zack19
New member
Ive been trying aviation gas lately in a '98 700 srx mtn (stock everything). but has a digitron on it. Normally runs about 1000 to 1200 degrees when pushing it hard, but lately has been running 1200 deg minimum and 1500 deg if your trying to be carefull. 1700+ if your really working it hard, same altitude, same clutching, same everything execpt the av gas. Still running it with the oil injection but added some yamalube mix oil to the gas tank to help just in case. Rode it for 4 hours at these temps and was expecting a meltdown because we were working it really hard (yes it smoked 800 mountain cats) but by checking the plugs during and after they were burning perfect.
Question is; anyone have any experience with this? Is it possible to run these high of EGT's without melting down a piston? Meaning higher EGT's with av gas are normal?
There is a Vari-flow installed and we had it to rich the whole time,...but with these temps we expected a meltdown within minutes,....but it ran hard the whole day until pulled back into the shop ( the arctic cat guys were tired of being beatin by a machine ten years older).
Any input into the av gas situation is appreciated...
Thanks all!!!
Question is; anyone have any experience with this? Is it possible to run these high of EGT's without melting down a piston? Meaning higher EGT's with av gas are normal?
There is a Vari-flow installed and we had it to rich the whole time,...but with these temps we expected a meltdown within minutes,....but it ran hard the whole day until pulled back into the shop ( the arctic cat guys were tired of being beatin by a machine ten years older).
Any input into the av gas situation is appreciated...
Thanks all!!!
Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft. It is generally of a higher quality than fuels used in less critical applications such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures, amongst other properties.
The net energy content for aviation fuels depends on their composition. Some typical values are:[1]
BP Avgas 80, 44.65 MJ/kg, density at 15 C is 690 kg/m3
Kerosene type BP Jet A-1, 43.15 MJ/kg, density at 15 C is 804 kg/m3
Kerosene type BP Jet TS-1, (for lower temperatures) 43.2 MJ/kg, density at 15 C is 787 kg/m3
Aviation gasoline with an octane quality of 100 is often cheaper than 100 unleaded, thus it may look attractive to performance enthusiasts. First and foremost, 100 octane Aviation fuel contains tetraethyl lead (TEL); since 1996 it has been illegal to use leaded gasoline in a licensed street vehicle and you can be fined us to $25,000 for using it. Plus, leaded gasoline will damage the oxygen sensor(s) and catalytic converter(s) found in modern vehicles.
Aviation fuel is designed for low speed aircraft engines that run at 2700 to 2800 RPM at 10,000 feet altitude. Aviation fuel often contains hydrocarbons that are detrimental to the performance of a high-horsepower street car.
There are two grades of 100 octane aviation gasoline. One is identified as 100LL and is blue in color. The other is 100/130 and is green in color. The second number (130) shown for the green fuel is a measurement using a supercharged octane test engine. Although this 130 octane number is higher, it is achieved from an entirely different test and rating system than octane numbers determined with normally aspirated engines. For comparison, Rockett Brand 111 octane tests out at over 160 octane using the supercharged aviation method that indicates Rockett Brand 111 has a significant advantage in anti-knock ability over 100/130 aviation gasoline.
Lead in the form of "Tetraethyl Lead", sometimes called TEL, is an anti-knock compound. When TEL is added to gasoline, it raises the octane number and therefore reduces the chance for detonation. If you have a race engine with very a high cylinder pressure (due to a high compression ratio, a high boost turbocharger, a supercharger, and/or a nitrous oxide system) you may need a leaded racing gasoline.
The net energy content for aviation fuels depends on their composition. Some typical values are:[1]
BP Avgas 80, 44.65 MJ/kg, density at 15 C is 690 kg/m3
Kerosene type BP Jet A-1, 43.15 MJ/kg, density at 15 C is 804 kg/m3
Kerosene type BP Jet TS-1, (for lower temperatures) 43.2 MJ/kg, density at 15 C is 787 kg/m3
Aviation gasoline with an octane quality of 100 is often cheaper than 100 unleaded, thus it may look attractive to performance enthusiasts. First and foremost, 100 octane Aviation fuel contains tetraethyl lead (TEL); since 1996 it has been illegal to use leaded gasoline in a licensed street vehicle and you can be fined us to $25,000 for using it. Plus, leaded gasoline will damage the oxygen sensor(s) and catalytic converter(s) found in modern vehicles.
Aviation fuel is designed for low speed aircraft engines that run at 2700 to 2800 RPM at 10,000 feet altitude. Aviation fuel often contains hydrocarbons that are detrimental to the performance of a high-horsepower street car.
