Engine/Transmission (1998.5 - 2002) Why Banjo Bolts???

[jerryrigg]

Does anybody have a clue as to why DC/Cummins/Bosch uses banjo bolts instead of 90deg AN fittings on the VP44??? Is there an advantage to banjos that I am unaware of?? Were they just on sale when the VP44 was designed?? Just curious.



-Matt

 

[Bigsaint]

I think that's a great question, one I have also wondered about. If you look at any tech. info on fuel systems, the banjo bolt is always shown in the "wrong way" picture .



I removed all mine inbound and replaced them with Weber fittings and 90 degree hose ends, works great.



Scott W.

 

[cscott]

Banjo bolts are a solution to a problem that does not exist on our trucks. Banjo bolts are required when you have a tight fit, such as with carburators that have a air cleaner clearence problem.



They are most likley used becaues they are cheep.



If you look at the fluid dynamics and the number of direction changes the fuel must make going through the banjo bolt it is obviously not a good thing.



I don't have any proof but I would not doubt that this extra resistance may be playing a part in the failure of our lift pumps.



More resistance to the flow more back pressure the harder the pump must work.



I have removed all the banjo bolts on my truck and replaced them with AN fittings and braided stainless lines.



Craig

 

[HVAC]

ISB History

The clip on fuel boxes debuted in mid(blue box) to late (TST) "99. And in very early "00 it was discovered by a pal of mine that with a clip on box our fuel pressure was bottoming out! Hence the advent of the -6 fuel system. After conducting this experiment for myself with my blue box on high, I verified the fuel starvation problem and began building replacement fuel systems to send my friends who were following me on the performance trail. Upon testing the -6 systems it was concluded that one could maintain 5 psi with a fuel box employed.



The stock system with the banjos is fine for a stock truck. However, testing proved it was not nearly adequate for a highly modified rig.



Guess what was found to be faulty next? That's right, LIFT PUMPS! Aaarrrrrr



Your resident historian... .

 

[illflem]

Banjo bolts have been used on diesel fuel systems for at least 50 years. Think you're going to have to look at more recent developments for your 24 valve fuel system problems.

 

[EMDDIESEL]

I would love to change all my fuel lines to AN fittings and braided stainless hose, but if i did, i am guessing my warranty is toast if my Injector pump fails???? Andbody know?

 

[Sky]

illflem







Posts: 5730





:--) :--) :--)

 

[JMarkos]

Has anyone noticed an increase in fuel pressure by changing out to ray's bolts?



Another ? From what HVAC is saying with my mods should I still be able to get 8-10 psi at WOT? With a new pump I am only seeing 4-5.

 

[HVAC]

Ray's banjos would help you pick up that WOT pressure. I choose to go with larger fuel line as well.

 

[illflem]

EMD, if your dealer has any sense he should love the fact you increased your flow rate with bigger lines, saves the VP. But how many dealers operate with the concept of sense? Comes back to how good your relationship is with your dealer/

 

[jbone]

I'll bet you a dime to a dollar that PRICE had something to do with DC using banjo--or whom ever made the decision..... R, J. B.

A dime times 500,000=:-{}

 

[MikeR]

Do not think for a minute that banjos are only used on dodge diesels. Every single car manufacturer has been using banjo bolts in every single engine for the past two decades... gas and diesel. Cummins also uses them in big diesels. Nothing new here.



Banjo bolts are also used to hold your brake lines to calipers and such. It's just a clean, safe and very secure way of building a line system for a liquid to travel through.



-Mike

 

[Gary - K7GLD]

PERSONALLY, after LOTS of reading on various aspects of LP and VP44 issues - it seems pretty clear to me that the primary culprit in fuel flow problems/failures is NOT the requirements related to fuel supply to the ENGINE, but rather, the required COOLING flow to the VP44!



Let's face it, the fuel consumption of the Cummins itself is FAR less than what the existing LP is capable of putting out - and it's only various contributing factors that place unusual demands upon the stock LP - restrictions in incoming flow due to various fittings, added to the seemingly high volume demanded by the VP44 for cooling purposes seem to be what actually overwhelms the stock LP. The band-aid approach of adding a separate pusher pump most likely merely masks the REAL problem - which more often than not, MIGHT be greatly reduced merely by providing greater, and less restricted flow clear into the VP44.



For sure, the Cummins ITSELF doesn't require the 75 gph or so spec'd for the pumps currently used!

 

[HVAC]

Something I wrote regarding cooling fuel requirements as related to pump sizing-

-----------------------------------------

For a rough example:



Let's say we are driving for 60 minutes at a rate of 100 mph.

We reap a mighty 14 mpg during this scientific experiment.

We find our fuel consumption is 7 gallons of #2 diesel.

This represents 30% of our total requirement using a generally accepted figure.

The balance of the fuel is used for cooling purposes and recirculates back to the tank.

Now we can calculate our total fuel requirement for a 200 horsepower engine to be 25 gallons.



OK, assuming engine efficiency stays the same (it doesn't), how much fuel would

it take to power a 400 horsepower engine using the above parameters?

What would be the total fuel requirement including fuel for cooling (70%)?

To simplify things, let's say the horsepower increases incrementally with the addition of fuel.

This should mean that our 400 hp engine will need 50 gallons minimum to function properly.



Does this mean we need a pump that can produce 50 gph?

NO!!! Pumps are normally rated in terms of free flow performance.

