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Old 12-21-2010, 08:19 PM   #30 (permalink)
Allch Chcar
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Join Date: Jan 2008
Location: North Coast, California
Posts: 429

Cordelia - '15 Mazda Mazda3 i Sport
90 day: 37.83 mpg (US)
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Quote:
Originally Posted by rmay635703 View Post
This is a Myth, running the car at STOICH under high power burns exhaust valves, lean might cause misfires (maybe) leading to a burnt piston. Lean is always cooler than stoich, most cars run RICH at WOT AKA 10-12 to 1 instead of 14.x to 1 (stoich) to cool combustion as stoich makes more heat.

Cheers
Ryan
The peak temperature actually occurs beyond stoich at around 15% lean at 17:1 AFRs or Lambda 1.15. 1 is Stoich and .88 is peak leanest rich power on Gasoline. I don't have a chart handy but I could find one if you like but I'm a little concerned about going offtopic as it is.

Where the Lean burn is safe is actually past 17:1 where peak BFSC occurs and peak temperatures are acheived and into the richest Diesel range past 20:1. Hondas run lean burn into that range and are designed to be capable of 24:1 at a maximum. But lean burn destroys the EPA emissions score for a given vehicle due to the increase Oil consumption hence why I believe current engine designs with lean burn are heavily neutered/limited. The Manual InsightI has much a better MPG score but the emissions are 2 vs the 6 the Automatic received.

The biggest problem is that this Club doesn't have any members yet. Other then those trying to gain entry no one here has hit 50 yet. And why exclude Hybrids and Diesels? Isn't it limiting enough that you made it Auto only? Why not one or the other. The only Diesels capable of 50mpg are VW or Euro market only while the current top MPG car in the US just happens to be an Auto only car, the Prius. Seems a bit too exclusive don'tcha think?
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