Optimal Air-Fuel Ratios

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vwlover77
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Location: North Canton, Ohio
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Optimal Air-Fuel Ratios

Post by vwlover77 » Fri Sep 23, 2011 2:11 pm

So, if you've got access to one of those handy-dandy LM-1s or another wideband O2 sensor-based device, what are the "optimal" air-fuel ratios for various conditions?

Idle
Level road low speed cruise (say 40-45 mph)
Level road highway speed cruise (say 65 mph)
"Normal" acceleration up through the gears
Full-throttle just-trying-to-maintain-speed hill climb (in whatever gear is appropriate)
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Amskeptic
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Re: Optimal Air-Fuel Ratios

Post by Amskeptic » Sun Sep 25, 2011 9:17 am

vwlover77 wrote:So, if you've got access to one of those handy-dandy LM-1s or another wideband O2 sensor-based device, what are the "optimal" air-fuel ratios for various conditions?

Idle
Level road low speed cruise (say 40-45 mph)
Level road highway speed cruise (say 65 mph)
"Normal" acceleration up through the gears
Full-throttle just-trying-to-maintain-speed hill climb (in whatever gear is appropriate)
Can of worms ....

Low load most efficient use of fuel 13.7:1
Full throttle at torque peak 11.0:1
Full throttle at horsepower peak 10.7:1 is coolest on CHTs, but expect lousy fuel economy.
Nice to shoot for 15 + on throttle overrun and idle.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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