im starting my single turbo project soon but im not sure what size turbo to use right now i have a fresh 385 stroker about 425-450 hp with 6 miles on it im only lookin to get about 600-625hp im thinkin a gt45 turbo but hey what do i know.... thats why im asking u guys so let me know what u think

 

you can go as small as a GT40 but you don't necessarily need ball bearings. a lot of garrett's GT turbos are also offered in journal bearing. the smaller turbo will be easier to control but will make more heat/detonation.

 

I asked this same question a few weeks ago, i dont know anything about the garrett's compared to Master Power. I bought the Master Power T70 with .96 A/R, shipped for $710. I'm putting it on a 425hp 377 stroker. The T70 is rated from 450-700hp

 

http://www.turbobygarrett.com/turbobygarrett/

Check out the turbo tech section.... There's lots to learn but take your time and it will make sense

Once you've done the math you can decide which turbo best suits your needs.

There's compressor maps and actual turbo dimensions that might come in handy too

 

what r u doing for headers?

 

Yea but the only way to use their advisor software is you gotta go buy a $400 Iphone for the "free" ap

 

I'm making my own headers. There are actually lots of pictures on here of how some have fabbed up their turbo headers. Just take some time and browse around.

 

Ya I thought that was funny too, I don't have an iPhone but tons do.... maybe you can borrow a friends "phone"

Anyways, I do my homework the old fashioned way... with a pad of paper & a calculator.

Turbo Tech 103 is great information!!! and lets you get into the heart of the calculations.

 

the compressor should be mated to the application. if you are looking for an early bump to VE and plan on running pump gas then you should choose a compressor with its maximum flow right around your peak power.

If you are looking for a more slower spool, higher RPM VE bump (more peak power less midrange torque), with cooler air at higher rpms coming from the compressor then choose a compressor with its efficiency range about dead center for the engine's peak flow. If you then raise the boost and use race gas you will still have plenty of compressor left to make more power.

Then mate the turbine to that application. the first compressor would like a smaller turbine because it wants to get the compressor going as quick as possible. The second compressor doesnt care about the early spool, it requires the exhaust flow of a larger turbine housing, so it needs to be bigger.

Examples!
you want to make 600 horsepower, use pump gas, street car. needs quick spool.
-choose a compressor that flows a max of about 65lb/min and use a smallish turbine.

you want to make 650-700 horsepower, use pump gas, occasionally race gas @ 850+ horsepower.
-choose a compressor that flows about 65lb/min in the center of its map, and running off the edge around 90lb/min. the GT42 comes to mind iirc. Then you need that big turbine of course...