Freebie - how hot is your fuel?

fmorelli

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So this is steady state driving, with little stop and go at all. I'm seeing a 40 degree temp increase on my fuel (from ambient) which I suspect is heat build-up under the car by the exhaust. Unless someone has another bright idea? My temp measurement is literally under the driver seat area on the fuel line. I'm thinking a heat shield formed as a "tube" over the fuel line area, and a NACA duct to drive air through the tube. Anyone else notice this?

Filippo

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ms335i

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Wow, that is pretty dang warm. I wonder what it gets to when it's in the mid 90s and traffic. That being said, I doubt it is something that will affect performance but I could be wrong.
 

fmorelli

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Wow, that is pretty dang warm. I wonder what it gets to when it's in the mid 90s and traffic. That being said, I doubt it is something that will affect performance but I could be wrong.
You could be right. My back of the Internet volume calculator for ethanol seems to indicate that 40 degrees F only affects the cubic weight by 1%. Would rather have someone with expertise weigh in as we're out of my area of knowledge :).

Filippo
 

InnovativeAuto

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I had issues with fuel temps in my 996tt when doing a dual 044 setup. Porsche uses a cooler integrated with the A/C line which I bypassed running -8 line to the rails. I installed an inline aftermarket cooler in the d-shaft tunnel and it helped a ton! Yes, you will loose some hp with higher fuel temps.
 
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The Convert

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I don't know what the Z's fuel line routing look like compared to the exhaust, but my money is that the rise of due to the fuel pump(s) and radiant heat coming off of the pavement.
 

doublespaces

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I had issues with fuel temps in my 996tt when doing a dual 044 setup. Porsche uses a cooler integrated with the A/C line which I bypassed running -8 line to the rails. I installed an inline aftermarket cooler in the d-shaft tunnel and it helped a ton! Yes, you will loose some hp with higher fuel temps.

How much is what I'm wondering
 

Rob09msport

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So this is steady state driving, with little stop and go at all. I'm seeing a 40 degree temp increase on my fuel (from ambient) which I suspect is heat build-up under the car by the exhaust. Unless someone has another bright idea? My temp measurement is literally under the driver seat area on the fuel line. I'm thinking a heat shield formed as a "tube" over the fuel line area, and a NACA duct to drive air through the tube. Anyone else notice this?

Filippo

View attachment 16235 View attachment 16236
What's crazy is that was on full tank how bad would that be on a quarter is my question.
 

NoQuarter

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You lose about 3% in density of the fuel going through the injectors. So for the given volume the injector is letting through, there is less fuel molecules entering the combustion chamber.

Fewer fuel molecules means a loss of power, but with our ECU, won't it just adjust the injector duty cycle to allow more in if the targets are not met?
 

fmorelli

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I don't know what the Z's fuel line routing look like compared to the exhaust, but my money is that the rise of due to the fuel pump(s) and radiant heat coming off of the pavement.
Wouldn't radiant heat run the temp up on the outside temp sensor, which is mounted on the bottom of the car?

Fuel on Z4 runs on the driver side rail (exhaust passenger side rail). But then runs over diff in front of axle and LPFP is on the exhaust side. Photos should help.

Filippo

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Jeffman

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It’s not lower density of the fuel that’s the problem, but rather temperature. Colder fuel reduces charge temperature the same way colder IAT does. The overall temperature of the fuel and air mixture in the cylinder is what’s important.

Bottom line: Colder fuel very important...
Filippo’s observation about the fuel heating up in his Z4 is important to take note. How to prevent fuel heating? Is the fuel line too close to the exhaust? If so, insulate the fuel line. Too much heating of the fuel by the upgraded LPFP? If so, look for a cooler LPFP or an external fuel line chiller. Etc. etc.

Quick question: Who’ll be the first vendor to come out with an N54 fuel line chiller? My money is on @TwistedTuning who is very innovative on new products. :)
 

Optigrab

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It’s not lower density of the fuel that’s the problem, but rather temperature. Colder fuel reduces charge temperature the same way colder IAT does. The overall temperature of the fuel and air mixture in the cylinder is what’s important.

Bottom line: Colder fuel very important...
Filippo’s observation about the fuel heating up in his Z4 is important to take note. How to prevent fuel heating? Is the fuel line too close to the exhaust? If so, insulate the fuel line. Too much heating of the fuel by the upgraded LPFP? If so, look for a cooler LPFP or an external fuel line chiller. Etc. etc.

Quick question: Who’ll be the first vendor to come out with an N54 fuel line chiller? My money is on @TwistedTuning who is very innovative on new products. :)

What about the MR 5 fuel line heat shield?
0001090000056_A?$img_size_380x380$.jpg
 

chadillac2000

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I took this screenshot earlier today on my way home from work. This was after sitting in stop and go city traffic for about 15 minutes after being on the highway for a half hour prior. Temperature was 81 degrees out.

basWKX7.png


I wonder at what temperature would we start seeing issues arise? There were plenty of days in the dead of summer recently where ambient temperatures were over 100 here in the Carolinas, and I'm assuming fuel temperatures were much higher than seen above, but I never noticed any problems. As explained above though, colder fuel seems to mean healthier combustion.
 

The Convert

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Someone who takes a screenshot of their fuel temp needs to hop out of their car and hit the pavement with an ir camera to see how hot it is. I bet most of the heat is radiating off of the pavement. The rest is likely from pump heat and fuel pressure.
 

Jeffman

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Someone who takes a screenshot of their fuel temp needs to hop out of their car and hit the pavement with an ir camera to see how hot it is. I bet most of the heat is radiating off of the pavement. The rest is likely from pump heat and fuel pressure.
Upgrade your iPhone to iOS 12 which now includes an IR camera app. o_O
 
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AD-ENG

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This temp comes from the pump and radiant heat on the tank. On a deadhead system this measurement is somewhat moot. It's like putting an IAT sensor pre turbo. You think that fuel is hot? Measure it in the high pressure rail!

As long as the fuel doesn't boil, then you're ok. If you are concerned about fuel temp effects, then you need to measure where it matter... the tank and the inlet of the hpfp. Once the hpfp has it the pressure is too great for it to boil until it leaves the injector.