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Cold gas = more power?

4K views 28 replies 22 participants last post by  purpletriumph 
#1 ·
So I was at work and its like.... 43 degrees turned my bike on to warm it up. Warmed it up nd took off, so when I go WOT the bike pulled like a mofo.! Was it the cold air its sucking in cause I know motors work better with cold air yeah. But what about fuel? Does it make difference if the gas was cold cause I could feel my tank freezing on my legs..
 
#4 ·
Yep, as illustrated by our super/turbocharged resident nutters, our bikes are restricted by air, and not fuel, intake.
 
#7 ·
If i recall correctly back from my automotive class in highschool... you want cold air and warm fuel.... Cold air is more denser you thus giving you more oxygen which is the key to the gas igniting, then you want warm fuel as it being warm helps the gas vapors atomize better allowing for it to mix better with the more denser air.

It follows the same principles, i believe, of using NO2 super cooled, dense air mixing with the fuel gives better HP....

please dont quote me any of this, this is just things i think ive picked up over my short years here on earth
 
#8 ·
If i recall correctly back from my automotive class in highschool... you want cold air and warm fuel.... Cold air is more denser you thus giving you more oxygen which is the key to the gas igniting, then you want warm fuel as it being warm helps the gas vapors atomize better allowing for it to mix better with the more denser air.

It follows the same principles, i believe, of using NO2 super cooled, dense air mixing with the fuel gives better HP....

please dont quote me any of this, this is just things i think ive picked up over my short years here on earth
Sorry that's not the case. You want the charge to be as dense as possible therefore colder is always better. Fuel chilling has been banned in almost all racing series for a reason.

BTW, cool fact, the mclaren SLR actually uses the AC system to cool the fuel before it's injected.
 
#12 ·
All I know is on the race bikes a lot of the riders have heat reflecting tank covers while they are sitting on the grid to help the fuel from heating up too much. Fuel is probably a balance of not being cold or hot, just room temperature for best performance.
 
#13 ·
Those reflecting covers are probably just to stop the fuel from heating, expanding and spewing out on the ground, thus effectively giving you less fuel for the start of the race than you initially put into the tank. They would only want to carry as much fuel as they need to save weight.

Most series have a fuel limit too, so if you only are allowed to have a 17 litres and you spew 1 litre out on the start grid, theres a good chance you arent going to finish the race.
 
#15 ·
Those reflecting covers are probably just to stop the fuel from heating, expanding and spewing out on the ground, thus effectively giving you less fuel for the start of the race than you initially put into the tank. They would only want to carry as much fuel as they need to save weight.

Most series have a fuel limit too, so if you only are allowed to have a 17 litres and you spew 1 litre out on the start grid, theres a good chance you arent going to finish the race.
bingo. :thumbup: but not only that

there was a point were race teams were cooling fuel to just above the freeze point as to get the maxium into the tank, this since has been regulated buy most motor sporting bodies. from memory moto gp teams are allowed to cool the fuel to 17 degrees C ( dont quote me on that)

if you have a 21L tank (like moto gp) and you can get 21.3 L in by cooling the fuel that .3 of a litre could mean you can run that extra bit of full throttle for say 2 laps which could mean winning or losing. hence why its regulated

sure theres a lot more elements to this and racing but thats for another thread

(insert link here)
 
#14 ·
There are a few reasons to control the temperature of fuel, and very seldom does it have to do with outright power.

First off, optimal fuel temp can increase combustion efficiency but the effect is typically <1%.

Second, there are different factors at play with aviation applications and automotive.

The real answer is it is vehicle specific. Understand there is FAR more air than fuel in the combustion chamber at any given time so the density of the charge is rarely a concern with the gas, that's an air concern. Also, consider that the specific heat of gasoline is relatively low, so whatever heating/cooling is done can be changed quite easily making it a difficult/futile endeavor.

So anyway, in aviation, turbine engines have no predetonation issues to contend with and warmer fuel DOES atomize better, thus (and in combination with the issue of frigid temps at altitude) you will typically see aircraft heat fuel for atomization and also to simply put more energy through the engine (more in, more out) as turbines will GENERALLY (this is very general I know) put out more and more power until material limits are reached (over temp/speed).

