Sonny

Hi All,

I have a Garrett T3 from an old Volvo. I removed the compressor housing and measured the compressor wheel with my caliper. The inducer diameter was 1.674" and the exducer diameter was 2.367".

According to this chart: http://www.turboneticsinc.com/catalog/comp_wheels.html

... I have a "50 trim" wheel in this turbo. Is that correct or am I leaving something out? The compressor a/r is .42. The turbine housing is .48 a/r and has the "standard" turbine wheel as far as I know.

I want to make 275-300 hp with this turbo on a built ZC. I figure it will take about 15 psi of intercooled boost to make this much power.

Based on my calculations (I'm about 1/3 of the way through 'Maximum Boost' right now), I need a compressor that will flow about 30lb/min. To get this number, I used a max RPM of 8000, Volumetric Efficiency of 95%, engine CID = 95 cid, and PR = 2.02 (15 psi of boost).

It looks like the 50 trim is little too small for 30lb/min with a pressure ratio of 2.02 ((14.7+15)/14.7). Do you guys think I just "try out" the turbo like it is and then upgrade later or should I go with a 60 trim wheel and and new housing/backplate?

Well...it started out as a simple question.

Thanks,
Sonny


[Modified by Sonnyballs, 12:46 AM 4/27/2002]

AlphaKennyWun

yea, try it out. You can always change it later. Its neat to see the power differences between two turbos. What have you got to lose?

Sonny

Well...I guess I've got nothing to lose by trying.

Sonny

PrecisionH23a

nice calculations


[Modified by GudeH23a, 1:05 AM 4/27/2002]

Snafu-Si

How they heck you calculate all that stuff! ****... can you do my Accounting homework? Please?

BlueShadow

also, I think your turbine might be a little too small... but I'm not so sure since you are talking about a ZC, and I have only ever done numbers for H22's and B18's.

d16twannabe

read Maximum Boost form Corky Bell, that book change all thoughts i had on turbo charging, he gives you every formula you will need to run a great set up, they aslo turbo a nsx. the only thing that sucks is that he mainly talks about v8 when doing calcs.

BlueShadow

here is a jpeg I did a while back that shows you how to do the calcs. I got the calcs from Maximum Boost, but these should not be your only method of selecting a compressor. It doesn't go too in depth into the Ideal Gas Law, also the JPG is for non-intercooled boost. BUT I have double checked my numbers with those on http://www.turbofast.com.au/turbomap.html turbo calculator and the numbers come out very close for both intercooled and non-intercooled.

also check out this useful link on how to read compressor maps
.
.
https://honda-tech.com/zerothread?id=142398
.
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[Modified by BlueShadow, 7:43 AM 4/27/2002]


[Modified by BlueShadow, 7:46 AM 4/27/2002]

Sonny

Good post, BlueShadow! Thanks for the info.

How do I factor in intercooler efficiency when looking at a compressor map? If this is covered in Maximum Boost, I have yet to get to that part.

Do I just increase the VE a touch to compensate for the intercooler? I'd imagine that I must also factor in pressure drop.

I know that it will be impossible to get it exactly right on paper, but it's always fun to try to get it close and see what happens.

Thanks,
Sonny

BlueShadow

The calculations for figuring intercooler efficiency and PSI loss is on page 50-52 of Maximum Boost. I think that the efficiency of the intercooler would raise the amount of power you get in the end, and the intercooler PSI loss will offset the efficiency of the intercooler.

So on the compressor map you would be getting a rise in efficiency

example: If on the map you were at 70%, with the addition of an intercooler that would raise it up slightly from 70% to maybe 75-80%.

If you know your bore and stroke for your motor, you can use this site to check your numbers and see how much your off by. My numbers aren't off by very much when I compare them to the website.
http://www.turbofast.com.au/turbomap.html


[Modified by BlueShadow, 2:26 AM 4/28/2002]