24V vs. 12V Pop-Off's

Same price if it wont hurt ya I would run .120"s also.
Why not?
Brandon
 
The big lines is to relieve pressure of of the pump. I think the main thing is that you should have the entire fuel system from one company so they can set all sizes and pressures accordingly.
 
Smokem said:
Depends on the injector and RPM.
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Weston I cant see how power will be lost could u explain for the less fortunate? I looked at it this way with my 13mm at 5000RPM it would keep the wear on the pump down? Am I lost?
Brandon
 
XTrEmE9156 said:
Raising relief pressure retards timing slightly but I raised the pressure in my 94 to 4200 and advanced the timing 2 degrees and picked up 60 rwhp and 80 rwtq with the same tips
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Hum......I run 4200 and 20 degrees and have for years, runs good and clean for a poor boys 12V.

Jim
 
97' CTD said:
U brought it up, explain why is it a bad thing I never said etheir way I just asked?
Brandon
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with volume pressure is lost, therefore you'll need more timing and a higher pressure. which is working the pump as hard or harder. can you push water out of a garden hose faster by letting it flow or putting a nozzle on it?
 
2000wvdodge said:
with volume pressure is lost, therefore you'll need more timing and a higher pressure. which is working the pump as hard or harder. can you push water out of a garden hose faster by letting it flow or putting a nozzle on it?
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it still has to reach the same pressure to pop-off. so which flows more at X pressure, a 1/2" garden hose or a 3/4" garden hose?

i am gonna run the .120's because i got them for a good deal, if someone can show me the data that they are going to hurt me then i'll trade them to someone who "needs" them
 
2000wvdodge said:
with volume pressure is lost, therefore you'll need more timing and a higher pressure. which is working the pump as hard or harder. can you push water out of a garden hose faster by letting it flow or putting a nozzle on it?
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I do not see the timing factor being that much? 1 degree? Needing higher pressure I do not see etheir the pop off is the same wether u use a 10"ID hose or 4"ID hose it does not change the pop of the injector nor the pressure in the line needed to pop it? Correct? How does adding timing to the truck hurt the pump? it functions the same wether called upon to inject at 40* advanced or 20* retarted that has no effect on the wear on the pump.

As to your garden hose idea all u are referring to is a injector which has nothing to do with the size of the line. Like I said wether it be a 2" or 4" hose the only difference I see is the amount of liquid that the hose will displace not the pressure.

Im with TJ I have seen this line size been hashed over and over yet no one has brought any real world evidence to the table stating 1 size is far superior to the other untill then I really think it depends on how 1 looks at the scenario......

Any thoughts?

PS I think fulmer IIRC dyno'ed stock vs. .093"s im not sure if he did .120"s or not but im pretty positive he saw no gain nor loss on the dyno this seems to be the only hard evidence on this subject........
Brandon
 
had I been buying my lines new and paying full price I probably would have just gotten the .093's, but the .120's were used a couple times and I got them $200 cheaper than new ones.
 
2000wvdodge said:
with volume pressure is lost, therefore you'll need more timing and a higher pressure. which is working the pump as hard or harder. can you push water out of a garden hose faster by letting it flow or putting a nozzle on it?
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Maybe I am not understanding what your saying, but it seems you have it backwards. I have had people tell me larger lines will drop timing. Sadly alot of info you get from people in the diesel world is their misunderstanding of what happens. They don't put any thought in it, or just don't understand.
What has been explained to me why you lose timing is they are saying you have to fill more volume, and move more mass. Well I have thought about it, and I don't buy it. Lets say you need 100CC of fuel, well with a .084 line you will have to push the column of fuel lets say 1". A .120 line you will have to push the column of fuel, lets say .75" So the fuel can travel slower, which will result in less pressure loss(do to friction, frictional losses are velocity^2). I haven't seen if the OD is the same, on the .120 and the .093, if it is you can loose some wall strength, and that can allow some distortion which could make the sytem elastic which could cause a delay in timing. So now that I typed that up, lets have some discussion about the flaws of my thinking.
 
ok, i think i was getting ahead of myself last night, but .120 lines still arent relieving the pump though, right? you still have to push the same amount of fuel and you are taking static timing out of it by putting a bigger straw for the fuel to run through right?
 
In my feeble mind, once the truck is running, the .120 lines shouldn't affect timing, but pop pressure will/does;) You still push the same amount of fuel with each stroke, regardless of what size lines are on the truck, but it will take longer to fill the .120's...so it my take an extra rev or 2 to fire up, but then the lines should be full have no effect...I don't know for sure, just thinking out loud.


Higher pop pressures do affect timing, how much, I don't know...yet. I have the timing light handy, and a set of DDP4's at normal pressures, and a set at 4200...I can swap them in and find out the difference in timing sometime!

Chris
 
2000wvdodge said:
ok, i think i was getting ahead of myself last night, but .120 lines still arent relieving the pump though, right? you still have to push the same amount of fuel and you are taking static timing out of it by putting a bigger straw for the fuel to run through right?
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Your pump is pushing XXX CC, whether it is in a .120 line or a .078 line. Think volumes, and if you are pushing fuel in a .078 line and in a .120 for the .078 line to keep up you will have to have the fuel travel a great distance, for that to happen in the same time frame will require greater velocity. With greater velocity you have greater pressure drop.

