ZX6ROCKET

Hey guys,

I'm looking into 4.56 gears for my 5.4. Can anyone tell me roughly what rpm I will be at doing 80 mph on the freeway? Also, will I be able to hit 100 mph still?

Please don't chime in and guess if you don't have 35's and 4.56's.

Thanks all!

madeSICC

Your probably gonna look at about 2300 rpm.

and what the **** are you doing going 100 mph in a truck. are your tires even rated for that speed. your truck would probably be screaming at 100mph

FSU FX4

Theres absolutely no point to run 4.56 with 35s. Im running 35s with 3.73 gettin 16mpg and plenty of get up and go

schissler

i call bull**** on that ahah

i had 35s with 373 and theres no effin chance your getting 16mpg...maybe your driving downhill everywhere you go

secondly there is NO get up and go with stock gearing. its absolutely total **** to drive with like that

i have 456s now and youll be around 23-2400rpm at 80mph..

if your running MTs on your truck their only rated for liek 90-95mph....

FSU FX4

16mpg is what my Gryphon says. And im not racing anyone, not sure why you would want to go that fast in a 4x4 truck anyways, but its enough for me.

F150Gamer

I have 35's and 3.55 and I'm lucky to get 15mpg on the Hwy I'm looking at getting some 4.10's to give the truck some more grunt

gnardawg83

Man I had 35's and 3.73s and I was getting 8 to 9 mpg haha. But then I got some 4.56s, cold air intake, throttle body spacer and then I was getting 12 mpg and I was happy Now I have 33's still with the 4.56s and I'm running about 2400 RPM at 80 down the freeway getting like 13 mpg,....and my speedometer stops at 101 and it was at like 4000 RPM haha. But now with the 33's it feels like I don't have a first gear when I take off cause it shifts so quick

FSU FX4

Theres a thin line between higher/lower gear ratios and tire size. with the higher gear ratios you can offset the low mileage with bigger tires, but if you go too small like 33s with 4.56 youll get bad mileage. If you go too big with too low gear ratio, same result, poor mileage. My uncle is runnin 33's on his dodge 2500 diesel and gettin 15mpg with a 4.10 rear end

madeSICC

I get 15 consistently with my truck on stock gears. I usually am turning around 15-1700 rpm cruising speed in the interstate.

ZX6ROCKET

I don't usually ever hit that but some instances have arrisen lol. Speed ratings? Who needs stinking speed ratings! At 100 mph right now I'm at like 2500 rpms. I need gears BAD. Truck has 0 pull and 0 power. Full throttle is pretty much the same as half throttle until the truck gets to 4k rpms and then I hit my powerband. Its pathetic. A honda civic would rape my ***.