Substitute Reg for Prem? Re: OT: Oil companies

[amalventano1 at tds.net (Allyn)]

The 'recommended' minimum octane is based on the minimum the ECU is expected to compensate for, and to some extent it may not be
able to compensate for (physical, non-adjustable parameters like compression ratio, etc).

On the flip side, lower octane is generally more efficient, provided the ECU can properly adapt.  Without the extra octane boosters,
you essentially have more gas in your gas.  Sure its not a huge difference, but with todays prices, every little bit helps.

HTH
Al
 

> -----Original Message-----
> From: Chris [mailto:open.seas@verizon.net] 
> Sent: Friday, July 28, 2006 5:31 PM
> To: scirocco scirocco
> Subject: Substitute Reg for Prem? Re: OT: Oil companies
> 
> For our "other" vehicles - reducing fuel costs. I've heard 
> that reg gas can be used in place of prem gas for "recently" 
> manufactured cars (that were designed for prem) because the 
> ECU will make all necessary adjustments. T or F ?
> 
> (I tend to think of high compression and/or increased 
> ignition timing advance as creating the need for the 
> anti-knock qualities of prem fuel. 
> If the amount of advance was the only reason the mfr required 
> prem then retarding the ignition would seem to be an easy 
> change for the ECU. High compression would be a different 
> matter. I think it was Don Walter that mentioned that a 
> different cam grind would allow a high compression engine to 
> run lower octane fuel. Can an ECU make an adjustment of valve 
> timing or an equivalent change?)
> 
> (Of note is that Saab has an engine that, if I recall 
> correctly, can move the head slightly in relation to the 
> block to lower compression.)
> 
> (I did read that cars built w/n the past 5 or 10 years were 
> designed with the capability to adjust or adapt to the use of 
> alternative fuels, but the article did not mention what other 
> mods might be necessary. That is, I don't think the ECU by 
> itself would allow the use of 100% ethanol, especially due to 
> the 50% to 100% increase in volume required to use ethanol.  
> Not to mention the waxy build up and the material needed for 
> "rubber" type components in the fuel system.)
> 
> Chris
> 
> Tonee Northam wrote:
> > I tend to switch stations, BP Shell, Mobil,  every now and 
> then just to see if my car performs better.
> >    
> >   Our MV can run on e85 which nobody around here carries, 
> but I just wonder how much corn it would take to fill a 18 gal tank.
> > 
> > Blake <blake@clockworm.com> wrote:
> >   i like BP gas - seem to make my machines run better
> > 
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