Octane rating in France - Germany? What compression should I use?

[Chuckcruzin1986]

I am building a 2.7i M20 engine for my 1986 325es which I will be shipping to France when I move there. It just dawned on me that I really need to build the engine for the gasoline they use.

So, does anyone know the octane rating "over there" and a recommendation for my compression ratio?

Thanks
Chuck

[lateracer]

In general, the more you can raise your compression (a la custom pistons) the better on a 2.7. There aren't really any considerations you need to make if you're doing a budget build and/or your compression is going to stay below 10:1, just about anything should do.

European octane is generally rated 4 to 5 points higher for the same fuel, so an 89 octane here might be a 91 or so there. Lower octane won't hurt a lower compression motor.

[nando]

they use RON octane ratings, we use PON. different ratings, PON will always be lower. generally 95 RON = 87 PON.

[Chuckcruzin1986]

Octane rating in Europe

they use RON octane ratings, we use PON. different ratings, PON will always be lower. generally 95 RON = 87 PON.

That helps a lot. I thought europe had much higher rating but it still seems a little higher.

My real question is how high should I make my compression. I am planning on milling my head .050" which should bring me to about 10 - 1

Good or bad idea?

Thanks, Chuck

[felix]

Sorry, been away for a bit... you can get 99-100 octane in Western Europe that is equivalent to 93-94 octane in the US.

[nando]

10:1 should be fine, even for 92 octane.

an agressive cam will reduce the tendancy to knock at peak torque, the higher the compression the more agressive cam you should use. 10:1 really isn't that high anyway, many factory engines these days are 10.5:1.

[der affe]

have you concidered building the motor/fuel system to use E85?
isn't it cheaper and more readily available over there? remember that fuel costs are going to be higher over there too. just a though......