Engine/Transmission (1998.5 - 2002) What makes 24v H.O motors different?

[jkidd]

What makes 24v H. O (ETH) motors different? I know they have 10 HP more than the standard CTD (ETC).



Should one go about modding any differnetly?



2001 H. O. 122k miles 6spd... stock

 

[Partyat33]

Different injection pump, different ecm, higher compression ratio.

 

[nps]

The pistons, injectors and VP44 are different. The motor has a higher compression ratio compared to the ETC.



As far as mods go - the same boxes, injectors, turbos etc. all produce similar results. In some cases a little more, in others a little less. But the same parts and same upgrade paths.

 

[Partyat33]

Generally speaking an SO motor responds better than an HO motor for bombing. The pistons in an SO vp44 are bigger than the pistons in an HO motor.



Dennis

 

[Holysmokes]

Please forgive the stupid question; But how can I tell which one I have? HO vs. SO? I know it tells you on the window sticker when their new but I purchased mine used.

 

[nps]

Please forgive the stupid question; But how can I tell which one I have? HO vs. SO? I know it tells you on the window sticker when their new but I purchased mine used.

Look on the engine data plate - side of timing cover by the VP44/APPS. Should say, among other things, 235hp or 245hp.



Also, your sig says you got an auto. The HO motor only went in front of the NV5600. So if you have a 5 speed or auto, then you have a SO.

 

[Turbo Tim 1]

Look here: www.dodgeram.org it explains the difference in the two engines pretty good. Bore and stroke are the same on both engines but fueling is different.

 

[Hohn]

Some specifics:

The VP44 on the HO has plungers that are . 5mm smaller (7. 5 vs 7mm)



The compression ratio is higher, raised from 16. 4:1 to 17:1



Injection timing is slightly retarded on the HO, to reduce peak cylinder temps, and thus NOx with the higher Compression.



The ECM is programmed to use a higher percentage of the smaller pump's limited capacity.



Injector sets generally make 15-20 more hp in an HO truck.



Fueling boxes generally make 30-35 more hp in an SO truck.



HO tops out around 550-570hp on just #2. SO has gone to 700 on just #2.



HOs tend to run hotter EGT in stock form due to retarded injection timing.



ECM limits boost on HO to 26psi, but only 21psi on the SO, IIRC.

 

[c-hawk]

Very good post Hohn.



That's all the differences i could think of plus more.



One thing i see a lot is people saying the H. O. has more timing... but from sources i trust very much the H. O. has less timing, like your saying.



I didn't know the H. O could make 26lbs without defueling.



Chris

 

[jkidd]

great info...

I have checked out the links and am glad to hear such a response. I just bought a VanAAken Box and ordered a BHAF and am looking for some injectors. rv 275 or maybe some that sell on Ebay... or any suggestions??? I am new to this game, and just got guages( not installed) I would like some power, but don't want to significantly shorten my engines life.



Has anyone ever put a vp44 from a SO into a HO?



thanks again

 

[CJ Lagos]

I also remember something about piston cooling?

 

[nps]

I also remember something about piston cooling?

They all have piston cooling - acheived by spraying the piston skirt with oil from below.

 

[Supermod56]

I have checked out the links and am glad to hear such a response. I just bought a VanAAken Box and ordered a BHAF and am looking for some injectors. rv 275 or maybe some that sell on Ebay... or any suggestions??? I am new to this game, and just got guages( not installed) I would like some power, but don't want to significantly shorten my engines life.



Has anyone ever put a vp44 from a SO into a HO?



thanks again

Put a 4" pipe on it (first thing you should do) and some Don's Mach injectors, either 1. 5's or 2's, I just bought a set of 1. 6's because they work great with my Catcher ECM, don't have em installed yet. They are expensive, but from what I have seen on here, well worth it!!! If money is an issue the 275's or the 300's will work fine. And I have not heard of anyone putting a HO pump on a SO motor, don't think it will work, but I could be wrong!



Tom

 

[Hohn]

HO and SO pumps don't swap, because the ECM can't talk to the FPCM. It goes into limp mode. If the ECM was reprogrammed, it might work. I dunno.

 

[darkhorse]

I am looking for some injectors. rv 275 or maybe some that sell on Ebay... or any suggestions???



Check the classified on this site. There are some good buys on injectors there... . like my Mach 1. 5's

 

[SpicyJam]

The SO pump will work on an HO but you will need the ECM out of a 2001 5spd truck. A fueling box will only add about 90hp to a HO where as you can get 145 - 150+ out of a SO, depending on who's box you use.

 

[JL penner]

Well this sucks!... ... . I always thought that having an H. O. meant my truck was just a little bit better. So the vp44 in an H. O. pushes a little less fuel? Would a HRVP44 make up for this? Would I have to change the ECM then? Also, does that mean that I really didn't get the 60 hp and 180 lbs. of torque increase from my edge EZ??????

 

[SpicyJam]

Well this sucks!... ... . I always thought that having an H. O. meant my truck was just a little bit better. So the vp44 in an H. O. pushes a little less fuel? Would a HRVP44 make up for this? Would I have to change the ECM then? Also, does that mean that I really didn't get the 60 hp and 180 lbs. of torque increase from my edge EZ??????

LOL... ... Yes you get the power from the EZ, just not the full potential of any box that taps the pump wire. The rev 29 pump will not work on your truck unless you change out the ECM... ... ... ... ... sorry

 

[JL penner]

Thanks for the good news about the EZ! I guess I shouldn't comlain too much. I hauled around 15,000 lbs ( 21 head of cattle avging 520lbs in a 24' steel stock trailer [4klbs?]) yesterday and never slowed below 60 up the hills, and I could cruise at 70-75 on the flats without feeling like I'm even pushing it. :-laf ... ... . Hope the GVWR Nazis don't read this post.

 

[SSabick]

The HRVP44 will work only if they put the SO hardware in it. Some call these the SHOVP44's. Sounds like they are the best of both worlds.