Chris summed it up, as the only time I can really see it rearing its head is when your firing it up. The column is full, if you put 2 cc in at one end, 2cc better come out on the other end.
 
Brandon, I ran several times with the .093 lines then with the stock lines but never back to back, having said that every time I ran the .093's I lost power.....quite a bit, the .093 lines drove ok till I got in high altitude then it would Gov spring bounce and you could forget about using the cruise control. I'd like to run a set of .084's but can't justify spending the money right now.

Jim
 
Dont run a .120 line. .093 is PLENTY and will work mucho better. I use .082 and it is more than enough. I have never seized a 13mm P pump. I have had this same pump on my truck for 5 years.

Flow is not about line size alone. In terms of converting a liquid to a vapor, pressure plays a huge part in success of that.
 
A VP injector that has not been converted will only run worse behind a P pump with large lines. It is not just resetting pop pressure. For the best results on an unconverted VP injector you need to run a small ID line. .082-.084 MAX. And it will still run with less than optimum results.

The pulse from the pump travels at roughly the speed of sound through the line when the system is properly matched. The length of that pulse is what changes with diameter. No matter what you do, the pulse will get shorter AND the pressure curve of that pulse will shorten with increasing the diameter of the "road" or "tunnel" that pulse travels down. Pretty simple to understand why the line diameter is sized in accordance with of the fuel slug being pumped and the pressure curve needed.

Think of it like this: Imagine a line diameter with an ID of 1/2 inch between the pump and injector. How much pressure could that pump really build up with a diameter that large? It would not even be enough to open the injector, much less inject ANY fuel. The same thing applies in any line diameter change. Increasing diameter lowers the overall pressure, speed and time the fuel has to overcome the injectors spring.

A VP injector is designed with delivery curve much lower and a spring pressure much higher. Forget the fk'n opening pressure. Thats a trojan horse that 99% of vendors and purchases get hung up on. The pressure curve the VP injector spring operates at is mucho higher than a P pump injector spring. It requires a higher pressure to keep it open throughout the delivery pulse of fuel coming from the pump. Resetting the pressure to a lower point only lowers the pressure required to initially open the stupid thing, not the force/pressure required to KEEP it open. The P pump has a crap/low pressure curve compared to a VP and of course A CR. It needs a spring with a low pressure curve required to open it and a pressure from the line feeding it.

We have been coverting VP injectors since the early days. Not just resetting opening pressures. Thats a novice's game.
 
I bought a set of DDP comp 250's this summer, I sent them in to get the pop-off's set for a p-pump conversion. I put them in and noticed the truck started a little harder and noticed it seemed like small drops of fuel coming out of the stacks. I towed a small boat and it completely covered the boat. I sent them back in and had them reset to VP spec's and the truck was fine, starts great and no drops of fuel out of the stacks. Not sure if there was something else wrong or not.
 
Soup Nazi said:
A VP injector that has not been converted will only run worse behind a P pump with large lines. It is not just resetting pop pressure. For the best results on an unconverted VP injector you need to run a small ID line. .082-.084 MAX. And it will still run with less than optimum results.

The pulse from the pump travels at roughly the speed of sound through the line when the system is properly matched. The length of that pulse is what changes with diameter. No matter what you do, the pulse will get shorter AND the pressure curve of that pulse will shorten with increasing the diameter of the "road" or "tunnel" that pulse travels down. Pretty simple to understand why the line diameter is sized in accordance with of the fuel slug being pumped and the pressure curve needed.

Think of it like this: Imagine a line diameter with an ID of 1/2 inch between the pump and injector. How much pressure could that pump really build up with a diameter that large? It would not even be enough to open the injector, much less inject ANY fuel. The same thing applies in any line diameter change. Increasing diameter lowers the overall pressure, speed and time the fuel has to overcome the injectors spring.

A VP injector is designed with delivery curve much lower and a spring pressure much higher. Forget the fk'n opening pressure. Thats a trojan horse that 99% of vendors and purchases get hung up on. The pressure curve the VP injector spring operates at is mucho higher than a P pump injector spring. It requires a higher pressure to keep it open throughout the delivery pulse of fuel coming from the pump. Resetting the pressure to a lower point only lowers the pressure required to initially open the stupid thing, not the force/pressure required to KEEP it open. The P pump has a crap/low pressure curve compared to a VP and of course A CR. It needs a spring with a low pressure curve required to open it and a pressure from the line feeding it.

We have been coverting VP injectors since the early days. Not just resetting opening pressures. Thats a novice's game.
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So are you saying that the injection lines are empty between injection events? Even if you have a void in the line, wouldn't the void be of the same volume, regardless of the line size? If the line is not empty, diesel is considered a non compressible. So if the line is full of fuel, your not having an increased volume to fill, your injector is still taking the same CC, so your still pumping the same CC into the line/injector. Am I looking at this all wrong?
 
I run .120 lines and dont notice anything out of wack, and thats with .093 tubes.....although they were already on the truck when i bought it.

but I do see the reasoning behind losing HP with the bigger lines and a regular P-pump, even though its not much. But in a pulling truck, with the fuel that are running through 13mm pumps, will it lose HP then? with big everything (DV's, Holders, lines and some times tubes) isnt it our goal to get as much fuel as possible to the injectors? I could see losing HP with a big pump, small lines and big injectors....the lines would be a choking point
 
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