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Old 07-24-2021, 02:07 AM   #60 (permalink)
Isaac Zachary
High Altitude Hybrid
 
Join Date: Dec 2020
Location: Gunnison, CO
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Avalon - '13 Toyota Avalon HV
90 day: 40.45 mpg (US)

Prius - '06 Toyota Prius
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Quote:
Originally Posted by Hersbird View Post
I don't know the specifics, but read when dodge put out the V10 in 1994 it was because the older 440 big block just couldn't get complete enough burn in the big cylinder holes to meet modern emissions. The v10 shared the same bore as the 360 V8 which had just been modernized in 1992.

So a reliable thumper like a Honda 90 may not scale up as well as you might think. Then again the biggest container ships use massive, massive reciprocating piston engines. They are efficient and meet modern emission requirements but emissions for 1000 foot container ships might be much more lax than new car emissions.
If cylinder size (several small cylinders vs a few big cylinders) has an effect on emission my guess is it would be NOx.

Say you take a single cylinder engine and an 8 cylinder engine both with the exact same displacement. The 8 cylinder engine will have 4 times the surface area (if I did my math right) that the combustion gasses will come into contact with and therefore absorb more heat. Absorbing more heat leads to cooler combustion which leads to lower NOx emissions but higher CO and HC emissions. But CO and HC emissions are much easier to deal with in a catalytic converter than NOx emissions.

The wankel engine has a poor volume to surface area design. Maybe making it much bigger would help that???
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