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RE: [T3] Pollute less with more gas? (was: Dual carb versus EFI ? )

On 15 Nov 2001, at 17:48, Erkson, Toby wrote:

> "...cars which pollute less, use more gas." i.e. the last sentence ;)
> FI is better than carbs for reducing emissions as well as increasing gas
> mileage.  That's where my confusion lies...lays...is... :)

Okay, gotcha.

I don't know why this should be true, but here are just a few datapoints from 
my experience. 

Across the 6 years of the type 3 EFI the gas mileage our cars got came 
slowly down as the emissions regs tightened. I ASSUME that our cars 
polluted less as this happened.

In general, I hear gas mileage figures for OE dual carb type 3s that are better 
than what I expect to see for the EFI cars that I am familiar with. Mike 
Wodkowski's 72 seems to be a counterexample of this, but I'm at a loss to 
explain it because he's driving MY old engine with MY complete old EFI 

While I tend to discount many of the high gas mileage reports to limited data 
(a single tank, poor measuring conditions) or just owner enthusiasm, I can't 
ignore all of it.

I suspect that your gut feeling agrees with mine: Efficient use of gas should 
lead to more perfect combustion and less pollution. Clearly some of today's 
cars get much closer to this ideal than our cars and maybe there are modern 
concepts that could be applied to our engines, like combustion chamber 
shape. But I think the air cooled engines often come up agains NOx 
production limitations that force us to run rich in order to keep combustion 
temps (and NOx production) down.

Another point here is that during the early 70s, as emissions regs were really 
clamping down, the gas mileages of all cars that I was familiar with seemed 
to be slowly declining, if you stick to comparing the same model cars with 
the "same" engine, but just different pollution control measures. OTOH, this 
was just about the worst period ever for cars, as the automakers had little 
experience worrying about either gas mileage OR emissions, and the results 
were generally pitiful.

Again, this is just my impression.

Jim Adney
Madison, WI 53711-3054

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