Hiya all,

I was directed here by a friend of mine who I'd been speaking to about an on-board fuel cooler in my sprint/hillclimb saloon car. He suggested I put forward my thoughts on here and see what you technical guys n gals throw into the pot. Sorry to have my first thread as an enquiry, but races to be won this year and I'm keen to get something built soon!

I have an issue with the fuel system on my car collecting an enormous amount of heat from various sources (exhaust and engine) which means whilst it's running, the fuel can reach temps of 35c easily which is affecting power quite dramatically! I've insulated what I can to slow the heat absorbtion but now want to build an on-board cooling system capable of feeding the engine with petrol at around 0 degrees c. This has shown an extra 60hp on the dyno.

Here's a few ideas that have been put to me so far:

1) coil 10mm copper pipe inside a sealed aluminium tube full of water, freeze the water before each outing and pass the fuel through the copper pipe to the engine as the ice melts.

2) fit a small pump to a 10 row oil cooler, submerse the cooler into iced water and pump the fuel through this from the base of the tank back to the top of the tank. This could be kept inside the car and run as the car is driven.

3) fit a copper coil into the tank and pass liquid nitrogen through to cool the fuel in advance of arriving at the start line.

The quantity of fuel I'm talking about would be around 5 litres at a time and the base of the tank has a cylinder below to act as a swirl pot. There's spare fittings on the swirl pot (3 litre capacity) to allow me to try option 2 above. I already carry a large quantity of ice in an insulated container to keep the beer cold for the weekend so I have a source of ice at hand.

Would it be possible to build a 12v system capable of cooling this amount of fuel in around 10 minutes yet have it small and light?
Ideally I'd like to be able to chill the fuel to around -5c at the tank so it reaches the engine at around 0c.

Am I asking the impossible?

A few more points: The car is used for Sprints & hillclimbs and is therefore only ever driven hard for a maximum time of 30 - 120 seconds. This is why I can get away with carrying only 4 litres of fuel.

The car has a tunnel underfloor with an air gap between the bodyshell and the tunnel which the exhaust passes through (almost all the car length), this is where the bulk of the heat is picked up by the fuel.

The factory aircon has been previously removed for weight saving!

Any input would be greatly appreciated.

Many thanks in advance