"FULL LOAD" FLOW TESTING proves - "Prime-Loc" WILL NOT HARM YOUR INJECTION PUMP!!!

[BillW]

Testing Continues to Prove - "Prime-Loc" WILL NOT cause injection pump failures. We (Ashland Technologies, Inc. ) have received a test report from our independent testing company. This most recent test monitors fuel flow to the injection pump under "full load" conditions. They found very little difference in amount of fuel returned under varied conditions. So we continue to determine that "Prime-Loc" is NOT reducing the amount of fuel that is delivered to the injection pump. This should conclude in your mind that "Prime-Loc" does not, and will not cause injection pump problems. However, we will continue to conduct additional testing and status each of you on our findings.

Following are some of the common questions that have been raised about the "Prime-Loc" system and injection pump failure.

1. Will "Prime-Loc" reduce flow to my injection pump and lead to a failure? - NO!

Below testing conducted under operating conditions shows without a doubt that the "Prime-Loc" system does not reduce the flow of fuel through the injection pump. In both cases the system is returning nearly ½ gallon of fuel per minute. This means that the necessary fuel is flowing through the pump to lubricate and cool it. Which in turn means the "Prime-Loc" system can not harm your injection pump.

2. Why is it more important to measure fuel flow volume instead of pressure?

Fuel flow testing is much more accurate than pressure testing. Pressure testing has many variables, and can be very, very misleading. You can have high pressure with low flow, and you can also have a situation with low pressure and high flow. The bottom line is that flow testing is much more important and accurate in this instance.

Rattlin has done an excellent job in his last post explaining this, and introducing information on the Venturi Effect. This effect has been explained by Craig Earls, Aerospace Engineer from Massachusetts Institute of Technology (MIT) as this - "The Venturi Effect happens because fluid pressure drops as the fluid speed increases. If you force a fluid (for example: air or water) down a tube with a narrowing in it, the fluid will move faster through the narrow part. When it starts to move faster, the pressure drops. " Because the fluid is moving through the system faster at certain points, the pressure will drop, but the amount of fluid through the system will remain the same. The Venturi Effect is used in designing and operating the carburetor of internal combustion engines. It purposely creates a low air pressure situation so that fuel is pulled into the air stream and mixed properly for combustion.

Pressure also drops because the injection pump is actually pulling fuel through the system, which reduces and/or relieves fuel pressure in the system where you are measuring it. The VP44 pump is equipped with an internal suction pump. This pump works to actually move fuel through the system faster, thus further reducing pressure. Yet again, volume is unaffected.

Also, the electric lift pump (on the new 24V) provides a steady supply of fuel, regardless of the demand of fuel the engine places on it. Mechanical pumps increase pumping capacity when the engine requires more fuel, the electric pump does not. This too will effect the way pressure is measured, and may lead to incorrect conclusions.

3. Why is there a reduction in pressure when the "Prime-Loc" is installed? Should I be concerned with this? - NO!

When engine load is increased, it needs more fuel to operate. The electric pump is pumping at the same rate that it did at idle. Which means that it places responsibility on the injection pump to pull fuel through the system. In a NON-"Prime-Loc" situation, this pulling increases the velocity or speed of the fuel flow from the lift pump to the injection pump, which in turn reduces or more accurately relieves fuel pressure. Does this pressure drop mean that you are moving less fuel? NO, more fuel is moving through the system although pressure was reduced!!!

The narrowing from the "Prime-Loc" hoses and check valve cause the fuel to flow even faster through these components. As we have seen above, in the NON-"Prime-Loc" situation, higher fuel flow rate results in a reduction in pressure. (Venturi Effect) By having a "Prime-Loc" installed on your Dodge, the same amount of fuel is being moved through the fuel system (lift pump to injection pump); however, the average speed at which the fuel flows is higher, and the pressure is then lower. This is why there is such a drop in pressure when the "Prime-Loc" is installed, yet flow volume is unaffected.

4. Will this effect my hoursepower? - NO!

Fuel volume and the rate that it is delivered to the injection pump determines horsepower, not pressure. As these tests prove, fuel flow is not decreased with "Prime-Loc" and thus horsepower is not effected either.

