How do delivery valves do their magic?

[86burbguy]

I couldn't help my self, all my digging in to what a delivery valve does and I had to try some. I went and ordered a set of DPP's "Magic" 042's.

All I can say is wow! These new DV's hit like installing bigger injectors did. I have nothing but a seat of the pants dyno to go by, feels like a 100hp with no tuning and pulls hard to 4000rpms! Yes it is smokey and hot, but wow, feels like the front end lifts up a few inches and speedo moves like a tach.

Installing the DV's is a lot easier than injectors and feels like about the same bang.

After some tuning i broke down and put a fuel plate back in the pump and had to slide the AFC back a little to get to a place where the pre boost screw actually does some thing.

Now I can see that I am going to need more air and studs before I am going to be able to use all the fuel I can push now.

[liteweight]

Hey 86burbguy
Been noticing nobody wants to come to the party huh??? Too bad, because there are guys on this forum that have the knowledge but just choose not to share it with the public. One of the guys is banned from this site. Too bad, because he brought alot of good knowledge here & was willing to share it with us.
Glad you like your .042's cause I recently just purchased a set for myself also. I'll be installing them at the same time as the rest of my build, with a set of SDX 7X010's, a modified HX35 over a S472, ported head, manifolds, water meth, etc, etc. But, instead of only diesel flowing through them, they will mostly have WVO.
Keep us informed on your new tune up.

liteweight

[86burbguy]

Here's a quote from another thread that explains it a little (edited slightly for focus):

Originally Posted by White Knight

Originally Posted by my Bosch book (ISBN-3-934584-68-3)
The delivery valve is fitted between the plunger-and-barrel assembly and the high pressure delivery line. Its purpose is to isolate the high pressure delivery line from the plunger-and-barrel assembly. It also reduces the pressure in the high-pressure delivery line and nozzle chamber following fuel injection to set static pressure. Pressure reduction causes rapid and precise closure of the nozzle and prevents undesirable fuel dribble into the combustion chamber.
Basically the valve has two purposes: 1) to isolate the plunger and barrel from the fuel line and 2)to put a clean end to the fuel delivery.
The valves are opened based on the pressure in the plunger cavity and closed by the force of the spring above the delivery valve.



The shoulder is what retracts the fuel from the injection line. Changing the shoulder length has a direct effect on how much fuel is removed from the line and how far the valve needs to travel before fuel can flow around it.
In the case of laser or full cuts there is no shoulder to retract fuel on the delivery valve is often unable to do its job effectively. Because of this laser cuts often have poor end of injection characteristics and allow fuel to dribble into the cylinder long after the injection event should have taken place. This process leads to the smoke and heat associated with laser cuts.

Changing the other characteristics of the valves changes how well the fuel will flow around the valve and help to provide a smooth flow of fuel to the injector.
So basically:
Quote:
Originally Posted by Signature600
In complete laymans terms, the injection is not crisp...

Chris

[drooling piston]

thanks 86burbguy! that shed some light on what they actually do.

"Changing the shoulder length has a direct effect on how much fuel is removed from the line and how far the valve needs to travel before fuel can flow around it."

After reading the above statement I can see they are more than just a check valve and how changing them can change the performance of the engine.
If they are cut to shorten the amount of travel before the fuel can flow around them they are also advancing the timing of the injection event.

I'm glad to hear you are really liking your new 42s

[96dieselram]

so my question to this whole ordeal is why is everything so topsecret? everyone with a 12 vlve has them, and wants to make there truck run amazing and that is what i thought this forum was for? if its not then what is this forum for? cuz if you can get in trouble for asking a question that requires "TOP SECRET" information, then tell us what is so dang top secret about it? i dont see a prob with know good things about our trucks?

On the other hand. Thank you very very much for asking this question. im deff subscribed and want to know more. and thank you for the info 86burbguy. good info.

[glfredrick]

I suspect that this issue is akin to bolting a Holley 750 double pumper onto one's stock chevy 305 and expecting it to go faster because it has "race parts" on the engine. I hear it works even better if you paint some stuff yellow.

I expect that people just dump in bigger DVs or "full cut" DVs and see what happens, then they have to be excited because they've added the power parts, even if their truck sucks to drive after that.

Some, however, actually search about for the best application and "tune" their engines for best performance based on the desired usage. Many others just swap parts and hope, then make a cult out of "roallin' cole" (spelling intentional). Information would be helpful, but I expect that in the case of DVs, with all the other variables, one will just have to get used to the idea of trying a few combinations.

[86burbguy]

Understanding why some thing works and how it changes things is the door way to making intelligent decisions.

For example, with my new piece of DV understanding- I know why full cuts move more fuel and why they are smokey. No shoulder means sloppy closing of an injection event, fuel still showing up late in the game.

On a daily driver, I get it, not street friendly!
So for a street truck a DV with some shoulder is a better choice.

Beyond this point of understanding I am still in the dark, though not nearly as dark as before I searched through 50 pages on one forum and 63 on another reading every DV thread that came up.

I have also noticed that some of the genius on the forums tend not to spoon feed us info, but will throw out hints and require much personal digging, some times dropping hints over the course of 20+ pages of a thread before the light bulb will go on for us.

The reward for personal study is understanding, how do you think the genus's got their genius in the first place. Some times I think their silence is intentional as they are trying to help us become what they are!

[96dieselram]

It makes sense but to be honest. Not everyone can read a hint and get it then do research and read more more more stuff. I read but dont comprehend what im reading. So if someone gave me a hint to find out about these. I wouldnt see it or understand. I work on my truck by trial and error. (if i dont have the info) but if someone explains what i ask for. Theres no problem. All im saying is. Someone asks a question. These smart people are here to help and this forum is here to help i thought. But ohwell. Lol. Life moves on. And we all have good info about somethin. Good post. A little off track. Sorry bout that. Lets get back ontrack

[12valvedriver]

So, since less shoulder on the DV makes the fuel delivery become longer, would it make since that with a larger DV aka an 024 or full cut, allow you to bump the timing and gain hp at higher rpms while maintaining the better torque number of retarded timing? I am thinking this because you would be injecting fuel all the way from like say 25* through like 5* (numbers could be way off, just throwing them out there to clear up my explanation).

Obviously you will provide more of a smoke show as well because you wouldn't be able to burn off the fuel in the end of the fuel injection while at higher rpms. Does anybody else know where I am going with that? Or am I way off track?

[96dieselram]

Makes sense to me. I understand what your saying. But like he said. If we are off. Let us know. Lol.

[86burbguy]

Interesting observation, with 042's my cruising EGT has gone down almost 100* back to 600* where it was before I went to taller tires. Low and part throttle response is noticeably better.

I would like to know what effect DV's have on timing.

[country_hick]

Originally Posted by 86burbguy

Interesting observation, with 042's my cruising EGT has gone down almost 100* .

When you fill up a time or 3 come back and tell us how your mpg changed up, down, or not at all. (lower egt's is a good thing)