xxshatteredsoul

Just wondering what everyone runs for gas in their 7's. I have been running the middle grade one. You know you have your lowest middle and highest at the pump. Anyone beg to differ that I should run higher or lower i want to use the lowest because of gas prices but thought i should stick in the middle i dont know.

jrs10

87 octane... lowest available here.

You can get away with the lowest octane available as long as yer not pinging on the stock motor.

steve84GS TII

N/A rotaries love 87.They are low compression and not very prone to detonation with natural aspiration.Forced induction rotaries should run midgrade or premium,depending on mods and driving habits.
I always run 76 brand premium(a lowly 91 octane here in CA) in my TII engine.
I ran 76 brand, 87 octane in all my N/A engines,including a lively 13B 4 port with a Yaw carb and RB exhaust,and I never ever once heard a ping or rattle,even with the timing cranked up and lotsa load.

Anex 570

N/A rotary engines are High compression... the Turbo ones are low. 87 octane unless you have turbo, or live in Iraq. I'm very upset about gas if you cant tell..

steve84GS TII

Yes,N/A rotaries are higher compression than the turbo rotaries,but ALL rotaries are low compression next to comparable piston engines.
9.4 to 1 and under, makes for a pretty low compression ratio, and rotaries are anything but lean burning,which makes them more detonation resistant.

xxshatteredsoul

So should i switch to use low instead of the middle stuff?

Anex 570

Well the middle stuff is better gas and all, but its still more expensive then the cheap stuff. Theres not going to be a possitve difference between the the 2 likely, so I would just say go with low to save a little money, that you could put into other things like ignition and what not.

LongDuck

One of the benefits of the rotary engine is that you don't have to use high-test fuel to prevent pinging - they are much more resistant to pinging (in N/A) than piston engines.

The 'ping' is predetonation of the fuel as it's being compressed. In piston engines this can be caused by something as simple as carbon buildup on the valves or spark plug that remains hot enough to ignite the compressed air/fuel mixture before the spark is designed to set it off. The end result is a piston that's being forced down while still on the upstroke, posing great resistance to the crank bearings, connecting rods, and valvetrain - your 12a or 13b has none of these parts!

The lowest grade fuel that you can find is more than enough to keep clean combustion and provide good power throughout the rpm range. The only noticable difference you will find between lowest and highest grades is 1) cost and 2) higher exhaust temperatures due to unburned fuel being expelled into the exhaust headers where it's ignited by your cats. Overheating cats can result in internal breakdown and high temperatures.

So, you see, there are actually bad things that can happen when you use a fuel grade higher than what your engine needs. HTH,

xxshatteredsoul

Well in that case i'm gonn save myself some money in the future, thanks guys.

therotaryrocket

turbo engines aren't really low compression, think about it...if they are ran without forced induction then yes but when you're shoving in 6psi of extra pressure into the engine it tends to get high pressures. anyone care to correct?