Push Rod

[quote author=Gary - KJ6Q link=board=4;threadid=7170;start=30#71821 date=1038159178]<br>1) bypass - by actual measurement, not an offhand from-the-hip guess by a Cummins tech - AND, THAT was figures done <br><br>2) Bottom line here is, no matter HOW big a fuel line you run to the VP44, it can only flow 45 GPH *max* - larger lines for the benefit of various pump schemes *might* be a good thing - sure aren't gonna HURT anything - but don't expect miracles from their use, or expect that bigger lines alone will seriously impact VP44 lifespan...<br><br>3) Read the threads - those aren't just shadetree mechanics - there are guys posting there who are aftermarket manufacturers of performance parts and guys operating their own independent diesel performance shops - they make their livings doing this stuff...<br>[/quote]<br><br>1) I'm not sure who your Cummins techs are, but I would never post information that was from-the-hip, nor unverified by other sources. I have a great deal of respect for the techs at Cummins Mid-West in my neck of the woods. They too make their living doing this stuff, and in circumstances as demanding or more so than the diesel performance market. I too make my living doing this stuff, and as such need to take care that the products I sell and develop will function as advertised, and indeed benefit my customers. As such, I tend to not only seek information from diesel performance shops, but general diesel repair shops, engineers, and any other reputable source I can lay my hands on.<br><br>2) Again though, we're talking apples and oranges. I only suggest opening up the lines and replacing banjos to preserve lift pump integrity, not extend VP44 life, although maintaining lift pump integrity directly influences VP44 life.<br><br>3) I've read the threads closely on the TDR. If I'm not mistaken, the test was done by Bill Kondolay, a man whose intelligence and integrity are beyond doubt. However the experiment he conducted does not address my primary premise as he changed multiple variables, including the actual lift pump and 1 of the '44 supply lines (from lift pump to fuel filter canister). He should have also measured fuel pressure further down the line, as well as at the lift pump outlet. My premise is this:<br><br>Opening up the banjos and the line I.D. between lift pump and filter canister, and filter canister and VP44 reduces stress on the lift pump. This is proven when replacement of banjo bolts results in an increase in fuel pressure at WOT. Pressure is a direct function of resistance to flow. More pressure = less flow resistance, if the volume remains unchanged (which Bill's test did verify with his flow test on the return line). Less flow resistance means less stress on the lift pump, and therefore longer lift pump longevity. And in practice this has proven itself too many times to be ignored.<br><br>I'm hoping by early next year I'll have more evidence. A test laboratory in Pennsylvania has been commissioned by Bosch to study to the effects of opening up '44 supply lines, including simple cross drilled banjo bolts, different banjo fittings, and larger ID lines. When Bosch has released the information, I've been promised a copy by a friend who works in the lab.<br><br>Rod

Edward

I have a 2001 and the restriction in the fuel system is the line between the factory fuel pump and the fuel filter. That line is 1/4, which ends up being .17 inside diameter according to Aeroquip. This is less than 3/16 of an inch. I agree the banjo bolt system is restrictive because the fuel flow has to change directions so may times to get through one. The other line sizes are as follows. The line to from the tank to the pump is 3/8, which comes out to .3 inside diameter. The line from the fuel filter to the VP44 is 5/16, which is .23 inside diameter. Replacing the banjo bolts will help but that alone does not cure the most restrictive point in the fuel system. It is easy to get rid of all the banjo bolts and replace them with –6 fittings. This gives the same diameter fuel line from the fuel tank to the VP44. No restrictions except for a dirty filter perhaps. No backpressure on the pump except for the filter and then VP44. The problem in my view is pressure drop due to restriction not just a simple lack of pressure on the pump end.

Push Rod

Hey Edward!<br><br>Whose -6 fittings are you using? I looked high and low for fittings whose inlets/outlets were the same size/larger than the shank ID of the banjo bolts, but couldn't track any down. So we went with larger banjo fittings and the bolts, but I would rather have a standard fitting (less expensive than the machined banjos I'm currently using).<br><br>Rod

Edward

Rod <br>I made my own 6 AN x 12mm fittings. Like you I could not find any so I bought some 6AN x 3/8 pipe and turned the 3/8 ends down, cut them to the proper length and tapped them. Being a machinist comes in handy sometimes. ;D<br>

Scotty

All the boasting bragging still does not tell me why the factory lift pumps fail early in their life even on a stock truck.<br>Just today on a truck with EZ and Stage threes and a factory lift pump that has 30,000 plus on it, at WOT it would bounce from 12 psi to 5 and all over in between. The truck was stuttering as well.<br><br>Following other threads for over a year now on that other site called TDR where it once was a good informative site that did not have an aura of 'jump all over anyone with an opinion or suggestion that did not correspond with the folks in the know over there', [LOL] I found that many ideas approached/attempted failed to give a reliable pump with longevity. <br><br>So how long will a VP-44 last with pressures of 0 psi. Where can we measure the internal pressures and volume inside the VP-44 to see just whats going on? Don't give me a link or a thread or a statement, give me the way to test it and I will do it for myself.<br><br> <br><br>As mentioned...a solution rather then findings would be great for all.

Scotty

Good info Gary...what about altering the return gph?<br><br>I wish I knew more about the seals of the VP-44 but maybe if the return was restricted just a small amount it could either gives us a great result or maybe a problem with heat and lube and seals. Just thinking out loud here...why have a fixed rate of 30 as opposed to maybe 25 or 27 or?<br>I know one thing, trying to take some of the return fuel back to the pump is not good...too HOT!<br>Of course this approach is kinda like the supply issue...bottom line is trying to work around the limits of the VP-44. We must address THOSE issues and I bet theres a simple way to do it that will enable folks to press on in the HP race and have some reliability.<br><br>That old site your on was perty darn cool at one time. <br><br>Just a bit of humor there. heheh