kmcmahon93

im buying a new engine with a performance cam and i was wondering if i should use my 650 holley (laying around) instead of buying a different carb? i will need a intake manifold, were should i get it? turbo intake manifold if they make them.

Alex123456

Check out 22rte-trucks.com, tons of turbo info. I think there is a guy over there that makes a turbo manifold. LC engineering does too. Otherwise, look for a stock turbo manifold.

xxxtreme22r

Ok where do I start with this one......

the holley 650 is gonna be way way way too much for that motor. And explain to me how a turbo manifold is gonna work on a carb truck? Yes carb truck CAN be turbo'd but they would use the same carb manifold. with an air cleaner adapter (most likely have to be custom made) on top of the carb. Now a turbo exhaust manifold from an RTE would most likely be used to drive the turbo however.

Not knowing the holley 650 will be too much for the motor and the fact that not knowing a turbo intake manifold would not work on a carb' truck, my advise to you would be not to even attempt to try to turbo a carb'd truck.

xxxtreme22r

I have so wanted to build a carb'd turbo truck for a while, but even I am not brave enough to do it. I wish I knew if the guy in PA/MD/NJ has started or finished his. Gonna have to hunt on Pirate, I think he might be on there.

I was just talking about that the other day too. Carb + Turbo + Propane. Sounded like an insane setup.

peow130

Yeah a 650 CFM carb is nearly double the CFM of a stock aisin..
soo...
enjoy running extremely rich, and spending the extra money to run a 4 barrel carb in a 2 barrel configuration.

Alex 400

if you are set on runny a 4-barrel, you could get a 390 cfm holley, but it would still be too big. It is designed for stock 302/305 v-8's and 6 cylinders (chevy or ford 240's and up). I you want a performance carb looking into getting a weber carb or something like that.

Like this.
http://www.jtoutfitters.com/k746-343...ck-p-4929.html

or

http://www.chircoestore.com/catalog/...ducts_id=11154

yeehaw1

D.o.a. ?

xxxtreme22r

Yup D.O.A. aka D.O.A. (Dominating Others Attempts) Racing Engines aka Dead on Arrival.

Lots of problems with their engines.

kmcmahon93

I started it and the turbo manifold, I am really good with rotary engines and that's what my 650 is for. Mazda has intake manifolds for turbo, the boost goes in about halfway down the manifold not through the carb. I want to try this on a piston engine. I also have a dual webber set up for rotary engine I could get sizes and find manifold for that to 22r

Homeless dog & truck

Better ck with LCE it takes a special carburator and a carb hat

xxxtreme22r

gonna have to look this one, up but does not make sense to me you would make boost without a sealed carb. You'd be sending boost out the top of the carb through the air filter.

xxxtreme22r

mazda drawthough setup: now I just got to figure out how this thing works lol.

Draw-Thru Setup, it uses a 4bbl 390 cfm double pumper on a rotary motor

Carburetor Type and Size: In most cases the same sized carburetor is used on a turbo installation. Many people use a side draft or downdraft Weber 40 or Dellorto.

Still think that 650 is not too much ??? I do.



another setup. my guess is a Weber 40 here:

xxxtreme22r

ok, now this makes sense, but by looking at it I would highly recommend against going with either setup. Because it sounds like you don't fully know how either setup works.

"the boost goes in about halfway down the manifold not through the carb." Half correct, it goes "under" the carb opening which has been plated off. The carb gets put on on the turbo compressor inlet.

With a draw though it is impossible to inter-cool the turbo.

But to each his own, just don't come back here crying for help rebuilding because you blew up your motor.

DRAW THRU CARB
- Extreme vacuum condition if the turbo is at boost and throttle is closed could suck the oil out of the turbo bearings. (never use a turbo off a diesel engine in a draw-thru setup because it lack the seals and will leak)
- If oil gets into the air / fuel mix, it lowers your octane immediately, and pinging will start at lower boost pressures.
-FIX- Need turbo with a positive (Carbon) seal on the compressor side of the turbine
-FIX- Run a oil cooler before the oil inlet into the turbo. This will cool the oil down and help it from being sucked through the seals or blown through the exhaust side (cooler oil is thicker). Also makes the turbo run cooler and last longer.

