Krob

First off thanks to all of you that put up with my incesent dumb questions.

This one in my series of dumb questions is about fuel milage but i didnt want this thread to get labeled that, those threads seem to get into a compitition of people and swearing about what they get.

When driving should i be shifting to the lowest gear possible for fuel economy once up to speed, or should i try to be keeping it above a certain rpm. Ive always figured lowest rpm with out lugging it but i wanted to see what all you said.

Im already getting very exceptable fuel mileage especially when on freeway (18+ typically) but i thought i would ask about around town and such.

Oh additionally when travelling with a load lets say 750lbs+ what rpm range should i try to stay above for optimal fuel milage.

THanks for putting up with my continous rediculous questions.

bent valves

On my truck with a 5 speed and an SO engine, I have read that the lowest fuel usage is at an engine RPM of about 2100 RPM. This is where I try to cruse to maximize mileage. It may be different on your 6 speed. Around town there probably is no hope for good mileage.

Krob

Alright 2100, thats the kinda info im looking for. Thanks bent valves, someone else will probably chime in with more advice tonight thanks.

GAmes

When accelerating for shifting up, or whatever, I try to keep my boost below 10 psi when empty and 20 when towing heavy. When climbing hills, when I get to 20 I slow down and shift down.

Krob

Alright explain the boost thing to me, i understand what your saying but why?

CoastalDav

My truck gets its best fuel mileage on the hyw running without really slowing down to much is at 68mph. 65 mph is even better if you can stand it. While comming back from Gilroy CA, I averaged about 650 miles between stops for fuel running at 68. Above 70 the mileage drops quick.

If you have the instant fuel mileage indicator in your overhead console, it will indicate your mileage as you drive and will allow you to select the best gear if towing, or speed for mileage without having to run thru a tank of fuel to see what you did. Its a tool and may not be totally right.

Dave

GAmes

It is the "eggshell under the lead foot theory". If you accellerate slowly enough to keep the boost under 10 (or 20) the fuel is burned and not wasted. The same under heavy load going up hill. Higher rpms and lower boost are more efficient.

Krob

Alright that makes sense that kinda what i figured but i thought id ask for clarification.

Yeah that milage indicator is probably way off but at cruising a higher number is better then a lower number. thanks

Tate

I think that is the lowest amount fuel burned for a given hp, lb of fuel per horsepower-hour. I got my best mileage driving around 1600 rpm. It was terrible weather, so it was easy to go slow. Managed just over 21. Doing 2000-2200 rpm, I'm in the 17-18 range.

As for the boost thing, it takes fuel to generate boost. More boost produced, more fuel consumed, and vice versa.