The Stovebolt Site Forums The Shop Area The HiPo Shop Turbocharged 235?

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?

I have no idea what most of that means because I am new to most of this stuff...but it would be different. Especially when you open your hood and onlookers can see the ground! Crazy idea, but I like it!

Check out Santillis Book on hopping up the Inline6.
It is on the later engines (1962 and up) but the Turbo and Blower capitels mean the same for a 235/261

Frank

I've had conversations with Leo Sanducci on super charging 235/261 engines.Leo favors exhaust driven superchargers on an inline engine due to the intake and exhaust being on the same side makes the installation fairly simple.
A suck through system is easy to build,if the system is designed properly,throttle response and or turbo lag shouldn't be an issue.The supercharing will add power without requiring the engine to rev any higher than stock,a good thing considering the 4 main bearings and somewhat marginal rod strength at higher revs.
The stock cast pistons should be ok with 5-7 psi boost if detonation is keep under control.A stock 848 235 head on a block with the usual .020 below deck height at tdc flat top stock pistons has an actual static compression of 8-1.Should be ok using 91 octane pump gas.
6 psi boost on an engine with limited breathing like a 235 might produce a realistic 200-220 HP and perhaps 300 ft lbs of torque.According to Leo,each psi of boost will give about 10 percent added power.A stock 235 has maybe 115 real HP,engines typicaly modified with more carb,cam and compression have 160 -170 HP maximum.The turbo power will come on low in the power range.And if you can make it all yourself,the cost will be quite reasonable.
The limiting factor is again the breathing.The restrictive ports and combustion chamber design will raise the intake manifold psi,crating more heat and pressure,raising the onset of destructive detonation.

Yes, when I held the turbo up next to the exhaust port, I could see how easy it would be to turbocharge that engine.
I've built turbo systems before, but I need to explore some of the new turbo controls that are on the market. The ricer movement would be helpful here, Greddy and HKS for example.

Having more power on tap in the 2000 to 4000 rpm range would give a truck what it's lacking out of the little 235. But I couldn't ask more than 7 psi out of the system because it probably would cause damage.

i considered doing the same thing, even did all of the research, then changed my mind.

-you should do a blow through setup. it is pretty easy to modify a holley or edelbrock carb for blow through. a draw through system is bad because the gas will eat away at the seals in the turbo, plus you cannot use an intercooler with a draw-through system-you will have serous fuel puddling issues
-mount the intercooler in front of the radiator so it gets the proper airflow.
-you need a way to raise fuel pressure 1:1 with boost, so either get a good electric pump with a regulator, or modify a mechanical pump to be boost referenced.
-the wastegate is controlled by a spring, there are different ones for different boost levels. your turbo may have a wastegate built in it
-for a blow-off valve, if you want to be budget, plumb in a radiator cap in the tubing after the turbo, it will relieve pressure when you let off the throttle. get a 7 lb. cap
-i would make the exhaust pipes as big as possible, maybe a 2.5" (or even 3") downpipe to the turbo, and a single 3" pipe fromt he turbo to the tailpipe

that should get you started...

two good references:
http://www.turbomustangs.com/forums/
"Maximum Boost" by Corky Bell - available at most bookstores

If you use forged pistons or keep the boost to 4psi or less it will probably work good for a while.

You could always add an aftermarket fuel injection computer to control things. That would make things MUCH more reliable. You would have full control over the ignition timing. There are a lot of companies that make good universal setups: Wolf, Haltech, Electromotive, Motec, etc. There's NO better way to control the motor, especially with a turbo.

Hotrod,
You've obviously given this a lot of thought, but I need to point out that your idea for changing the spark advance is wrong. While you're correct in thinking you want less advance in a charged engine than a naturally aspirated engine, you will still want the spark to advance more as the RPMs go up. If you change the vacuum advance from port to manifold vacuum, you will actually have more advance at idle than you do at higher RPMs. This will cause a retarded spark at higher RPMs and overheating, definately something you don't want in a turbo motor. Also, I agree with 1-ton about not being able to use an intercooler with a draw-through, you need to keep the carb as close to the intake port as possible.

This is just my two cents worth so feel free to tell me to take a walk if you think I'm full of it

while you are being novel, i would go with fuel injection. it would help with fuel distribution issues with the intake manifolds available for the 235. something like magasquirt, it is an affordable diy fuel injection system.

www.megasquirt.com

as for ingnition, you don't want to retard the timing. you just want less total timing. you want the timing to slope up, but not a whole lot.

this will help too:
http://www.msefi.com/msinfo/ms2/

Actually, even though switching the vacuum advance to manifold vacuum would have a retarding effect, the distributor still has centrifugal advance. I'm really not sure how that would work out, but I was hoping for a "cancelling effect" so that I don't get total timing retard. I was hoping for a slower advance than stock, but still a mild advance.

I tend to agree with the blow through set up. I had a friend once that turbocharged an old carbed truck with a suck thru system, and he said carburetor icing was a serious problem in cooler or wet weather.

Blow off valves are plentiful in the junkyards.
I might have to alter the position of my alternator, it's a little in the way.
My waste gate is vacuum actuated, so it needs a controller. I thought about wiring up a vacuum solenoid with a boost-referenced electric switch, which would work, but I'm not sure how I'd control the on-off-on-off cycling at the 7 psi limit. But I'll check into those links you guys sent me.

Thanks very much! Keep the feedback coming. Even if I don't do it on this motor, my brother is wanting my help to convert his tired Toyota pick up truck to run with a Jeep inline 6 and 4-speed. I might do all the research, and end up putting it on that Jeep motor. I believe it's around 300 cubic inches, so there's even more potential there.

He doesn't have the engine bay space like I do though!