Injector Tips/ Nozzles and Wear Factors

[JAG1]

Anyone know what type of steel is used on diesel fuel injector tips? Has to be pretty good steel to help stop premature wear. To also fight against dirty fuel wearing out the tip. Another question too is how do they adjust them to get a balanced flow match?

[Mopar1973Man]

2 hours ago, JAG1 said:

Anyone know what type of steel is used on diesel fuel injector tips?

It some pretty hard steel I know that. 

 

2 hours ago, JAG1 said:

Another question too is how do they adjust them to get a balanced flow match?

 

Match the flow ot the nozzle flow rate and then the pop pressure as well. I'm sure there is much more to it but most of its how the pop pressure and lift of the pintle in general speak. 

 

As for wear I typically would say double filter your fuel. Like myself I've got a 3um filter on my AirDog 150 and then a 7um filter in the stock filter can. Lubricity of the fuel plays the other role which Bosch states <406 HFRR and the common US diesel fuel is ~520 HFRR so increased lubcitiy will improve injector performance. 

[Doubletrouble]

 Does the addition of 2cycle oil add enough lubricity to make up the difference stated above?

 Also, you run a double filter. Mine is a more factory setup with a fass ddrp. Technicality it should be moved to the frame to act more as a pusher pump rather than a suction pump. Will it function correctly if I move it to the frame and place some sort of filter between the tank and the lift pump and the still use the factory filter on the engine? I guess my concern would be a filter adding to much of a restriction between the tank and pump. Seems it would kind of cancel out the benefits of moving it to the frame. Is this thinking on track or way off?

[Mopar1973Man]

Yes. This was tested at 200:1 ratio and it still pulled 462 HFRR IIRC. Estimated 128:1 ratio is in the high 200s to low 300s HFRR for sure.

[Tractorman]

9 minutes ago, Doubletrouble said:

I guess my concern would be a filter adding to much of a restriction between the tank and pump. Seems it would kind of cancel out the benefits of moving it to the frame. Is this thinking on track or way off?

 

Personally, I would not be concerned about the pressure drop generated by adding another filter in the circuit.  If you add the filter, the pressure drop will be the same across the added filter regardless of the lift pump's location.  I think a frame mounted lift pump will be more efficient and you would always have a positive pressure supply to the added filters - that also equates to less chance of drawing in air.  By the way, five years ago I removed my in-tank lift pump and installed a used FASS lift pump on the frame rail -  not added filters, just relocated the lift pump.

 

I believe a lot of folks are putting way too much emphasis on a specific fuel pressure gauge reading.  Having a pressure gauge at the inlet of the VP44 injection pump will tell you that there is specific pressure at a specific time, but it does not say anything about a specific flow.  However, it does tell you that the lift pump must be be trying to flow more than the VP44 is accepting at any time, otherwise the pressure would not be there., I say this because there are some very important unknown pieces of information regarding the vane pump inside the VP44 injection pump.   For example:

 

What is the internal vane pump's displacement (in gallons / hour) at a specific engine rpm?

What pressure is the internal vane pump's relief valve set?

 

Just knowing this information would go a long way to gaining a better understanding of how this fuel system works.

 

- John

 

 

[Doubletrouble]

The only requirements I'm aware of are that the relief valve on the vp44 is set at or about 14 psi to vent any pressure above that setting which then returns to the tank to carry heat generated by the vp44 away from the pump itself and also warm the fuel in the tank I would imagine.

 Anything dipping below 14psi and your barely supplying enough fuel to satisfy the vp44 let alone cool it down. 

 That is my understanding of it at least. If I am wrong someone correct me.

 Now based on that if one were to upgrade to a big line set up, say from oem to 1/2" but running at the same pressure the volume would increase significantly but hopefully not so much so that your actually over supplying the vp44 which would put it at a constant relief valve open situation and in turn basically pressurizing the return lines I would think.

 Again, if I'm wrong, please correct me.

[Mopar1973Man]

If I recall the internal pressure is roughly 60 PSI heading to the distributor to be pumped up again. Also remembeer the VP44 is half the RPM at idle is only 400 RPM's on the pump.

[LorenS]

@Doubletrouble I have a frame mounted DDRP, this is what I installed for a screen to protect the lift pump.

 

 

[Doubletrouble]

 Thanks @LorenS, that's a nice clean set up. What size lines did you use?

[wil440]

2 hours ago, Doubletrouble said:

The only requirements I'm aware of are that the relief valve on the vp44 is set at or about 14 psi to vent any pressure above that setting which then returns to the tank to carry heat generated by the vp44 away from the pump itself and also warm the fuel in the tank I would imagine.

 Anything dipping below 14psi and your barely supplying enough fuel to satisfy the vp44 let alone cool it down. 

 That is my understanding of it at least. If I am wrong someone correct me.

 Now based on that if one were to upgrade to a big line set up, say from oem to 1/2" but running at the same pressure the volume would increase significantly but hopefully not so much so that your actually over supplying the vp44 which would put it at a constant relief valve open situation and in turn basically pressurizing the return lines I would think.

 Again, if I'm wrong, please correct me.

I've tested the return line on my truck with a length of tubing on the Tee at the back of the head and it then sitting in the filler neck and I can say for certain that on my truck I get a lot of fuel returning to tank at a idle FP of around 10 psi. I have a mechanical pump and FP builds very fast after idle also

[Tractorman]

2 hours ago, Doubletrouble said:

Again, if I'm wrong, please correct me.