TEST RESULTS

Test was conducted on 12/08/00 on a chassis dynamometer to simulate actual "full load" conditions.
Test Vehicle - 1999 Dodge Ram Diesel ("Prim-Loc" Equipped)
Room Temp - 70 degree's
This test was run multiple times with the exact same results.

PHASE 1 - STOCK FILTER SYSTEM TEST
Ran truck in 4th gear at 59 mph, 2450-2500 rpm's (below governor cut-off) and were recording 168-173 hp. With the return line running into a bucket, and everything settled out, the return line was directed to six (6) separate containers and timed for exactly one minute. Each was weighed to be exactly 3 lbs - 15 oz. The fuel temp was 103oF.

PHASE 2 - "PRIME-LOC" FILTER SYSTEM TEST
After re-installing the PL9899ISB kit complete with 28"-#5 hose and check valve, the unit was re-ran under the same conditions. The weight of each of the six (6) containers was 3 lbs. - 14 oz. A very slight, and consistent reduction. The horsepower was not reduced, still 168 - 173 hp. Fuel temp was 105oF.

We feel that this testing clearly determines that "Prime-Loc" will NOT cause injection pump problems. There is ample fuel being delivered to the injection pump to lubricate and cool it. The reduction in pressure is a result of an increase in the velocity of the fuel flow because of a slight narrowing in the passageway. The suction pump in the injection pump also contributes to this loss in pressure. It actually relieves the pressure by pulling fuel through the system.

We will continue to provide updated data and information as it becomes available.


------------------
Bill Wydra
Ash-Tec, Inc.

 

[Dane]

Bill, glad you posted. I do understand the venturi effect and agree that pressure reading from any tap that has fluid flowing past is not a good way to measure flow due to the venturi effect. I'm glad flow tests show the PrimeLoc is not the great flow restrictor we worried about. HOWEVER, you should increase the internal diameter of the ports on the PrimeLoc. Smaller ports mean less flow for the same pressure. The math doesn't lie. Even if it's currently ok, what about marginal lift pumps or bombed trucks? Bigger passages would make lots of folks sleep better at night. As always, just my opinion...

------------------
2001 HO 6 speed Regular Cab SLT 4x4 3. 54 anti spin 2500. Used for the daily grind and sneaking away to some secret Baja beaches toting a cabover

 

[Berserker]

I think that BillW has some good points. #ad


I can understand the desire for larger lines - I might add them myself.

Question: Is there some reason that we can't use Vaughn's stainless steel lines and completely bypass the original factory mounted fuel filter location? Can't we go from the lift pump directly to the Prime-Loc in-port then from the Prime-Loc out-port to the injection pump? I know that we would need different fittings but can this be made to work?

Bottomline, is there still some disagreement out there?

Berserker
(just trying to get to the bottom of this)


------------------
99 2500 QC LB 4x4 Auto, Laramie SLT, driftwood. Cummins 24v w/ 275 HP injectors, Edge Products EZ & Banks Stinger Plus kit minus Ottomind, TST 10 level PM3, Stainless Steel fuel lines, EGT and Boost gauges on A-Pillar mount, Prime-Location fuel filter kit (removed pending outcome of testing), MagHytec Diff and Trans covers, ConFerr front heavy duty axle truss w/skid plate, EZ Change oil drain plug, BFG 35x12. 50x16. 50 MT's, Tuff Country 5” stage II lift-kit, Rhino liner, Smittybilt nerf bars, Warn chrome Transformer brush guard w/Warn12000 winch, Tow Hooks, Xenon fender flares & Abbott Electronic Ratio Adapter. DTT's Valve Body & Torque Converter.

MyTruck

 

[Rambling]

Again, my apologies for another long post. My intent here is to help make sense of the situation.

Disclaimer: Statements/opinons expressed on this forum are solely my own. Statements/opinons expressed are based on my professional training, personal technical experiences and just plain living xperiences. I have no affiliation with Ashland Technologies. I have not and am not being compensated by Ashland Technologies nor any employee directly or indirectly.

