Octane Rating

["Kevin Randle" <randle@cae.ca>]

On May 7,  6:16pm, TFP wrote:

> Subject: Re: Stick vs Auto
> VERY INTERESTING!!!!!
> Thanks for the info...  Anyone else have any PROs/CONs about the
> automatic???  Hey, and since you mentioned it, what OCTANE do they
> recommend you put in these little beasts?  My buddy works where I
> bought my car as the head mechanic (manager) and he said the cheap
> stuff is fine....  I think I prefer about 89 or even the 92 octance
> stuff. I can ONLY find in my manual that it should be a minimum of
> 86 octane - unleaded!!!
>
> Thom
>

Hi Thom,

The back of my gas cap door has a sticker that says:

"Min Octane 87, premium recommended."  Here in Canada, premium (super)
is usually 92.  From what I remember from my Thermo II class, octane
acts as a "pre-ignition" retardant.  Something about it being a big
chain molecule, and takes longer to ignite.  Therefore in engines with
high compression, higher octane fuel is required in order to avoid ping
(pre-ignition).  I don't have the specs on hand, but I seem to remember
that the VR6 has more or less the same compression ratio as VW's 2.0,
which runs fine on 87 octane.

Octane also, I think, has higher energy content, so for a given squirt
from the injector, you get a bigger bang.  I think that's why you (and
I) prefer the higher octane fuel.

Regards,

- -- 
+-----------------------+-----------------------------------+
|                       |              CAE Electronics Ltd  | 
|     Kevin Randle      |                      PO Box 1800  |
|     randle@cae.ca     |  St Laurent, Qc, Canada  H4L 4X4  |
|                       |         (514) 341 2000  ext 2301  |
+-----------------------+-----------------------------------+