- Restricting the intake to the turbo will lose compressor efficiency.
- Air-Fuel mixture must pass through the turbo
- Fuel must stay suspended in the intake charge
- Compressor turbine will throw the fuel against the turbo shell, causing a lean-out condition, thus turbo lag.
- Fuel is denser than air and tends to separate in the turbo and puddle up
- Turbo less efficient because it has to pump heavier mixture
When carb causes a pressure drop and the turbo tries to increase the pressure there is a loss in efficiency, which translates into a hotter mixture in the engine which limits the boost you can run and your power.
-FIX- Water / Alcohol Port Injection
-FIX- Avoid Extra Intake bends
- Heat needed to keep the carb from Icing

Draw-Through: Generally speaking, there's 2 ways to use a carburetor with a turbo engine...draw-through or blow-through. The draw-through arrangement is where the carb is arranged first and the turbo then sucks air through the carb. This has the benefit that it doesn't require any special carb changes because the carb is just seeing more air flow through it. The main drawbacks are that the fuel-air mix must pass through the turbo. Since fuel is denser than air it will tend to separate in the turbo and puddle up. Don't expect instant off-idle throttle response. The turbo also becomes less efficient because it has to pump this heavier fuel mixture, and it is trying to do it's job after the carb has already caused a pressure drop. You basically have the carb causing a pressure drop and the turbo trying to increase the pressure. The efficiency losses translates into a hotter fuel-air mix in the engine which limits the boost you can run and your power.

Now here's the confusing part to me. The majority of the people with Carbureted Turbos run them in a draw-through arrangement and they say you get more power that way. Personally I don't agree with that thinking and some of my research has led me to believe otherwise. I tend to believe that the power difference they speak of is related to people not using fuel enrichment in a blow-through setup. I have not tried either so you should make your own decision and there are certainly plenty of engine builders who would argue the point.

In addition, In a draw-through system it is possible to create an extreme vacuum if the turbo is at boost and you shut the throttle. This vacuum will have a tendency to suck the oil out of the bearings. You will need to use a turbo with a positive seal on the compressor in a draw-through arrangement. Diesel turbos do not have this seal. I think most gasoline cars do have a positive oil seal but with the popularity of fuel injection on the newer cars I'm not positive.

Blow-Through: In a blow-through arrangement the turbo is going to blow pressurized air through the carb and then into the intake. This presents two problems: First, a carburetor does not understand pressure. Remember, a carburetor supplies fuel by creating a pressure drop across the venturi. If the carb sees a 2 PSI pressure drop across the venturi, it will supply that much fuel whether you are at 0 boost or 15 pounds of boost. This would cause the engine to run very lean at max boost, but it can be fixed with some form of fuel enrichment. The second problem you will encounter is that when you put pressurized air into the carb, it will make the fuel flow in ways that it is not suppose to flow. The pressure will try to crush the fuel float, it's going to want to blow fuel mix out the throttle shaft, or back into the fuel line. Don't be discouraged though these problems have all been overcome with varying degrees of success. The book Turbocharging by Hugh MacInnes covers a lot of the carburetor mods you can implement to have a successful blow-through turbo setup.

Homeless dog & truck

Going by memory but the catolog mention that you need a "carb hat". I'll be at LCE end of the month I'll ask him about this and get back to you XXXtreme22R

peow130

Also.. Tuning is a pita.

xxxtreme22r

yeah I remember the carb hat. It's not just LCE that has that. It's a weber part. Don't think it fits the stock AISIN. Not sure if it supports boost as it was meant to adapt a snorkel onto the weber carbs. They also have one for the holley as well.