Owned by the math: Turbo building question
 

I've read the turbo size selection section in corkys Bible about 50 times now, and everytime I think I've got the same idea of what I'm doing with the numbers.

Basically I've run the numbers the best I can understand to obtain what I'm looking to get out of the turbo and I know that I'm doing something wrong because every turbo that you all are using in the T3 series shows on the map that its WAY off the page for the flow and pressure ratio.

I know more than one of you are running the China Charger T3/T4 turbo which I was going to buy, advertised specs of it are T3/T04E with a .63 turbine 62 trim wheel, .50 compressor with 48 trim wheel.

To the point: Found in a box in my attic an AiResearch Garrett turbocharger that I've had sitting around for about 10 years now and noticed a few things about it. Its non-gated turbine housing of .63 ar, unknown wheel trim, the compressor is a T3 40 trim. Obviously that compressor housing and wheel are not optimal for what I'm trying to do, infact its pretty tiny. It has < 2" inlet on it.

Looking on Turbonetics website I've found some TO4E compressor wheels and housings that should work on my turbo, along with a backing plate and I've got around $300 invested after the upgrades. My problem is, I can't figure out for sure what TRIM to get for the compressor.. They list 40, 46, 50, 54, 57, and 60. Here again, my math fails me as every one of those compressors comes up way out of range on the map for each unit. Not really sure what I'm doing wrong, looking for some advice from someone thats more sure of what they're looking at in this department. :confused:

Theres a lot of variables in this equation and at this point in time I'm not really 100% sure what I'm trying to do.. but I know I'd like to make over 250rwhp (with room to grow,) would like threshold around 3000rpm, spin the motor to 7000.. Engine displacement should be about 2 liters when I'm planning on this turbo. Is that asking too broad of use from a small displacement turbo?

Sounds like my turbo.

Mine is a .60/.63 Garrett T3. From what I have read it is a 60 trim. However a 60 trim T3 is no where close to a T3/T4 60 trim.

.63 is the biggest pure T3 exhaust housing garrett made, found on the ford mustang/tbird SVO's, XR4Ti's, thats it iirc.

I have read they are good to 300whp. Who knows? Curious as to what it will spool at on my setup.

Not to hijack:

ETD BP Mani
3" Turboback, no cat.
TiAL 38mm rerouted into exhaust.

Waiting till spring to install.

you want a T3S60 like brainy's.

i hear it makes your car like a gyro

Wow I win retard of the month. After typing that all out, I went back to my turbo maps and found that EVERY trim turbo listed is spot on...

1800cc, 7000rpm, 85%VE, 15psi comes out to 2.02 pressure ratio and requires about 26.5lbs/min flow. 2.02/25.6lbs fits on the center island of every map except the 60trim.

Something must've been wrong the last time I was looking at that chart... *sigh* Thanks for the help! lol.

splitime may still have his t4 compressor for sale
https://www.miataturbo.net/forum/sho...3&highlight=t4
(i'll be going 2871r, for better or worse)

Holy crap! According to the map that turbo should work well between 7 and 20psi! :eek5: Totally forgot he was selling it. Thanks again. :D

seems to work fine for me.

You are asking a little too much. A T3 with a .63 A/R won't likely spool at 3000 rpm unless it's a real tight turbine wheel. None the less, if this is what you want you need to run the .48 A/R turbine housing. The compressor is less problematic. Since you are starting at about 250 RWHP, you would probably be best initially served with a 46 trim or a 50 trim compressor. Neither would be a bad choice. Nearly any of the T04E compressors other than the 54 and 60 trim maps looked ok, but I would want an anti-surge housing on the compressor.

FWIW, I don't have the anti-surge housing.

Mark