Need Opinions. Have nothing to compare to.
"The clue [relationship] here is rich idle, lean cruise, leaner (leanest, actually) part-throttle acceleration and rich WOT. The leanest is at mid-load, half-throttle or so.
The thing to understand is most engines respond to being leaner than stoichiometric at part-throttle because the lean exhaust gas has hot unburned oxygen, and hot oxygen improves combustion"
In summary "at moderate to mid load, engines will run lean and like it, and burn much less gas while doing so. They must be rich at idle and very low load, lean in the middle, and rich at WOT." The load where richer is needed varies with engine, gearing and vehicle. It may be 60-70% as shown here, or as high as 90%. Load relates to manifold vacuum, and therefore is used to signal the opening of the power valve, letting more fuel into the main circuits.
"This ... graph is from Walter B. Larew, Carburetors and Carburetion. At the time he wrote his book on carburetors he was a retired Brigadier General who taught Military Science at Cornell, among his other accomplishments. He published this carb book in 1967.
He didn't specify an engine type for this graph but his information is in the context of engines in general. His sources were most likely military aviation research. The math in his book is from NACA TR-49 and similar publications.
This graph is representative of a richer part-throttle that may be necessary to tolerate with an engine that has radical valve timing and perhaps not so good A/F distribution at part-throttle."
quote and graph from Tuner on Innovate Motorsports Forum and reposted at RFS.
F is Fuel/Air ratio for gasoline. Invert the numbers on the vertical axis to convert to Air/Fuel ratio.
0.08 = 12.5
0.667 = 14.7
0.06 = 16.6
Constant power is any steady throttle condition.
Steady 15% might be something like driving 40 mph on a flat.
Steady 25% might be sameat 60 mph or 40 mph up a long a grade.
Steady 100 % might be something like towing or dragging max load up up a really steep long grade, foot to the floor, without losing or gaining speed.
The acceleration loop shows that maximum acceleration (full throttle) has about the the same fuel-air needs as constant 100 % power.
"The clue [relationship] here is rich idle, lean cruise, leaner (leanest, actually) part-throttle acceleration and rich WOT. The leanest is at mid-load, half-throttle or so.
The thing to understand is most engines respond to being leaner than stoichiometric at part-throttle because the lean exhaust gas has hot unburned oxygen, and hot oxygen improves combustion"
In summary "at moderate to mid load, engines will run lean and like it, and burn much less gas while doing so. They must be rich at idle and very low load, lean in the middle, and rich at WOT." The load where richer is needed varies with engine, gearing and vehicle. It may be 60-70% as shown here, or as high as 90%. Load relates to manifold vacuum, and therefore is used to signal the opening of the power valve, letting more fuel into the main circuits.
"This ... graph is from Walter B. Larew, Carburetors and Carburetion. At the time he wrote his book on carburetors he was a retired Brigadier General who taught Military Science at Cornell, among his other accomplishments. He published this carb book in 1967.
He didn't specify an engine type for this graph but his information is in the context of engines in general. His sources were most likely military aviation research. The math in his book is from NACA TR-49 and similar publications.
This graph is representative of a richer part-throttle that may be necessary to tolerate with an engine that has radical valve timing and perhaps not so good A/F distribution at part-throttle."
quote and graph from Tuner on Innovate Motorsports Forum and reposted at RFS.
F is Fuel/Air ratio for gasoline. Invert the numbers on the vertical axis to convert to Air/Fuel ratio.
0.08 = 12.5
0.667 = 14.7
0.06 = 16.6
Constant power is any steady throttle condition.
Steady 15% might be something like driving 40 mph on a flat.
Steady 25% might be sameat 60 mph or 40 mph up a long a grade.
Steady 100 % might be something like towing or dragging max load up up a really steep long grade, foot to the floor, without losing or gaining speed.
The acceleration loop shows that maximum acceleration (full throttle) has about the the same fuel-air needs as constant 100 % power.
