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Discussion Starter · #1 ·
Well I pulled the turbo and manifold off tonight. The manifold had a crack in it so I sent it out to get fixed/replaced, then Jet Hot coated. I decided to measure my compressor wheel

I get right at 3.0" On the Exducer, and right at 2.32" Going by the catalog on Turbonetics Website it is a 60-1. It is in a TO4b compressor housing, .48ar exhaust with a clipped stage one wheel in it. Very nasty turbo (as in I dont like it).

I am having a hard time measuring the inducer. I tried to get the dial caliper to run right over the shaft and measure from there (as to get exactly 180* from one another. It is a little tough.

How bad is this compressor wheel for a miata. How much better would it be in a T04E housing (not planing on it for the miata, but for selling it when the 50 trim comes in) I know I would have to change the backplate. But either way is there any other way to see if it is inded a 60-1.

Thanks.
 

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TurboMiata said:

I get right at 3.0" On the Exducer, and right at 2.32" Going by the catalog on Turbonetics Website it is a 60-1.
It could also be a 60 trim T-04E.

It is in a TO4b compressor housing, .48ar exhaust with a clipped stage one wheel in it. Very nasty turbo (as in I dont like it).
What a POS! The fact that it has a T-04B housing probably means it is a 60-1. That thing is a pile.

But either way is there any other way to see if it is inded a 60-1.
60-1 will have 7 main blades and 7 splitter blades. A BCI-4 or BCI-8 T-04E wheel will have 6 main blades and 6 splitter blades. I can't tell you if it's a BCI-4 or a BCI-8 without seeing it up close.
 

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TurboMiata said:
You think the Non clipped stage III in a .63 with the 50 trim will spool better than this thing? Just courious.
Probably. It will definitely support a lot more power.

Where are you buidling boost now?

Rob
 

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Hey dude, I did some actual matching for you (I'm testing out some changes I made to my engine matching program and needed a test case), and I think I'm going to recommend you go with a 46 trim compressor instead of the 50 trim. This will hurt high-end performance a *little* bit (very little, I think).

Looks like at ~4000 RPM, you could run into a surge problem at high boost. Looks like the turbo is coming up on boost faster than I initially thought it would. Normally, I wouldn't sweat this, but because of where it is on the map and in the engine operating zone, it could be a problem.

Minor change, and if you've already ordered the turbo and can't change back, I think you'll be OK with the 50 trim, I just think that the 46 trim will work a little better.

I'm predicting you should be coming up on full boost about 4000 RPM, and the turbo looks like it should be good for nearly 400 whp at about 24 psi (without a cat!).

Have fun.
 

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Discussion Starter · #7 ·
I have already ordered the Turbo, but I "Might" be able to change it. Right now with the my POS turbo it was building boost at about 3500 and full boost by 4600. That was about 15lb. On the .63 housing it got full boost by about 5200 I would see full boost. It was horrible. The .48 actually felt the same if not better on the top end. :D

With the 46 trim how much top end do you think I would loose, and how much mid range do you think I would gain with the 46 trim. Will passing through the surge line kill the turbo?

My VE is going to be pretty good as I have a fully ported head, and a equal legnth (nothing like FMAX crazy tube maze :D) tubular manifold.

How much better do you think the 46 trim will spool over the 50.
 

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TurboMiata said:
I have already ordered the Turbo, but I "Might" be able to change it. Right now with the my POS turbo it was building boost at about 3500 and full boost by 4600. That was about 15lb. On the .63 housing it got full boost by about 5200 I would see full boost. It was horrible. The .48 actually felt the same if not better on the top end. :D
The new turbo should spool as well as or maybe even a little better than your old turbo with the 0.48 housing.

With the 46 trim how much top end do you think I would loose, and how much mid range do you think I would gain with the 46 trim.
Performance will be about the same

Will passing through the surge line kill the turbo?
That depends on whether or not you surge while coming up on boost. My experience is that you usually don't get surge under highly transient conditions, so you probably won't get surge as you're coming up on boost. Switching to the 46 trim, though, should have a minimal impact on performance and will make surge much less likely.

Part number for the 46 trim wheel is 448347-3
 

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Discussion Starter · #10 ·
So you dont see any loss in power with that turbo. Say at 15lb with the 50 trim I make 310 at the wheels. What would you guess I would make with the 46 trim?

You also said it should spool similar to my current one. Did you notice that I said it was clipped (biggest mistake I ever made) It is very slow in transient response.

Also when you say full boost by 4000, do you mean 15lb or 20 (not that it matters much, just courious)

You also mentioned before a 50 trim can move 450hp worth of air, how much will the 46 do?

Thanks again man.
 

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TurboMiata said:
So you dont see any loss in power with that turbo. Say at 15lb with the 50 trim I make 310 at the wheels. What would you guess I would make with the 46 trim?
It will be about the same, at least within my ability to predict it. Keep in mind I don't have any engine data, and am working based on what I deem to be reasonable assumptions.

You also said it should spool similar to my current one. Did you notice that I said it was clipped (biggest mistake I ever made) It is very slow in transient response.
I would say that your current turbo with a .48 housing has about as good a response as you can expect for a big turbo... well, it's slow to build boost (to take 1000 RPM to go from boost threshold to full boost in a small A/R turbine housing is odd), but I'd say expect boost threshold about 3500-4000 RPM, and full boost by 4000-4500 RPM. 'Full' means 20 psi, but there won't be much difference between 15 psi and 20. These numbers are rough. In higher gears, full boost will be developed closer to ~3800 RPM, but I have to make a lot of assumptions since I don't have much data.

You also mentioned before a 50 trim can move 450hp worth of air, how much will the 46 do?
About 415. Here's a good rule of thumb: air flow goes with inducer area. Trim is (inducer diameter/exducer diameter)^2. Therefore, for constant compressor exducer diameter, flow (and hence the power the compressor can support) scales with trim. If a 50 trim can support 450 hp, a 46 trim can support 450*(46/50) = 414 hp.
 

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Discussion Starter · #12 ·
When you say it can support 450whp or 414 as you say, are you talking about WHP or Crank?

Thanks for all the valuble info.

And you think response and spoolup will be about the same between the two, Just that the 46 wont go through the surge line as much.
 

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TurboMiata said:
When you say it can support 450whp or 414 as you say, are you talking about WHP or Crank?
Again, you're getting to the point where the assumptions made are too broad to be more specific. I personally don't buy the old '20%' rule of thumb, so if you put out 350 whp, I'm not gonna believe you're putting out 440 at the crank. I think the difference is probably closer to ~20-30 hp; far less than you would expect to see from tuning variations.

And you think response and spoolup will be about the same between the two, Just that the 46 wont go through the surge line as much.
Right
 
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