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Thread: T3/t04b V trim

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Posts: 1-10 of 21
2010-07-06 13:11:55
T3/t04b V trim
I bought this a lil while ago. Just wondering if someone can tell me something about them and the compressor map. I've tried to learn how to read compressor maps but I guess I will have to get someone to show me.

I could of sworn I started a thread about this last night but I don't see it.

2010-07-06 18:12:50
I'm shooting to run 15-20psi. I'm trying to guesstimate by using a compressor calculator if the turbo will surge on me on not. I'm starting to understand maps a little more. I've ran it at 15psi before and I don't believe I've ever heard surge coming from the turbo but by calculations and the graph it would show at 15psi that i'm on the left of the surge line in the lower rpm's. By calculations at even 25si and 7500 rpm it's still in the 70% island but I worry about surge.
2010-07-06 20:02:57
Well Jeff at Turbo auto doubts that I will ever see surging On Daily driven 18psi. I guess soon I'll update with dyno dynamics graphs.
2010-07-06 20:36:39
2010-07-06 20:53:38
Hush you!!!!
2010-07-07 02:57:03

using a calculator from Squirrel Performance. I had to work out the HP to be 280 to get it to plug in 18 psi. This is more of a guesstimate I'm sure but still a little scary.
2010-07-07 16:46:25
Using the most "realistic" values I could to plug into the calculator I came up with this map:

That's a target of 241 HP (to end up with 18 psi).

Using the same data on a GT2860R gives this:

So we know something is quite wrong with the calculations. Personally, the old T3/T04B and similar turbos are not something I'd put on a car. They are just too inefficient. However people do it and it works. The real trouble with this turbo is that it is quite large. It is capable of flowing like a GT3076R however it's surge line is much worse. It is much steeper. We know the GT3076R works on an SR20 without surge. Here's that map:

Even a GT3582R will work without surge on a high flowing SR20. Here's that map:

Somewhere between the Gt3076R and the Gt3582R is the surge limit for a typical SR20. If I massage the data put into the calculator to make the lines work that way, I think we can get a good idea of what's going to happen with the T3/T04B.

I'll come back after I've done that.
2010-07-07 16:55:23
Yah, forget all that. I see where the problem is. The boost expected at which rpm is wrong. It's a slow spooling turbo, so let me put those numbers in.
2010-07-07 16:59:50
Yah you're going to be real close to the surge limit at 15 psi and likely over the limit at 18 psi. The turbo is just too big and has a crappy surge limit (narrow map islands). I'd be surprised if you didn't run into surge problems if you try to go much above 15 psi. It's a valid concern at least.
2010-07-07 18:33:15
Thank you Ben. I'm glad you chimed in. Guess If i want more power turning up the boost is not gonna be the way.
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