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  #11  
Old 02-19-2013, 09:08 AM
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I run 91 in mine for the fact it's the only thing you can buy around here that's ethanol free, I trailer and always buy at the fast stations locally that I've had good luck with. 91 octane is still cheaper than diesel for for my truck so I don't notice the money difference


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  #12  
Old 02-19-2013, 10:20 AM
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The marina where my slip is lewisville,tx only sells 93 octane but its only 50 cents more than going rate of premium so about 4.50 which is not too bad I have 04 x2 and can fill up and go all day at 100 bucks.
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  #13  
Old 02-19-2013, 10:36 AM
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I am guessing that my LT-1 recommends 89, but she runs just fine on 87. There is a gas station just up the road from me that has no ethanol 87 so that is usually what I put in it. It is about 20 cents more than regular with ethanol, but to me it's worth it to get more gas in your tank.
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  #14  
Old 02-19-2013, 10:59 AM
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Originally Posted by CC2MC View Post
I am guessing that my LT-1 recommends 89, but she runs just fine on 87. There is a gas station just up the road from me that has no ethanol 87 so that is usually what I put in it. It is about 20 cents more than regular with ethanol, but to me it's worth it to get more gas in your tank.
My MC manual requires 89 or higher. Does anyone know if a lower octane (87) gas will have a negative impact on the engine or just have slightly reduced performance?
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  #15  
Old 02-19-2013, 04:46 PM
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Originally Posted by kjohnson View Post
My MC manual requires 89 or higher. Does anyone know if a lower octane (87) gas will have a negative impact on the engine or just have slightly reduced performance?
No reduction in performance. Gasoline is a mixture of chemicals. Octane is included to prevent pre-detonation. (pinging) You know, that rattling noise, some engine will make. If that is happening, it will ruin your pistons.

Simple rule, higher compression ratio, higher octane. Older engines, under 10:1 can typically run 87. If there no engine issues, and gas is of good grade.

I typically run 89, in my Expedition and boat. Both will run will on 87. My MC 205 is a 9.5:1 engine. I usually run 89. I figure 89 is the most sold product, so in theory, could be a more consistant quality.

Also, gas in Oklahoma seems to work better, and usually cheaper, than East Texas. Go figure.
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  #16  
Old 02-19-2013, 05:38 PM
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The LT1 has a 10.4-1 compression ratio, even with reverse cooling I wouldn't run 87 in it unless all you do is put around at idle or cruise
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  #17  
Old 02-19-2013, 05:52 PM
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Originally Posted by 1redTA View Post
The LT1 has a 10.4-1 compression ratio, even with reverse cooling I wouldn't run 87 in it unless all you do is put around at idle or cruise
Even with the detonation sensor dialing the timing back it's still pushing things in the wrong direction using 87.
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  #18  
Old 02-19-2013, 07:02 PM
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Quote:
Originally Posted by kjohnson View Post
My MC manual requires 89 or higher. Does anyone know if a lower octane (87) gas will have a negative impact on the engine or just have slightly reduced performance?
I found this on the internet. Unlike many other internet articles, this one is written in a way that makes it seem like it's correct. Their bottom line is that for most engines, running lower octane will not harm the engine, but the increase in fuel usage will approximately equal the fuel savings if you are supposed to run on a higher octane but only run the lower one.

http://forum.roadfly.com/threads/126...ctane-gasoline

There was also an exposť on Canadian TV before Christmas on a show called marketplace.

http://www.cbc.ca/marketplace/episod...ump-facts.html
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  #19  
Old 02-20-2013, 12:38 AM
jsta281 jsta281 is offline
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Hello all mostly a lurker on here. I have some experience with octane and performance engines as I run A boosted Mustang at the dragstrip That requires greater than 91 octane fuel.

In short lower octane fuel actually burns faster then high octane fuel so running the lowest octane fuel possible without detonation (pinging or worse) will yield the best performance.

My "race car" which is really a street legal car I race requires 96 octane. Here in utah 91 at the pump is all you get but for a few places that sell 100 octane. I run a fuel additive called Torco accelerator. 32 oz into 10 gal of 91 makes 96. 32 oz into 20 gallons will easily net you 2 or more octane points.

The point is if you were somewhere and needed a little insurance for octane this works well.

If you buy it 5 gal at a time you can buy it for $250 or 12.50 per 32 oz.

It's alot easier then hauling around gas cans full of 93 or 91 if required.

It is unleaded and 02 sensor safe, I have run it in my car for at least 6 years with no negative effects on emissions equipment.

Just a suggestion.
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  #20  
Old 02-20-2013, 11:52 AM
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Another thing to consider. Engine Nut, who works for Indmar, once posted here that the reason Indmar called for 89 octane was due to the fact that most people use their boats infrequently. 87 octane is fine, but 86 is not. So, to avoid having people fill up with 87, then leave the boat sitting for a month or two between uses and starting it up with what was no longer 87 octane fuel, Indmar recommended 89 octane so that there would be a little buffer for less frequent users.

I think it is a good idea to stabilize any fuel you don't intend to burn off in the next two weeks before that last outing of the weekend.
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