<VV> MPG -$$ are not the point

[FrankCB at aol.com]

Padgett,
       The BIG MPG advantage that modern engines have over Corvair engines is 
the more precise control of A/F ratios going to the cylinders using port 
injection and computer control and FEEDBACK from O2 sensors.  These enable 
cruising with near stoichiometric A/F ratio to every cylinder, something that the 
STOCK Corvair can hardly accomplish.  
       The second big MPG advantage modern cars have is very low RPM cruising 
speed with overdrive transmissions.  My 95 Trans Sport does 60 mph at 1800 
rpm whereas my Corvair does the same 60 mph at 3000 rpm.  That's another reason 
why the Trans Sport despite having a 40% larger engine (3.8 liters) and about 
40% more weight can easily better the Corvair's MPG.  On a long trip to Jim's 
I can (and have) gotten 28 mpg by MOSTLY keeping revs from exceeding 2000 rpm 
(not always, but mostly).
       Now if we set up computer controlled port injected EFI with wide band 
O2 sensor feedback on our Corvairs, we could even set it up to run cruising 
speeds at A/F ratios LEANER than stoichiometric, perhaps as much as 16+ to 1 A/F 
ratio.  Since this results in increased NOx emissions, modern emission 
controlled cars aren't allowed to do this (at least not yet), but if you don't tell 
the EPA, I won't tell the EPA.<GGGGG>
       Since the air/fuel mixture in the 150/180 gets "blended" by flowing 
through the turbo compressor wheel DOWNSTREAM of the carb, it seems to me that 
it would do a better job of mixture distribution to the individual cylinders 
than the NA engines whether they use 2 or 4 carbs.;  But I haven't seen any data 
to back that up.
       By the way, just who is this guy "Yout" that "wants to know"?(:-)
       Regards,
       Frank "full of wild ideas" Burkhard  


In a message dated 8/23/05 10:36:05 AM Eastern Daylight Time, pp2 at 6007.us 
writes:

> The point is not the MPG, the point is the competition. My daily driver has 
> 
> a 3800 and is sitting on a 19.6 mpg average right now because I have been 
> doing a lot of short, in town driving with the a/c going. I fill it up 
> about once a month so the price of gas does not affect me much.
> 
> My feeling is that the Corvair being 3/4 the engine size and 2/3 the weight 
> should give appreciatively better MPG under the same conditions. The fact 
> that the technology is 40 years old is not that important. The fact that 
> the technology, particularly the intake manifolding, is pretty bad even for 
> the time is not.
> 
> Am curious how the turbo, which uses long tubes and the mixture drawn 
> through the turbo compares with the 110 for mixture distribution across the 
> cylinders, anyone ever run any tests ? For that matter I never got any 
> replies to my question about which cylinder runs the hottest - anyone know 
> that ? Is not anywhere I spotted in the stock engine test (though the MPG 
> vs fractional load charts are interesting). Yout wants to know.
> 
> Padgett
>