what octane should i be using?

[StrokedSix]

i have the basic 2.7 stroker build with a stock "i" cam and an Alpina 2.7 tune. i'm using 89 octane right now and it seems to be working fine. what do you guys use? should i go down to 87?

using 89 octane, i averaged 26.7 on a 300 mile trip averaging 70 mph. how does that compare?

[BahnE30]

when selecting the proper octane for your engine, don't worry about mileage, worry about pinging and knocking, which are signs of detination, if you are hearing this, use higher octane, if you still get pinging and knocking once you've gotten to the highest available, retard the timing.

[StrokedSix]

i don't hear any pinging or knocking with 89... should i try 87 then?

i'm still curious to see what mileage other stroker guys are getting.

[nando]

what's your compression ratio? also, do you have a chip? both of those are important when considering your fuel.

I'm using 92 with 10:1.1 and a bavauto chip. it seems to run fine. but just because you don't hear pinging doesn't mean it isn't happening...

[SpecM]

-You say you have a "basic" 2.7 stroker... so you used s-eta pistons or what? If so, then your CR is only 8.5:1, fairly low. I ran 89 oct in my old '88 325 (s-eta), but no chip, and that's what will make the difference in yours.

[robsgotit]

i assume he's got an "i" cam in an "e" head like i do,

how can one retard the timing without an adjustable, cam gear??? is it possible?

[StrokedSix]

what's your compression ratio? also, do you have a chip? both of those are important when considering your fuel.

I'm using 92 with 10:1.1 and a bavauto chip. it seems to run fine. but just because you don't hear pinging doesn't mean it isn't happening...

i am using a chip from an Alpina 2.7... i don't drive the car much now that i am back at school, but i'll try 87 octane next time i need to fill up and see how it does with that.

[bmwdude]

I didn't know Alpina made chips? I thought that it was the complete ECU from the C2 2.7 or B3 2.7 one had to get.

[nefarious7907]

I know of few places around here specifically porsche tuners that can rip custom chips. Imagine Autosport sound familar to anyone???