over heating 07/yzf450


28 replies to this topic
  • mdem07

Posted June 19, 2008 - 06:43 PM

#21

Back when I rode the Outdoor National circuit in 1984, I remember seeing Jeff Ward's factory Kawasaki mechanic take his gas tank out of a cooler full of ice and install it on the starting line right before taking off. So there must be something to "cooler is better". Not sure. BTW, did anyone else watch the Freestone National Race on Speed this week? Notice that Cody Cooper's mechanic poured something from a thermos into his gas tank on the starting line. Wonder what that was?????

  • KJ790

Posted June 19, 2008 - 07:27 PM

#22

Back when I rode the Outdoor National circuit in 1984, I remember seeing Jeff Ward's factory Kawasaki mechanic take his gas tank out of a cooler full of ice and install it on the starting line right before taking off. So there must be something to "cooler is better". Not sure. BTW, did anyone else watch the Freestone National Race on Speed this week? Notice that Cody Cooper's mechanic poured something from a thermos into his gas tank on the starting line. Wonder what that was?????


Factory mechanics keep the gas on ice still today, especially when it is hot out. They carry the gas in a thermos to keep it as cool as possible for as long as possible. It was 105 degrees in Texas for Freestone, they were doing everything possible to keep cool.

  • grayracer513

Posted June 19, 2008 - 10:31 PM

#23

The more you vaporize the fuel and keep it mixed with the air, the more it works to the advantage of getting all the energy out of the fuel. A hotter temp will help keep the fuel vaporized and mixed better along it's path to combustion allowing a more consistent fuel mixture. All this would be good for mileage. I'm not sure it applies to getting power out of your dirtbike though.

If you are talking about intake temperature, you are correct as to lowering emissions and increasing fuel economy, but for power production, you want a cold intake.

Theoretically speaking your engine will perform better at 180 than 230. Whether this is true in an actual situation, I don't know. Odds are the performance difference would be minute.

The idea of setting fire to gasoline in the first place is to get the heat out of it and convert it to mechanical energy. What then is the good of wasting nearly 40% of the energy extracted from the fuel by heating water with it? A cooling system that is so effective that it keeps an engine at 180 degrees is a parasitic loss of power the less energy is drawn off by the cooling system, the more is used to create torque.

Bear in mind, heat I'm talking about is in the combustion chamber. It is still true that colder intake air and fuel produce more power, but the more heat that stays in the combustion chamber, the better.

This is not entirely theoretical, either. Norton experimented with a bi-metal cylinder head (an iron combustion chamber dome in an aluminum head) on a 500cc Manx engine and gained one full horsepower in the bargain.

Kyocera once built an experimental engine completely without a cooling system. It was made entirely of ceramics, and had to have an elaborate direct injection system to keep the gasoline from igniting on contact with the thing. Power was said to be 30% greater than the same engine configuration conventionally cooled. It didn't get much farther, because there were certain practical problems involved with using an engine that developed exterior temperatures of 2400 degrees for much of anything, but they proved their point.

So does any of this mean anything to any real people? Yes. Over cooling the engine is bad. Running it a bit on the hot side is good, as long as the cooling system retains coolant, and the engine stays cool enough internally to allow the lube system to protect it.

  • KJ790

Posted June 20, 2008 - 03:45 AM

#24

If you are talking about intake temperature, you are correct as to lowering emissions and increasing fuel economy, but for power production, you want a cold intake.

The idea of setting fire to gasoline in the first place is to get the heat out of it and convert it to mechanical energy. What then is the good of wasting nearly 40% of the energy extracted from the fuel by heating water with it? A cooling system that is so effective that it keeps an engine at 180 degrees is a parasitic loss of power the less energy is drawn off by the cooling system, the more is used to create torque.

Bear in mind, heat I'm talking about is in the combustion chamber. It is still true that colder intake air and fuel produce more power, but the more heat that stays in the combustion chamber, the better.

This is not entirely theoretical, either. Norton experimented with a bi-metal cylinder head (an iron combustion chamber dome in an aluminum head) on a 500cc Manx engine and gained one full horsepower in the bargain.

