What did Cummins do to the H.O. Engines to give them more compression
vs. the S.O. ?

 

First year for the H.O. was 01 and here are the differences (from dodgeram.org):

"What's new in the ETH engine:

* Electronic Controls: New ECM calibration and fueling algorithms.
* Fuel Pump: Increased fuel flow in the Bosch VP44 injection pump.
* Injectors: Designed to provide increased fuel flow.
o Injector note posted to the TDRoundtable by tgbol:
+ ETH injectors (3946306) flow 600cc at 100bars for 30 seconds
+ ETC injectors (3944828) flow 640cc at the same test.
* Turbocharger: Revised wastegate setting for 26psi at the turbocharger outlet.
o Manifold boost specification is 43.5 inches Hg / 21 psi
* Head: Valve seat inserts for added durability.
* Pistons: New pistons with higher 17:1 compression ratio.
* Flywheel: New flywheel with 330 mm diameter clutch (vs. std. 310 mm).
* ISB Design Improvements and Features - from 1998 Mastertech
* FWIW: Reports from owners indicate that ETC engines are more responsive than ETH engines are to the major fueling boxes."

 

the pistons have a higher compression height. in laymans terms there a little taller from the top ring up...

 

Hey guys, I really appreciate the help!

 

don't forget the vin has a 7 instead of a 6...that and the HO seems to have more top end power and less lowend power compaired to the SO

 

I dont know about that, I have a HO and my dad and grandpa both have the SO and mine seems to out pull thiers, with better mpg too. That might be because of the stick over the auto though.

 

So with those mods to the Vp44, does that mean you are less likely, or more likely to have a problem with the Vp44? I always wondered about that....

 

From everything i've gathered less likely, but negligibly so. The pumps themselves are inherently the same so reliability issues are the same, BUT the HO pump is supposed to cool itself better and I can only see that helping it last longer, even if just a day .