Gearing question (part 2)
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Gearing question (part 2)
Okay, so in another thread, I mentioned that my new F150 4.6L, will have 3.55 gears (could have gotten 4.10's, but wasn't figuring for larger tires :-(
After ordering the truck, I decided on 305/65-18"s.... 33.7" diameter (3" more than a stock XL... 2" more than a stock Lariat) so, not too extreme, but anyway....
Now, I will "always" be towing, but it will be a very light load. My boat, motor, and trailer only weigh about 1000 lbs total. I'm confident that my truck as it will be set up, will be able to pull my boat down the freeway, without any problems at all.
But I'm concerned how it will do pulling my little boat (and itself) up fairly steep hills, with a 4.6L and 3.55 gears....
Senior member JMC had said
.....and this makes all the sense in the world to me.... Except theirs just one thing.... JMC said
But to be quite honest, for myself, "more power" will be important 5% of the time, while better mileage will be most important, the other 95%....
I guess the best thing for me to do, is to get the truck and try it... Then take it from there.
But anyway, the reason I'm posting this is to ask, if some of you gearing pro's would, for just a minute, please shift out of that "more power" train of thought, for a minute, and into the "better economy" train....
"IF" (as long as) I'm able to pull my little boat, with 33.7" wheels, up over a steep hill every now and again, then my 3.55's should give me better mileage, for the other 95% of my driving, correct ? (obviously not better than it would with smaller tires.... but better than it would with 4.10 gears, right ?)
Just curious,
Fish
PS, I'm always hearing.... more power, more power, more power..... Well, if you can afford "more gas" then "more power" to ya' :-) I'm just a poor guy who'd rather be fishing, than working to fill his gas tank.
After ordering the truck, I decided on 305/65-18"s.... 33.7" diameter (3" more than a stock XL... 2" more than a stock Lariat) so, not too extreme, but anyway....
Now, I will "always" be towing, but it will be a very light load. My boat, motor, and trailer only weigh about 1000 lbs total. I'm confident that my truck as it will be set up, will be able to pull my boat down the freeway, without any problems at all.
But I'm concerned how it will do pulling my little boat (and itself) up fairly steep hills, with a 4.6L and 3.55 gears....
Senior member JMC had said
To make power the 4.6 needs to turn at a higher speed. Its torque peaks at 3500. The closer you can spin the engine to that number the more powerful it will be. Obviously you do not want to spin at 3500 going down the highway. At 70mph with your tires you will be turning about 1740 rpm in OD and 2480 in 3rd. Your stock tires would have put you at around 1950 rpm 2780 rpm respectively. Most people find a gear that will return the rpm to where they were before the tire swap. While this is a step in the right direction they forget about the effect the increased weight of the new tire/wheel combo will have on the power to the wheels. 4.10s will put back close to stock but I would go to a 4.30 or 4.56.
The closer you can spin the engine to that number the more powerful it will be.
I guess the best thing for me to do, is to get the truck and try it... Then take it from there.
But anyway, the reason I'm posting this is to ask, if some of you gearing pro's would, for just a minute, please shift out of that "more power" train of thought, for a minute, and into the "better economy" train....
"IF" (as long as) I'm able to pull my little boat, with 33.7" wheels, up over a steep hill every now and again, then my 3.55's should give me better mileage, for the other 95% of my driving, correct ? (obviously not better than it would with smaller tires.... but better than it would with 4.10 gears, right ?)
Just curious,
Fish
PS, I'm always hearing.... more power, more power, more power..... Well, if you can afford "more gas" then "more power" to ya' :-) I'm just a poor guy who'd rather be fishing, than working to fill his gas tank.
Last edited by Fish Chris; Jun 11, 2008 at 02:57 PM.
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From: Missouri
If you're gonna be doing a lot of highway driving, keep your 3.55 gears. If you're going to do a lot of city driving, you probably wouldn't notice much of a difference. You *might* see a small increase with the lower gears because the engine wouldn't have to work as hard to accelerate.
Even then, gears are an expensive mod, and I don't think the fuel savings would pay for them.
Even then, gears are an expensive mod, and I don't think the fuel savings would pay for them.
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From: The LBC (Long Beach, CA)
If you're gonna be doing a lot of highway driving, keep your 3.55 gears. If you're going to do a lot of city driving, you probably wouldn't notice much of a difference. You *might* see a small increase with the lower gears because the engine wouldn't have to work as hard to accelerate.
Even then, gears are an expensive mod, and I don't think the fuel savings would pay for them.
Even then, gears are an expensive mod, and I don't think the fuel savings would pay for them.
See how it does.
Note that few peeps turning stock-ish tires haven't reported significant MPG reductions.
My case was a little extreme...I went from 3.31 to 4.10 and noticed no mpg change.
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I went from 3.55 to 4.56 at 85% Freeway so the RPMs are a little more, Towing or Hills are a blast dont even notice the almost 2K behind me so to comp for the increaded rpm I bought a programmer and just run the gas millage tune even for towing.
In hindsight I would of goten 430s for mostly feeway driving.
In hindsight I would of goten 430s for mostly feeway driving.
