok, so now I am in the middle again. How much is another housing? Where do you recommend I get it?

Buying another housing does kind of negate the whole "same price" deal and effectively makes the T04R cheaper than the 4088 so I am not sure about that.

Will the 4088 really be that much more superior with a close to 1.00A/R housing compared to the T04R with a 1.01A/R?

Also, My manifold is not divided due to design/space constraints, does that offer a benefit to any one of the two turbos?

Thanks.

Chris

 

They should be quite close in a back to back comparison if they had similar housings.

In that case, I'd probably more so opt for the 4088 since the .81 will more then likely be open volute. Try it, if the hotside's holding you back, sell yours and buy another.

 

Ok I see. I had read somewhere that the GT series where optimized for twin scroll housings. And yes the GT4088 I am being offered has an open volute. The T04R has an open volute as well. I guess I have some thinking to do.

Any more input?

Thanks

Chris

 

I wouldn't put it on an rx8, not enough exhaust power, go with something smaller

 

What are you basing this statement on? It seems that a lot of what's "known" about the RX-8 is based on speculation based on the fact that the car's engine management is so complicated, the complex intake manifold, bad exhaust manifold design and the 10:1 compression ratio. The compression ratio actually helps it spool turbos very quickly, specially with the right manifold design. All you have to do is add the surface area of the 3 exhaust ports to see that there is plenty of exhaust port area. All it takes is some clever design ideas to figure out how to play with the intake manifold so it works to your advantage(the last runners don't normally open until about 6500rpm, which takes a toll on spool).

The car this is going in already maxed out a T04S at 400+whp 14psi with good power up to about 7800rpm, after that the power falls. It has a 4" exhaust and it seems to spool it almost instantly(some boost from 2500rpm and full boost by mid 3000) even with the light gearing on the 8. I am shooting for 500whp on E85 next and I would like to hold on to the power past that rpm being that the engine originally was designed to generate max power at 8500rpm and revs to 9250. It all points to the turbo being the bottle neck right now.

About the exhaust flow, lets just say the engine has been massaged and with the way the 6 runner intake manifold is being run there's plenty if exhaust power....

Chris

 

I am running the gt4088 journal with a 1.06 hotside. I am still in the process of putting the car together so no data on the turbo yet . In theory it should produce 500 around 20psi according to Garretts comp map....

Hotside, imo is really an engine killer if not big enough to keep back pressure to its lowest possible minimum. Let the engine breath, all to often you see small turbine housings on big ported engines that suffer because of the back pressure.

Just my two cents

I chose the gt4088 journal setup for a little more spool with a bigger hotside, of course this is just theory as of today. I am hoping in the next couple of month I will be finishing up and can post some numbers. Should be a bitchen turbo though.

 

4088 is good for 500 RWHP at 19-20 psi

http://www.rx7store.net/v/vspfiles/photos/Dyno12-2.jpg

Not sure what it would do on an RX-8 but I think the .81 A/R is to small for high HP application.

 

Hey chrisrx8pr...wanted to share my setup I just test fitted. This is a great turbo..hope you check it out and enjoy it.

G