fuel coolers do they work???

[Art Racing]

Sorry, bit late on this. Supra has a fuel cooler, it is plumbed between the pressure regulator at the end of the fuel rail and the top of the surge tank. It is basically just a small oil cooler with smaller AN fittings than normal, and is mounted in front of the radiator next to the engine oil cooler. Theory (and practice) is that there is quite a build up of heat in the fuel as it passes through the fuel rail etc, that isn't so bad for the fuel that is immediately injected, but what about the fuel that isn't? If you plumb it straight back to the surge tank, you could be recirculating it over and over and just heating it up, and the fuel pump etc. The cooler avoids this. I don't know if it is such an issue for sprint races etc, but would definately have been a problem at long races hence why my car has one. And as we are trying to keep it original we have kept it, but again I don't think it will matter in our 6-10 lap races.

John
ART Racing
1983 Group A MA61 Supra

[Grant]

I saw an interesting factory fuel cooler idea the other day on a TVR. They fitted a jacket around the low pressure line of the A/C pipe and passed the fuel around it. I thought it was a neat idea and probably too hard to do.

[river]

Hi,

Remember the episode of Myth Busters where they were trying to cool beer quickly? One of the ideas they used was a copper coil tubing, with dry-ice packed around it. Problem was it froze the beer. However it may not freeze petrol and if the coil tube was in a small insulated box, packed with dry-ice it may be okay for a short race.

Also, you could probably muster up something fairly easily using Peltier devices. It won't get as cold as the dry-ice, but at least it will always be available as soon as the ignition is switched on.

seeyuzz
river

[nick.parker]

Hi,
A few months ago, I drove my car for about 90 minutes on a hot day (36+ degrees). .
I logged my engines lambda over the whole drive. When I went back through the log, I discovered that on average (freeway and stop start driving) the lambda had got about 0.1 leaner from the start of the drive to the finish..i,.e. a real trend!! I think this may have been due to my fuel getting hotter and hotter. My car (4AGZE AW11) has a Walbro 255 pump. After the drive, I noticed fumes coming from the fuel tank area, and when I opened the fuel cap there was a fair bit of pressure released, this hasn't happened since that hot day.
My car 3/4 full of fuel. Actually maybe the positive fuel tank pressure was causing the problem, I am not sure.

Does anyone know the figure for fuel density vs temperature? if its significant I plan to add a fuel temp sensor and a compensation table to my ECU.

Regards, Nick.

[Joshstix]

The Walbro is quite a big pump for a GZE. You're moving the fuel through the hot engine bay a lot of times which is going to raise the temp of the fuel appreciably.

Lets look at the fuel flow you have, the pump is rated at what 255lph? Say it flows 200lph at the average fuel pressure you'll be using, then we're pumping the entire contents of a full AW11 tank through the engine bay once every twelve minutes. I don't know how big GZE injectors are so lets say they're ~350cc, assuming that over a typical drive the injectors average out to run at 50% duty cycle over all then it should take just under an hour to empty the tank. Even at this inflated rate you're still moving the fuel through the engine bay at least 5 times.

The less fuel in the tank the worse the situation gets.

This can be a big problem for a car with such a small engine bay as an AW11.

[LeeRoy]

I was sorta looking at them the other day and was wondering on what gains they would have but in regards to denser fuel and a programmable computer i'd imagine that you could just up the fuel pressure or have injectors opened for longer to get the same result.

Also with the accident fuel spraying out thing theres not too many other places but the front of the car that would be anywhere near as effective. I spose under the diff could work cause people put diff oil coolers under there and some 4x4's put radiators just above that on the trays underside.

Would there really be a point on such a thing on a say 200rwkw street car or is it just wank and show?

- LeeRoy

[EldarO]

Hey all

Fast fours or hots fours tested this sometime ago on a worked xr6 turbo. They recorded something like a 3degee increase in the heat. That was from before the pump and after the pump i think. so by the time it gets downs to the injectors that would of dropped but gone back up because of under bonnet temps. So is there really any point to cooling the fuel down unless you can get it to drop like 15degrees????


Cheers
Craig

i have this mag in my room, on the pile, if you want me to scan it or somesuch crap :/

Eldar.O.

[EVOSTi]

if you read my previous post on this, you will note that i had a problem with the heat in my fuel being so bad, it caused failure to my fuel pump. my car is around the 200RWKW mark so yes, a fuel cooler can be a good thing. but it also depends on other things, like how your system is connected. as i mentioned, i ran my return line from the rail back to the main tank rather than back to the surge tank, and this has completely elliminated my problem. at the same time however i got a lift pump that would outflow the VL high pressure pump, this is obvious as you dont want the high pressure pump to flow more than the lift pump is giving it.

[LeeRoy]

So the main problem here is pretty much the heat the fuel pump adds, and the heat added by under bonnet temps, and where you could safely mount a cooler. Ive seen an oil cooler setup that was mounted horizontally on brackets that extended from the sump, would something like that be a good place in your opinions cause its not directly at the front of the car and is hidden pretty well?

- LeeRoy