Just curious what octane are you using for your 325is? (87')

[optimusp517]

I've been filling up with 91 cause I believe the manaul says it, but what does everyone fill up with? I live up here in the Pacific Northwest so I'm not sure if that has any effect on which octane I should be using.

[AdamF 88iS]

91. Mine pinged with anything less around here.

[The Fast One!]

run mine on 87 ALLLL the time, no pings or anything, car runs great and fast.

don't have 91 around here just 87, 89, and 93. should prolly put 89 in it just to be safe though.

[StereoInstaller1]

Too much octane is bad. Higher octane ratings mean lower combustion temperatures: more unburned fuel. That is how detonation is controlled, by reducing temperatures in the combustion process.

Read this http://auto.howstuffworks.com/question90.htm so you understand what octane means.

M20's are a low compression ratio engine. Higher octane gas is a waste (and by "waste" I mean fucking stupid) unless you are chipped and have radically advanced your timing curve, or have a shaved head/block/different pistons whatever.

Luke

[RobertK]

Too much octane is bad. Higher octane ratings mean lower combustion temperatures: more unburned fuel. That is how detonation is controlled, by reducing temperatures in the combustion process.

Read this http://auto.howstuffworks.com/question90.htm so you understand what octane means.

M20's are a low compression ratio engine. Higher octane gas is a waste (and by "waste" I mean fucking stupid) unless you are chipped and have radically advanced your timing curve, or have a shaved head/block/different pistons whatever.

Luke

I use 93 religiously with 3.5 oz of Acetone to every 10 gallons in both of my cars. Unburned fuel is also caused by the surface tension of gasoline and how well it can be ionized.

The acetone helps to break the surface tension of the gasoline much like how jet dry in your dish washer breaks the surface tension of water. It also causes much more of the gas to be ionized when injected into the combustion camber.

[James Crivellone]

91 in mine, although I require it due to my Mark D Chip

[PУCCKAЯ_e30ka]

89, not too high, not too low

[HST]

I use 93 religiously with 3.5 oz of Acetone to every gallon in both of my cars. Unburned fuel is also caused by the surface tension of gasoline and how well it can be ionized.

I think he means 3.5 oz per tank.
I do the same in my E36, 4 oz per tank.

[RobertK]

I think he means 3.5 oz per tank.
I do the same in my E36, 4 oz per tank.

Fixt!

[e30Matt]

I run 93 due to the chip (JC). I wish we had something between 93 and 89 though.

[mspiegle]

If your car runs fine on 87, DO NOT use higher octane gas. It will eat up your cat faster, lower your gas mileage, and provide LESS power.

[optimusp517]

If your car runs fine on 87, DO NOT use higher octane gas. It will eat up your cat faster, lower your gas mileage, and provide LESS power.

I'm going to give 89 a shot and see how the car runs... Just alwasy wondered even though the manual instructed 91 for the car.

[erik325i]

I'm going to give 89 a shot and see how the car runs... Just alwasy wondered even though the manual instructed 91 for the car.

The manual does not call for any higher than 87 octane for 325s. Only m42 and s14 powered vehicles require 91 octane.

I only put 87 octane in my car. never had any problems with it.

-Erik

[Digitalwave]

I use 93 religiously with 3.5 oz of Acetone to every 10 gallons in both of my cars. Unburned fuel is also caused by the surface tension of gasoline and how well it can be ionized.

The acetone helps to break the surface tension of the gasoline much like how jet dry in your dish washer breaks the surface tension of water. It also causes much more of the gas to be ionized when injected into the combustion camber.

How could you possibly need 93 octane and acetone on a stock M20?

[augusta325is]

The manual says 91 but it does not mean 91 OCTANE. I use 87 all the time no problems and ALSO 3 oz acetone to every 10 gallons.... About 20 mores miles out of a tankful after I started it.