Raptor 100 or 150?

[JAG1]

11 hours ago, LorenS said:

At WOT, I can't imagine you need the relief to be open. The fuel you're burning is still passing through the VP absorbing heat.

You cannot break MoparMans rules around here. No ones ever found out what happens when you do. MoparMan say 14 p.s.i. minimum pressure at WOT. So at idle you should be set at 19 to allow a drop of 5 when gettin' on it and that's if you have half inch line kit all the way.

[wil440]

4 hours ago, JAG1 said:

You cannot break MoparMans rules around here. No ones ever found out what happens when you do. MoparMan say 14 p.s.i. minimum pressure at WOT. So at idle you should be set at 19 to allow a drop of 5 when gettin' on it and that's if you have half inch line kit all the way.

Well I sortoff are   as right now I'm at 5psi at idle on the low gearing for the assassin, 2 micron Cat filter with my gauge on the VP side, correct me if I'm wrong but isn't the stock filter 10 micron ??

I'm seeing a huge amount of volume going back to tank but only 5psi at idle, now if I clamp off the TEE return I get some serious psi at idle, open return line the volume back is considerable, I've changed the overflow which has a bypass anyway before the 15psi regulation thats built in, if I gear the pump up I'm all good but I'm thinking too much psi is just increasing the fuel temps for no reason, I do have a 5 micron Fleetguard filter on it's way to test.

I'm happier with huge flow rather than huge psi and my fuel temps are very low, we'll see when the 5 micron filter is fitted

and to clarify 5psi at idle and 25psi at 2k and I have checked for flow with the return placed in the filler neck to see whats happening

[JAG1]

Yes I know Wil.... flow and pressure are two important measures, that when you begin to restrict the flow pressure will increase, if measured before the restriction like a banjo bolt.. That's why it's important to pay attention to the amount that it drops at WOT. Additionally, the gauge designs available are perhaps more cost effective being made for measuring psi rather than flow. Not sure on that, but the overflow valve opens at a certain point represented by psi., 14 being the minimum required to keep it open for cooling.

Further more your non electric lift pump being that it's mechanical, will increase the required pressure (and flow) when needed, if the regulator is adjusted properly. I believe the regulator for your L/P is on the return line.

 

Unlike the electrical pumps that typically drop or lose pressure at WOT, yours will keep up with demand as RPM goes up.

 

I don't think I'M able to contribute much here.... just thinking out loud hoping I hit on something is all.

Edited August 8, 2020 by JAG1

[wil440]

36 minutes ago, JAG1 said:

Yes I know Wil.... flow and pressure are two important measures, that when you begin to restrict the flow pressure will increase, if measured before the restriction like a banjo bolt.. That's why it's important to pay attention to the amount that it drops at WOT. Additionally, the gauge designs available are perhaps more cost effective being made for measuring psi rather than flow. Not sure on that, but the overflow valve opens at a certain point represented by psi., 14 being the minimum required to keep it open for cooling.

Further more your non electric lift pump being that it's mechanical, will increase the required pressure (and flow) when needed, if the regulator is adjusted properly. I believe the regulator for your L/P is on the return line.

 

Unlike the electrical pumps that typically drop or lose pressure at WOT, yours will keep up with demand as RPM goes up.

 

I don't think I'M able to contribute much here.... just thinking out loud hoping I hit on something is all.

Jag

If you take a look at the overflow valve there is a drilling in it that is always open, certainly on a 98.5, this with a mechanical pump at least sends a lot of fuel back to tank all the time, I'm pretty sure most of my excess fuel is returning to tank from the VP overflow whether it's through the small drilling at idle or close to idle or the actual 15psi relief, my pressure regulator is in a separate return line and that's what stops psi going above 25.

I was thinking depending on what the 5 micron filter does I may use the higher gearing for the pump which gets me around 12 to 15 psi at idle and drill the pilot relief in the overflow a tiny bit bigger doing this will mean nearly all excess fuel will be returned from the vp.