Bill W. contacted me concerning my comments in my post on the Venturi effect. I believe Bill and the Ashland staff will be candid with any information they obtain concerning their test results, good or bad, on the Prime-Loc system. (Wrote this offline - it's good to see some new and reasuring data)

Like many others, my first reaction on reading Bill W's post concerning the loss of pressure but still getting the same volume at the return line from the injector pump was one of disbelief. I felt, like many others, that something was amiss. The problem was/is that the flow (volume measured in gpm's or more accurately by weight) under the two different fuel system configurations being almost identical did not fit with my first thoughts on the effect of the apparent pressure loss others were reporting. So, was Ashland's flow data wrong - not likely since it would be so easy to disprove their data- , was the member's pressure data wrong - not likely either as the test data came from more than one straight up member -, or was my interpretation of the data wrong. Since the
last reason was more likely, I spent quite a while trying to resolve the conflicts and post something I hope would be constructive. Guys, when I have known valid data and it doesn't fit with what I know, then the problem is more likely with what I don't know rather than the data. Like I said before, if a little knowledge is dangerous, then I'm real dangerous.

There isn't space (and it's boring as well) to go in depth on fluid dynamics (besides I don't know enough really) but I think I have a couple of practical examples that we all know, while aren't perfect, might demonstrate some of the principles at work here. First principle, pressure reduction with rapidly moving media. Non pressurized paint guns (you know, the kind with the screw on cup and a small hole in the lid) siphons the paint right out of the cup by passing high velocity air over the top of the siphon tube stuck into the paint cup. True, it's air pressure on the outside that pushes the paint up the siphon tube but it's the loss of pressure above the siphon tube due the fast moving air that makes it all happen. If we seal the hole in the lid, there would be a slight vacuum in the cup (yeah, I know and no paint spray either #ad
). Second principle, a restriction, increased velocity, and no change in volume before and after the restriction. A river flows into a narrow gorge and exits out the other side. The volume entering and exiting the gorge is the same (except what evaporates, splashes on the shore or pumped out to water the fields #ad
). However, the water in the gorge is moving a whole lot faster than the water in front or after the gorge. Before the gorge the river may even be moving quicker than after the gorge because of energy lost in the canyon but the volume has to be the same.

I know, it's easy for me to say it's ok, I don't have one. I didn't install a Prime-Loc for the same reason I haven't installed many things on my truck - it wasn't something that I thought I needed/wanted. Would I feel comfortable about installing one on my truck now? In all honesty, it wouldn't bother me. I still don't feel the need/want (sorry, Ashland #ad
). By the way, I don't have a K & N filter either. It isn't because the K & N got bad press on this forum just awhile ago. It just wasn't/isn't on my need/want list (sorry, K & N #ad
).

------------------
<font color=#990000>~<font color=#990000> '99 2500 SLT <font color=#990000> ~ QC ~ 4X4 ~ LB ~ Auto ~ 4:10 LSD ~
<font color=#000000>*<font color=#990000> BD E-brake<font color=#000000> *<font color=#990000> BD Autolock<font color=#00000> *<font color=#990000> Gear Vendor OD<font color=#000000> *<font color=#990000> Jordan Research 2020 T-brake <font color=#000000> *<font color=#990000> Bullhide spray-in Line <font color=#000000>*
<font color=#000000>*<font color=#990000> 2k Komfort 5'er - 9,700 lbs <font color=#000000> *
<font size=-2>... Lookin' for the 'RE' to go in front of my 'TIRED' so's I got more time to Play!... <font size=-1>



[This message has been edited by Rattlin (edited 12-13-2000). ]

 

[gitchesum]

Ok, I can give some validity to the lower pressure/higher volume theory.

At the oil terminal I work at we use a series of booster pumps to feed a large high pressure pump. After reading the reply from Ashland I started watching more closely how our system works.

When I'm pumping oil, using only the smaller booster pumps, the pump pressure is about 130psi. The volume is about 2500 barrels per hour. (105,000 gallons)

When I turn on the big pump unit the pressures at the small pumps drop to about 96psi but the volumes jump up to about 3800 barrels per hour. (159,600 gallons)

I know this is a different application but it does show that it is possible to have a higher volume of product pumping at a lower pressure.

Something else I've noticed at most of the facilities I've been to is that all the small booster pumps are located closer to the supply of oil. Therefore maybe the lift pumps on the really should be closer to the fuel tank rather than mounted on the engine.



------------------
Curtis Harris

"JAWS"(The Great White)
Updated 11/19/00
1997 Club Cab Dualie
correctly valved 5 speed. White, Brown Manf. brushguard and rear bumper,Sprayed in liner, Stock plate and AFC properly adjusted. That's all for now. More to come.

