CARB SHOOTOUT-2 BARREL VS 4 BARREL, ORIGINAL 4412 VS XP4412 VS QF4412, 650 v 750 CHOKE v 750 v 950 

Some of those monster Pro Mod nitrous engines flow some serious air. Without exhaust and intake runner/tube tuning, they would be so weak.

I don't know if 14.7psi from the atmosphere is enough to push the airflow to supersonic speeds, maybe it's possible with some serious forced induction but the shockwave and general restriction from the carb would cause such a pressure drop it may not be worth it

@@EpicScandinavian Sonic-flow carburetors have already been invented, so yes, ambient pressure is adequate. In FACT, the "music" of the intake trumpets for a Ferrari or even a dual-quad Hemi's carb barrels is the shock wave from the flow past the intake valves, even as the much-louder sound from the exhaust valve is the shock wave from the flow past the exhaust valve. I think the main obstacle they faced was placing the fuel flow in relation to the shock front: before it, while flow is sonic/supersonic, in it, or after the shock front, which would be higher pressure and subsonic. With a change in air velocity, the shape of the shock front changes, and so does the position thereof. The shock wave greatly aids the energization and dispersion of the fuel atomization. A carburetor that would automatically adjust the fuel introduction point to ensure a predictable level of airflow and pressure drop at the fuel introduction point was the aim of some of them. Without a predictable ratio between airflow mass and fuel mass, the carburetor hits an obstacle in its function.

Un common by it being common but uncommon in coversions

NOT ON AN ENGINE DYNO

I FLOWED A 750 WITH AND WITHOUT A CHOKE HORN

I have never seen a 2-brl that does better than a 4-brl set up

@@richardholdener1727 If I read it right the 650 brawler was in the 393 CFM range the 500 CFM 2 bbl was 420 and the XP was 470 all of the four barrels that he tested for way under the advertising cfm. I have a 600 Holly 4160 right now and based on his numbers it's probably only flowing close to 490 or low 500.

@@richardholdener1727 I had both the 350 and the 500 I currently have the 600 CFM 4 bbl now yes there was a difference at wide open throttle but it didn't have the wow factor compared to the 500 CFM 2 barrel it had before . The big difference was in gas mileage because of a small primaries on the 4 bbl it's far better on gas with the four barrel primary side 12 to 15 mpg. I was only getting 8 to 10 with the 500 CFM 2bbl the 350 2 bbl was better on gas than the 500 and only a slight loss in WOT between the two-barrel carbs both two barrels rev to 45 to 4700 RPM the four barrel 600 CFM Holley rev to 4700 RPM as well and that was due to the restriction of the truck heads that came on the 360 /390 F100 and f250s.

@@grandmasmalibu awesome explanation thank you!

I have built several with the down leg ring removed and at the same time the power piston and primary metering rods removed. Works great in a boat or towing/rv application where the engine will be under constant heavy load.

@@carguychris85 good info thanks for the response!

I know 1ATM = 14.7 PSI = 29.92" Hg...what's the deal with water? Is it an "EPA thing" B/C of Hg? It just seems weird to throw in a third redundant measurement system.

@@bcubed72 Just sorting it out loud, flow benches use "h20, so as explained, Richard is flowing on a water rated scale and we're comparing to a hg scale when we talk carbs. But it's a water scale when we talk heads. Should all be done in one scale of course. I think Piston aircraft still use Mercury, hence all the different scales. ISO the lot I say.

HOW ABOUT TESTING THEM UNDER THE SAME CONDITIONS LIKE THEY DO IN REALITY?

155

Saw that! As usual with a piece someone would just toss for an upgrade, I was pleased to be wrong

YES-THAT IS WET FLOW (CARBS ARE RATED FOR WET FLOW)

@@richardholdener1727 Ok I get that but it didn't look like in your video you were wet flow testing the carbs. Does your flow bench correct the results for wet flow, or do you have a formula to correct the data? Is there a rule of thumb like dry flow is 10% greater than wet flow or some other percentage?

On a race application they constantly check valve lash as an indicator of cam and or valve seat wear. Those high hp engine have a ton of seat pressure. When one spends 50 grand on an engine they want any indicator of wear to try preventing metal In the oil. Just My thoughts. May be other reasons.

@@Mike-xt2ot I run 500lbs and never an issue.

THEY ARE NOT RATED AT 28 INCHES-PLUS NO FLOW BENCH WILL SUPPORT THE FLOW OF A DOMINATOR AT 28 INCHES

I bet the flow bench will do almost everything up to a dominator

28 inches-stated in the video

Especially the 1 barrel that would be great

@@SpecialAgentJamesAki I would bet the 1 barrel would give it tons of low end torque

NO NEED

a 4-brl if one is avail

@@richardholdener1727 how much cmf? 400?or bigger? I am sorry i ask you again 😬

add the flow numbers

isn't an engine at about 2cfm/hp?

@@exploranator I think it's about 1.4 hp/cfm.

Probably would gain you a fair bit of part throttle response

He did this test and some other related stuff in this video ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--Uqsf-ljNt4.html

I saw some data where the Carter types flowed about 100 cfm less than the Holleys with the same rating. So a 650 Holley flows about what a 750 AFB.

Have done a flow test on a Weber 38/38

There was the one where he tested a bunch of carbs on a straight 6 I think he put a dominator on it

I DID A 1050 DOMINATOR ON A 1-BARREL OPENING ON THE 292 SIX CHEVY

@@richardholdener1727 Yeah, I saw that Richard, but I was thinking more of a 4 barrel shootout where you start with a 600 and go all the way up to a 1050 dominator on a mild small block using a 4 barrel intake of course.

Hey, what do you mean by that? I am still learning my first carbed build and I am seeing that supposedly if I put too big of a carb on the car it will have poor throttle response. I have a 351W with a Weiand 174 that I am putting together. I was given a 850 Double pumper and I'm not sure if that will be too big. Weiand recommends 750cfm for this blower on a stock 302. I was debating a 750 vacuum secondaries rather than the DP

@@timothylockhart2009 Double pumper on a blower always. You want as little restriction on the intake side as possible on a roots blower. I ran a 950HP on a 144!

sure