Four barrel carb ?

[David B]

I just picked up a four barrel carb intake from an early 630 cs from the junkyard. Does it sound realistic to use it with a holley blow through carb in a turbo set up? It has already been ported to take a holley 500. And it fits the head that I have. I thougt that I could gasket match it for a b35 head.

[turbodan]

I dont see why not, but carbs in general are a huge disadvantage on M20s and M30s.

[Rich Euro M5]

To add to what Dan's stated, another potential problem is proper fuel distribution. In NA applications running a little lean in a cylinder generally won't do any damage. Not so in a FI environment. I would think the safest way to turbo with carbs is to utilize Weber sidedrafts. Each cylinder would have its own carb and you'd have better control over A/F ratio of each cylinder. Plus it would have huge eye candy potential over a single 4 barrel.

Rich

[Big Bronze Rim]

Yes it could work, but I'm definitely not a fan of carbed FI cars. Rich makes a good point about fuel distribution. One blow through carb is bad enough to setup for FI to work right, I can't imagine how horrible multiple carbs would be. Other that the apparent simplicity of the system, I can't think of any way the carb would be superior to a good fuel injection system on a turbo car.

[David B]

I did notice the intake is basically a chamber that has all the unequal length ports off of it. It would seem the two inside cylinders would run rich while the ones further from the carb would run a little leaner. I thought the simplicity and cost was favorable. I see large V8s that are using blow threw carbs with either one or two turbos or a blower making huge power with one holley carb. I was curious that under pressure it may atomize the fuel better for an even afr ?

[turbodan]

Big V8's make huge power because they're big V8's. That doesn't mean they're efficient. Thats something we have to worry about with small displacement motors.

The big, big power turbo V8's are running port fuel inection these days. Thats the good stuff.

Atomization would be about the same. It would improve as flow increases, but it still wont be anything like the atomization of a fuel injected system. Especially at lower engine speeds and whenever you're off boost. Under manifold vacuum, where you spend most of your time, a big blow through carb on a relatively small displacement motor will leave a lot to be desired. There will always be that comprimise between peak power capacity and part throttle efficiency with carbs. This is simply a non-issue with fuel injection.

[David B]

Thanks for the info I suppose I`ll stick the intake in my shop along with all the other stuff I think I might use on day but probably never will.

[canyoncarver]

and theyre far more forgiving than fi..........

http://videos.streetfire.net/video/turbo-349-stroker_153882.htm

476rwhp......9psi boost, no intercooler............


call dustin at:

http://cprstreetmachines.com/index.htm


questions never hurt.....

[turbodan]

Just because that big ass V8 made a lot of power doesn't mean it did so efficiently. M30's dont have 349 cubes.

That same motor at that same boost pressure could probably put down 600rwhp with port injection, timing control and intercooling.

[Big Bronze Rim]

"Friends don't let friends put a carb on a turbo car."
If people think turbo cars are finicky and tempermental, try putting a carb on one. Almost everything about a good fuel inj. setup will dominate a similar carby setup. I daily drive my turbo car and I wan't it to run right all the time, idle with the AC on when its 100F out and run right when its 35F out and I don't even have to retune. Good luck with that on a carb'd car.

[Milwaukee's Best]

[turbodan]

Sure. Nothing at all. But it should be understood that fuel injection with ignition control is better in all applications. It'll make better power, more reliably, more consistently and more efficiently.

The only thing I have a carb on is my lawnmower.

[Milwaukee's Best]

[turbodan]

wat

[paul burke]

I have been waiting for someone to inquire about this. I have blow through Holley based carbs for gasoline and E85 fuels, and am currently building an m30 for myself using this method.The factory manifold is restrictive so I am building a sheetmetal one to replace it.

[canyoncarver]

[turbodan]

And what? Are you saying the fuel injection wouldn't run better? Because thats what I'm saying. Theres no question if carbs work. They do. Fuel injection just works better.

Go ahead and try a blow through carb on a non intercooled M30. Lets see how much power that'll make.

[Boosted67]

[philip1]

blowing through a carburetor will allow intercooling. I've done both and tuning is a bear but it is far superior to carb alone.

Datsun L20b 6.5:1 comp t3/4 hybrid draw through Holley 750 vac secondary. 500hp and 12 sec 1/4 mile at 27psi 1 gallon of anti detonant per pass.

Nissan Z22s blow through intercooled t28/45 baby potato turbo 4 psi 193hp.


These same engines would be making much more power injected.

L20 efi same turbo (Not mine) has seen 600hp

Z22 with EFI easily makes 250hp at 6psi

[turbodan]

My challenge stands. If anyone wants to try a blow through carbureted M30 turbo motor, we'll just see how much power it makes. I have a hard time seeing anything but a draw through turbo making a big dent in IAT's. I could be wrong though.

I like intercoolers. I know they work.

[Boosted67]

[paul burke]

I've had intake temps low enough to build frost on the manifold using E85 on other apps, and I have yet to see an aftermarket fuel Inj. setup that did everything it was supposed to. Usually have some glitch that you can never tune out. We all can attest to that. Just looking for something else to play with.

[paul burke]

Boost is a number you see when your motor starts resisting the movement of air through it. Make it more efficient, boost goes down,heat becomes controlable , Hp goes up.

[turbodan]

Giant V8's seem to make power rather easily. Not suprisingly though.

[Big Bronze Rim]

Megasquirt is cheaper than the price of a quality carb(assuming it's bought new) and associated turbo carby parts(carb hat or sealed box). If a car is already FI it seems absolutely foolish to step back to a carb. I agree with Dan that while a carbed FI v8 will make power, I would be willing to bet that it'd make more power and drive better everywhere with fuel injection. Mike Murillo here in San Antonio has built an Outlaw class Fox body Mustang that makes in excess of 3000hp with a 541ci TT v8. Not a carb in sight.
Mike Murillo's 3000hp Mustang