 

[HVAC]

I have been tinkering with the fuel system for some time now. I have no interest in the Prime Loc and would not purchase one. I have had good results from increasing the fuel line size and relocating the pump to the tank. I would throw a flag at that stock lift pump and penalize it 15 yards #ad
The holley worked better then the stock pump and the Mallory I have now is even better.

If the Prime Loc has any fittings with a smaller ID then the stock fuel system then I would have a problem with that (since I don't like the stock fuel supply). From the testing that I have done the fuel system needs to be upgraded on a BOMBed truck or your running with 0 PSI fuel pressure.

An example was given above that mentioned a difference in pump configuration. This could compensate for a restricted supply line to a degree. But when the pump configuration stays the same (as in our trucks) and the supply lines become more restricted then I have to believe the resultant volume is deminished. My latest fuel system modification netted me 36 horsepower on my truck so I have people beginning to look more closely at the fuel system on our trucks.

------------------
Nowel/Performance Diesel

 

[ggorremans]

Beserker.
At least in the 1st geners, the fuel filter head contains a fuel heater. Bypass the stock OEM filter head as you propose would bypass the heater.
Don't know about the '94 and newer trucks...
gary

------------------
'92 W250 LE 4x4, NV4500 5spd, Borgeson steering shaft, PrimeLoc

 

[Rambling]

Zowee, Gitchesum!!! #ad
That's 52% increase in flow with a 30% drop in apparent pressure. Guess YOU do get more through a pipe.

HVAC, maybe you could borrow Gitchesum's big pump and put it in place of the injector pump. #ad
With the mods you have and the way you keep going, you'll need all the fuel you can get to shove through those injectors. #ad



[This message has been edited by Rattlin (edited 12-14-2000). ]

 

[gitchesum]

Yeah HVAC, we could install the pump in the back of your truck (if it'll fit). Heck, the motor that runs the big pump is only about 3500hp. It's got a 24 inch line coming out of it so fueling should not be a problem.

 

[HVAC]

#ad
#ad
#ad
#ad


------------------
Nowel/Performance Diesel

 

[Sasquatch]

I've had a P-loc kit on my truck for three years with no problems at all. I wonder what the "empirical" evidence is that there may be a real problem with the Ashland technology? In other words, as was the case with the recent flap over Firestone A/T tires, there was a lot of evidence (many accidents, deaths, etc. ) that a problem existed. Discussion/debate abounds about whether the causes of the tire failure were under-inflation, or design/engineering flaws, but nobody can conclude that there isn't a problem of some kind related to the tires; too many failures have resulted -- whatever the cause -- to conclude that the tires are fine and there is a statistical anomaly.

This should be the case with the P-loc systems, too. In other words, if there is an inherent design flaw in the system, there would be lots of "real world" (setting aside, for the moment, the lab analysis presented above) testimonials about injection pump failures from P-loc owners. If there have been lots of unhappy people making such claims, I haven't heard about it.

Just as there is now a raging debate (between Firestone and Ford) vis a vis the "real cause" of these A/T tire failures, I'd imagine that many/most of the folks who are using the P-loc technology are ALSO bombing the crap outta their trucks. In other words, what is the empirical evidence that, in the "bombed truck" scenario, it is the P-loc system (and not some "go-fast" component) which is the culprit that caused the pump failure?

Finally, lots of us measure fuel pressure and flow rates across the P-loc "butterfly" and fuel pressures appear more than adequate. Again, I'm running a pretty "hot" pump and have done so for over 70,000 miles with no problems. Where are all the folks who are experiencing problems?

We don't need further "proof" to conclude that the fuel-sending units on these trucks suck the big one. Why? Because there are hundreds of testimonials to that effect. I would think, were there a real problem with the P-loc technology, that we'd have seen many, many posts documenting problems with failed pumps -- not just a couple.

