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Old 07-17-2009, 03:16 PM   #11 (permalink)
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Originally Posted by RandomFact314 View Post
So how would using more fuel get me more MPG?
While I doubt the ebay resistors are sufficient for this, it is a fact that gasoline produces more btu's per pound burned at 12:1 air:fuel ratio than at the stoichometric ratio of 14.7:1 at sea level - so it is feasible that running rich can net greater mpg's than running stoich or lean.

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Old 07-17-2009, 03:41 PM   #12 (permalink)
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Originally Posted by shovel View Post
While I doubt the ebay resistors are sufficient for this, it is a fact that gasoline produces more btu's per pound burned at 12:1 air:fuel ratio than at the stoichometric ratio of 14.7:1 at sea level - so it is feasible that running rich can net greater mpg's than running stoich or lean.
How can that work? If it's rich, not all of the gas can burn so there'll be some unburned gas. If it's lean, it would help ensure that almost all the gas would burn.
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Old 07-17-2009, 04:10 PM   #13 (permalink)
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How can that work? If it's rich, not all of the gas can burn so there'll be some unburned gas. If it's lean, it would help ensure that almost all the gas would burn.
Stoichometry being what it is, going leaner than the stoich. ratio for your fuel can have no positive effect on efficiency.

I've read that in practice, going from 14:1 to 15:1 has the effect on predetonation of going down 2 octane points, going to 16:1 increases likelyhood of predetonation by 2 more - as an example 87 octane gas would behave like 83 octane gas at a 16.7:1 AFR - which of course would cause your engine computer in a modern car to retard timing significantly and as such reduce power output and efficiency. Not to mention the engine damage likely from increased combustion temperatures at lean ratios.

Unfortunately now that I actually have reason to back up my statements I'm unable to find the publications I had learned this from. Well, like anything else do your own research and do what makes sense to you AFTER doing your own research (and not before, because most people are retarded - myself included - and just going on "common knowledge" alone never got anyone anywhere)
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Old 07-17-2009, 04:54 PM   #14 (permalink)
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Check here for how lowering the intake air temperature signal to your computer can increase your mileage
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Autospeed is an excellent source for ideas.
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Old 07-17-2009, 05:54 PM   #15 (permalink)
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Hello -

I think the better MPG claim is just a "get on the MPG bandwagon" lie.

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Old 07-17-2009, 06:35 PM   #16 (permalink)
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There isn't really a "predetonation", it's either detonation or preignition.

Combustion temps do not continue to increase over (leaner) than stoichiometry.

The detonation threshold gets more critical with increasing manifold pressure.

(numbers are approximate)
<750 millibars, stoichiometric and leaner is generally safe, only the flame speed slows (if leaned out) thus timing must be increased to compensate if running on the lean side.

>750 millibars, requires richer than 14.7; latent heat of evaporation plays a role in detonation resistance so under this circumstance, the octane vs afr arguement is valid.


I think it could be an opamp and something to shift timing, or maybe something to reduce map signal so it runs leaner and with more timing then it normally would. Obviously, this could be more stress on the engine.
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Old 07-17-2009, 08:10 PM   #17 (permalink)
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Quote:
Originally Posted by shovel View Post
Stoichometry being what it is, going leaner than the stoich. ratio for your fuel can have no positive effect on efficiency.

I've read that in practice, going from 14:1 to 15:1 has the effect on predetonation of going down 2 octane points, going to 16:1 increases likelyhood of predetonation by 2 more - as an example 87 octane gas would behave like 83 octane gas at a 16.7:1 AFR - which of course would cause your engine computer in a modern car to retard timing significantly and as such reduce power output and efficiency. Not to mention the engine damage likely from increased combustion temperatures at lean ratios.

Unfortunately now that I actually have reason to back up my statements I'm unable to find the publications I had learned this from. Well, like anything else do your own research and do what makes sense to you AFTER doing your own research (and not before, because most people are retarded - myself included - and just going on "common knowledge" alone never got anyone anywhere)
What if you lean out the mixture and then use water injection? I have never heard of an engine that runs rich to be efficient. There are lean burn engines that are more efficient.

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If America manages to eliminate obesity, we would save as much fuel as if every American were to stop driving for three days every year. To be slender like Tiffany Yep is to be a real hypermiler...

Allie Moore and I have a combined carbon footprint much smaller than that of one average American...
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