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post #11 of 32 (permalink) Old 05-10-2014, 01:07 PM
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If you're tuned for a better fuel though it will make a difference, for example I have a 91 octane tune.

Dustin, let me get the strait, you've put E85 in your car? I'm surprised it even ran and if it was running I would imagine it being way too lean.

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post #12 of 32 (permalink) Old 05-10-2014, 03:39 PM
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not many people get a tune for gas though, I accidently one day put 93 in my truck because I lost my mind and pushed the button thinking about my miata. I did about 1/4th and then switched to 87. The tank of gas seemed to last a little more than typical but I did take a different route to work that week so that is where the difference was. I remember when gas was .89c a gal back in the early 2000's here and I would put premium in my cavaliers thinking it was better... boy, I was just throwing a couple extra bucks out the window, after a few fill ups with premium my car begin to run a little funnier so I switched back to 87 and it improved.

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post #13 of 32 (permalink) Old 05-10-2014, 07:10 PM
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I would stick to what the owners manual says... Im sure they tested the cars with all types of different fuels, and decided that regular is fine for the 2.2's. I have heard of people switching from using 87 to 91 every few months, for one tank to help clean things out, but I don't really know how well that works.

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post #14 of 32 (permalink) Old 05-10-2014, 10:24 PM Thread Starter
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Right. The myth going around here is that higher grade fuels have certain additives that will clean/lubricate injectors and what not, as well as burn cleaner by reducing harmful emissions. I fill up from time to time with 91 when the price drops on Thursdays. I haven't got anything more out of my car than with 87, or at least nothing I've noticed anyways. It usually comes out to $2.50ish extra to fill up on premium so I'm not too concerned.

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post #15 of 32 (permalink) Old 05-13-2014, 06:59 AM
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I read the other day that the LAP 2.2 has a compression ratio of 10 to 1. That's pretty high for regular isn't it? I know a lot of people have said use what the manufacturer says, but I don't understand how most cars above 9.5 to 1 usually recommend higher than regular but GM says the 2.2 LAP with 10 to 1 can run on regular.

Granted there's a lot of other factors involved but the CR plays a major role in deciding when knocking occurs - which is a purely what higher grades are meant for (I doubt they clean out anything - but I'm not a chemical engineer).
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post #16 of 32 (permalink) Old 05-13-2014, 07:17 AM
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Quote:
Originally Posted by andrewcarr1993 View Post
If you're tuned for a better fuel though it will make a difference, for example I have a 91 octane tune.

Dustin, let me get the strait, you've put E85 in your car? I'm surprised it even ran and if it was running I would imagine it being way too lean.
Yep car has been running on E85 since new. Thats regular up in Colorado.
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post #17 of 32 (permalink) Old 05-15-2014, 07:19 AM Thread Starter
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No ethanol in my area. Best brew on tap is 94, and only at certain stations.

Doesn't Colorado usually have higher grade gas than other parts? Something to do with high altitude and less oxygen molecules in a given amount of air I think.

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post #18 of 32 (permalink) Old 05-15-2014, 09:14 AM
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Quote:
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I read the other day that the LAP 2.2 has a compression ratio of 10 to 1. That's pretty high for regular isn't it? I know a lot of people have said use what the manufacturer says, but I don't understand how most cars above 9.5 to 1 usually recommend higher than regular but GM says the 2.2 LAP with 10 to 1 can run on regular.
It has to do with direct injection, a car cannot detonate if fuel isn't there yet. Plus now with both variable cams you can play with ignition timing a lot more so you don't need gas with reduced volatility.

Look at the new Buick Encore, it is Turbo and still runs on regular gas recommended by GM.

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post #19 of 32 (permalink) Old 05-15-2014, 10:45 AM
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I'd go broke running 91 all the time like the manual suggests.
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post #20 of 32 (permalink) Old 05-15-2014, 11:50 AM
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From the owners manual...

Gasoline Octane
If the vehicle has the 2.2L L4 engine (VIN Code H), use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, you might notice an audible knocking noise when you drive, commonly referred to as spark knock. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, the engine needs service.

If the vehicle has the 2.0L L4 engine (VIN Code X), use premium unleaded gasoline with a posted octane rating of 91 or higher. You can also use regular unleaded gasoline rated at 87 octane or higher, but the vehicle's acceleration could be slightly reduced, and you might notice a slight audible knocking noise, commonly referred to as spark knock. If the octane is less than 87, you might notice a heavy knocking noise when you drive. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, you could damage the engine. If you are using gasoline rated at 87 octane or higher and you hear heavy knocking, the engine needs service.

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