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post #11 of 29 Old 12-22-12, 02:46
Dewilmoth
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Originally Posted by jardineD675 View Post
Does it heat it for aircraft because of the freeze point and for high altitudes? Having it banned from competitions sounds like it def gives an edge.

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Yep, you're right. "The heater removes water droplets and ice crystals from the fuel." I still can't find any real evidence online that cold fuel makes more power.
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post #12 of 29 Old 12-22-12, 02:52
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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.



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post #13 of 29 Old 12-22-12, 05:17
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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.

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post #14 of 29 Old 12-22-12, 06:14
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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 )

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.

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post #15 of 29 Old 12-22-12, 06:53
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Quote:
Originally Posted by sirhosis of deliver View Post
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. 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


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post #16 of 29 Old 12-22-12, 11:16
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So what's the best fuel to use, performance wize and to give moto longest life possible.

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post #17 of 29 Old 12-22-12, 11:20 Thread Starter
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Lotta interesting things I didn't know..
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post #18 of 29 Old 12-22-12, 15:20
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Originally Posted by jardineD675 View Post
So what's the best fuel to use, performance wize and to give moto longest life possible.

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Geez dude... just 2 posts up. If figured my novel would have nailed it.

Basically, if you have to ask, it doesn't matter.

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post #19 of 29 Old 12-22-12, 16:32
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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.
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post #20 of 29 Old 12-25-12, 19:55
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air is denser and less humid at lower temp --> more power
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