webers for supercharging?

[two89w]

Can webers be used for a blow thru supercharging application?

[Paul Thompson 'Hooligan']

I have seen a supercharged Pantera GT5 that used Webers on a 351 Ford - BUT, they were sucked through -

If you try to pressurise the inlets, I would guess they won't work as the fuel delivery relies on a drop in pressure within the card to suck in the fuel through the various jets. [img]/ubbthreads/images/graemlins/confused.gif[/img]

[Kevin M]

For a Blow-Through installation, you would certainly have to use carb boxes and pressurize the carbs. Even then I don't know if it would work. I would contact Ingeles: http://www.inglese.com/ and Pierce: http://www.piercemanifolds.com/products.htm and talk to them. If it has been done, one of them will know about it. (If the carbs are going to be hidden in a box anyway, you might want to consider the Vortec / Holley carb system).

Good luck and keep us posted if you do decide to try it. I would be very interested in hearing how it works out.

Kevin

[Bill Musarra]

You might try and contact Lotus as they use (used) the Delorto side drafts between the turbo and the engine. Worked fine on my 85 Turbo Esprit.
Bill

[DaveWharran]

CB Perfomance used to offer Dellorto downdraft blow through kits for VW's. They pressurize the top of the carb (float bowl vent, air correction, etc.
I see they now offer a Weber 44IDA blow through kit.
Weber blowthru

You might contact them for info.

[Mark Worthington]

I have to ask; why? Webers are used in NA applications more for aesthetics or originality than performance or cost effectiveness ($/cfm). With a blower you will lose any shred of originality and you will spend much more than a Holley 4-barrel or even an nice EFI setup with much more difficult tuning and driveability. I just don't see the point, unless you like to do really difficult stuff just to prove it can be done.

[Kevin M]

I certainly agree with Mark, as I mentioned in my earlier post Vortech makes a blow through system for a Holley carb that is hidden in a pressure box. If you can’t see the Webers anyway, that would make a lot more sense.

That said, if you are still thinking Webers, remember they use very low fuel pressures (2½ to 3½ psi.). You will need to reference an adjustable fuel pressure regulator to boost pressure to keep the 3 psi. differential constant or your mixture will go off completely.

Kevin

[two89w]

I have no intention of putting a blower on my car it was just a question to see if it could or has been done.
"Webers are used in NA applications more for aesthetics or originality than performance or cost effectiveness ($/cfm)."
I thought webers were a performance carb?? Or will i make more hp with a 750 and a single plane manifold?

[Kevin M]

In the 1960s, intake manifold technology was very primitive and Webers made more power than a 4-barrel intake system, primarily because they don’t interact and therefore allow equal mixtures to each cylinder without one disrupting flow to the others. They also had the advantage of being much more adjustable for tuning purposes.

Webers do, and have always suffered from reversion issues. When that pressure pulse happens at intake valve opening, it has no place else to go but back up through the carburetor. The carb doesn’t know or care which direction air is moving, if there is flow, it meters fuel. (This is the place that fuel injection has its one big advantage). In an SAE technical paper, Ford engineers estimated that the 1963 Indy winning engine lost 3 to 4 gallons of fuel pumped out of the carb mouths and lost to the atmosphere during the course of the race.

By the nature of an IR type system Webers really haven’t evolved or gotten any better. It is what it is, and other than changing the length of the intake runners to change the resonant frequency, there isn’t a lot you can do with it.

There has been a huge improvement in 4-barrel manifold technology in that same period of time. Today, you can expect roughly equal power from a 4-barrel carb, Webers, or fuel injection. There will be some places in the RPM band where one or the other will make a little better power because of tuning, but overall, across the entire RPM band they will be similar. Also with newer carbs like the Demon RS carbs from Barry Grant, you now have just as much tuning and configurability as Webers.

The bottom line is that Mark was quite correct. Today Webers are strictly for looks, and for that matter, Fuel injection is not a performance improvement either although it does have advantages in cold starting and a few other drivability areas.

By the way, if you really want to know about this in detail, try to lure Adam into this discussion.

Kevin

[DaveWharran]

VW had a Solex dual carb setup for the air cooled flat 4's in the mid/late 1960's. The carbs had fuel standoff even with the stock cams. They ran lean with the air filters off because the filter body had a built in velocity stack that was maybe 4" tall. With the air filter off, your hand would get wet with fuel if you held it just above the carb inlet with the engine running.
IR systems, particularly with 48IDA Webers, would really wake up the little air cooled engines. Fuel mileage was horrendous, but you could get 200+ HP out of them if built properly.

[Mike Dozier]

Advances have been made in both carburetor and intake manifold design. The 426 Street Hemi with dual quad
Carters made an average of 450 hp on the dyno. Testing by Mopar proved they could get same HP with a single 4 bbl Holley on a well designed dual plane intake...so that's what they use on their new crate engines. Much simpler/cheaper, but of course not original for those seeking to restore.

For all out racing, muliple carbs may have a slight HP advantage...but the additional cost/complexity isn't justified on the street. Of course the visuals and sounds of multiple carburetion is another story...
The howl of dual quads, tri-power, etc is pure adrenalin.

MikeD