I'm getting very lost when researching this subject. I can't figure out for the life of me the difference. I thought the compressor side was the non-downpipe side and the turbine side was the side with the downpipe attached to it. Which one is which?

Also, when people mention it has a .96 a/r or .70 a/r ... which side is that? Sorry for my stupid questions.

 

The compressor is the inlet side, the side that does infact compress the air and sent it on its way.

The turbine is the side the used exhaust gass's pass though which power the compressor

As for the a/r's, what that is describing is the area / radius ratio's of the turbine housing

What that is is a ratio of the radius of the turbine housing from the center to the center of the turbine turbine scroll against the area of of that given section of the turbine scroll

The turbine scroll is that thing that looks like a cone wrapped around the housing

For more information, i sugesst buying Corkey Bell's Maximum boost, it is where i started to learn more indepth information of the turbocharging subject

-Jacob

 

The only thing else I need to know is which ratio do people talk of when they mention it has a .84 a/r, .96 a/r, etc. They usually only mention one so is that the compressor side?

 

a/r ratio is Area/Radius. The area refers to the size of the tubing that makes up the scroll. The radius is the measurement from the center of the tubing to the center of the shaft. Its kind of hard to picture that in your head. I believe a/r can be used for turbine and compressor sides as they are both scrolls.

Check out this site for a good visualization of a/r: http://www.turbominivan.com/tech/turbo201.htm

And people are *usually* referring to the turbine side.

 

is a .84 a/r turbine and a .70 a/r compressor size turbo good for a stock ported motor? Seems like the concensus would be yes. How much of a difference is a larger compressor a/r going to be?

 

The A/R ratio is a type of aspect ratio, so the correct A/R ratio for a particular application depends on the size of the turbo and the specifications of the engine.