<VV> Conversion to EFI: Is it really cost effective? (reply, long)

[NicolCS@aol.com]

Blaine, my '66 140 EFI gets about 30 mpg at a constant but gentle 70 mph with 
24.3" tires and a 3.27 axle.  My carbureted '67 140 4-speed with the PG140 
cam set-up and 3.08 gears gets in the low 30s.  The carbureted '67 did 38.9 in 
an econo-run once. (at a constant 40-45 mph :(

Don't get me wrong, EFI is great but there are three places to tune an 
engine: max power, max emissions, and max fuel economy.  If you use oem hardware 
like I did, it will be tuned to a compromise in the middle, not max economy.  If 
you go for an aftermarket ecm, you can calibrate it anywhere you want but they 
take lots of time and $$$.  The biggest factor in F/E is friction 
(engine/road/air).  If you recalibrate your carbureted engine for lower friction (i.e. 
lower rpm) and gear down the axle to match the engine, you will probably get a 
bigger bang for the buck than EFI.  You can get some of the benefit of EFI by 
using an oxygen sensor based air/fuel ratio meter to calibrate your carburetors 
for maximum economy.  Also pay attention to intake and exhaust flow to 
improve breathing.

At the moment, my carbureted '67 beats my EFI '66 in fuel economy by several 
miles per gallon.  Next winter I plan to re-cam the '66 EFI car and I have 
already re-geared it(3.08).  This might put it ahead of the carbureted '67.  
OTOH, if the jets in the '67 are spot-on, the EFI car will probably just match it. 
 

Reducing friction, engine vacuum (a big vacuum pump takes power), and 
reducing intake and exhaust losses will improve fuel economy.  How the fuel enters 
the air, carb or injector, isn't as important as the other factors.  I wouldn't 
plan on efi paying itself off without other changes.  BTW, I figure my Fiero 
EFI, with "pull and save" components, cost alot more than $1000.
Craig Nicol
65 Corsa 140 EFI (Datsun/Binion)
66 Monza 140 EFI (Fiero)
67 Monza 140 with whack-o cam and gearing

<snip>
I am beginning to collect parts to do a fuel injection conversion...  Before
I get too excited about this project & invest in the big $ items, I would
like to hear some first-hand accounts on fuel economy.  If there is anyone
on the list who is running EFI on their Corvairs, please share with us your
average MPG stats.  With the outrageous gas prices lately, it's starting to
make more sense to do this conversion... But it depends entirely on what the
expected MPG increase would be.<unsnip>