I've given this a lot of thought, and even though I'm planning on V8-ing my '52 GMC, I was originally thinking about trying to turbocharge my 235. Although I'm planning on selling it, I wonder how hard it would be to turbocharge it.
I've got a Garrett T03 with a 0.52 A/R from an IROC-Daytona with a Turbo III engine. That was a 135 cubic inch I-4 with 4-valve Lotus head. I also have an extra intercooler, as well as a variety of titanium mandrel bent pipes, left over from working on jet engines for 20 years.
I know the pistons are cast, but they're also thick. If I keep the boost down to 6 or 7 psi, I really don't think a piston is going to melt, especially if I intercool.
The single exhaust pipe is ideal for a turbocharger. I only have to make an adapter. The turbo physically fits really well on that side of the motor. The best place for the intercooler is probably under the turbocharger.
Blow through or suck through? I think suck through would be easier. Blow through, you have to pressurize the entire carb and use a blow off valve. I'd probably mount the carb on the turbo itself and run a pipe from the intercooler up to the intake manifold. I'd have to make the manifold for the carb, which would be a 90 degree mandrel with a carb flange adapted to the top of it. Then I'd have to make a flange to mate the intercooler return pipe where the carb used to reside.
BUT...keeping the fuel in state could be a problem. I can see the potential for fuel puddling and long cranking times before initial start up. In that case, maybe blow through makes more sense. Much shorter path for the fuel to flow, and all you're doing is introducing pressurized air to the carb in its original spot.
The exhaust is still a single exhaust, but for turbo efficiency, the exhaust should be no less than the exit size of the turbine, which is 2.5".
The turbo is oil and water cooled. Both are easy. Plumb the oil from the external filter, through the turbo, and then gravity feed to the tank for the return line. Water can be supplied from the heater hose, in and out.
You don't want too much timing advance under boost. So instead of having the vacuum advance running off of ported vacuum, I wonder if running it off of manifold vacuum would work. Then the distributor is advanced at idle and set at the correct amount of advance there. When rpm's climb, manifold vacuum goes away. You need a check valve to prevent pressurization, okay no problem. Then the vacuum advance is turned into a type of timing retard under boost. I wonder if that set up could work.
The only other question is how to keep the waste gate set at 6-7 psi. That could be the most expensive part of the project.
I wonder how much that'd be good for. 250 hp? 400 lb-ft?
How crazy or feasible do you guys think such an idea would be?
