Gas Question

[12 o'clock]

Can i run 115 octane gas on the stock 450 and if so will it perform any better

you could but i doubt you would notice a difference, the only reson to use higher octane is if you ahve a high comp. piston you will have better luck with oxygenated sp? gas on a stock bike but still not too much diff

[mikes450r]

using a higher octane gas that is not needed can actually cause you to lose hp..

mike

[trost66]

I heard the same thing about loosing horsepower with high octane fuel when you don't need it. They say the motor will run to cool and it will not put out as much power. The motor is made to run so hot so it will put out certain amount of btu and that where you get your power. I think it was somthing like that

[12 o'clock]

what about using high performance coolants in the radiator?doesnt that help the enginge run cooler and if that is the case how does it not rob it of horsepower

[mikes450r]

i believe hes talking about the time of detanation on the quad...not the temp

[12 o'clock]

i see makes more sense now`

If you use race fuel in a stock engine you get a lot of unburned fuel coming out of the exhaust. It will rob you of horsepower.

[DaveEX7]

How about super/ premium octane (93)? Will that rob you of any hp on a stock motor?

[DaveEX7]

bumpage

[wanta450]

what octane gas would you guys recommend for a stock 450r

[watts16]

the manual say 91

Any pump gas 91 to 94 would be fine.

[DaveEX7]

Originally posted by wanta450
what octane gas would you guys recommend for a stock 450r

Like 450R Racer said... 91-94 or plus unleaded up to ultra 94 unleaded and that crap inbetween =)

[JW450R1]

i was running 50-50 mix with 110 sunoco purple and 93 pump gas.my 04 450r ran like crap.stalling. it was to much.i started running regular,and now it runs great.u only need high octane race gas for hopped up motors up dome pistons

[Rico400]

we run premium only... one time someone in our group bought regular for us all and we didnt know, and we were wondering why all of our bikes were running like crap. he changed plugs and all that stuff, then he said it might be because we were running regular.... so we went and got some premium and that bikes were running awesome....:devil:

[GPracer2500]

A fuels octane rating is a representaion of the fuels ability to resist detonation. And that's it. A fuel with a high octane rating doesn't contain more energy or yield higher HP or anything else. [note: there are some race fuels that do yeild higher HP all by them selves (oxygenated race fuels) but that is independent of the fuels octane rating. Some other fuel characteristics may help tiny amounts in producing power, but not octane.]

Detonation is an abnormal combustion phenomenon in which the air/fuel mixture at the very edges of the cylinder explode before the flame front reaches that area of the cylinder. When the spark plug fires the air/fuel mixture doesn't "explode" like we commonly think it does. It burns at a regular and predictable rate starting at the spark plug and spreading outward. As this burn is taking place expanding gasses are produced and the pressures inside the cylinder rise rapidly. This increasing pressure can get so high that the air/fuel at the edges that hasn't started to burn yet can reach a point where it spontaniously explodes. This is detonation. When it occurs you'll hear a tell-tail "ping" or "knock" noise coming from the engine. Detonation produces lots of heat and hurts HP. In severe cases it will destroy an engine. It's a little more complex that that but that's the jist of it.

High compression ratios, lots of ignition advance, high temperatures, and high engine loads create conditions that favor the occurance of detonation. So, it's the particular tune of an engine and its operating environment that dictates the engine's octane requirement. If an engine doesn't detonate on 91 octane fuel than using 100 octane fuel does nothing.

Sidenote: the compression rating that really matters is dynamic compression which is different than compression ratio. An engines dynamic compression doesn't start until the intake valves close on the compression stroke. So, cam specs effect the all-important dynamic compression. Aggressive cams typically leave the intake valves open longer which lowers dynamic compression. Also, the density of the intake air affects dynamic compression. If you run a compression check at sea level and then again at 5000 feet, the sea level test will yield a higher figure. This is why many cities at high elevations (Colorado Springs CO for example at ~6500 feet) have a low grade of fuel rated at just 85 instead of 87. Engines at that altitude don't need as much octane because they don't have as much dynamic compression.

Ok, essay over--carry on....