------------------
97 2500 4x4, club cab, auto, 3. 54 limited slip, JRE 4" exhaust, Dr. Performance Fuel system (370 HP), "Twister Turbo," Geno's guages -- Boost, EGT, transmission & Rear -- MAG Hytec covers, SunCoast Converter/Transgo shift kit, Brite Box, tons o'chrome under hood, Prime Loc, EZ Drain, Seat covers, wood dash, Rancho Suspension, Warn M12000 Winch on Warn Brush Guard, Warn driving and fog lights, Hella twin back up lights, 285/75/R16 B. F. G. ATs on Mickey Thompson "Classic" rims; Linex bed liner, BD exhaust brake, Optima, "Red-top" batteries. Northwest Custom mudflaps, front/rear, and stainless rocker panels.

 

[Ron Duncan]

Thanks BillW!
In the past I have enjoyed the discussions on the worth of our stock lift pumps. I have said before, the real test would be in the amount of fuel returned from the injection pump. I believe the by-pass valve this fuel must goe through is set at 14#. It would appear the pressure between the lift and injector pump is meaningless at RPMs above idle.
I had talked to several of the aftermarket power suppliers and none of them thought we had a problem but agreed further investigation was needed. Lawrence at Diesel Dynamics was the first to show me the internal lift pump inside a torn down injector pump.
I have often wondered why the proponents of new pumps and big lines have never done this test. I realize the more BOMBing you do the more fuel you use and there may indeed be a problem. For us mostly stockers it seems a half gallon of cooling fuel per minute should be enough to keep the injector pump cool.
Thanks again BillW!

------------------
'99 Quad long bed, 4x4, 5 speed, 3. 55 limslip, DD stage IIs/boost module and elbow, US Gear D-brake, Mag-Hytec, 4" exhaust, gauges, stock filter, air bags and a bunch of other stuff. Pull a 30' Wildwood
fifth wheel.

 

[HVAC]

Ron,

&gt;In the past I have enjoyed the discussions &gt;on the worth of our stock lift pumps.

Do you feel the stock lift pump is adequate? Did you hear about the recall?

&gt;I have said before, the real test would be &gt;in the amount of fuel returned from the &gt;injection pump. I believe the by-pass valve &gt;this fuel must goe through is set at 14#.

Please test this for us Ron. Your data will be appreciated.

&gt;It would appear the pressure between the &gt;lift and injector pump is meaningless at &gt;RPMs above idle.

Zero PSI is OK with you? Please ask Joe Donnelly about the fellow in your area running 1/2 psi on his 24v truck.

&gt;I had talked to several of the aftermarket &gt;power suppliers and none of them thought we &gt;had a problem but agreed further &gt;investigation was needed.

Your right, Banks will not experience a problem with the level of performance they offer. Also, you won't encounter problems with 275 horse injectors or a VA box. BUT, for those running a fueling box the pressure drops off the gauge!

&gt;Lawrence at Diesel Dynamics was the first to &gt;show me the internal lift pump inside a torn &gt;down injector pump. I have often wondered &gt;why the proponents of new pumps and big &gt;lines have never done this test.

Yes, there is a rotary pump in the front of the VP44. This pump scenario may work nicely for some applications like a four cylinder Iveco. But Ron, there is a reason Cummins/DC has installed a lift pump on the block to pull the fuel from the tank, don't you agree. Do you suggest the lift pump is of no consequence?

&gt;I realize the more BOMBing you do the more &gt;fuel you use and there may indeed be a
&gt;problem. For us mostly stockers it seems a &gt;half gallon of cooling fuel per minute &gt;should be enough to keep the injector pump &gt;cool.

BINGO!!! We're not talking stock here.

In summary I would like to say that fuel delivery has been tested and found to be siginficantly improved via the addition of the 3/8" fuel lines and the elimination of the banjo bolts and fittings. This is regarding a truck with a fueling box such as a PM3, Power Edge, Blue Box etc.

Beyond that I measured a difference of 36 horsepower as a result of further fuel system modifications on my last visit to the dyno. I would be interested in any testing data regardng this subject.

------------------
Nowel/Performance Diesel
635 horsepower
13. 1 ET @ 112 MPH



[This message has been edited by HVAC (edited 12-17-2000). ]

 

[Evan A. Beck]

Right on the money, Nowell! #ad


BillW...

So are you saying fuel pressure doesn't matter? Let's see some REAL tests... I mean ON THE ROAD tests. There is only so much you can do on a dyno. I'd like to see what lasts longer: A truck with zero psi of fuel pressure towing uphill in the summer at 70 mph, or a truck in the same situation, but with 10 psi of fuel pressure. Try that and see what happens.