Kyocera once built an experimental engine completely without a cooling system. It was made entirely of ceramics, and had to have an elaborate direct injection system to keep the gasoline from igniting on contact with the thing. Power was said to be 30% greater than the same engine configuration conventionally cooled. It didn't get much farther, because there were certain practical problems involved with using an engine that developed exterior temperatures of 2400 degrees for much of anything, but they proved their point.

So does any of this mean anything to any real people? Yes. Over cooling the engine is bad. Running it a bit on the hot side is good, as long as the cooling system retains coolant, and the engine stays cool enough internally to allow the lube system to protect it.


Agreed, that is why I said theoretically speaking. By keeping the engine itself cooler, you would be keeping the intake charge cooler. Your reasoning is exactly why I said cooler is better to an extent. Of course there is a point where cooler is not better, as there is a point where hotter is not better.

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  • grayracer513

Posted June 20, 2008 - 05:58 AM

#25

The intake charge on a short tract engine like the YZF is only incidentally exposed to the heat of the engine, unlike a automotive engine closed in under a hood, or worse, with a carburetor sitting on top of it, boiling away. You bike does expose the fuel to some heat, but nothing like that, and it's only going top be a performance factor in a situation like a tight, slow enduro section....where power isn't a factor. At speed, the whole fuel system is very well air cooled.

So, like I said, you don't want to boil out the coolant, and you don't want to burn off the oil, or melt any parts, but short of that, heat isn't a bad thing.

  • Scooter426

Posted June 20, 2008 - 07:46 AM

#26

Heat reduction in these engines is obviously important. Beyond the intake air temp, operating oil temp also has an effect on engine performance and longevity. The factory race teams spend a lot of dollars on add-on oil coolers that are integrated into the lower radiator tanks. Remember, these factory race engines are in a state of tune way beyond the average bike we ride. Stock bikes are not running as hot as a factory tuned AMA race bike.

  • blue9red9

Posted June 20, 2008 - 07:54 AM

#27

I would think that the synthetic oils used today could take the heat way up and beyond what would be required to boil out coolant of any type. Cold intake = good power. Hot combustion temp also is good for efficiency. Ever see at the drag races where guys put bags of ice on their intakes? That works to keep that intake charge cold but for bracket racing why bother I always wondered.

  • grayracer513

Posted June 20, 2008 - 08:32 AM

#28

operating oil temp also has an effect on engine performance and longevity. The factory race teams spend a lot of dollars on add-on oil coolers that are integrated into the lower radiator tanks. Remember, these factory race engines are in a state of tune way beyond the average bike we ride. Stock bikes are not running as hot as a factory tuned AMA race bike.

Oil temperature doesn't affect performance at all once it's hot, but it will impact longevity if it gets too hot, thus the concern with oil coolers. You're right about the basic formula, too; more power = more heat. Oil temperature is on of the things that limits how hot an engine can be allowed to run.

I would think that the synthetic oils used today could take the heat way up and beyond what would be required to boil out coolant of any type. Cold intake = good power. Hot combustion temp also is good for efficiency. Ever see at the drag races where guys put bags of ice on their intakes? That works to keep that intake charge cold but for bracket racing why bother I always wondered.

Synthetic oils can tolerate more heat, just not "way" more. First, synthetic oil is basically just oil, except that it's man made. Some improvements have been made with synthetic bases vs. natural petroleum, of course, but it's not huge. But, that also means that the blender gets to decide what to put in it, instead of deciding how hard he should work to get stuff out, so it is exactly what the blender wants it to be, and nothing extra. Among the things that gets left out are the more volatile solvents, which will evaporate too easily, reducing the oil volume, and other components that are prone to oxidize, or turn acidic with heat. So overall, synthetics are more heat resistant.

It's abit far off topic, but bracket racing is about consistency. You want the engine to run exactly the same all day long. Icing the intake is a way to make it run at the same temperature each run.

  • mdem07

Posted June 21, 2008 - 02:19 PM

#29

My wife & i are going riding today at cross creek cp in bastrop tx.. I just wanted to say i really thank all of you for the info . I realize that the factory bikes are way different than production bikes . I remember another time that Jonny O's factory honda 125 " yeah right " had some kind of problem and there were six Japanese tech/mech looking at a one inch thick stack of blue prints of the bike . So you're exactly right about their bikes not being the same ! Everyone keep your wheels on the ground and your feet on the pegs!!





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