[Diy_efi] Emissions Numbers...

Adam Wade espresso_doppio at yahoo.com
Wed Feb 16 23:23:24 GMT 2005


--- David Cooley <n5xmt at bellsouth.net> wrote:

>> 'course, if he was going THAT lean, he'd have
>> probably passed on NOx, yes?  Lots and lots of O2,
>> lots of HC, almost no CO, and fairly low CO2 and
>> NOx.

> Not necessarily... Lean mixtures burn hotter, and
> heat is the main factor in generating Nox.  EGR
> cools the burn and reduces Nox.

It also reduces pumping losses, leading to increased
economy at part-throttle cruise.

But combustion temps do not follow a strict linear
curve based on mixture.  We were talking about running
well lean of stoich, and NOx numbers drop as you go
more than a bit leaner than stoich, indicating a drop
in combustion temp.  This makes sense, since with the
available fuel being increasingly "diluted" by air,
flame front travel slows notably.  It's the same
principle that drove emissions engineers to use EGR;
move the burning bits further away from each other,
and flame front travel slows, as does overall
temperature during the burn.

=====
| 82 Honda CX500 Turbo (Cassandra)  90 Kwak Zephyr 550 (Daphne) |
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |
| M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |

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