Turbocharding CPI engine?
 

Like the title says. I got a 95 GMC Jimmy with the CPI engine and since I'm rebuilding my Cummins, I'll have an extra turbo. I know, I know, there's lots of threads about turbocharging the 4.3 but I can't find any (with good info) with the CPI. It's going to be an off road truck so no emissions. With that being said, has anyone done this? Does anyone have input/suggestions? Has anyone come across threads with info on turbocharging a 4.3L CPI engine?

Thanks in advance. :icon_playing:

Bump!! Anybody got any info?

i've thought about this before with mine. Could imagine it would be fairly straight forward. Engine internals arnt capable of supporting forced induction from the factory, 9psi is pushing it. ECU tune would be a must. If you beef up the bottom end and do a low compression build you could boost the crap out of it. My only thought is that I think the 95 had a plastic upper intake? idk if it can take the pressure or not compared to the cast ones used in 92-94

Another thought, you know how much crap on these trucks is vacuum actuated? What does forced induction do to vacuum again? Just keep that in mind

hard part is fuel control. I dont think The regulators can be adjusted well enough to compensate.

Mine has the aluminum upper intake. The big, funny looking one with the spider injector. I've read other threads were the intakes you're talking about can hold at most 14 psi (not recommended though). You would still have vacum to a degree since you'll still be using the throttle plate. As for fuel, i've heard the regulator for the spider injectors like on mine, are controlled by manifold air pressure. Not sure if that's true or not, but there are also aftermarket regulators controlled by the boost for the turbo.

When I replaced my fuel pressure reg. on my 95 it was just a spring valve, so something different would be required. I'd also wonder if the spider can be upgraded to flow more fuel or if you are limited to the stock spider, which I'm sure would struggle.

Yea, that's a good question. I'll just have to keep looking around and hopefully more people chime in with ideas/solutions.

what about the size of the Cummins Turbo
Thinking that's its just to big to be able to work well

I would think it would work. The cummins is a 6 cylinder as is the 4.3 and it's a 57 inducer (pretty sure) with a 21 exhaust turbine. on my stock cummins, it's a bit laggy and pretty sure it supports up to around 250-300hp. I would just have to regulate the boost.

there aren't any 92-95 spider injector upgrades. I've looked, the only thing you can do to upgrade them is a custom fuel rail system. One problem i see is the regulator is controlled my manifold pressure (not the map sensor). When under vacuum fuel pressure goes down, closer to atmosperic pressure the pressure rises. I wonder if it would increase more with greater than atmosperic pressure? that would be interesting, lol