 

This is not a case in which you are right or wrong.   Over the years there have been many posts on this site (and other diesel sites as well) that have portrayed a strong belief in that if the lift pump does not maintain over 14 psi at all times, then fuel return flow from the VP44 is greatly diminished, thus causing damage to the VP44.  I do not believe that this is the case at all, and here is why:

 

The lift pump flow feeds directly into the suction side of the internal vane pump (inside the VP44 injection pump).  Since this vane pump is a positive displacement pump, engine rpm determines the input flow and the output flow of this vane pump.  The lift pump can and does provide a positive charge  to the vane pump inlet, but the lift pump cannot push more flow through a positive displacement pump than the positive displacement pump is flowing, hence the pressure rise on the fuel gauge.  The fuel flowing out of the internal vane pump is subject to a much higher pressure relief valve setting (I've read somewhere between 120 -200 psi, @Mopar1973Manmentions 60 psi).  It is a good portion of this flow from the internal vane pump that makes its way over the 14 psi overflow valve and returns to the fuel tank.

 

@wil440, thank you for your timely post.  Your test supports what I am trying to portray.

 

- John

[JAG1]

12 hours ago, Doubletrouble said:

 Does the addition of 2cycle oil add enough lubricity to make up the difference stated above?

 Also, you run a double filter. Mine is a more factory setup with a fass ddrp. Technicality it should be moved to the frame to act more as a pusher pump rather than a suction pump. Will it function correctly if I move it to the frame and place some sort of filter between the tank and the lift pump and the still use the factory filter on the engine? I guess my concern would be a filter adding to much of a restriction between the tank and pump. Seems it would kind of cancel out the benefits of moving it to the frame. Is this thinking on track or way off?

What I have read in a diesel marine book where lives depend on those engines to stay running at sea, says that you want your big filter before the lift pump. Called a 'pre filter', it needs to remove any water before it can get emulsified by the lift pump, because once the water becomes mixed, the secondary filter has a harder time removing the water. Also the lift pump needs protection from any dirt or sediment in the fuel.

 

BTW, I'm not arguing with Tractorman nor Moparman otherwise I'd get the snot beat out of me if I try to act like I know anything....

Edited November 16, 2020 by JAG1

[Mopar1973Man]

Hence why I still keep the stock filter being most all replacement filters for the stock can are design to be water blocking (Fleetguard). Now the AirDog fuel filter is not water blocking (but the Fleetguard is)

[LorenS]

9 hours ago, Doubletrouble said:

What size lines did you use?

I used 3/8", but only because I bought all the fittings, etc., a few years ago before I knew everyone was going to 1/2". That filter head is tapped for 1/2".

 

3/8" has a cross sectional area 44% larger than 5/16" so I have no plans to change it.

 

The whole setup has a low pressure drop, based on catalog data and my experience watching the VP fuel pressure gauge.

[Mopar1973Man]

 

Another though. Being my AirDog 150 is a 3 line pump. This means the air that is captured is returned to the tank. But... Since there is only a small part of the fuel past along to the VP44 this means majority of this fuel is recirculated and re-filter several passes. Technically it called fuel polishing. You constant filter and refiltering the same fuel will keep fuel to the engine cleaner. Then the stock can has a filter too it will stop any particulars that slip through. Yes it does happen even with a 3um ahead of 7um filter. 

 

Full 1/2" line here from the tank to the VP44. Now my pressure is very stable with +150 HP injectors and wired tapped Quadzilla on KILL will not drop fuel pressure below my 13 PSI warning light. Very rare to see it even come on. I might drop -2 to -3 PSI from idle to 100 MPH WOT. Stock line is 6mm ID which is smaller than 1/4" fuel lines. 3/8" lines are restrictive still can flow enough so pressure drop is more pronounced on 3/8" line vs 1/2" line. So if you planning for more power you'll have to upgrade again to 1/2" lines. 

[Doubletrouble]

 I will have to upgrade in steps as money permits. That being said, with a fass ddrp and 1/2" lines through the oem filter will this be a stable system? I don't know where my fuel pressure sits right now other than some testing in the drive way with a gauge. I will add gauges next year along with the fuel system upgrade.

 It's been a crazy year with this covid stuff so my income this year has been all over the place. Just going to work with what I have through winter and hope next year is better.

[Mopar1973Man]

I get it. Like Eileen's Son with his Ford only can do so much with limit incomes. Need to for sure add a fuel pressure gauge when you can so you can monitor your pressure to the Vp44.

[LorenS]

7 hours ago, Mopar1973Man said:

So if you planning for more power you'll have to upgrade again to 1/2" lines.

If I ever hit 325 HP I'll be shocked. Zero plans to join The 500 Club!

[That Guy]

I tested some nozzles off a tank for rockwell hardness and came up with 55-60. Hard for a steel, but not as hard as tool steel. The needle would have to be the same otherwise differential wear would take place. 

 

A pre filter makes a huge difference particularly with decades long reliability. We were running stuff that was the original pump from the late 60's.

That is a 15" wrench for size, the two lines came in from 50 gallon tanks of the respective sides of the tank, goes into the box where stuff settles out, through 4 overlapping screens into the pump, then to dual filters before the injection pump. The filters going to the injection pump never had any build up on them. Had a few tanks that would get gunk built up around the pre filter until we pulled the tanks and had them cleaned.

 

50 years of gunk.

 

Process of cleaning.

 

Back together and mostly ready to go back into service.

[Mopar1973Man]

2 hours ago, LorenS said:

If I ever hit 325 HP I'll be shocked. Zero plans to join The 500 Club!

 

Just install a Quadzilla your in the high 300's to low 400's HP just with a Quadzilla being there is about 120 to 180 HP gain. Just throw in a set of injectors you could hit 500 without much effort. I know I'm close with just the Quadzilla and +150 HP injectors to 500 HP mark.

 

Just think stock is 235 HP SO/245 HP HO another 90 HP on stock truck would get you to that. Like I said a Quadzilla on a stock engine will surpass that in a single mod.