So you think you know your turbo trims?

[MikeMurphy]

All this talk about the .50 trip t04e compressor is great info. But I was hoping for some info on the best T3 turbine available for a low boost KAT.

I understand a higher A/R such as a 0.83 is going to spool slower than say a .48, but will allow for less air going through the wastegate. What im looking for is the most efficient turbine as to lower the manifold pressure as much as possible, and dont mind giving up some early spoolup to do so.

Anyone have some solid info on this? Is a T3 at all good for this?

[C-Kwik]

define what you mean by low boost.

[MikeMurphy]

5-10psi, focusing around 7.5

[aleph1]

Thanks for bringing this up, I am also curious as I want to run 7-8psi daily. I hear the .63 is the best for a street setup. But I might be leaning towards a .48 for more initial response...anyone have any experience with the above?

[C-Kwik]

Both the T3 60 and super 60 are fairly close in efficiency. The Super 60 has a slight advantage as you near redline, but both will be in the 60 percentile range by redline.

As far as turbines, A/R is only a small part of the equation. As I've said countless times before, A/R is not the size of the turbine. It's the size of the nozzle. If you really want to look at a turbo size technically, you need the compressor trim, and A/R and the turbine trim and A/R. And with T4 turbines, another factor that can be looked at is the difference between the Tangential and on-center housings. Keep in mind that turbine trim will have a lot more to do with spool-up characteristics of a turbo than the A/R alone.

As far as the size, I'm biased towards larger turbos. If I must choose from a T3 turbine, I'd get the larget trim I could, and keep the A/R a bit high as well. But that's just me. I personally wouldn't go smaller than a T4 turbine.

Keep in mind that this is the problem with choosing turbos. Everyone wants different things. There is no one "best" turbo. I'm not trying to bash anyone here. Just trying to bring the level of understanding in here up a notch. To look at a turbo more comprehensively will help you to make a better choice and promote more technical discussions.

To elaborate, aleph1, instead of asking what the best street set-up is, perhaps ask, what kind of spool-up and boost levels does someone have with a Stage II T3 Turbine with .63 A/R with x compressor wheel. Asking for fact instead of opinion will help you to decide what is best for you.

Again, this is not a bashing post and I'm not picking on you aleph1, I only used your example since I could see it as I typed this. I'd love for more of you to just be able to look at things a little bit more critically and make your choices based on technical data rather than relying solely on someone elses's 'opinion'. An opinion is too subjective and for most of us, a turbo is a substantial investment. I'd hate to see a person make a bad choice for themselves because they relied on opinion instead of something more concrete...

[aleph1]

I know what you mean Ckwik and I understand perfectly. I am that way most of the time also. But its hard for me to say exactly how a .63 A/R T3 turbine will react differently than a .48 as I've never drove a KAT with either...or any KAT at all =( All I have to go on is from what other people have said about them.

What I mean by a "street" setup is that the specs are generally accepted around here as the best balance of power and response for street driving. Of course I dont know personally, due to what Ive said above. But I trust most people here enough to base my decision on it...which I still haven't made up yet. If anyone with a KAT wants to give me a ride, that would be cool =)

So by your advice, what kind of spool and boost do you KAT people get with StageIII wheel and .48 A/R T3 turbine, with a T4 .50A/R .50 trim compressor NON ball bearing?...of course if anyone has this setup or something close to it.

[C-Kwik]

But as I was saying, it's the way the question is stated. If you were to ask me what a streetable set-up is, I'd go for a full T4. But that's my opinion. Someone else may say a full T3. But the reason why a person has that opinion is important. But If I tell you my T04B with xxx specs spools to 6.5 psi by 3500 RPM, that gives you something you can relate to better. That's all. =)

[MikeMurphy]

Its often difficult to tell exactly how the turbine is responding. For the compressor you can just look at the charge temps, which is extremely important to me, but beyond that is the turbine. There is serious power to be made with a highly efficient turbine design and I would love to tap into that. I find it difficult to isolate the manifold and turbine variable from the entire setup and base it on whp. There are so many damn factors to get some real information on this and I was hoping the only way to get this is baseline runs with each turbine on the same compressor, which isnt reasonable.

Who do you know that has a straight T4 design? What sorta specs and numbers were they looking at? Dynos?

[C-Kwik]

Yeah, there's not a whole lot of info out there for turbines. So asking around can be a big help. For T4's you can get an idea from People who have NSPORT or XS Engineering Kits.

[MikeMurphy]

Great! I didnt realize that nsport or xs uses a straight T4.