Just have quick question, lol

[451Mopar]

Carb with electric choke is nice if it is more a driver than race car.
I originally had a 850 DP with manual choke. First time out, the choke was not connected, and got sucked closed. Though I broke the engine?
Then I just wired the choke open so it wouldn't close. Had some other manual choke carbs, and they are OK, but I prefer the electric choke versions.

 

[1STMP]

Late again to the party, but there is a
mathematical formula for determining
required cfm.
The formula for calculating how much CFM (cubic feet per minute) an engine requires is: CFM = Cubic Inches x RPM x Volumetric Efficiency ÷ 3456.

Any ordinary stock engine will have a volumetric efficiency of about 80%. Most rebuilt street engines with average bolt-ons have a volumetric efficiency of about 85%, while race engines can range from 95% up to 110%.
Example: Using a 355 CID engine x 5,500 max rpm = 1,952,500
Take 1,952,500 x .85 = 1,659,625
Then 1,659,625 ÷ 3456 = 480 CFM
Hope this helps, it's worked for me on
multiple builds. The one thing to keep
in mind is to be honest as to where
your max rpms will be.

 

[66Satellite47]

Formulas are accurate for some things, interesting for others. Absolutely correct on being realistic about the RPM.
Problem with volumetric efficiency is that's a wild *** guess. So many variables.
A smaller carb CAN work well, just maybe not optimal. I was truly shocked by how well a single 650 DP worked on my 7000 RPM drag motor. Not ideal, but not terrible. BTW must have had pretty good VE. It was a 451 low deck, made about 600 HP.

 

[1STMP]

Formulas are accurate for some things, interesting for others. Absolutely correct on being realistic about the RPM.
Problem with volumetric efficiency is that's a wild *** guess. So many variables.
A smaller carb CAN work well, just maybe not optimal. I was truly shocked by how well a single 650 DP worked on my 7000 RPM drag motor. Not ideal, but not terrible. BTW must have had pretty good VE. It was a 451 low deck, made about 600 HP.

True on the variables. Altitude, air density,
humidity, temperature, all have an effect.
The overall tuning relies on where the
PowerPlant will spend the majority of
It's useful life. The applied formula does
give a reasonable starting point.

 

[mach123]

So is going efi that much more then carb, but I see so many options to go and what makes you decide on what direction to go. Like 2barrel, 4 barrel 6 pac, manual choke, auto choke, is there a list out there showing options and cost aprox so we can shop the proper way the 1st time lol