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I am about to start working on a 261 to install in a 52 1.5 ton chevy. I was thinking of installing a single small turbo to improve torque. I would like to use a draw through set up with the stock carb for simplicity. I would like to use the factory powerband just more low end. Should I pursue this or leave well enough alone?

I'd like to hear more about a draw though system. Never thought of that. Might be an option for an updraft carb.

You might want to ask that question over on Inliners. More of that mod is done there than here. www.inliners.org

if you go to the keystone turbo website there is a picture of an international with a black diamond six with this type of set up. They say it runs really well and looks simple enough to rig up.

I really, really, really want to put a turbo on my old sixer, as well. I am thinking a blow through set up would be best, but that is just my opinion. Icing of the venturi is a bit of an issue with the draw through set up. A blow through does take a little more fab but it is not that difficult. How much boost are you planning to run? How much more torque are you looking to get out of that old tractor motor?

Mitch

What do these motors make stock? I've seen like 80hp? Is that correct? This is interesting stuff here.

the mid-50s 261 was rated at 148hp

Bill

That's awesome. I've been bouncing between sites trying to learn more. Too bad I have to work I could read this stuff all day.

If you want more low end, go for a 292. They have a ton of off idle torque.

Whitedog,
292 is a good suggestion for more torque. But he will miss out on a lot of fun and braggin rights. I have all these mental pictures of a well thought out set up of an old, original-looking engine with a fricking turbo on it! So it boils down to practical vs ridiculousness.

A turbo will not increase low end torque- - - -not enough exhaust gas volume to spin up the turbine. For better low end, increase the compression and/or get a longer stroke.
Jerry

I just saw a McCullen (sp) supercharger on a early 50's Ford Sedan with a stock looking V8 and small carb...it really looked neat. Don't know if it would help or not.

Mike B

Turbos are driven by exhaust pressure so the output is flat at low end, begins to climb at mid range and climbs steeply at top end, great for racing.
Super chargers are driven by the engine so they give a linear boost, That is why they were used on work engines like the Detroit diesels.

If you want to help an engine breath use a super charger. If you want a spike in top end horse power use a turbo.

If the turbo is sized properly you can build plenty of low speed torque. Think diesel. Also there are some pretty neat modern tubocharged gas engines out there. The manufacturer I work for has a 2.3 liter 4cyl that is at peak boost of 13.5lbs by about 1900 rpm. Peak torque is 260 lb ft at 4500 rpm, but the engine is at 90% or more of peak torque from 2000-7000 rpm. Pretty impressive for an engine of only about 140 cubic inches. Of course this is achieved with a variable inlet turbo and modern electronic engine controls. I would think if you sized the turbo to build boost and torque at your desired RPM you could make some impressive gains. The main tradeoff would be the lack of that big turbo push at higher RPM,s because of the restrictive inlet needed to produce the low speed boost would create a drop in boost as RPM increased. The main concern would be the detonation that comes with high boost levels and engine loads at a low engine speed. This would be very difficult to control in a relatively ancient engine design even with modern (computer) controlled boost, fuel, and spark.

do it. A turbo is load dependent, not speed dependent, A draw through, although simple is really no longer recommended by any manufacturer, due to the excessive heat production. However to qualify that statement, if you are only going for a 3-4 psi boost, you would probably be alright. Oh and they don't use blowers on Detroits for power production they are for scavenge air. I haven't seen a 2 stroke diesel that doesn't provide some sort of scavenge air system. They would scarcely run without them. It is when you add the turbos that they start producing power. All that being said turbo installation is quite involved, and like everything in an engine build you need to decide on what you are trying to accomplish, and choose your components to achieve that end. nonetheless, a turbocharged application can give you an incredibly powerful engine that can be driven to the store.

Superchargers are harsh on pistons. Lots of heat. A mild turbo would be better In my opinion. Only thing to worry about is egt - exhaust gas temp - when jamming up a hill or towing. Make sure to let the turbo relax after a good drive also. You don't want to shut it off and bake the oil in the turbo itself.

A ball bearing turbo would be the prefered route. They use less oil and spool faster.

On the other hand a roots blower would be kind of cool. The newer Eatons have by-pass valves that open and shut sort of like a waste gate. So, you wounldn't have to worry about blowing your intake off. Not for sure how they would react to a carb setup. Most of them are injected.

Here's some inspiration from the Aussies on a Holden 6.

http://www.tttperformance.com.au/itemdetailspage/13021

Roots style are cool, also the least efficient. I have an 871 on my small block. It has a parasitic 60hp it takes just to run it. I'm not sure what it would be on like a 144powercharger. Definetly would be cool though.