Just to recap IF the overflow is a genuine Bosch 467 445 003 it has a bleed orifice and does not need to see 14/15psi to flow fuel back to tank, if the lift pump is man enough there is plenty of flow BUT while looking for a overflow valve all in the USA I found some pictures show NO second small drilling, I just picked up a genuine Bosch valve  8 miles from home here in the UK

I will add DO NOT take this as true on another truck, I have spent time checking my truck and I am happy I'm getting good flow back

[JAG1]

Interesting  points Wil, however my day is running short so I have to read in depth when I get more time, Thank you for the report it's very interesting.

[dripley]

The few overflows that I have seen have the small bypass hole. So fuel should always get by. What quantity gets by I dont know.

[oldbeek]

On 8/6/2020 at 5:58 PM, JAG1 said:

That isn't enough pressure at WOT. You need to stay above 14 to have the return fuel cooling that you need, esp. during hard pulls when the injection pump gets the hottest. Mopar1973Man calls this a slow death to the VP44.

the pump at idle is 22psi. 6 psi drop and still 16 psi at the inlet banjo (WOT)  with a direct connected hydraulic gauge.

[LorenS]

4 hours ago, wil440 said:

I'm happier with huge flow rather than huge psi

If you have a relatively fixed orifice (the relief valve) then in order to get huge flow you need high pressure. Just like with DC electricity, if resistance is fixed then voltage (pressure) and amperage (flow) are proportional.

 

16 hours ago, wil440 said:

70% of the fuel should go back to tank at all times

Perhaps that is true.  I have about as much faith in "technical writers" as I do engineers that eagerly wear ties or skirts to work. And I am an engineer who grudgingly wore a tie for six years - I'm now back where I started, wearing Carhartts and a Cummins ball cap or hard hat.

 

However, we all know that 70% return is NOT just from lift pump pressure, there is a lot that is returned from downstream of the internal rotary vane pump. In fact, because the specification for the lift pump is 10 PSI and the relief valve is set to 14 PSI, it would APPEAR that the designers intended none of that return flow to be caused by the lift pump. I say appear because all we have is the technical writer's (likely wrong) interpretation.

 

I believe over 15 PSI at moderate throttle is a very good thing to keep fuel temps low. Whether or not this is required at WOT when large volumes of fuel are passing through the pump, I am not certain. But my Vegas money is on "no". Your electric lift pump is putting just as much - if not more - fuel through the VP at WOT as it is at idle. And so is a mechanical lift pump, at a given engine RPM.

[wil440]

10 minutes ago, LorenS said:

If you have a relatively fixed orifice (the relief valve) then in order to get huge flow you need high pressure. Just like with DC electricity, if resistance is fixed then voltage (pressure) and amperage (flow) are proportional.

 

Perhaps that is true.  I have about as much faith in "technical writers" as I do engineers that eagerly wear ties or skirts to work. And I am an engineer who grudgingly wore a tie for six years - I'm now back where I started, wearing Carhartts and a Cummins ball cap or hard hat.

 

However, we all know that 70% return is NOT just from lift pump pressure, there is a lot that is returned from downstream of the internal rotary vane pump. In fact, because the specification for the lift pump is 10 PSI and the relief valve is set to 14 PSI, it would APPEAR that the designers intended none of that return flow to be caused by the lift pump. I say appear because all we have is the technical writer's (likely wrong) interpretation.

 

I believe over 15 PSI at moderate throttle is a very good thing to keep fuel temps low. Whether or not this is required at WOT when large volumes of fuel are passing through the pump, I am not certain. But my Vegas money is on "no". Your electric lift pump is putting just as much - if not more - fuel through the VP at WOT as it is at idle. And so is a mechanical lift pump, at a given engine RPM.

to get huge flow you need over capacity not pressure,  and for the technical writers that was direct from Cummins not Dodge or Chrysler but Cummins but hey what do they know

The only return that is anything is the vp, the return from the back of the cylinder head really isn't much compared to the vp this is from a Bosch certified fuel shop who see vp's every single day here in the UK spoken to on thursday, bearing in mind Dodge was a tad late to the vp party compared to Europe.