Fun fact, the SR-71 blackbird had a system to burn off the hottest fuel first, as it used the fuel on board as a heatsink integral to the airframe. It pulled heat away from the engines, avionics, etc.

Now in an automotive capacity typically you are fighting detonation. In this case cooler fuel can help combat cylinder temperatures and fight detonation. Understand that this IS hurting combustion efficiency somewhat but it's a lesser of 2 evils. Lose 2 hp on ideal combustion or gain 20 in a more aggressive tune?

There are other factors for specific vehicles as well. For instance, old porsche race cars had fuel lines routed over the exhaust and would experience vapor lock when fuel in the lines boiled. Fuel temperature management became essential, for reasons that had nothing to do with the actual running of the engine (well besides it NOT running :rofl2: )

I'm willing to bet dollars to donuts these new cars with A/C mounted fuel coolers also have some kind of temp sensor for the gas and can adjust the ignition advance to make more power with a cooler gas temperature, without the worry of detonation.

*****TLDR: you, at home, will never notice a difference. Go make some ben franklin's and buy some expensive computers and maybe you too can realize the <1% power advantage of fuel heat management.
 
#19 ·
Cold fuel produces more power. Not because it's denser, but because the first chemicals to evaporate are the power-producing volatiles. That's why at Daytona for instance, they pour chilled fuel into the tank and leave an insulating cover over it.

Colder fuel also helps cool the engine a little, and you need all the cooling you can get when you're squeezing 135 hp out of a 600.
 
#21 ·
Cooler gas helps to keep a lower temperature in the cylinder head.I don´t know exact values but it has to be a pretty smal benefit.
A much bigger benefit would be injecting more fuel than necessery at 0% throttle (e.g. at braking). It helps to cool the cylinder due to atomizing of a liquid extracts heat from the envrironment.
 
#23 ·
I can't speak to the colder = more power conversation but I just came across this interesting bit of news from a blog written by Kevin Cameron:

"We are lucky to get time with experienced engineers Jeremy Burgess and Tom Houseworth. Burgess mentions in passing "the 20 large freezers that the teams have to carry with them." They are to chill the fuel, shrinking it so that more will fit into the 21-liter tank volume each prototype bike is allowed. Hydrocarbons shrink at a rate of about one cc per liter, per degree Centigrade, so cooling the fuel from room temperature to the freezing point of water lets a team put 440 extra cc of fuel into the tank."

Link to complete article: http://www.cycleworld.com/2012/11/29/valencia-motogp-to-eicma-2012-kevin-cameron/
 
#25 ·
Cold air please.

I agree with other saying about cooler air offering more power as it is denser therefore you increase volumetric efficiency. Basically the amount that you can fill up the cylinder with ignitable fuel/air before compression/power strokes.
I always thought that colder fuel would offer the same but from what some have said it seems that warmer is better? I did read up a while ago that GP teams freeze their fuel in some cases for longer tracks especially so that can have it extremely cold when they go to fill up their fuel tanks, as it allows them to put more fuel in initially as it has contracted. I can't remember what bike mag I read that in but it did sound rather extreme...
 
#26 ·
I agree with other saying about cooler air offering more power as it is denser therefore you increase volumetric efficiency. Basically the amount that you can fill up the cylinder with ignitable fuel/air before compression/power strokes.
I always thought that colder fuel would offer the same but from what some have said it seems that warmer is better? I did read up a while ago that GP teams freeze their fuel in some cases for longer tracks especially so that can have it extremely cold when they go to fill up their fuel tanks, as it allows them to put more fuel in initially as it has contracted. I can't remember what bike mag I read that in but it did sound rather extreme...
Just seen the reply above. Kevin Cameron. There we go ;)
 
#27 ·
I also have a Triumph car, which cools its fuel when the air conditioner is on:thumbup: by using fuel line coiled around the cold piping to the car cabin.
hmmm... its probably trying to stop the fuel vaporizing before it hits the carburetors, but it may also replenish some of the horsepower that the air-con takes away.

Cold fuel is good for horsepower:cool2: but because it atomizes poorly, it could mean worse economy:scooter:.
Cold air is denser so there's more air getting in, which also makes the bike's ecu put more fuel in.

that's my take on it...
 
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