Rear ends and transmission compatabilities

That started with the 7 series. The RTO12513 and 14613 were single over and ended in .87.

 

The will put you running 65 @ 1600 in 12th (direct). The problem I see with dropping the rear ratio that far is what it will do to your low & reverse ratios. @Cowpie1 is running even lower rears, but he's also running an 18 to get the lower ratios in 1st and reverse. Unless you happen to have a 'B' ratio 13, which is fairly rare, you'll be really tall in those gears.

 

I have an n14 select plus with 10speed fuller nd 3.70. I want to pdi it to 600HP with 2050 torque wen I O/H it.. wat would be a good transmison for it.

 

I ran a 9400 international with 11r22.5s 3.55rears and a 13 behind an isx set at 1800 on breakin pulling a 48 10' spread with 46k on the deck she would out pull most I came up by loaded In TN and that area, I was always a cat guy until I drove that rig. I swear by a 13 or a 15 with deep reduction for off road applications. I may not be right but I have ran everything from a 5WITH A 2SPEED REAREND to an 18 they all have a purpose and use if I was grossing 100k I would want an 18.

 

The simple goal being running in direct at desired speed in low end of torque curve. My money’s with Cowpie as I’ve heard this time and again from Pittsburg Diesel and all the other experts.Swift used to run 279 or close to it with 11.1 Detroit and 9 speeds or 10 spd directs at 55 mph years ago. No one could understand why. My exact #s are probably off it’s been 25 yrs ago.Looking back I should have bought that old Swift truck to haul the lightweight auto parts. But I needed a 425 Cat in a western Star much more Lol

 

Both of my old 99 12.7 Detroit’s get best mpg @ 1375 w/13 355 24 Lo pro’s as long as I’m running flat but heavy in hills I might as well have a Cat. Too busy winding it up to 1750 just to get up the hill to worry about mpg’s!!!

 

That's pretty sad. I typically run around 1475 RPM at 65 in direct (16th) on low pro 22.5 rubber, and I can typically walk hills pretty good under a heavy load. Sure a lot better than many of the newer trucks are doing. Typically no higher than 900F on pyrometer under a pull also. And the average mpg is just under 7.5. I guess it depends on how things are set up, but I find my S60 does it's best work between 1400 and 1500 RPM. That is using a BW 171702 turbo asymmetric turbo in place of the stock waste gate turbo, and I have a blanket on the turbo. 874,000 miles on the motor and only uses about 2 qt of oil in 23,000 miles and the used oil samples look as good as when the motor only had 50,000 miles on it.

 

I need that turbo. About time for a new one anyway. I run 1500 at 65 with my set up. Had a on dash info on last truck studied it for a long time when I first got it. Always beating the cruise letting it lug easy up very small hills and letting up on it to the point of barely topping hill then giving it fuel very easy on way down to regain speed staying at 62 mph. Made a game of it. Had the computer showing up to 9 mpg. It would lie progressively more the higher it went when checked at fueling. Computer 8.0= 7.6 / 9.0=8.3 And so on.The truck had 178k when I got it.Got tired of that game. That Truck was within of 6.5-7 mpg on avg.Back then I talked to fleet mgr at Werner when they were running same trucks same mpg’s on fleet avg.Ive only been able to squeeze 6.2 on my current Nov 98 built 12.7 Usually about 5.5 w/idle time and running heavy at 65-70 mph. Guy I bought it from told me it was that way since new. It definately needs help will be overhauling soon.Looking for more torque. Without breaking bank.

 

The new Peterbilts are comming out with ISX 500HP, 10SPD Hight torque along with 3.42. Heard a heavy hauler using this and pulling 140k lbs