I was just wondering how you turbo a small block 350 carbuerated w/ headers? what size turbo would you need?

 

It seems to be the same with every turbo application, alot of money and months of headache's worth of fabrication. my buddy has an 88 Iroc w/ a carbed engine. I just figured it might be easier than doing say a 3.4 v6 since there's alot more room in the third gen's engine bay.

 

Blow through sytems, such as a turbo feeding a carburator usually create big headaches, especually with fuel delivery, they work much better with port injection.

 

anyone have info on a 2.8 turbo what would I be look'n at mess'n with? Is there no use for turbo if I have an automatic?

 

If you think about it, carbed turbo applications are easier. It gets more fuel with the greater pressure differential with the air flowing through. Bernuli's Principle. The faster the flow of a fluid, the lower pressure it has. If you set your jets to a point where it is the maximum fuel with out over flooding the engine the turbo will use this principle to help extract more fuel than the jet was rated at. You're going to have to modify your vacuum advance with heavy weights and heavy springs. You want to retartd your timing about 1 degree for every 10 hp.
http://www.jegs.com/webapp/wcs/store...27913_-1_11911
Turbos can be used on autos and manuals. Such as Gail Banks 6 gun shooter system.

The turbo size depends on how much boost you want to run and how much your bottom end and valve train is modified. For a stock setup, I'd recomend a T3/T4 Hybrid. The turbine will spin at the speed and drag of a T3 (smaller turbo) yet the impeller will move as much air as a larger T4 compressor. This is a pretty good sized turbo for a stock motor with boost from 8-13PSI. You're going to have to make a set of custom headers. Take a weld your own header kit and then use that flange as your base. Take the tubes and then work them up into a plenum. Each primary comes up to one perpendicular tube. For the T3 mount, use 3" pipe. Then weld one of these on to the ends of it: http://www.jegs.com/webapp/wcs/store...27901_-1_11911

Get a gasket and then mount the turbo. On the back of the turbine, that is your exhaust. You're going to have to run a waste gate and a down pipe. Then you'll need to run oil lines to the turbo. Drill out your oil pan with two holes. A feed line and a return line. It'll have enough suction to pull oil into the turbo. Make sure you prime the lines. Then you'll have one more inlet and outlet for your coolant lines. Tap into the coolant lines from your heater hoses. Unless you have an aftermarket intake that'll have more holes. Then as far as the intake. The compressor face is where the air filter goes. If it is really close to the exhaust, i'd make a heat shield. If you need to get the air filter away, you can use silicone boots and piping to redirect the filter. Then the output goes to the pressure plenum. Drill a hole for a blow off valve. http://www.jegs.com/webapp/wcs/store...26399_-1_11911
Since you don't have a computer, you can vent it into the atmosphere. The blow off valve will be controlled by a "positive" vacuum line aka a boost reference. You can get that anywhere between the turbo and the carb. Then your wastegate is controled with the same principle unless you get an electronic boost controller.

 

You could also go with an STS turbo kit.

 

Your theory is good if the supercharger or turbo is pulling air after the carb, such as a carb mounted on top of a roots blower. When you try to blow air into the carb, you are going to get fuel delivery problems, especially when the boost is higher than the fuel pressure. At this point the engine will starve for fuel as the pressurized carburator will not let the fuel in. Higher fuel pressure is not the answer beacuse it will cause flooding at low boost. The problem can be handled by adjusting fuel pressure in concert with the boost, but it is a real pain in the **** the get it right. Blow through is a good set up for those that rather tinker with than drive the car.

 

The theory of fluid dynamics, the roots style blower would be more efficient if it would compress the air before it entered the carb. But it is a pain in the *** with the fuel. If you do a forced air induction, you'll need a 1:1 boost reference fuel pressure regulator. Bernulli’s principle would actually suck the fuel from the jets. It's like a perfumer or a spray bottle. Higher velocity of the fluid results in lower pressure.

 

Are you speaking of "Bernoulli's Principle"?

I'm guessing that you're some sort of engineer, as I've seen engineer's often try to apply one principle to an automotive obstacle when there's much more involved.

If you're speaking of Bernoulli's Principle (and I'm no engineer), my understanding of it is that it applies to fluid pressure, differentials due to velocity and the volume of the chamber that it's flowing through. This doesn't encompass nearly all (let alone in its entirety) the apects of a fuel system. Classic over-simplification. The "like a perfume atomizer" comment is the exact opposite of what's going on here as well. Try using an old-style perfume atomizer---but let's include all of the variables--this time try it in a room pressured to +1 BAR positive. I think you'll quickly find that you're not getting nearly the same results now.

As for the blow-through setup for forced induction, you'll need to either buy a special carburetor, or modify your existing one to work in a positive-pressure environment. 1) Your stock carburetor isn't built to seal against positive internal pressures, and probably won't come close to doing so. 2) You're going to have to address the aspect that's being discussed (which if my understanding of Bernoulli's Principle is even close to being correct--has nothing to do with this situation) with fuel pressure overcoming the positive airflow pressure. Yes, an adjustable fuel pressure regulator is needed---to add additional fuel with the increased airflow. However, what happens when you're exerting pressure on the jets and back into the bowls at positive boost?

You need to compensate for this by pressurizing the bowls in direct proportion to the boost levels you're running too keep the correct volume of delivery.

You can purchase Blow-Through carbs from various places (I think Demon makes on, but I have no idea as to specifics on it), and unless you purchase a unit like this, carbed forced induction systems can be a complete PITA to get running correctly, and more importantly *KEEP* running correctly.

Draw-thru setups can be even more of a headache and are much more restrictive in what can be done with them.

My money would go towards updating to a FI unit of some sort---even if it's a stock system out of a junkyard car to use as a foundation.

PS to Shnormo: I'm intending to berate you, it's just that I think that you're applying the wrong theory here. Don't feel bad either--I've had an engineer try to explain to me once that since gas expands at higher temperatures people were dumb to be using larger cat-backs and smaller downpipes in turbocharged cars (I.E., 2.5" downpipe and a 3" cat-back) with a straight face. "You know---because the exhaust is hotter when it first leaves the engine". Guess he didn't know that velocity and scavaging also comes in to play.