# Side draft Carb choices



## cabriosnap (Apr 24, 2009)

Not 100% sure what is out there in the world of side draft's. I am very new to the smaller multiple 2 barrlo carb setups. 


for my build i am requiring about a 400 cfm carburetor. Problem is i plan on running multiple carburators, so i need to do some number splitting... 

I am trying to desing my build around using three 2 barrel side draft carb's. my main issue is if i do this i will need 3 carb's between 130-150 cfm's. This is where the tricky part comes in, as i dont really know what options i have available aside from weber side drafts. I have been doing research in my spare time on the subject, but i figures posting in here and getting input from carb user's would be a good idea as well  

If it come's down to it, i also have the option of running 6 very small carbs (linkage and tuning nightmare, and trying NOT to go this rount) or running two 200 cfm carbs (can be done, but the bigget carb size may intrude with my radiator support and grill) 

Any advice on where to look for some 130-150 cfm side draft options would be great. I am open to aftermarket or OEM options...i know some people have used older bmw carbs on builds like this, but again i dont have much of a clue on this. I know 4 barrel's....not 2 lol. 


In case anyone is interested, this triple 2 barrel setup will be going on a 3.0L 12v vr6 build...


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## candm (Apr 27, 2003)

not sure of the flow #s, but based on engine size, say 500cc per cylinder, 45 webers with 36 chokes should be fine to start with. you then have the option to increase choke size if you need more airflow.


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## cabriosnap (Apr 24, 2009)

candm said:


> not sure of the flow #s, but based on engine size, say 500cc per cylinder, 45 webers with 36 chokes should be fine to start with. you then have the option to increase choke size if you need more airflow.


 
something along the lines of this model with a 36-38mm choke? are you suggesting using just a single weber 45?


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## candm (Apr 27, 2003)

3 DCOE 45 carburetors


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## Glegor (Mar 31, 2008)

why cant you run a 4bbl, and a custom intake mani?


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## cabriosnap (Apr 24, 2009)

Glegor said:


> why cant you run a 4bbl, and a custom intake mani?



having a larger single carb is going to cause me to literally have the carb sticking either out of the hood, or out of the grill to obtain any kind of extra room for fabing up an intake manifold with enough spread/volume to give each cylinder with even flow...making manifolds for every 2 cylinders or even 3 cylinders per carb will in turn be a much more even air/fuel distribution....at least in theory.

regardless of whatever setup i end up going, I'm going to have to fabricate a manifold/manifolds. I'm a fabricator by trade, not worried about it. really looking forword to showing off my skills really...

also, side draft 4 bbl? lol....multiple smaller side drafts really is the only way to go for this build without having some sort of vw muscle going on lmao


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## veeyarrSUPERsix (May 5, 2009)

im looking in almost the same range as you for carbs... except smaller. im twin turboing a 550cc motorcycle and want to run either a single 2bbl or 2 1bbl side drafts...CANT FIND ****

i used a cfm requirement calculator and came up with approx 90 cfm needed (at 100% volumetric efficiency, estimated, running low boost on turbos) 

what calculation are you using to split into multiple carbs? just straight division? (90 cfm rqd split into 2?)


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## cabriosnap (Apr 24, 2009)

i was using a program i found on the net. i know i have it bookmarket....somewhere...

let me see if i can find it and post a link up...

as of right now i am still working on exactly how i want this whole motor mocked up and designed....my freaking thought process seems to be shifting almost daily right now in what direction to go...

as of right now, i would still LOVE to do a triple carb setup....but duels are looking more and more practical as of right now...


still sitting at the drawing board with this damn motor hahaha. luckily the car already runs and drives so this isnt setting me back really. I've got nothing but time right now


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## FatDubMK3 (Jan 18, 2011)

For the guys running Dual DCOE's/DHLA's, where did you find your Manifold?


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## vwgroundpilot (Mar 7, 2004)

An option for fabbing a manifold: loop it up over the top of the motor and put the carbs on the back of the motor... same configuration as the stock intake manifold on the original 12v VRs. Hell, you could possibly use the OEM lower manifold runners, make your manifold with a flange that bolts up to it. Think like fabbing a tube header. Have a 6-port flange that bolts to the OEM lower manifold, run tubes up over the top of the motor, then terminate with 3x 2-port flanges for Weber DCOEs or similar. 

This should also allow you to tweak the runner lengths so they are all effectively the same... the way the factory did (since 3 of the cylinders are on the "far side" of the motor and have longer runners to the intake valves within the head). 

You should have plenty of room in the engine bay to put some heat shielding between the carbs and the exhaust manifold/header. If you're really into custom work and want cold air, make it a "cowl induction" style hood and draw high pressure air from the base of the windshield. 

Also... double-check the carb size calcs... 45mm is on the big side for a 3.0L 6-pot motor. A built 2L 4-pot (same displacement per cyl) will run like a raped ape on dual DCOE 40's. A little less peak HP, a little more useful torque. 

I had a 12v VR6... loved that motor. Dammit, you're making me want to build a carb'd one now. Only I'd want to stuff it in something more fun like a Caterham 7... Crap, that would sound wicked and run like a bat outta hell.


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## veeyarrSUPERsix (May 5, 2009)

^your ideas....they make me tingle :beer:


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