Best diff ratio for highway towing?

[pronstar]

Did your sniper tune remove the speed limiter on your truck?

I can't imagine that your natural top speed would be much above what you are seeing anyways, these trucks are not very aerodynamic. Think about it: huge frontal area, crappy coefficient of drag, and just 232-hp.

If you are at 4300 rpm @ 106 mph then you are likely not in top gear/overdrive. OD is very tall on these trucks, and most cars on the market in general.

If you have a super-tall final drive, then a shorter gear could help "real" top speed, though the "theoretical" top speed would be less. Which is precisely why many cars won't reach top speed in the top gear. Top gear provides a higher theoretical top speed, but the motor doesn't make enough power to pull it.

 

[ELVATO]

Yea, it kinnda did. It'll go up to 100 and it seems as if some of the power is cut out or something, and it will slowly climb to 106 with the engine screaming. I'll send you the video.

Hmm, it seems I might have to look into possibly getting a shorter gear.

Thanks for the info

 

[green03]

Yeah it should have full power in all the gears.... unless it is going into some kind of lugging mode..... send video but be safe!

 

[ELVATO]

Yea, it's the one you've already seen, green.

 

[danketchpel]

I have the factory 3.73 gears with the HD towing package. It's not bad that way but if I were towing fairly heavy loads (5,000-7,000+ lbs) regularly I'd opt for a set of 4.10 gears. The OD is so tall you'd still be running 2,500 rpm or less at 70mph.

BTW, what's all this top speed nonsense in a frickin box on wheels?

I don't even care what the top speed is on our's I'd never push it past 90-100mph anyway.

If you wanna go fast get a go fast car or motorcycle. These babies are better suited to towing your race car/bike to the track.

 

[blown87notch]

Mine came with the 3.73 for towing. Mine does ok in OD on the freeway towing, any kind of grade I push the OD button. No way you want to pull grades with it in OD, way too much heat.

As far as top speed....LOL no comment...(it's a big square truck..are you kidding?) A taller gear will raise your rpm per mph which may or may not change gas milage, which really depends on the load.

 

[pronstar]

Here's a link to pics of my speedo at various speeds with 285/60R18 tires and 4.10 gears.


http://homepage.mac.com/robbobster/PhotoAlbum37.html

Under 2,800 rpm @ 90mph.
2400 rpm @ just under 80mph.
2500 rpm @ 80mph.
Less than 2,000 rpm @ 60mph.

As you can see, RPM aren't excessive at all so highway cruising MPG is little changed one way or the other. OD is very steep on these trucks.

Power in the lower gears is nicely improved.