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School Me On Turbo Sizing

1K views 6 replies 6 participants last post by  Begle1 
#1 ·
1) How do you measure a turbos size?
2) Is a smaller exhaust housing always better?
3) Whats more important volume or pressure? Or do they coincide?
4) Is there any magic calculation for picking a turbo?
 
#2 ·
It seem sno one knows the anwer to these questions, even the magazines try to explain it and can't. I want to know too, I think we all do
 
#4 ·
LOL this is what I mean no one tells us what each part of the turbo does and how changing things effects things. All answers are not answers. Not dogging you just saying I have yet to see a post that actually really explains turbos.
 
#6 ·
Sizing a turbo is pretty much like rocket science (errr, turbine/compresor science i guess...)

1)Turbos can be sized different ways. One popular way of 'measuring' a turbo is by measuring the wheels O.D (typically in mm) and the turbine housings are usually measured in cm2 displacement. So you may see a number like 66/71/14, the O.D of the compressor wheel would be 66mm, the turbine wheel 71mm and the turbine housing would be 14cm2

2)Smaller turbine housings are not always better... A smaller housing will help spoolup, but can become a major choking point (restriction, at which point the drive pressures and egt will skyrocket). A larger housing is a tradeoff for slower spoolup but more free flowing.

3)This is one area that compressor maps are the key ingredient. Pressure and volume are dependant on the compressors wheel design/size amongst many other factors. Remember that pressure is only a measure of restriction, its the flow that you want, thus the reason for porting heads and opening up the intake/exhaust.

4)its all magic :D
 
#7 ·
1) How do you measure a turbos size?
In either centimeters or millimeters; exhaust wheel, intake wheel, exhaust housing area, intake housing area.

2) Is a smaller exhaust housing always better?
Yes, as long as the turbo doesn't overspeed.

3) Whats more important volume or pressure?
Or do they coincide?
Volume. Pressure is only significant because it gives more volume.

4) Is there any magic calculation for picking a turbo?
The more money the better.
 
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