Question for the Detroit fan club

[Lostsailor13]

The gear driven fuel pump on 53 series,how much fuel is it pulling at max volume the only flow specs I could find were .6 gpm at no load,so even at 2000 rpm might be somewhere around 50-80 gph,what is your estimates

 

[caltexflanc]

That sounds about right, they use fuel to cool the injector system so return a huge amount to the tanks. It's sometimes said, not inaccurately, that Detroits have a built in fuel polishing system.

Last I looked the net fuel consumption curves were on Boat Diesel.

 

[C lectric]

Which engine specifically I presume you are referring to the 4-53 but there are 6V-53's.

Engine such as Detroits and the older Cummins move several times the fuel they burn using the fuel as cooling for the injection system.

My older Cummins moves at full load and WOT about 80GPH and rated to burn 13GPH returning about 67GPH to the tanks.
Of course I never run it anywhere near that level.

DD are very similar. I figured about 7 times what its rated burn is.

Your 4-53 won't go through that much but I suspect 40-50GPH would not be out of line.

THat is the figure to use for any filtering estimating.

 

[Lostsailor13]

I figured it was somewhere around there,which basically solves my problem of adding a 12v polishing pump,once new gulfcoast F1 filter is installed plus racor 500 plus primary fuel filter,just running her hard will get them tanks clean specially when its choppy

 

[Lepke]

A 671 natural pump delivers 35 gallons an hour at cruising rpm. The pump appears similar to the 53s, maybe the same pump. The DDs have a constant flow thru the injectors for cooling. So don't do anything that restricts the flow.

I've found with Detroits, a turbo Racor with a 2 micron filter element and a good fuel additive will give you clean tanks quickly.

 

[Ski in NC]

The DD gear pump has a pressure regulating valve built into it. Fuel then goes to sec filter then into the rail/injectors. On the discharge of the return fuel rail is a restrictor fitting with a drilled orifice that limits the flow rate out the return.

The size of the gear pump (thus its potential flow rate), the setting of the regulating valve, and the size of the drilled orifice depend on the engine model.

The way it works is this: At idle, the reg valve is closed and fuel pressure pretty low. As rpm goes up, pressure rises and at some point the reg valve starts to open. Further rpm increase causes the reg valve to open further and fuel pressure is mostly peaked. Flow rate out the return orifice (and back to the tank) then is pretty constant.

You can measure return rate by directing return flow to a jug and timing it. Can also put a pressure gauge on the fuel rails to find out what rpm the pressure stabilizes. Usually around 60psi, probably 1500rpm.

Don't leave a pressure gauge on the fuel rail as pulses there will break a gauge and you will have a fuel leak. Oil filled gauge is the best to damp out those pulses. Even if oil filled, don't leave it installed.

 

[Nomad Willy]

With all that flow I would think the filters would get half plugged and not be able to gracefully pass that much fuel.
Instead of a 2 micron filter I would think it would take almost that many filters in parallel to match that flow w 10-30 micron elements to make the flow?
Are the filters themselves huge?

 

[caltexflanc]

It's pretty simple to permanently install a fuel pressure gauge on Detroits after the pump.

Just another health of fuel system data point.

Note, you only need one, have a choice as shown below of where / how to mount. The filter head that converts the engine to spin-ons from the OEM canister comes pre-tapped.

PRESSUREGAUGES

 

[FF]

"With all that flow I would think the filters would get half plugged and not be able to gracefully pass that much fuel. "

The on engine fuel filter (about 10 micron) is not very large , but it seldom sees much dirty fuel as the fuel is constantly cleaned.

A 2 micron primary filter will tell the operator when the fuel is contaminated .

 

[caltexflanc]

The proper sequence of filters specified by Detroit for the 2 cycle engines are 30 micron primary, the 7 micron secondary, and then on some engines the screens on the injector system, which are about 2 micron. I asked three different old timer Detroit mechanics how many times they had to change or clean the screens and they all said never. It is also extremely rare that you have the secondary clog before the primary. I've never had that happen or known a Detroit owner who did.

As a matter of practice, I typically replaced the secondaries (spin ons) while I was changing the primaries, even if they didn't indicate needing it.

I refer people who haven't read it, to Tony Athens' discourses on progressive filtration.

 

[C lectric]

Tony Athens has his own site at www.sbmar.com

Look up his articles especially about fuel filtering. THe info is free and there is a lot of it.

He has done a terrific job.

 

[Ski in NC]

It's pretty simple to permanently install a fuel pressure gauge on Detroits after the pump.

Just another health of fuel system data point.

Note, you only need one, have a choice as shown below of where / how to mount. The filter head that converts the engine to spin-ons from the OEM canister comes pre-tapped.

PRESSUREGAUGES

Don't leave a pressure gauge on the pressurized side of DD fuel system. Pressure pulses from injector operation creates severe pressure pulses that literally breaks the gauges. Fine for test purposes, or put a blocking valve in and leave it isolated unless reading gauges.

Seen some really messy leaks from what seemed like well engineered gauge installs. One even included an industrial pressure pulse damper. Gauge still broke. You do not want pressurized fuel leaks.

 

[caltexflanc]

Don't leave a pressure gauge on the pressurized side of DD fuel system. Pressure pulses from injector operation creates severe pressure pulses that literally breaks the gauges. Fine for test purposes, or put a blocking valve in and leave it isolated unless reading gauges.

Seen some really messy leaks from what seemed like well engineered gauge installs. One even included an industrial pressure pulse damper. Gauge still broke. You do not want pressurized fuel leaks.

I respect your opinions immensely Ski, but installed as shown relative to the secondary I have not heard of or seen any issues. If one is diligent about proactively changing the filters, I do see the pressure gauges as a "nice to have" but certainly not a "need to have".

That said, for any inexperienced folk reading this thread asking themselves "which one of these guys should I follow on this issue?", take Ski's advice.

 

[Pete Meisinger]

My F.L. probably returns about a half gallon an hour. I sometimes wish it were more to do a little more filtering but, "It is what it Is'.

pete