Date: Mon, 9 Dec 1996 17:56:31 -0800 (PST)
From: Mike West <mwest@cdsnet.net>
Subject: Smog stuff for you heads

 This piece of fluff or whatever name you want to apply, deals
with the burning rate of fuels/explosives and the new smog 
requirements.

 At this point (the top of the page) I have no idea where it's 
going to end up. Clueless isn't correct tho, I have some clues!

 I would call this "half-baked", not enough data.
Also, I'm not sure you can't change the "burn rate" of a gaseous
mixture by changing the pressure or temperature. No data.

 It is fairly safe to assume tho, that increase of press. or temp.
will increase the NO2. Pressure will pob'ly increase CO. Guesses.

 This partly deals with the MEP numbers I gave you in the last
post.

 Ideally, a fuel or propellant or explosive will have a burn rate
in feet per second that will match the end of it's work cycle.

 Then the MEP or Average is just Psub1 - Psub2 divided by 2.

 Psub1 being the starting pressure or peak and Psub2 being 0,
the ending pressure.

 That would be an ideal efficient setup.

 The fuel was completely burned and nothing left but vacuum.

 To achieve that the burn rate would equal the rate of the piston 
speed.
 It would burn and expand, pushing the piston until just before
 or at the end of the piston travel, it just runs out of fuel.

 That would be an efficient burn, but not a very good engine
pusher. 

 It would mean that after the halfway point it was pushing less 
and less until it ran out altogether.

 So for good power, we'd want a lot of extra fuel in there that
would keep the fires going and the push on even at the end of the
stroke.

 There would still be unburned fuel of some fair proportion in 
the exhaust.

 This is what the racer is telling you when he says " better rich
than lean".

 So using the averages given in "Heads . . . .", the pressure at
the end of the travel in the stock 1600 are still 32 psi, 284 lbs
of force on the piston. So there is some unburned fuel at the end.

 We need to go back briefly to the dyno tests that started all this.

 Those people were looking for power, not Smog II.

 Now let's look at burning rates: "I'd like a gasoline that will
turn out zero hydrocarbons at idle please." 
 The gas company does blend a fuel to a "burn rate spec".

 Since the burning rate is a constant, if it's totally burned at 
the relatively slow speed at idle, it stands to reason if the
piston speed increases, the fuel is still burning at the idle
speed no matter how fast the piston moves.

 Crank it up to 2500 and suddenly I have fuel that didn't get burned 
in the exhaust!

 Where the hell are we ?

 Octane rating: I just throw this in while I look for my spare 
sack of wits.

 Octane rating is the anti-knock characteristcs, right?
It really means the fuel burns slower.  Say what? 

 You might want to look into doing the smog check on low
octane.

 So I go back and tune my car for 2500 rpm and no HC's.

 Now it won't start and won't idle. Not enough fuel at the low
rpm's.

 So 13 little Japanese engineers go into a huddle.
There are 13 because 13 is funnier than 12. Ask any comedian.

 So what did they come up with? Being told they have to burn this
stuff that only works at idle didn't bother them.

 Then came Smog I. So they stuck a catalytic converter in there
to burn the extra fuel in the exhaust.

 Then came Smog II. You notice a trend here? They knew about this 
before we did.

 For Smog II on the same gas as last time or worse or whatever is
being sold this week at Price Chopper, they are going to need an
on board tuner.

 Enter the little computer chip and sensors that talk to each 
other and adjust accordingly.

 Acura, I think, even has a dual cam setup, one is electronic and if 
the car needs some heavy breathing the electronic cam takes over
and gives a higher lift. Wow!


 You and I are still out in the back yard trying to get the dual
carbs balanced or the left wheel fell off.

 So we have a fuel that needs to be adjusted rich at idle and 
lean at operating speed and this must be done between here and
the freeway. Relative terms, a "clean burn" is what we want thru
the whole rpm range.

 "Well it's not so black that it can't get blacker" as we Irish 
say.

 It is possible for the government to have the fuel made to such,
and the smog requirements to such, that you will be non-compliant 
over-nite. Even a good engine.

 Back in the land of reality, some are passing and some are not.

Some are setting the carb to the 2500 rpm standard and limping 
down for the smog check. Then going home and fixing it.

 Still takes a very clean efficient engine. And a catalytic conv.
  Don't forget to put the stem seals on!

 If  they get to the point of mobile butt sniffers and random
checks we may all lose.

 The temporary solutions may lie in chemistry.

 We may have to rejet or even re-carb. One for the test and
one for the road.

 Another will be the after-market fuel injection rigs.

 Adjusting the timing and fuel mix like we were pilots. Kewel! 

 The rules have always been "adapt or die". We are going to have to
get smarter faster or we will be eliminated.

 Who knows?  You could be raided tonite by the BATF as a 
member of an unapproved cult.  :-)

 west