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  #1  
Old 07-12-2005, 11:57 AM
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SVX Gas

Is it necessary to run the SVX with 92 Octane Fuel? With prices going up and up (1 gallon of 87 is 2.26), can I run it with 89? I just don't know why I would have to run 92 through it.
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  #2  
Old 07-12-2005, 12:17 PM
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if you don't run at least 91 you risk pre-ignition in the combustion chamber, which can destroy the engine.

even if the pre-ignition doesn't reach that level, the on-board computer will retard timing in an attempt to avoid knocking - which will reduce gas mileage enough that I suspect you will actually use enough more gas to pay the difference.

as an alternative the ECU tuning mod will allow the running of "regular" through use of an alternate fuel mapping (I suspect it runs quite rich).
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Old 07-12-2005, 12:22 PM
sharky512345 sharky512345 is offline
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Running 92 instead of 87 is only a couple dollars more per tank. I don't think it is that big of a deal to spend two or three dollars more a tank. I paid 2.69 a gallon yesterday to fill up.
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  #4  
Old 07-13-2005, 01:31 AM
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I've done it and have only noticed a slight difference in power response. My experience is that the ECU adapts very well to whatever I put in it. I calculated the difference in cost between the premium grade and the cheap stuff and found that it only costs me about $100 per year. I figure the extra horsepower is worth the money. If I didn't want power, I wouldn't be driving an SVX.
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  #5  
Old 07-13-2005, 05:55 AM
red95svx
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Quote:
Originally Posted by Manarius
Is it necessary to run the SVX with 92 Octane Fuel? With prices going up and up (1 gallon of 87 is 2.26), can I run it with 89? I just don't know why I would have to run 92 through it.

The SVX has a high compression engine. High compression can easily lead to engine knock if too low of an octane is used. When the computer senses knocking it will retard timing to help lessen the knocking. Retarded timing causes lower engine performance and lower gas mileage. Using a lower octane on the SVX to save a two or three bucks at fill up is false economy and if done on a repeated basis, potentially dangerous. Consider the extra expense of premium to be insurance against engine performance problems


Dave
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  #6  
Old 07-13-2005, 06:05 AM
red95svx
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Originally Posted by UberRoo
I figure the extra horsepower is worth the money. If I didn't want power, I wouldn't be driving an SVX.

Yep. This ain't no 91 Legacy L




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  #7  
Old 07-13-2005, 10:38 AM
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Quote:
Originally Posted by UberRoo
I calculated the difference in cost between the premium grade and the cheap stuff and found that it only costs me about $100 per year.
Personally I think it'll be a wash. From my experience with my former 300ZX TT (yeah I was a poor college student at the time), when I could afford premium gas my mileage would be around 21-22mpg in mixed city & highway. When I ran 87 octane, it would drop to around 19-20mpg in similar driving. I wouldn't be surprised if the extra 2 mpg I got in fuel economy when I ran premium would effectively make the cost-per-mile similar to when I ran regular.

-Chike
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  #8  
Old 07-13-2005, 11:44 AM
lee lee is offline
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Chike - here I go, getting ready to embarass myself by doing math in public, but....

using 20mpg on regular, 22mpg on premium (your figures), you would use 5 and roughly 4.55 gallons to go 100 miles. At $0.20 difference per gallon (what it is around me anyway) and using $2.25 and $2.45 (what I saw yesterday), the costs to travel the 100 miles would be:

$11.25 regular
$11.14 premium

so, over the course of the average driver's year (12K miles), the difference would be $13.64 cheaper to use premium - not to mention what savings would come about through less stress on engine internals.
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  #9  
Old 07-13-2005, 01:33 PM
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ensteele ensteele is offline
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Lee - I like your math whether is is true or not! That is why it is interesting to do the math on the cost. You may not be saving anything and be doing harm to the engine.
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  #10  
Old 07-13-2005, 02:14 PM
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I guess that means when I come into getting an SVX, I'll be having to put premo gas in it.
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(8/23/07-Present) 1995 Subaru SVX LSi (197k) Polo Green (#1102) 03/95
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  #11  
Old 07-13-2005, 02:39 PM
KCROGUEDOG
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or just buy huge quanities of oct tain booster and do some math and figure out how much to use to bring u to around the 90s.
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  #12  
Old 07-13-2005, 05:41 PM
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Originally Posted by KCROGUEDOG
or just buy huge quanities of oct tain booster and do some math and figure out how much to use to bring u to around the 90s.
I think that would cost more than premium gas. Anybody ever able to go down to the air port and fill up with the 100+ octane gas? I hear it is amazing.
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  #13  
Old 07-13-2005, 06:41 PM
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Chiketkd Chiketkd is offline
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Quote:
Originally Posted by lee
Chike - here I go, getting ready to embarass myself by doing math in public, but....

using 20mpg on regular, 22mpg on premium (your figures), you would use 5 and roughly 4.55 gallons to go 100 miles. At $0.20 difference per gallon (what it is around me anyway) and using $2.25 and $2.45 (what I saw yesterday), the costs to travel the 100 miles would be:

$11.25 regular
$11.14 premium

so, over the course of the average driver's year (12K miles), the difference would be $13.64 cheaper to use premium - not to mention what savings would come about through less stress on engine internals.
Your math looks sound to me Lee. When I finally sat down and figured this out for myself back in college, I only put premium in my 300ZX TT and utilized the campus buses more often!

-Chike
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  #14  
Old 07-13-2005, 08:32 PM
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ensteele ensteele is offline
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Quote:
Originally Posted by Manarius
I guess that means when I come into getting an SVX, I'll be having to put premo gas in it.

I would.
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  #15  
Old 07-14-2005, 06:17 AM
dcarrb dcarrb is offline
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Quote:
Originally Posted by Kiteless
Anybody ever able to go down to the air port and fill up with the 100+ octane gas? I hear it is amazing.
As Dave mentioned earlier, AIRCRAFT GAS CONTAINS LEAD.

(Do not run leaded fuel in an SVX.)

Besides, the higher octane won't make a bit of difference, performance-wise. Aircraft and racing engines require higher octane to prevent knock; it's not like running nitro or something. So it's not amazing.

dcb
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