OK this must be the biggest noob question that i have ever asked, but i jsut cant find otu what A/R stands for and its bugging the hell out of me... like a T3/T4 with a 50 A/R commpresor and .63 A/R turbine... I sonud like an idiot but i just cant figuar it out.. haha. Thanks!

 

area/radius ratio

It's how you tell the sizes of turbos apart. You take the area of the fan and divide it by the radius of the fan (or was it the other way around?) and it gives you the ratio size of that fan.

 

Cool thanks!

 

That is not exactly right. If you were to "unroll" your turbo compressor housing, you would end up with a cone. If you take a cross section by slicing the tip of this cone at any point, you have the A in A/R. Now roll the cone back up. The distance from the center of the area you found before, to the center of the compressor wheel is the R. Generally speaking higher A/R's will make a higher peak power number higher in the RPM range and a lower A/R will help out things in the low end. Also, the point you take the area from doesn't matter because the distance will change proportionally and the A/R will be the same for that turbo.

 

I didn't feel like taking the time to look it up earlier, but I just wanted to check to make sure. I looked in my copy of Maximum Boost in pg 32. You were right, the A is actually the area of the opening/funnel/whatever, and the R is the distance from the center of the turbo to the center of the circle in A.

 

https://honda-tech.com/zerothread?id=1023414

 

We need avatar police.