Fuel temps walbro vs FASS/Airdog etc.
06-19-2009, 07:59 AM
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Fuel temps walbro vs FASS/Airdog etc.
I've been very happy with my walbro setup, but I sometimes wonder if my fuel is getting unnecessarily hot during long trips. After driving an hour the fuel temp is usually 150* or more. I'm considering buying a different type setup if it will help keep fuel temps down. What are you guys with FASS or Airdog systems seeing?
06-19-2009, 10:42 AM
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I don't have a temp gauge for the fuel, but I've heard the fuel temp coming out of the vp can be 150 degrees so I don't think it has much to do with the lift pumps. I've also heard of guys filling up when they burn off half a tank to try and keep the fuel temps down.
06-22-2009, 12:50 PM
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Anybody ever install a cooler in the return line? Barry grant has some billet heat sink type coolers, and I see flexalite makes one for about $50 that will fit beside the frame rail. I guess it's worth a shot. I've driven an hour during the summer and seen the fuel temp at 160, even with a nearly full tank. 
06-27-2009, 09:14 AM
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Since this thread came up, I brought up fuel temp on my monitor, and I noticed the most I saw was 130F with around 1/4 tank of fuel after 8hrs of driving . typically it seems to slowly climb to around 115-120F. seems to go up a degree or so every hour or two. it has not been very hot here, between 18-20C (not sure what that is in F) I've gone thru 4 or 5 tanks of fuel and have to pay more attention to outside temps and tank level to draw a better conclusion. have noticed that fuel temp drops soon as I fill up.
I have an AD150.
I'll try to keep notes on the fuel temps compared to fuel tank level/outside temps/intown and hiway speed temps
I have an AD150.
I'll try to keep notes on the fuel temps compared to fuel tank level/outside temps/intown and hiway speed temps
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06-27-2009, 01:42 PM
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MOst of the time high fuel temps are due to a fuel delivery system that is way oversized.
A bypass-type regulator will help a lot by letting the bypass flow in a low-pressure loop. This also reduces the stress on the fuel pump, since it only has to make as much pressure as the reg is telling it to.
I've said it before, but I think a bypass style regulator with filtration and cooling on the return line is a fantastic idea (I'll claim credit until someone else does
)
A bypass-type regulator will help a lot by letting the bypass flow in a low-pressure loop. This also reduces the stress on the fuel pump, since it only has to make as much pressure as the reg is telling it to.
I've said it before, but I think a bypass style regulator with filtration and cooling on the return line is a fantastic idea (I'll claim credit until someone else does
)
06-27-2009, 03:28 PM
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Hohn, I've seen 168-170*F for fuel temp with my Holley Blue/ Vulcan big line setup when driving for a few hours here in the Vegas heat. I've thought about a fuel cooler but haven't pulled the trigger just yet.
06-27-2009, 04:32 PM
#11
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Since getting an Adrenaline I have been watching Fuel Temps! Mine average around 150* in the winter and 160* this time of yr (over 90* everyday).
They vary with full tank vs low fuel levels.... winter vs summer..... and with OAT!
Previous studys have shown fuel in tank averages 15* above OAT. I suspect fuel temp in VP-44 is directly proportionate to fuel temp in tank!
Justin, Why does lubricity drop off after 160*?
Source?
RJ
They vary with full tank vs low fuel levels.... winter vs summer..... and with OAT!
Previous studys have shown fuel in tank averages 15* above OAT. I suspect fuel temp in VP-44 is directly proportionate to fuel temp in tank!
Justin, Why does lubricity drop off after 160*?
Source?
RJ
06-27-2009, 04:49 PM
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Source: Cummins Fuels requirements publication
Why: It's mostly related to loss of viscosity. Diesel fuel at high temps gets less and less oily and more "watery".
Cummins application installation bulletins furnished to OEMs says they must be able to deliver fuel to the engine at less than 71C-- that's about 160F on the nose. (ok, 159.8F is you want to be precise).
Our various abuse tests even reulate fuel temps to below 165. This is one kind of abuse we don't test-- except one particular test cycle which lets it higher than that (not really relevant anymore-- test was designed for older cam-actuated injectors).
Why: It's mostly related to loss of viscosity. Diesel fuel at high temps gets less and less oily and more "watery".
Cummins application installation bulletins furnished to OEMs says they must be able to deliver fuel to the engine at less than 71C-- that's about 160F on the nose. (ok, 159.8F is you want to be precise).
Our various abuse tests even reulate fuel temps to below 165. This is one kind of abuse we don't test-- except one particular test cycle which lets it higher than that (not really relevant anymore-- test was designed for older cam-actuated injectors).
06-27-2009, 05:00 PM
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http://www.greenfuels.org/biodiesel/res/oem_CUMMINS.pdf
Quote:
Quote:
Temperature
Temperature causes changes in engine power because it affects both viscosity and density. An increase in
fuel temperature will cause a decrease in viscosity, which will reduce power due to internal leakage in the
fuel system as described above. The maximum recommended fuel pump inlet temperature for Cummins
engines is 70°C [158°F].
An increase in fuel temperature will also cause a decrease in fuel density (increase in API gravity), which will
reduce power due to lower energy content of the fuel. On Cummins engines using the PT®, Quantum, or
HPI fuel systems, the power loss due to increasing temperature is less than that on engines using the in–
line, distributor, or CELECT™ systems (less than 1 percent per 5°C [10°F]), due to the inherent viscosity
compensating characteristics of these systems.
Temperature causes changes in engine power because it affects both viscosity and density. An increase in
fuel temperature will cause a decrease in viscosity, which will reduce power due to internal leakage in the
fuel system as described above. The maximum recommended fuel pump inlet temperature for Cummins
engines is 70°C [158°F].
An increase in fuel temperature will also cause a decrease in fuel density (increase in API gravity), which will
reduce power due to lower energy content of the fuel. On Cummins engines using the PT®, Quantum, or
HPI fuel systems, the power loss due to increasing temperature is less than that on engines using the in–
line, distributor, or CELECT™ systems (less than 1 percent per 5°C [10°F]), due to the inherent viscosity
compensating characteristics of these systems.
06-27-2009, 07:19 PM
#14
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One other consideration.... Quad instrumentation seems to read high. My Cummins 180* T-Stat reads 185-188*.
So maybe my fuel is running cooler than indicated.
RJ
So maybe my fuel is running cooler than indicated.
RJ
06-27-2009, 08:35 PM
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Lets not forget that the optimum temp. for diesel fuel is 68*. So the cooler you can keep it the better. A fuel cooler is a great investment that will pay for itself in better mpg's and longevity of injection systems.
There is a reason that the GM 6.6L has a fuel cooler from the factory.
There is a reason that the GM 6.6L has a fuel cooler from the factory.
