Originally Posted by Eddie Foy
How do you measure quantity? How do you measure volume? Are they not the same? a Gallon is a quantity and a volume.
I am not trying to bust your chops. Just trying to understand what you are saying
Eddie-sorry it took so long to get back to you.Been kind of busy.Quantity is single gallons I.E.-how far can I go on one gallon of gas.Volume is GPH(gallons per hour) or gross amount of gas with hopefully a three port regulator and return.Here the question is by a lower rpm with o/d,how much of that gross available gas/return line is the engine going to use.If working the engine at the beginning of it's torque curve and more strain in that region but less gas peddle is going to use less volume or more.Most people relate to using more gas by a raise in rpm,but is is possible to use more volume of gas at a lower rpm because additional loads to maintain the torque at a lower rpm.
This whole question about o/d trannies still falls out on engine efficiencies/torque.The stock GM truck 454 engine's head port size/camming is very poor as is the SCR.(Static compression ratio)The way to capitalize on a o/d is to use aftermarket heads(not talking high dollar aluminum heads.But there are decent improvements in aftermarket cast iron heads like from RHS with a slight increase in SCR) and re-cam it according.You increase the torque at that same o/d lower rpm saving on the volume of gas.
On the P30 chassis with the dual rear wheel/454 option the rear end gear ratio is already 4.56.I have the build sheet from GM's archive.Before any changes are made,you should have done the compression/leakdown tests to evaluate where the engine is at.Unless you have owned the unit since new,you don't know what the cruise speed the united was used at and by the time of 80,000 to 100,000 some are pretty tired with 4.56 rear end ratios.Valve springs,rings,bearings,etc.My point is you can't or shouldn't look at these units the same way you would look at how many miles they have on them as you would look at any other vehicle.