i am tryin to figure out what size turbo i have on my 97 chevy 3500 f code 6.5. how can i go about finding out what size it is.

Since you have a 97, it's likely that you have the GM-8 turbocharger.

There should be a tag somewhere with "GM-8" engraved into the aluminum compressor housing.

Other ways to tell is the wastegate vacuum actuator on the GM-8 is a vertical mount, so the actuator pulls up or is pulled down during opperation, where earlier GM-X turbos had horizontal wastegate vacuum actuators.

Also the GM-8 has the free flowing turndown elbow on the turbine outlet, where earlier ones were a tad more restrictive.

Lastly, the GM-8's wastegate "potter" valve is IN that elbow, where the earlier ones the wastegate valve was in the turbine housing.

thank you i did find the plate and it is a gm-8 turbo. is that the best out the gm turbos? and what boost should it be putting out? i am getting my gauges put in and i would like to know where it should be for boost.

Yes, it's the best of the GM-X series turbos used on the 6.5

Some people get different results, but on my truck with the stock vac system running the wastegate, I'll see as high as 13psi spike, or with torque converter locked, but WOT is usually around 10psi.

Cruising at lower speeds is usually 5psi, on the highway at 120kph I'm lucky to see 1psi.

hey thanks for the help. i am getting rid of the vac system and getting the heath boost controller. i would like to see 15 psi with out blowing up my engine.

hey thanks for the help. i am getting rid of the vac system and getting the heath boost controller. i would like to see 15 psi with out blowing up my engine.

I made my own version of heaths turbomaster, and have had it up to 18 psi (not sustained for very long) without any issue, so I know the engine can take it, I backed if off for a max of 15psi and the only issue I had with the spring controller set for 15psi, the truck would defuel when I'd be cruising on the highway.

Personally, I'm sticking with the vac system for now.