stroker4501

What is the difference between the two? What years came with which one? Which one is better? and can you change between HO and SO pumps? and what do the two initials mean im guessing HO is High Ouput, but whats SO mean? thanks in advance. mario

mopar-or-no-car

High output vs. standard output
The six speed manual trucks are all high outputs. You can put either one on,but the standard output is capable of more power. Someone else will know more and can explain why it is capable of more, I forgot what the actual differences are.

afoulk

I'm not sure on the exact measurements, but I think the HO pump has 7mm plungers in it while the SO actually has 7.5mm plungers, which is probably why they are capable of more power. I believe the HO pumps used higher fuel pressure to help boost the power a bit, but actually used slightly smaller injectors than the SO engines as well.
I put a SO pump on my HO a few thousand miles ago because I'm planning on around 550hp someday. They say the HO pumps will support just shy of 500hp and 150hp injectors are about the biggest you can run with them until you start running outta fuel.
The HO engines also have about 1 point higher compression pistons in them I think. They are a little more sensitive to running modules with to much timing.
If your plans don't include anything that extreme, than I say HO is the way to go, but I don't know if the those pumps will swap onto a SO engine ok, I think it only works the way I did it. The 6-speeds (NV 5600) are almost indestructable, but you do have to be pretty religous about the maintnance on them for them to last. Only real disadvantage to them is that parts or a full rebuild are super expensive, and since NV doesn't make them anymore, they are getting kinda scarce.
Warning though, SO pump on a stock HO engine (such as mine) will kill a lot of your bottom end power. It only pays off once you start bombing it.

jakeydiesel

in 2000 the made a standard output 6 speed. in 2001 compression of the HO is 17.0 to 1 as the SO is 16.3 to 1...the ho has a bit more bottom end, and more power out of the factory, but wont go as high as an so injection pump, once modded. there are guys who swap pumps just fine, and others whom have problems...i have an so pump for my ho in the mail as we speak. -jake

blackdiesel

Your 2000 has a SO pump on it, and I would keep it that way. JMO

stroker4501

thanks for all the help guys and i just wanted to see which trucks had what pump. im glad i got the good pump out of the two tho.

Bob_24VCTD

98.5 - 5 speed 24v had the HO pump, or introduced in 2000?

johnh

ho was introduced mid 2000, but officially wasn't available until 2001 model year.... if i'm wrong sombody please correct me

stroker4501

so how do i tell which pump i have then?

johnh

you have the SO pump

afoulk

Just incase you would wanna double check, at the end of the part # should be a 27,28, or 29. 27 is the SO pump, 28 is HO, and 29 is the pump on the medium duty trucks. But yes, yours should be a SO.

blackdiesel

Who here has a factory HO, that's not a 01-02 6 speed? I have only heard of 1 that was special order with an auto. I know that they made some 99-00 with 6 speeds with the 1 1/4 input and the SO motor. but that's all I've ever heard. So if you have one inlighten me.

MikeBC

I just ordered my HO VP44, I'm sure I will have more questions soon!
I really hope this fixes my no power when cold & random no power issue.
I dont think its a boost sensor, when it has a loss of power it is a massive loss, and the 5.9 w/o boost would have to do way better than 40mph max unloaded on a level road. Just my opinion, and a $1000 guess

Bobcat698

MikeBC, where did you buy your pump?

MikeBC

Midwest - http://www.mwfi.com/VP44.htm

I found it for 950 somewhere in Florda, but I wanted to go with a more well known place, plus this site has helped me a TON, so I wanted to support one of the advertisers. I hope it all works out ok, they look like a larger company, but you never know! Plus needing the HO version I wanted to stay with a large company.

So, next week is the VP install!

Also, one of the NASCAR shops near me has a sweet little fuel pressure guage for just over $200. I figured I would get that and a APillar mount. The guage has a LED, 15psi range, a low psi memory, and a low psi LED. Its set up for the cup drivers. Figured I'd replace the scredner valve with this sending unit. Advice?