3.2 EURO P & C - Octane Thirst?

[Purrybonker]

Usual question now that I'm getting my mind around a rebuild - visions of euros or 3.4's dancing in my head...

Can anyone speak to the octane rating requirements for these engines? Would either of these make sense in a 91 octane jurisdiction? (well, maybe 93 if you don't mind a little ethanol).

[Wayne 962]

More info please - stock Motronic injection?

-Wayne

[Purrybonker]

Yes, stock motronic, I'm looking to lever that engine drop to future potential. 10.3:1 sounds attractive, but not if I would have to give away timing to burn 91 - 3.4 @ 9.5 or so would then make more sense.

Motronic today - other managment systems/options as the finances and spousal relations warm-up.

I see the euro 3.2 calls for 98 RON - I'm just not sure how that converts to our R+M/2 number.

[Steve@Rennsport]

P-Bonker:

98 RON is roughly equivalent to our 93-94 R+M/2 stuff.

If all you have is 91, then stick to CR's in the 9.5:1 area unless you can blend that with something better (unleaded race gas).

Any of these Mahle pistons can be machined a bit to lower the CR and the heads can also be modified to drop the CR a bit too. That would get the CR of the 3.4 kit down to something reasonable with single-ignition and pump gas. Without twin-ignition; "less is more",...

Remember, for street performance: "There is no replacement for displacement",....

[Wayne 962]

The one caveat with Motronic is that there is no knock sensor, so if you build too high a compression engine, you're stuck - you'll have to have a custom-chip made or install an engine management system so your engine won't implode from detonation...

-Wayne