Looking at 3 different STS turbos, all claiming they support up to 620 horsepower. They are mostly similar, however, their A/R's are different. They are .68, .81, and .96. Wouldn't I just want to stick with the smaller A/R turbo that can support the same horsepower the .96 A/R turbo could ? Is there something im not considering ?


Links to the turbos:

https://www.holley.com/products/engine/forced_induction/turbochargers/turbos/parts/STS202
https://www.holley.com/products/engine/forced_induction/turbochargers/turbos/parts/STS201
https://www.holley.com/products/engine/forced_induction/turbochargers/turbos/parts/STS208

 

Hp ratings mean very little, it all changes based on the particular engine it's bolted to. The 3 different a/r's are just a fine tuning tool. What's the setup, and what hp goals do you have?

 

Rebuilding a 355 lt1, 4l60e, 3.73 rear end. I’ve got nitrous but not like it’ll be filled all the time. Going for a rear mount set up and just want to make 500 rwhp.

Not exactly sure how to tell which of those turbos would be better exactly for my engine size.

 

Large exhaust housing are good for high temperature exhaust gas. High temp gas takes up alot of space so the extra exhaust housing displacement supports a lower pressure while the gas is very hot. This will help control pressure and temperature and promote longevity and reliability of the engine and turbo at high output. The drawback is due to larger size the turbo will spool more slowly, especially when the gas is cool.

Small exhaust housings are ideal for colder exhaust gas temps, like if the vehicle is used frequently in freezing weather or if the turbo is very far from the engine where the exhaust gas will be cold and condensed in volume. The turbo can spool more quickly but the gas may heat up much more quickly and pressure will rise much faster as power climbs and temperature throughout of the engine is increasing. It can be more dangerous or choke off the power potential of an engine if the pressure/temp rises too high due too small of a housing.

I think you would go for the smaller housing since you are thinking remote mount turbo. But is isn't that simple. before choosing any turbo you should look at the compressor and exhaust maps and determine the ideal pressure ratio and flow for the power you desire. Then modify the engine accordingly to hit those demands.

I would start by posting and learning how to read compressor map. Try to understand that then move on to the turbine stuff.