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Agreed...
Posted by PGAero

(# 1143) (more from PGAero) on Mon, 7 Mar 2011 02:36:41
In Reply to: Re: Check your mileage, john b

, Sun, 6 Mar 2011 22:00:20

The laws of physics do suggest that lower octane (and therefor higher energy density) fuel will be more efficient *IF* the thermodynamic process of compression, spark, and combustion remain fixed.

With our Saabs, this second piece of the equation does not remain fixed. The knock prevention in higher octane fuels allow for a more efficient (thermodynamically) set of running parameters. (Of course those changed parameters are also the ones that make the engine more powerful, and result in some heavier right-foot action from some of us, at least some of the time). High compression engines take advantage of this with every cycle.

Of course, changes in elevation and air temperature make a big difference too.

posted by 212.112.107...

Posts in this Thread:

$4.29 a gallon, No Snaab , Sun, 6 Mar 2011 08:49:57
- $7.90 in Pisa, OKSaabs , Wed, 16 Mar 2011 14:10:34
- $3.549/gallon for 93 octane in Detroit area, MI-Roger , Tue, 8 Mar 2011 16:33:49
- DISTANCE, Saabinhappy, Tue, 8 Mar 2011 12:25:07
  - Very valid point, AdamB , Thu, 10 Mar 2011 09:05:45
  - The U.S. is set up around the car. Other places,, Noel , Wed, 9 Mar 2011 14:16:30
  - we have similar distances here in Australia too..., sab, Tue, 8 Mar 2011 18:34:46
  - That's true, Kristjan, Tue, 8 Mar 2011 15:08:16
  - Re: DISTANCE, turbocon86, Tue, 8 Mar 2011 13:01:45
- $8.82 current Shell list price for regular in Denmark, AdamB , Tue, 8 Mar 2011 08:59:44
  - Re: $8.82 current Shell list price for regular in Denmark, JimBlake , Tue, 8 Mar 2011 11:02:43
- Re: $3.59 Greenville SC...bringin up the rear, baby!nm, scott k, Mon, 7 Mar 2011 21:32:04
  - $3,29 for 89 octane in OKC Monday evening, OKSaabs , Tue, 8 Mar 2011 04:39:34
- $4.019 Costco Premium San Diego, Mike Lynch , Mon, 7 Mar 2011 10:27:14
- $3.60 in central VA, nuotatore, Sun, 6 Mar 2011 18:25:32
- Re: $4.29 a gallon - still cheap there, LesH , Sun, 6 Mar 2011 17:40:07
  - $1.38/L ($5.22/gallon) for premium..., James, Mon, 7 Mar 2011 05:18:44
    - regular hasn't been under $1/L ($3.80/ga) for ages..., James, Mon, 7 Mar 2011 08:07:14
  - yet people still drive huge SUVs and full size trucks., LesH , Sun, 6 Mar 2011 17:44:17
    - Re: yet people still drive huge SUVs and full size trucks., kkelley, Tue, 8 Mar 2011 07:22:14
      - Used to do it, No Snaab , Tue, 8 Mar 2011 10:45:18
        Mostly agree., Noel , Tue, 8 Mar 2011 14:32:40
      - Re: yet people still drive huge SUVs and full size trucks., LesH , Tue, 8 Mar 2011 09:38:40
      - Re: yet people still drive huge SUVs and full size trucks., JimBlake , Tue, 8 Mar 2011 08:08:08
        Re: yet people still drive huge SUVs and full size trucks., Kristjan, Tue, 8 Mar 2011 10:20:20
    - Absolutely true!!, scottg , Sun, 6 Mar 2011 18:05:52
- And it's gonna get worse., Noel , Sun, 6 Mar 2011 16:52:17
  - Sounds reasonable but what about Autumn 2008?, AeroBaron, Mon, 7 Mar 2011 12:46:33
    - Re: Sounds reasonable but what about Autumn 2008?, john b , Mon, 7 Mar 2011 21:54:15
  - Yeah, lots worse unfortunately, john b , Sun, 6 Mar 2011 22:08:22
    - A friend of mine insists it's all fake...., Noel , Mon, 7 Mar 2011 10:53:21
      - Re: A friend of mine insists it's all fake...., john b , Mon, 7 Mar 2011 21:57:19
- Damn thats cheap! abt US$6.02 here in Oz, sab, Sun, 6 Mar 2011 13:01:11
- Sweden ~$7.76 a gallon, SWEDECAR , Sun, 6 Mar 2011 11:52:15
- Re: $4.29 a gallon, EGD , Sun, 6 Mar 2011 11:11:17
- $4.50 REGULAR in DC..., Craig, Sun, 6 Mar 2011 10:48:13
- Just filled Mobil 91 yesterday. $4.10 locally. n/m, SWEDECAR , Sun, 6 Mar 2011 09:46:16
- $3.79-3.89, Slug , Sun, 6 Mar 2011 09:23:06
  - Re: $3.79-3.89, EGD , Sun, 6 Mar 2011 09:36:31
    - $3.35 regular, Slug , Sun, 6 Mar 2011 11:09:44
      - Re: $3.35 regular, Aom, Sun, 6 Mar 2011 14:55:41
- Re: $4.29 a gallon, kkelley, Sun, 6 Mar 2011 09:09:17
  - Check your mileage, No Snaab , Sun, 6 Mar 2011 12:33:43
    - Re: Check your mileage, TML, Sun, 6 Mar 2011 18:50:41
      - Re: Check your mileage, john b , Sun, 6 Mar 2011 22:00:20
        Agreed..., PGAero , Mon, 7 Mar 2011 02:36:41
        And..., PGAero , Mon, 7 Mar 2011 02:47:20
        Re: And..., TML, Mon, 7 Mar 2011 05:04:14
        Glad someone is saying this..., Noel , Mon, 7 Mar 2011 05:52:32
- $3.73.., Chris9k , Sun, 6 Mar 2011 08:53:47

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