Author Topic: Fuel cooling - optimal diesel temperature??? (Read 10324 times)

jtanguay · « **on:** February 20, 2009, 11:36:19 am »

does anyone have the low down on the optimal diesel temperature??? i know some TDI's have fuel cooler/warmers to maintain optimal fuel temps...

anyone with VAG-COM knowledge of optimal fuel temp range?

thanks!

jtanguay · « **Reply #1 on:** February 20, 2009, 05:59:17 pm »

just did some reading... apparently it is 145F(62.78C) to 155F(68.33C)

that sounds a little bit hot... i thought cold wasn't so good, but i thought the right temp was closer to 15-20C.

anyone have any thoughts on this? i might build a controller to test this out.

http://www.freepatentsonline.com/4343283.html - this site is now saying "within 140° F. to 150° F." which sounds more like it to me.

burn_your_money · « **Reply #2 on:** February 20, 2009, 06:06:16 pm »

I have no idea but please keep looking and post what you find

truckinwagen · « **Reply #3 on:** February 20, 2009, 06:10:59 pm »

well, the volume of fuel shouldn't change much based on temperature, but the viscosity will, so I suppose that hot fuel will atomize better due to its lower viscosity, to the point of diminishing returns of course.

AudiVWguy · « **Reply #4 on:** February 20, 2009, 07:39:30 pm »

What about the viscosity of the fuel changing the fuel pump timing?

truckinwagen · « **Reply #5 on:** February 20, 2009, 07:40:37 pm »

that too, there is probably lots at play that we can only guess at.

jtanguay · « **Reply #6 on:** February 20, 2009, 08:01:41 pm »

Sooo... this really makes me want to test out a fuel heater/cooler now

does anyone know what the measurement of advance is? is that degree's? what is the relation between that and in 0. mm or does it matter? and the temp is obviously in deg F right?

the caveman · « **Reply #7 on:** February 20, 2009, 08:02:05 pm »

I can't say exactly what the optimal diesel temp is , but i do know that the temp you want it is below what you want to run WVO. I would also imagine that in an IDI pump it probably change it a bit but not much of an effect as in a TDI because of the fuel temp sensor in those pumps. I will also try to dig and find more precise info.

jtanguay · « **Reply #8 on:** February 20, 2009, 08:07:54 pm »

what i would like to know: is there a direct relation between fuel temp and injection timing? (without ECU control)

my best guess would be yes, but i can't see any useful applications of varying the fuel temp by much... (possibly cooler for more performance-50C, and hotter for fuel econo-60C???)

to properly read the above graph, does that represent the timing limits for the ECU? meaning that the red line indicates FULL advance and the blue means FULL retard? that could possibly help people with mTDI pumps. i'd still like to see a timing graph to plot timing vs engine rpm though... :wink:

that is for a 1.9TDI skoda engine code AGR (should be good for TDI's right?) any way of measuring injected quantity on an IDI pump other than with a test bench? and is that something that can be made variable on a mech pump, or no?

i would still like to see timing vs rpm vs fuel temp

Hey · « **Reply #9 on:** February 21, 2009, 06:55:55 am »

At higher temperature, the hydraulic head will also "leak" more diesel, resulting in a smaller amount of injection quantity and retarded timing.

I would suggest you to install an exit valve from a Tdi-e pump. There is a higher flow at high RPM and full load, resulting in more stable temperature.

gigaz2 · « **Reply #10 on:** February 21, 2009, 01:15:13 pm »

Quote from: "jtanguay"

that is for a 1.9TDI skoda engine code AGR (should be good for TDI's right?) any way of measuring injected quantity on an IDI pump other than with a test bench? and is that something that can be made variable on a mech pump, or no?

I have Lucas injectors in my 1.6td, one of them has the pintle lift sensor that the TDI's use.
one could measure injected quantity like the ecu does, by measuring the time the pintle opens.

it can barely be seen on this pic:

notice the thin wire and plug on the second injector, I have to use a 1.9 pipe for that injector as its the same height as a 1.9.

some BMW engines also had that injector, made by Bosch.

gigaz2 · « **Reply #11 on:** February 21, 2009, 01:19:17 pm »

Quote from: "Hey"

At higher temperature, the hydraulic head will also "leak" more diesel, resulting in a smaller amount of injection quantity and retarded timing.

I would suggest you to install an exit valve from a Tdi-e pump. There is a higher flow at high RPM and full load, resulting in more stable temperature.

interested on the differences in using different exit valves on a IDI engine

why do the tdi ones flow more at higher rpm?

jtanguay · « **Reply #12 on:** February 22, 2009, 06:30:49 pm »

any other input?

Dr. Diesel · « **Reply #13 on:** February 22, 2009, 11:13:32 pm »

Seems to me that after a certain length of time running, the pump is quite warm to the touch, what with being bolted to a hot engine... I'll hit mine with the infrared thermometer when I get home from work.

zyewdall · « **Reply #14 on:** February 23, 2009, 07:42:56 am »

Quote from: "the caveman"

I can't say exactly what the optimal diesel temp is , but i do know that the temp you want it is below what you want to run WVO.

Yes, we've found that WVO needs to be a minimum of about 180F in order to run well.

Author Topic: Fuel cooling - optimal diesel temperature??? (Read 10324 times)

AudiVWguy