HOLLEY PART 5 choosing the right carburetor using the volumetric efficiency formula

just an idea on how to choose the right HOLLEY carburetor based on air flow and intended usage

[reverenddave]

Thank you for taking the time to make your videos, I have 30 years of hot roding and racing!
And I have to say your videos have taught me a few things, so keep on keepin on
Well done!

[capitainecrunch]

The volumetric efficiency is the efficiency of the engine. It doesn't change regardless of the carburetor that you use. It changes according to the changes on the engine, different cam, different heads. You factor in the volumetric efficiency of the engine in order to figure out the carburetor you need, not the other way around.

[AngeloC]

The biggest problem I see on street cars is having to big a carb on them!!! Personally I run an 850 HP Holley on my 555 on the street but on the track I run a 1050 dominator!! Great video.

[chriscraft]

i didnt make this video acting like i know everything.. these are stock carbs that come on 454s.... the engineers must not understand what they are doing either.. we have all read theories on the subject.. the point is so you understand why they never put a 600cfm on a big block chevy from 65 on

[josephcalvosa]

Seems like you would want to build what you want to end up with. Instead of pissing money away on every intermediate step between where you started and where you will end up finishing, after you out grow the more conservative performance upgrades. I was given the advice of "build to your end goal". Your videos are great by the way, today I bought a 3301-1 for $10 and needed a crash course in these and your editing style gave me exactly the info in as little time as possible. Thanks man

[homotorsports]

Excellent Video!!!! Measure your 850 and make sure it`s not a 950...You might be surprised

[bwwb]

I gotta drive wide open with my 454, when I drive easy shit breaks for some reason lol

[jerrycoon]

This is a correct formula but there is one thing I don't think you mentioned. If I am correct, a normally aspirated engine will never run at 100% volumetric efficiency because of valve overlap and other factors. Supercharging or turbo or nitrous actually makes an engine exceed 100% volumetric efficiency. You are correct with the formula though and any numbers you would get would still be plenty close enough.

[capitainecrunch]

You are not actually multiplying a cubic foot (1720) by 2 but you are dividing the cubic inches of your engine (454) by 2. The reason is that your engine uses 227 cubic inches of air per revolution ( 454/2=227) because you engine only has 4 power strokes per revolution.
I read that a normally aspirated engine has a volumetric efficiency of 85% to 90%. A NASCAR engine might have a volumetric efficiency of more that 100%.
If you had an engine with 90% efficiency you would actually use 650 CFM at 5500 RPM.