The overflow has a bleed orifice which is open all the time and is nothing to do with the relief valve

My fuel temps are max 120f at 1/2 tank or thereabouts, 110f max full tank with a mechanical pump not electric so i'm not worried at all

[LorenS]

1 hour ago, wil440 said:

to get huge flow you need over capacity not pressure

And with that, I'm through trying to intelligently discuss this topic. Have a pleasant evening.

[wil440]

6 hours ago, LorenS said:

And with that, I'm through trying to intelligently discuss this topic. Have a pleasant evening.

The vp is constantly supplying fuel to the injectors.. lets say it needs 1 gallon per hour at a given rpm, if your lift pump is capable of 1 gallon per hour nothing will be returned from the vp, this is what keeps it cool and ok. in this scenario you have zero over capacity,  and to check how much fuel is going back disconnect the push on  fitting at the tee at the left rear cylinder head and a 3/8th rubber hose pushes over the steel stub just nice. Put it into the filler neck and start the truck. Works better with a mechanical pump as idle is the lowest flow

[JAG1]

15 hours ago, wil440 said:

Jag

If you take a look at the overflow valve there is a drilling in it that is always open, certainly on a 98.5, this with a mechanical pump at least sends a lot of fuel back to tank all the time, I'm pretty sure most of my excess fuel is returning to tank from the VP overflow whether it's through the small drilling at idle or close to idle or the actual 15psi relief, my pressure regulator is in a separate return line and that's what stops psi going above 25.

I was thinking depending on what the 5 micron filter does I may use the higher gearing for the pump which gets me around 12 to 15 psi at idle and drill the pilot relief in the overflow a tiny bit bigger doing this will mean nearly all excess fuel will be returned from the vp.

Just to recap IF the overflow is a genuine Bosch 467 445 003 it has a bleed orifice and does not need to see 14/15psi to flow fuel back to tank, if the lift pump is man enough there is plenty of flow BUT while looking for a overflow valve all in the USA I found some pictures show NO second small drilling, I just picked up a genuine Bosch valve  8 miles from home here in the UK

I will add DO NOT take this as true on another truck, I have spent time checking my truck and I am happy I'm getting good flow back

So there is a possibility that the 24 valve VP44 trucks, depending on the year, may not be alike, that some have an open orifice with an additional overflow valve that opens at the 14 psi? Am I understanding this correct? Don't know about the one on either of my 2 VP44 trucks, but one truck has the fuel return in the fill neck and at idle you can look in there and see a good steady flow returning back to the tank.

[wil440]

3 minutes ago, JAG1 said:

So there is a possibility that the 24 valve VP44 trucks, depending on the year, may not be alike, that some have an open orifice with an additional overflow valve that opens at the 14 psi? Am I understanding this correct? Don't know about the one on either of my 2 VP44 trucks, but one truck has the fuel return in the fill neck and at idle you can look in there and see a good steady flow returning back to the tank.

Yes thats correct Jag my truck has a small bleed..... don't know about other years. a fuel boss uses the return in the filler neck I'm looking at fitting that very same thing

[JAG1]

I have an extra VP core I'll look at that today sometime.

 

BTW, I think it's wise to save your VP44 cores if they are in good shape. As I understand many have been beat up after getting R&R and rebuilt a few times. From my first VP purchase in 07, the core was worth $200. Now they are at least double that. I think Mopar Man hangs onto all of them to create a shortage. 

[AH64ID]

Unless your power demands it go with the 100. 
 

The 150 can easily outflow your filters, which isn’t worth it IMHO. 

[NIsaacs]

I just changed out my Raptor 100 for a 150, no change in fuel temps. After a 5 hour 3 trip haul, easy down hill loaded, I am at 153*, 2/3 tank of fuel, 95* ambient.  I have it set at 17 psi, it helped a lot on cruise psi but WOT dropped to 8 psi

[jltait]

I ran across a new in the box Raptor 100 kit for $220, in a local ad. I am going to go ahead and pick it up. I have to do less explaining to the bride when I'm thrifty. We have a camping trip at the end of next week, and my fuel pressure drops significantly when I push the accelerator pedal hard. I think the 100 will do for now, I am pretty much stock.