Food for thought!

Dinner's ready...

 

[Ron Duncan]

Oh boy! More lift pump discussions!
First let me explain what I have always believed and BillW has proved:
The lift pump supplys fuel to the injector pump at low RPMs. The injector pump is actually a unit with two pumps. One to pull fuel from the tank to supply the high pressure pump for the injectors. At idle the external lift pump supplys fuel to the injector pump/pumps. When the engine starts reving, the injector pump assembly does ALL the work. When the internal pressure within the injector pump reaches 14# the excess fuel that cools the pump is returned to the tank. BillW reports 1/2 gallon per minute under load on a dyno.
Now, if the pressure after the external pump reads 0, we like to go into a panic, but what should it read if a better pump is sucking the fuel and supplying 1/2 gallon of excess fuel per minute? As Gitchesum has pointed out, if you put a strong pump after a weak pump the pressure in between is mute.
OK, having said all that, let me try to answer my very much respected friend Nowell's questions... ... ... .
Yes I feel the stock pump AND lines are adequate. The recall was for a very narrow band of trucks that apparantly couldn't supply fuel at idle. Also note the service manual does no address any pressure at high RPMs.
I don't have to test the excess fuel as BillW allready did. I think it would be hard to consume over 1/2 gallon of excess fuel per minute no matter how hard you BOMB.
I have been running zero pressure on my truck for over 15K miles, mostly pulling a GVW of over 18K# with no apparant damage or lack of performance.
The lift pump is not useless, it is there to supply fuel at low RPMs. The injector pump runs off the engine and cannot work to it's potential unless the engine is up to speed. The lift pump is electric. The manual actually says the lift pump reduces pressure above idle. Why would that be?
Evan, Yes he is saying the pressure between the external lift pump and the injector pump/lift pump does not matter. Read Gitchesum's experiences.
I'm playing Devil's advocate here 'cause it worrys the schit out of me when I'm working my truck hard. I also am cheap and would rather spend my money on my Jeep (my truck is the way I want it) rather than buying stuff I may not need.
Lawrence at DD told me (several months ago) that he has not seen an injector pump fail on a 24valve engine no matter how many mods they had. His truck is awesome and he pulls a fifth wheel.
What me worry?
You bet I would if I was running the kind of horsepower some of you guys do. If I was running 400 horses at the drags running flat out for 1/4 of a minute I would do all I could to improve the situation! In fact if I had any of the available boxes I would invest my dough... ... .....
Ron

------------------
'99 Quad long bed, 4x4, 5 speed, 3. 55 limslip, DD stage IIs/boost module and elbow, US Gear D-brake, Mag-Hytec, 4" exhaust, gauges, stock filter, air bags and a bunch of other stuff. Pull a 30' Wildwood
fifth wheel.

[This message has been edited by Ron Duncan (edited 12-18-2000). ]

 

[Evan A. Beck]

Ron, I am just trying to provoke further testing. That's why I started this whole thing a month or so ago. #ad


Seems like What I have been doing is working!

 

[John]

Sorry Ron I DON'T BUY INTO YOUR "theory"!!!! Have you even read the other threads regarding this subject???? Are you sure you heard Lawrence correctly regarding 24v injection pump failure? I know of MANY cases where JUST after the addition of a performance computer box, the Bosch VP44 grenaded.

I had -2. 2 psi at the outlet test port of my fuel filter housing when performing the on road testing portion of my Prime-Loc pressure tests. This was at light to light/moderate throttle... towing nothing. DO you really think the VP44 was working within it's efficiency range at MINUS 2. 2 psi? Another 24v Prime-Loc equipped Ram was tested the next week... it had -5 to -7 psi at near full throttle. BTW, when the Prime-Loc was removed my output pressure increased by 5 psi. If you want to leave yours on be my guest, mine's off... and staying that way! If you or anyone else has such great faith in the Prime-Loc system. . let me know, I'll sell you mine. Any takers? (that includes you BillW)

BTW Ron, there will be an article coming out in the next several issues (two part series) of Western RV that pertain to the lift pump as it relates to injection pump failures.

 

[Rambling]

As a technical person, I like data. When there's good data and appropriate scientific principles are applied, a sound conclusion is made.

