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Old 03-31-2008, 07:10 PM   #11 (permalink)
trebuchet03
MechE
 
Join Date: Dec 2007
Location: Bay Area
Posts: 1,151

The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by LostCause View Post
I think the goal is to never operate at light loads.
To add to what Metro has already said... For highest thermal efficiency - that statement is true... But engines are over sized for that sort of driving. If I operated my engine at peak load all the time, two things would happen

1. I'd get a helluva lot of speeding tickets
2. I'd drastically reduce the operating hours of my engine

It is because the drive train is so big that lower thermal efficiency (lower brake specific fuel consumption) can lead to lower specific fuel consumption.

If I had a 20hp engine in there - it'd be much easier to operate at peak load all the time and maintain a legal speed But, operating a 20hp engine near 20hp for it's entire life will reduce it's service life. The gentleman from wrightspeed motors claimed that your typical car has about a 5,000 engine life. But, that's because these engine live at lower rpm and at low loads for most of their lives....

Quote:
you guys are killing me with these abbreviations..
BSFC ? doesn't take that much more to type it out, stop being lazy..
Hypermilers like abbreviations I don't know why - but it has allowed the term CODFISH to exist Goofy

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