There are two grades of 100 octane aviation gasoline. One is identified as 100LL and is blue in color. The other is 100/130 and is green in color. The second number (130) shown for the green fuel is a measurement using a supercharged octane test engine. Although this 130 octane number is higher, it is achieved from an entirely different test and rating system than octane numbers determined with normally aspirated engines. For comparison, Rockett Brand 111 octane tests out at over 160 octane using the supercharged aviation method that indicates Rockett Brand 111 has a significant advantage in anti-knock ability over 100/130 aviation gasoline.
Lead in the form of "Tetraethyl Lead", sometimes called TEL, is an anti-knock compound. When TEL is added to gasoline, it raises the octane number and therefore reduces the chance for detonation. If you have a race engine with very a high cylinder pressure (due to a high compression ratio, a high boost turbocharger, a supercharger, and/or a nitrous oxide system) you may need a leaded racing gasoline.
Been there
When this happend to me I learned that I was using too much octane. The fuel burns slower and you end up with more heat in the pipe.....you actually are burning the last part of your fuel charge in the pipe. If the temp in the cylinder was 1,700 you would have probably hurt the motor. Start cutting your AV gas with pump gas. You will be able to watch the EGT numbers go down because more of the burn will take place in the cylinder where it is supposed to. You will also see a significant increase in power and performance. The sled might seem like it's runnig good right now but it has a lot more potential. Your plugs might look good but I'd be willing to bet that there are not very brown in color.....probably more like grey. As you cut it with pump gas keep an eye on plugs and piston wash. As a result you will see your EGT numbers go down.
Madmatt
When this happend to me I learned that I was using too much octane. The fuel burns slower and you end up with more heat in the pipe.....you actually are burning the last part of your fuel charge in the pipe. If the temp in the cylinder was 1,700 you would have probably hurt the motor. Start cutting your AV gas with pump gas. You will be able to watch the EGT numbers go down because more of the burn will take place in the cylinder where it is supposed to. You will also see a significant increase in power and performance. The sled might seem like it's runnig good right now but it has a lot more potential. Your plugs might look good but I'd be willing to bet that there are not very brown in color.....probably more like grey. As you cut it with pump gas keep an eye on plugs and piston wash. As a result you will see your EGT numbers go down.
Madmatt
I was told that bad things happen at 1400 to 1500 degrees is that correct? I have a 600 twin with wiseco pistons vforce3 reeds a 500cc cylinder head and a MBRP can rode the other day a EGT was around 1000F or less but was taking it easy seeing this was the engines first trip at the end of the day opened her up temp climbed to 1100 at WOT at top speed is this normal. At what temp will bad things happen? thanks
zack19
New member
Thanks DV8 and MADMATT, thats alot of info you guys know your stuff!! Ill try cutting it like you say and see, hopefully as you say the temps will come down, and more power is always good! The plugs where a nice medium chocolate brown though, but possibly due to the extra oil we mixed with the gas??
And for mtnmaxman, im not sure about your application but with the srx 700 we normally try not to let the egt's go past 1200 deg. I believe though that even on diesel trucks anything over that is considered your getting close to a meltdown?? Someone else on here would probably have a better idea though.
And for mtnmaxman, im not sure about your application but with the srx 700 we normally try not to let the egt's go past 1200 deg. I believe though that even on diesel trucks anything over that is considered your getting close to a meltdown?? Someone else on here would probably have a better idea though.
Extra oil
Yeah, stop putting the extra oil to it.....that will actually create a slightly leaner condition. Just start cutting it with 91 pump gas. The sled will wake right up. It will get much more snappy and revvy on low to mid range and top end will clean up considerably. You will most likely notice an increas in RPM. As I said though keep an eye on plugs and piston wash. I really believe the only way you could see EGT numbers that high and still have your motor in one piece is if you are still burning fuel in the pipe due to too much octane.
Lets not compare a two stroke to a diesel engine unless your two stroke has oil in the case to help cool it along with oil injectors spraying from underneath the piston to help cool the dome.
Good luck!
Matt
Yeah, stop putting the extra oil to it.....that will actually create a slightly leaner condition. Just start cutting it with 91 pump gas. The sled will wake right up. It will get much more snappy and revvy on low to mid range and top end will clean up considerably. You will most likely notice an increas in RPM. As I said though keep an eye on plugs and piston wash. I really believe the only way you could see EGT numbers that high and still have your motor in one piece is if you are still burning fuel in the pipe due to too much octane.
Lets not compare a two stroke to a diesel engine unless your two stroke has oil in the case to help cool it along with oil injectors spraying from underneath the piston to help cool the dome.
Good luck!
Matt
yamahauler4
New member
Stupid question: I rode out yesterday in minus teen conditions. Im jetted to run WFO in 10+. I just didn't do long pulls, and braaped alot... no issues.
Can using 91-93 octane in these conditions make up for lean jetting a bit? I.E. instead of rejetting (PITA), if you're worried, can gas get you through?
Can using 91-93 octane in these conditions make up for lean jetting a bit? I.E. instead of rejetting (PITA), if you're worried, can gas get you through?