Fuel Question?

[jleable]

I was reading my owners manual and it says that the 400ex is designed to run on 92 octane or higher gas. I was wondering how necessarry it is to do this and will it hurt your machine if you run 87 octane in it? Also if you add 104+ octane booster to 87 octane gas does that give it enogh octane?

[ExVillin400]

there is nothing wrong with 87 it's just that you hear knocking and pinging in the engine. just go get 92 or high and you'll be fine. i heard that running octane booster will turn you valves red.

[jleable]

anyone else heard anything?

[SGA]

There were some good posts about this awhile back. Use the search link up top to find them. I would not recommend running low grade in a 400. Use mid grade or higher. The knocking/pinging is not good for the engine over time. Rule of thumb; if it knocks/pings under acceleration, go to the next higher octane gas. If it doesn't, ride away.

[RED121572]

Ive had my 400EX for two and a half years and also rebult the motor myself. Here is my two cts on gas....

If you use 87, your gonna get some serious carbon build up on the inside of the head and in the exhaust. I have ran octane booster in the past and with only using it a handful of times, it turned my exhaust valves red......it will do the same to your plug as well. Dont tell me you just spent 6 grand on your machine and cant afford 92 octane!

My suggestion is just use 92-94 octane pump gas. :D

just add a cup of sugar to 87 octain and it will run like a beast:D

[Scott]

For any kids out there that doesn't already know it, that last post was a joke. If you somehow get sugar inside an engine, it will sieze. Period. If you add sugar to your gas, you'll sieze your engine.

PS. Might want to say that's a joke next time Matrix.

[R-Crazy]

the average premuim is 91 octane. you should be fine running it premium. just try it out.

dave

[PDunes300ex]

[QUOTE]Originally posted by RED121572

I have ran octane booster in the past and with only using it a handful of times, it turned my exhaust valves red......it will do the same to your plug as well. [/QUOTE)

What does it mean that your valves and plug turned red? Isn't octane booster designed to stabilize fuel and help it withstand detinating any place other than the spark from the plug. I don't see how octane booster could hurt. At the same time though...why would you use it unless you run a high comp piston?

[RED121572]

Just like anyone else that doesnt know any better, I thought I could get more ponies out of my bone dry stock 400 using octane booster. The booster didnt necessarily hurt it, but I didnt gain anything either. What I found out was that all my stock machine needed was just high octane pump gas. It ran just great on 92 unleaded.

Im running C-12 now, which is 108 octane. With the piston that I have, 100 octane is plenty. But at this time, Im unable to get a race fuel with lower octane. (I refuse to mix pump gas with race fuel)

[harebounder]

Why would you put octane booster in you'll pay 3 dollars for it risk putting different chemical in like alcohols in a motor not designed for it.

[lil400exman]

i run vp sugar and spice gas i run it makes me haul and it smells good too!

Originally posted by ExVillin400
there is nothing wrong with 87 it's just that you hear knocking and pinging in the engine.

Yes, but pinging and knocking are indicative of pre-ignition which will destroy an engine over time.

Remember that octane has nothing to do with power production in an engine. It is merely a rating on the resistance to pre-ignition. The higher the number, the harder it is to get the gas to ignite. A higher compression engine makes more power. But it's actually the compression ratio that dictates the octane necessary for the engine to run properly.

That's why you get the knocking with lower octane gas - it's igniting before it should due to cylinder pressure (compression) and heat. This is also detrimental to power production - it's the same effect as having the timing set wrong.

All in all you're better off to spend the extra $.10-20 per gallon and get the proper octane fuel for your engine. You'll get the power it should produce and it will last longer. Running higher than necessary octane, such as race gas, does nothing but waste your money unless your engine has been rebuilt to the point that it needs the higher octane fuel.

[RED121572]

Thou has spoken!!;)