I can't find any specs on the 6.5l GM diesel turbo, maybe someone here can help me out? I don't recall the model name, but GM-4 comes to mind. I've got an NOS turbo for a '93 6.5l, along with a 3.4l long block that I'd like to use in my '86 mpfi v6 car. My goal is just a cheap and fun project. If that setup would be capable of a 30-40% increase over stock, I'd be absolutely tickled. But at the same time, I don't want to put up with a significant amount of turbo lag if it's nowhere near properly sized for the application. I have basically no knowledge of turbocharging in a non-stock application.

And before any comments along the lines of "not worth it" or "just V8 swap it", my car in question is not an F-body. It is a fwd A-body with much less room under the hood.

 

Somewhere around 1990,GM had a turbocharged 3.1 in IIRC, Gran prix. Never seen one in person,but it was a single turbo. I kinda recall the 6.5 turbo was made by Warner-IHI.

 

Yeah, that was the McLaren Grand Prix. 1989 and 1990 too, iirc. I believe it was rated for around 200hp.

Yes, Borg Warner IHI something or other rings a bell.

*edit* I found it again. It's an IHI RHC6... I think.

 

Anyone with some insight?

 

id rather trade your 6.5 turbo for my 6.5 suburban and give you a properly sized VS turbo in exchange

 

Seems like a trade worth pursuing, imho.

 

First, realize that all the larger turbos started as larger diesel turbos until resent history because OEMs just didn't make large turbo gasoline setups.

Second, diesel engines spin at roughly 1/2 the rpm of a comparable gas engine, so you're talking half the air/exhaust flow for the same size engine. So as a rough rule of thumb, a 5.9L cummins turbo will work well as twins for a roughly 350-400cid small block (5.7-6.6L). Rules of thumb sometimes get you into trouble with these kinds of things, but generally they work. If you want real numbers then you will need to learn to read compressor maps and start digging for them. I'm not sure why they are not published more often, and I expected that that information would be more common by now but somehow it seems to have gotten less common.

Now, from memory (treat this with a grain of salt, I'm this information may be worth only what you paid for it)- the 90's 6.5L diesels used an IHI turbo, something like an RHB62. At the time the IHI turbos were a very modern design and often spooled faster then a comparable turbo from other brands. GM and ford turbodiesels have always used packaging specific turbos which can sometimes be hard to adapt to other applications, if I remember right the only real headache with this one is the large wide turndown elbow limiting mounting orientation, but if you can work a tight turndown into your design it is a very efficient design. The factory setups were something like 180-220hp, and I'm pretty sure that turbo could move around 300hp worth of air, maybe more (again, you'd have to find a compressor map to verify), which could be fun on a 3.xL V6...

I'd do it if I had the parts laying around, it would be fun and should be a more efficient then most people's aftermarket setups with turbo sized like, "I want XXX hp, this turbo will move XXXhp..."

 

Thanks, that is very helpful. Yes, it does have a tight turndown on the outlet and it is very close to the exhaust inlet too. I don't think that will cause any real packaging issues, just a minor annoyance. My car has what is essentially the very same FI setup as '85-'92 F-body, just with a transverse engine. TB inlet is on the passenger side of the car. The area above the trans and belllhousing has the manifold crossover (very helpful here), an offset thermostat housing (the intake base itself is mounted backwards compared to F-body) and the brake master cylinder. It's a fairly wide open area otherwise. Charge piping can run through the radiator support to an intercooler and then back through the rad support to the passenger side throttle body.

It may be helpful to mount the turbo tilted 10-15 degrees though. How close to level does the oil drain need to be?