Too much fuel

[Fired Up]

At WOT my motor calculates (454x6500rpm)to use 50 gph of fuel. I have the Holley mech fuel pump rated at 110 gph that is self-regulated at 6.5-8 psi. Using a single 850DP will I have to run a fuel block with a return line to the tank or can I just use the dual feed fuel line to the carb with no worries ?

[MikeF]

FU, Looks OK to me as long as there is no nitros involved. I'm not sure that carb is big enough though for the RPM your running. Check the vacuum @ WOT. What trim impeller are you running @ such a high RPM? Are you sure the pump is not a little loose? Or is it a V-drive? Mike

[Fired Up]

Thanks for the reply Mike. Yes, its a V-drive Flat. Motor is pretty tame: 454 (stock bore),Lg. oval port heads, roller cam,10:1 comp., single plane intake.

[e-ticket]

Fired Up
Are you racing this weekend?

[gnarley]

How To Calculate CFM:
Engine size (CID) x maximum RPM / 3456 = CFM
CFM @ 100% volumetric efficiency = 853.87731481481481481481481481481
Seems pretty close

[Thunderbutt]

Are you saying that you ran that motor at 6500 rpm for 1 hour and used 50 gal of fuel. I beleave a motor could use 50 gal of fuel in one hour, but keep it at 6500 for the hour is bullshit Originally posted by Fired Up:
At WOT my motor calculates (454x6500rpm)to use 50 gph of fuel. I have the Holley mech fuel pump rated at 110 gph that is self-regulated at 6.5-8 psi. Using a single 850DP will I have to run a fuel block with a return line to the tank or can I just use the dual feed fuel line to the carb with no worries ?

[pgf127rt]

TB, if you read the post it is a hypothetical calculation, if he ran that boat at 6500 rpm for an hour he would probably have run ashore on most ponds in 5 minutes, just my .02.

[Fired Up]

PGF127, good to hear from You. You are correct that my calculations were hypothetical based on my engine design,specifications and expected RPM range. Mr. Thunderbutt is obviously uninformed on the formula for "Required Fuel Flow" which is calculated in gallons per hour. Air CFM x 4.38 x .08 /6 lbs per gallon. Knowing this one can determine the size fuel pump required. Fuel pumps are rated by their capacity to flow in Gallons per Hour, another technical fact Mr. Thunderbutt is unaware of. E-ticket, good to hear from you too. I was at the races this weekend, but only to spectate. The boat is close to being done.....the answer to the above question I originally posted was answered this weekend.

[Thunderbutt]

Don't get all pissed off. If I have a 20 foot Spectra with a 454 and 2- 750 holleys and would burn 78 gal's of fuel in one hour and ten minutes. What size pump would I need and what rpm would I be turning? Originally posted by Fired Up:
PGF127, good to hear from You. You are correct that my calculations were hypothetical based on my engine design,specifications and expected RPM range. Mr. Thunderbutt is obviously uninformed on the formula for "Required Fuel Flow" which is calculated in gallons per hour. Air CFM x 4.38 x .08 /6 lbs per gallon. Knowing this one can determine the size fuel pump required. Fuel pumps are rated by their capacity to flow in Gallons per Hour, another technical fact Mr. Thunderbutt is unaware of. E-ticket, good to hear from you too. I was at the races this weekend, but only to spectate. The boat is close to being done.....the answer to the above question I originally posted was answered this weekend.

[pgf127rt]

Thunderbutt, probably about 6300 rpm, a Barry Grant 400, with a bypass would more than handle the supply, and if you are like me you would need to own the gas dock at the lake, j/k,