more hp less fuel?

[firebird_1252]

so i was thinking today, would i use more fuel with more hp? or less? my truck is a 435 c15 MBN motor, 10 speed, 3.73's 22.5 low pros. it dont do bad really but seems i'm always in it at 65 mph. i figured it out today, i'm getting 5.7mpg. i run off the rail so what i'm normally seeing, is the heavyest (so far) was 46k. lightest 20k. i'm in pa, running up and down 81/83 mostly. so do you think with more hp i'll do better on fuel or it'll stay the same?

[Mackman]

so i was thinking today, would i use more fuel with more hp? or less? my truck is a 435 c15 MBN motor, 10 speed, 3.73's 22.5 low pros. it dont do bad really but seems i'm always in it at 65 mph. i figured it out today, i'm getting 5.7mpg. i run off the rail so what i'm normally seeing, is the heavyest (so far) was 46k. lightest 20k. i'm in pa, running up and down 81/83 mostly. so do you think with more hp i'll do better on fuel or it'll stay the same?

I was told the more HP you have the better MPG you get. I dont know how ture it is. But a 550HP will work alot less then a 400HP to move the same 80k load. May be some turth behind it.

[rank]

You will use more fuel with more displacement.

We run 81 and 83 in NY and PA. We are always 80,000 southbound and anywhere from 30,000 to 80,000 northbound. I have a 10.7 L engine that got 7.5 average when I drove 60 - 62 mph*. The best the other guys with the 15 and 14 L motors could ever get is 6.

If I pulled 80,000 all the time or if I was in hilly terrain all the time, my mileage falls substantially. In fact, at 80,000 I would bet I get the same mileage as a big engine....but I'm getting over 8 mpg when I'm light and they are nowehere near that.

*I lost 3/4 mpg by putting new drives on.

[firebird_1252]

i'm starting to wonder if my guage is off.. i'm going to fill up tomorrow and see where its at.

today i went up to 80 (tobyanna pa) only had 18k lbs, left the cruise on for the most part barely used any fuel and only slowed down to where i had to drop 2 gears maybe 2 times? used alot less fuel. i think tomorrow i'm going out 44k. we'll see.

[BoyNextDoor]

my guage is wired too. It gets to the halfway mark in less than 5- gallons than the rest it goes down really slow. avarages still add up,. but the gauge is wired.

[mitchno1]

in new zealand we find the signature motors are most efficent fuel wise at 580hp mind you our diff ratios 4.3 or so plus 18 speed boxs so all makes a difference.

[firebird_1252]

when mine is full it goes way past full. i got 1018 miles out of my 240 combined fuel. no clue how much more i had to put in when i filled it because my comdata card has a $600 limit on it.

[Malaki86]

The last company I worked for decided to cut the fleet's HP in order to save fuel. We hauled 45k in/out of WV every day. They cut the trucks down to 350hp (compared to the 435/465 they had). The fuel mileage instantly dropped like a rock. Nothing like coming across I-68 and pulling some of the hills @ 10mph.

[Copperhead]

Companies always seem to change engine settings to compensate for drivers inability to drve right. If these companies would institute real monetary incentives, they would get better mpg figures. For instance, set a base line at 6-6.25 mpg. The driver will get 80 percent of the savings for mpg higher than that number. For getting 1 mpg better than the base line, a drver could potentially earn almost $8000 more a year. Let the engine operate the way it was supposed to, give the driver a real incentive to do better, and everyone wins.

[allan5oh]

Take the same detroit at 430 vs 500. The only difference between the two is when the second is making above 430 hp. Below that it is exactly the same motor. It's easier to get better MPG with the 430 because the same throttle position corresponds to less fuel. Imagine if you had an old mechanical turned all the way up, with a super responsive throttle. That first 10-20% or so is the same as an electronic motor at 100% throttle. Which one do you think will get better MPG?

[solo379]

That's surprised me, that nobody not even mentioned the torque! And that's, considering right specs and reasonable driver, is the only thing responsable to a difference with the fuel mileage. So, IMHO if you , while increasing the power, could increase the torque;-Go for it! Otherwise it would be the waste of money....