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Discussion Starter #1
I would like to know what the exact differences are between a 15* and 17* HPOP. I think the 17* was used 99.5-2003 and the 15* was used in the early 99 and prior trucks. But I'm not 100% sure on that. I also know that the 17* is a better pump out of the two. But other than that what are the differences? And what does the * stand for?

Thank you for your time!
 

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Here is some more reading on it http://www.powerstroke.org/forum/early-99-discussion/33766-new-model-17-hpop-early-99-a.html
15*= early 99 and 94.5-97,
17* = 99.5-03
The * sign is the best sign we can find on the key board to represent degrees (15* = 15 degrees). The 15* and 17* refers to the angle of the swash plate inside the pump. A swash plate is what the rotating group of a rotary piston pump rides on. The change in angle changes the displacement of the pump per rotation, steeper angle means more flow, more flow means it can keep the pressure up on larger capacity injectors better. Best mod is a dual pump system but they are very pricy.
Here is a pic of a pump I was playing with, the swash plate is the shinny aluminum part;
 

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good explanation ..and nice pic. I expected a hpop to be much different inside.

so what broke on that pump?

I just say the 15° is a whimpy lowout put version of a 17° pump.
there are other things to look at though.

there is joey's modded 17° pump..basically a pimped up stocker but flows better
but not as much as pulse. But also low $

I did some tests on dieselsite 's pulse unit. It made a very big difference. ok not full blown chip difference , kinda like adding 20tow tune feel. much more consistant smooth pull, 50~70 acceleration when up. mpg gains etc.

then there are the high dollar twins . the diy stealth which looks like the pic above.
and may not be even made anymore, with new stealth comming.
and joeys prebuilt twins....

big oil, and even bigger oil makes a difference you can feel. especially from an early 99

I usually just do 15* and 17* cause it is quick
but the "degree symbol " ° " is hold down alt ,type 0176 on the number pad release.
 

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Discussion Starter #4
That makes perfect sense. Thank you for the picture. It looks to me that they run exactly how a hydraulic motor runs.
 

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Just FYI, there was nothing wrong with the pump above BEFORE I took it apart. I got it on eBay for $50 with the IPR attached years ago when I needed an IPR. I threw the pump on a shelf for a spare. When I decided to do the 17* mod I figured I’d tear the pump apart to make sure there was nothing wrong with it and see if I could modify it to give more flow/pressure. These things work just like a hydraulic fixed plate piston pump but don’t come apart like normal hydro pumps and I basically ruined a good pump messing with it. I had fun doing it though. I got my new 17* pump on eBay for $350.
 

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50 bucks holy sleeping bidders batman...

you know there are things you can do with it.
actually like send it in for a core.
talk to Bob reily at dieselsite or jody
..might even get ya double your money.
that you paid for.
 

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rumor has it that both of the guys mentioned my Mike will give $100 for a core.
 

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I have the modded 17* from Joey at Terminator..... its AWESOME!!!

its no set of duals but I went from 1800 psi with my 15* to about 3300 psi!!!

and the price is nice too!!!
 
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