Some have speculated that there is less flow because there is less pressure.

Of all the posts on this forum, only one post has presented data that supports their position on the fuel flow question.

There have been no posts with data supporting the opinion/theory that the apparent pressure reduction reduces fuel flow. An increase in HP with larger fuel lines in place of stock fuel lines may indeed indicate a restriction for a super-modified set of wheels. I propose the theory that an increase in HP is due to better fuel quality being supplied not more flow. The increased line size reduces the many small points of turbulence in the flow of the fuel thus reducing the slight aeration of the fuel. Less aeration means more fuel delivered to the injectors. More fuel to be burned means more HP. Hey, just a theory. But it could be true.

Some have speculated that there is less cooling because there is less flow.

No post has presented data to support this opinion/theory. In general, a slower moving fluid will absorb more heat due to a longer exposure to the source of heat. We could measure the temperature of the returning fluid before and after installing the P-L. But since there is data that shows the volume of fuel being returned is the same and the surface contact area of the heat has to be the same, it would be a waste of time and money IMO.

Maybe some one can explain to me why the pressure at the input of the stock filter didn't increase slightly when the P-L was installed? I mean, when I put my thumb over the end of a hose, if there's a slight spray at the faucet because the hose isn't on tight, the spray gets stronger because the restriction caused the pressure to increase in the hose. It stands to reason a restriction after the stock filter input would cause an increase in pressure at the input to the stock filter. Just curious as to how come.

John, I'm not going to try and convince you to put the P-L back on your truck. I might stand a better chance of winning the WA state Lotto a couple of times and since I'm not there to play, you know how likely that is to happen. I do want to acknowledge and address the negative pressures that you measured.

I believe the apparent pressure losses are the same magnitude with the marginal lift pump as with the healthy pump because the injector pump is drawing the same volume with its internal pump. When the pressure at the stock filter input port in Steve St. Laurent's data table(with P-L) is adjusted to 10 psi and the same apparent pressure losses due to the Venturi principle (principles are theories that have been proven to be true ) are subtracted, negative numbers similar to the values you reported are obtained.

Once I studied everyone's data and applied what I felt were appropriate scientific principles, I was able to reconcile what at first appeared to me to be conflicting information… negative pressures, same flow volumes, and excess pressure losses through a very short hose. P-L may not be for everyone. It certainly doesn't appear to me to present a threat to stock or moderately modified trucks as I first thought. As usual, just my opinion.

This has been one heck of a good education on the fuel system. I certainly wouldn't have obtained this kind of insight without all of you. Thanks for all the posts.


***There was no intent to offend anyone in my post. If I have, I apologize. ***




[This message has been edited by Rattlin (edited 12-19-2000). ]

 

[Ron Duncan]

John,
I don't have a Prime-loc and have never seen a need for one. My theory pertains to a mildy modified engine such as mine, used for towing and normal driving.
When Lawrence told me he saw no problems he was referring to the HP mods he does. At the time he did not sell or recommend any of the boxes. I don't know if that policy has changed. I do know he was working up a lift pump and bigger line kit for those who felt a need for them. He also said he was going to do more research.
As I said, if I had a box I would look for help for the pump. I went for injectors instead of a box, due to the reported possibility of pump failures. I am still happy with my decision.
The Western RV article should be great!
I would like to see a pressure gauge installed prior to the 14# relief valve that returns fuel to the tank. This would really let us know what's going on! The 1/2 gallon per minute test only shows us that full 1/2 minute. I have to wonder how much fuel is being returned second by second during a full throttle blast.
My theorys are just my theorys and if I blow my VP44 up I will certainly share my experience and change my tune... ... .

 

[John]

Ron, I elected to sell both my PE (std. ) and my 10 level PM3 (neither had been installed) for the same reason listed by you. I too elected to go with DD Stage 3 injectors. I'm very happy with my choice.

As far as pressure monitoring; I just purchased (qty. ) 3 $PA combination gauges to replace my VDO Vision series gauges... I wanted/want to be able to monitor the fuel pressure on a constant basis. This follows on the heels of replacing the OE lift pump with a new one. I'm also finalizing plans to add an additional fuel pump with a pressure regulator. As you can see, I'm not taking this lightly.