I have a friend with a 220HP (crank) Chevy 350 truck. He's looking to turbo it as economically as possible. I thought of using a stock Evo turbo, as they can be acquired fairly cheaply.

He's looking for ~325HP (crank) from the turbo.

I've done some searching, but I haven't turned up any compressor maps or wastegate info.

The two problems I'm concerned with are:

1. It would only take about 8psi to achieve that power level. Would the compressor work with that much volume at such a low pressure ratio?

2. Since the turbo would be doing less work than it would on an Evo, the turbine would be handling less air. This means the wastegate would get a lot more air. Would it handle the load?

 

Why don't u ask this in a chevy forum?

Hang on a sec, what time is it?

 

Because it's information about whether or not the turbo would hold up... not about whether or not the engine would hold up.

I imagine Evo owners will be more familiar with Evo turbos than people that drive Chevy trucks.

...is it hammer time?

 

Good luck welding the custom manifold...that won't be very "economical" at all!

 

My friend is a trained TIG welder with his own supplies and welder. Would that be sufficient?

 

What part of IN are you in?

 

A single evo turbocharger would choke the exhaust of a v8 engine. You would need two turbochargers since the engine is twice the size. That's besides the point though.

Is this a carb'd engine? TBI? How are you going to tune for boost fueling? These are the things you need to think about. If all he wants is 325 crank you can easily get that by changing the intake, cam and exhaust. It will be cheaper and easier than trying to turbocharge.

 

you could probably get to your power goals just by swapping in aftermarket cylinder heads and a cam. Much easier than trying to sort out a single turbo setup on a v8.

 

Shelbyville

Isn't that what the wastegate is for?

It's an early 90s TBI truck. They came with terrible heads. When I told him he could get the power with some Vortec heads and a cam, he seemed to agree. Ten minutes later, he told me to help him find a turbo. He's pretty dead set on it for whatever reason. He's already been through the local junkyards, but hasn't found a large enough single turbo.

He already has headers and a straight pipe. He would tune it at shop on a dyno.

 

If he can weld, tell him to buy a Holset HX40 turbo from ebay. You can get a blown one for $150 or so. A rebuild kit is about $50. Use the stock 350 manifold and swap them around to the opposite sides. Weld on a t4 flange to one and fab custom down pipes to the exhaust. Figure out a spot to put a wastegate and you're golden. Personally, since he can weld, I would do twin Holset HX35's and make great power on pump gas all day.

 

Evo hotside is WAY to small for it to be effective. You will shoot for something in a t-4 footprint if possible. Remember you are dealing twice if not almost 3 times the exhaust volume than what the Evo turnine housing is designed for.

Bryan