you see them on the drag/hotrod scene now and then.

all this talk in other threads about return lines keeping your fuel cooler made me wonder if there wasn't something that we could do to help 'chill' our fuel to make more power, or to prevent vapor lock.

just throwin' it out there.

Interesting idea. It would be nice to cool the fuel before it goes to the injectors. How do the drag racers' ones work? Ice? Little radiators? I guess that could work if you had a fan blowing on it pretty hard.

The factory fuel pump is actually cooled by the fuel going through it (!!) I wonder how much the temp rises because of that and the pressure increase? I'd be surprised if it gets too much above ambient. Anyone know?

I thought about this as well, however most (all road racing that I have seen) race sanctioning bodies will not let you use one. At the drag strip I have seen the ones that look like a radiator and the ones the at are a coil in a bucket that you fill with ice.

QUOTE (Reiche @ Jan 25 2005, 02:43 AM)

Ice? Little radiators? I'd be surprised if it gets too much above ambient. Anyone know?

dry ice and alcohol.

SCCA will let you use a cool can of 1-qt or smaller in Prepared and above (SOLO-II).

it can work at AX where the run times are short, or if you have a nonrecirculating fuel system (carburetors - which means you're probably in at least Prepared class in a /4). in a recirculating system, all the fuel in the tank runs through the loop eventually.

the big heat increase comes from the right heat exchanger (if the early pump is in the stock location) and - in the case of the /4 - by running aaround the fuel loop in the engine compartment.

typical gasoline boiling point is 140F - think about that the next time you're on the track with a 120F track temperature on that 100F day...

the road race cars sometimes use small radiators (heat exchangers, really...) in the airstream.

i recall a trip i took in the '72 from Phoenix to San Diego when we hit the hotel ice machine and packed the entire gas tank area with cubed ice, and repeated the process at every fuel stop. car ran fine with no vapor lock issues, but it was pretty well sorted by then anyway. but cold fuel is denser and the more *properly metered* fuel you can get in, the more power youve got available...

For many years Jaguar used a fuel cooler - the fuel line was plumbed into a small canister surrounding one of the air conditioning lines. Not really applicable for making more power (turn the AC off, stupid ) but interesting.

I run a return type fuel regulator on my carb setup. Keeps the fuel cool by the recirculation back to the tank, just like the stock system.

I could develop a thermoelectric fuel cooler if needed.

QUOTE (James Adams @ Jan 25 2005, 07:45 AM)

For many years Jaguar used a fuel cooler - the fuel line was plumbed into a small canister surrounding one of the air conditioning lines. Not really applicable for making more power (turn the AC off, stupid ) but interesting.

nowadays most cars have vacuum and/or throttle switches that disengage the AC compressor clutch when "more" power is required, and when that happens, you know you have nice cool fuel.

the new Minis do the same. cool fuel is definitely A Good Thing in a forced-induction environment...

In colorado at altitude there is less cooling than at sea level.

ALOT of guys run fuel coolers in road racing out here.
I never finished my car (which blew up) but was briefly a part of a rotary SCCA spec-7 class out here.

the fuel cooler was absolutely Required on a hot rotary motor. NO one ran without.

I know of a colorado 3.6 914 with a front oil tank. He was having quite a bit of fuel problems and vapor lock. He believes it was because his front (hot) oil was pre-heating his fuel tank. He added a radiator fuel cooler in his front trunk. A small scoope under the floor pan picks up air and then exhausts back down the bottom after it exits his cooler.

stopped his fuel problems.

Years ago in SCCA, one of our competitors decided to use a cool can. Basically a coil inside a can filled with dry ice, mounted in the engine compartment. Great idea, but the venting of the can (Carbon Dioxide vapor) was to close to the intake of the carbs. On pre-grid, the fumes could be readily seen and when he went to start the car for the race....no go He was known thereafter as the "Ice Man".

QUOTE (brant @ Jan 25 2005, 07:52 AM)

In colorado at altitude there is less cooling than at sea level.

The real problem is that boiling-point (vapor-lock) is a function of two things - pressure and temperature. The higher the pressure the higher the boiling point. So, in Denver fuel will boil at a lower temperature than it will in LA. That's why people at high altitude have vapor-lock problems in the summer when people at sea-level usually don't.

I get a kick out of the west-coast contingent who always say "914's don't vapor lock". Well, if they were to drive one up a 9,000 ft mountain pass on a hot summer day they'd change their story. Unless it had a front-mounted fuel pump. (front mounted pump increases pressure in the lines and raises the boiling point)

-Ben M.

QUOTE (nebreitling @ Jan 24 2005, 11:23 PM)

just throwin' it out there.

dunno if one would need them on our cars.
my carbs are *freezing* cold, after a 2 hour drive, they're too cold to touch.
hurting your fingers cold.

that should cool the gas enough before it gets sucked in ...
Andy

QUOTE (SirAndy @ Jan 25 2005, 01:17 PM)

QUOTE (nebreitling @ Jan 24 2005, 11:23 PM) just throwin' it out there. dunno if one would need them on our cars. my carbs are *freezing* cold, after a 2 hour drive, they're too cold to touch. hurting your fingers cold. that should cool the gas enough before it gets sucked in ... Andy

Andy's got a point....on top of his head!

No really, with carbs the fuel flashing off (going from liquid to vapor) absorbs heat from the surrounding material (the carb), which probably does a helluva job of cooling the fuel in the float bowl, but little for the fuel in the lines.......I recommend keep your car floored at all times to keep a nice stead flow of cool fuel comin' to the carbs.

I actually had my Holley Bugspray ('68 Baja bug) carb literally turn into a solid block of ice going from San Diego to Denver.....had to divert one of my heater pipes to the air cleaner to keep it running [insert smilie freezing his ass off here].

Hmmmm.....anyone running carbs in colder climates have problems with carbs freezing?

Ive relocated my pump not to the front but closer to the motor actually right on the motor cross bar. I live in fla typical 90deg days and no vapor lok. My pump is air cooled even when stuck in traffic. I moved it because it made too much noise. I stripped the encrusted smoking rusted heat exchangers off the headers then blocked the blower passages in the motor that pushed the air from the crank blower into them but when I mounted my pump on the motor bar it lined up with one of my plugged ports and I opened it up and it blasts my fuel pump with fresh air all the time it is running. Sounds a little wak but it works for me.