In other words, with nothing hooked up to it.

So when we connect 10' of fuel line to the pump and then install a filter inline, we don't have 50 GPH!



In this example we need 50 GPH minimum.

When picking a pump I would not depend on it producing more then

75% of the rated free flow GPH to the engine.

So if we adhere to the data specified herein, a pump rated for 80 GPH

would perform at 60 GPH under load and cover our minimum recquirement.



Personally I prefer a bit more overkill for when the filter becomes clogged, or I add more

horsepower, or ??? .

 

[Gary - K7GLD]

THE above by HVAC pretty much illustrates MY point - better than 2/3 of fuel requirements for the 24 valve are NOT for operating the ENGINE, but to cool the VP44... That cooling requires a decent flow RATE, not necessarily PRESSURE...



And as HVAC states, losses in flow RATE created by various restrictions, fuel filter obstructions, etc. , ALL contribute to compromize the flow rate the VP44 needs for cooling, over and above engine needs.



Decent PRESSURE to the VP44 can be rather easily obtained down at the levels needed for engine power only, and various fuel line obstructions contribute rather little at that rate of flow - but when you add in the FLOW RATES needed to cool the pump too, those obstructions begin to be a very real problem!



And as a few here have discovered the HARD way, supplying TOO MUCH flow and pressure to cover line losses at MAXIMUM system demands can SOMETIMES overpower VP44 seals at lower engine demands, creating yet ANOTHER problem and VP44 failures!



Trying to overcome fuel line obstructions merely by increasing pressure and flow from a second pump MAY get the job done, but eliminating as many of the obstructions as possible isn't a bad idea either...

 

[jerryrigg]

I love it, always a ton of information!



Let me expand a little on my question. The only "advantage" I know of for a banjo bolt is the clearance available. This is not a problem on the VP44. I can think of several disadvantages of them, more parts: bolt, banjo, 2 gaskets. Rule of thumb more parts=more problems, they can be more restrictive (thats why Geno's bolts have larger holes). Yes they have been around for years, I've had them of various machines as long as I can remember. But... Is there any real advantage to them. If I do put them on and the VP44 dies on me I don't want the dealer to be able to say, the banjos were there because of blah blah blah so we can't warranty your pump. Knowledge is power and power defeats the enemy. DEWDO proved that with his victory in court over the Stealer. Congrads.



-Matt

 

[Gary - K7GLD]

Another factor worth considering for thos figuring to replace fuel lines and various connectors with larger diameter stuff to increase flow - fluid flow, like many other things, is like the weakest link in a chain - even if ya use 1 inch hose for fuel line with corresponding fittings, if the tank outlet, lift pump or inlet to the injector pump itself is restricted to, say 1/4 inch, THAT will determine the maximum flow you will get thru the system at any specific pressure - regardless of how fancy it looks, how much money you spend, or how large the REST of the system is...

 

[illflem]

Not quite true Gary. The length of the restriction plays a major role in pressure/flow drop. Good example is in irrigation systems, we never use a valve the same size as the pipe, too expendsive. Example: the full flow of a 4" pipe will pass though a 1-1/2" valve with only 0. 5 psi of pressure drop. Another rule of thumb is that a 90° elbow equals 50 ft of pipe friction loss. You can download this http://www.IrrigationTutorials.com/LineSize.exe. and see even though it only goes down to 1/2" tubing that pressure loss at our flows is nil.

 

[Gary - K7GLD]

"the full flow of a 4" pipe will pass though a 1-1/2" valve with only 0. 5 psi of pressure drop. "



But at what supply pressure? If the main line pressure is low, that figure might be a substantial percentage of the total - perhaps NOT if your supply pressure is high. My comments are related to both FLOW rates AND pressure where restrictions/obstructions exist. The above exiting pressure drop doesn't tell us anything without the incoming pressure specified.



If I run a 1/2 inch watering hose from a 40 psi source out in my yard, with a restriction down to 1/4 inch, at LOW flow/volume, I'll get nearly the same flow OUT of the hose that is going IN - but if I open the faucet wide open, what happens to that percentage in both pressure AND volume in/out of the hose?



The percentages change RADICALLY - the SUPPLY side pressure will rise to nearly the full 40 psi source value, while the pressure beyond the restriction will change comparatively LITTLE! Sure, total flow WILL increase - but be SERIOUSLY limited by the restriction further up the hose - and it will make precious LITTLE difference if the hose itself is 1/2 inch in diameter, or a FOOT in diameter - that 1/4 restriction will be what dictates total flow thru the hose at any specific pressure above the critical point of the restriction itself!



It's hardly practical to get into the various values of friction losses in our fuel systems with various diameters of line as compared to lumped restrictions at specific points - but I still consider my basic premise to be valid - and sure wouldn't waste a lot of time and $$$ in a larger line diameters and expensive fittings until I had determined that other unavoidable restrictions in the system wouldn't render my efforts pretty much a waste of time $$$ and effort...

 

[Big_Daddy_T]

To simplify matters a simple test would suffice. test pressure at the vp44 banjo before and after the upgrade. In this test it has been shown that for high volume the banjos are a restriction. Very few people may need the upgrade. Unless you have a major fueling box with some large injectors It may not be worthwhile. Also to put it in perspective. It will cost about 25 dollars to find out if drilled banjos will help. I myself have upgraded the fuel system because of my need for copious amounts of fuel.