Hey, I have just been wondering what the difference is between the H.O. and normal Cummins......different tubo, injectors, or programming??? Do 6 speeds come with the H.O. or is that an option you can get with the normal cummins? thanks.

 

Sounds like a good dealer question.

 

Here's a few things, not sure if this is every difference or not:

Higher compression ratio, 17:1 vs 16.3:1
Larger turbo
Higher output injection pump

From www.dodgeram.org

 

235 HP 460 TQ = SO 16.3:1 compression
245 HP 505 TQ = HO 17:1 compression

2001 & 2002 HO were only availible with the 6-Speed and vise versa

the SO trannys were either the auto or the 5-speed

a few 1999 and most 2000 trucks that were 6-speed were SO
because the HO was not released until 2001 model year.
I believe that there were a few 2000 that were HOs but I am not 100% sure on that.

The HO injection pump has a higher pressure...but is less capible of fuel volume when compared to the SO injection pump. That is why a lot of guys would rather have the SO engine because you can get more power out of the SO injection pump. The HO injectors are smaller as well but operating at a higher pressure.

The programming between the HO and SO are different as well. If you put an SO injection pump on an HO truck it will not work and vise versa.

The HO engine also has a 13" clutch while the SO is at 12.25"

there may be something else, but I think that is about it.....

oh yeah and I almost forgot....the HO is better

 

Six speeds don't "come" with an HO, but you couldn't get a five speed HO.
If you know what I mean.

I thought the VP44 differences were the only difference?

 

I believe that you couldnt get an SO with a 6-Speed either. In other words if the truck has a 6-speed then it has the HO. And if the truck has an HO then it has the 6-Speed. Unless you specially ordered the 6-speed or something like that....I think there is someone here who did that.

All that other stuff I mentioned are the differences as well as the VP44.

 

LMAO!

 

HEY HEY HEY that no funny!

and the HO engine IS better!

 

Oh my Ho is Ho Ho Ho cuz it has an 6 speed and 13 inch clutch.......

HoDiesel

 

turbo isnt larger. still HX 35W with a 12cm^2 exhaust housing which is the same as the 5 spd but, grant you, larger exhaust housing than an auto (9 cm^2).

 

Im with ya, I love my HO and it is better, just thought that was funny

 

Can you get an HO pump fixed with SO innards at rebuild time?

 

OK, larger housing. Autos have an HY35, I thought, though.

 

Yep, they are called Hot Rod VP's, or HRVP's. They also come with added timing. They have the larger plungers that allow the same amount of fuel volume, and keep all the good points of having a HO in the first place. However plan on spending at least $400 more for them. Only worth it if you are going to use really huge injectors, and a big fueling box.

 

My 99 auto has the HX35W-12. I did't think they started using the HY35W-9 on the SO motors till 2001.

Turbo LINK