# CFM on 40 or 45 Webers



## ThatsNotStock (Dec 30, 2004)

Anyone know how much air a pair of Weber/Dellorto 40's or 45's flow. Most American carbs are rated at how many CFM they are.


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## ABA Scirocco (May 30, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

Those types of ratings are not really well suited to Webers and Dellortos because unlike most North American carbs, they have replaceable venturies. So, for example, one could make a Weber DCOE 45 flow less than a Holley 350 or more than Holley 500 simply by swapping out the venturies, something that can be done in a few minutes without removing the carbs from the engine. 


_Modified by ABA Scirocco at 11:54 AM 5-31-2007_


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*

Thats right...totally forgot that fact. Do you know what a 2.0 ABA engine would need for a Dual carb setup?


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## ABA Scirocco (May 30, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

I'm certainly expert on the topic but it seems to me, there might be enough info HERE to get you started.


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*

Let me ask you this....what produces the most horse power or the best performance....stock CIS-E or Dual carbs?


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## ABA Scirocco (May 30, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

Carbs. Mainly because the stock manifold is quite restrictive and with the dual sidedrafts, it's pretty much a straight shot all the way to the valves. 
A friend of mine is making very close to 190hp at the crank out of a 2.0L-8V race engine with a single DCOE 45, with twin carbs he'd probably be closer to 200hp. Admittedly, that is a rather extreme example and not something the typical VW owner would be able to achieve but I mention this because it illustrates that a carb (or carbs) gives you a wider range of tuning options than you could get with CIS-e.


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*

LOL....my engine was built for a circle track racer....High comp springs, big valves, BIGGEST cam ever.....revs to 9g's...The guy I bought it from wasnt sure of the HP. What is his weber setup?


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

I ment...what is your friends carb setup


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## ABA Scirocco (May 30, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

Sounds like we're talking about rather similar engines, my buddy's car is circle track too, revs into the high 8's, low 9's. His set-up is a high compression 2.0L with a crossflow head, big but not stupidly large solid lifter cam, custom intake manifold and a single DCOE 45 with 34 or 36mm venturies.


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*

Well...Im looking for a single 45 setup now. What is he running for ignition?


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## ABA Scirocco (May 30, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

He's running an Electromotive HPX  ignition. 
There are no commercially made single sidedraft manifolds for a crossflow head except maybe from Bertils, so all of his manifolds are custom built. Making good useable power from the engine is all about finding the right combo, in dyno testing 10hp or more can be gained or lost simply by changing intake manifolds, some manifolds work well with certain cams and not with others and vise versa, finding the right manifold, cam combo that works well for a particular track is quite tricky.


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## ThatsNotStock (Dec 30, 2004)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*

Mine isnt going in a circle track car....I'm putting it in a 72 Bug...I have the complete CISE but am having issues getting it to work right. I was thinking of making an adapter to use a Holley carb on the CIS intake.


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## antichristonwheels (Jun 14, 2001)

*Re: CFM on 40 or 45 Webers (ThatsNotStock)*

I beleive a 36mm choke in a 40mm carb will flow up to about 400 cfm for both sides of a DCOE.


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## mack73 (Jan 2, 2002)

*Re: CFM on 40 or 45 Webers (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_He's running an Electromotive HPX  ignition. 


WOW that is some nice stuff. I'm tempted to ditch the 3 MSD boxes for the 1 XDI and go distributorless http://****************.com/smile/emthup.gif 


_Modified by mack73 at 9:17 AM 6-5-2007_


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