A/F ratio and 10% Ethanol
02-26-2011, 06:48 PM
#1
Registered
Thread Starter
Join Date: Oct 2000
Location: Spicewood, Texas USA
Posts: 1,382
Likes: 0
Received 3 Likes
on
2 Posts
A/F ratio and 10% Ethanol
Thought I'd throw this out there to generate some discussion. Seems now that everyone is being forced to run e10, there are some tuning factors to consider. Everyone knows that it takes more fuel to generate the same amount of power with e10. What we're seeing is a need to run the A/F about .4-.5 richer than with pure gasoline to get peak power on the dyno. I can see this being an additional evil of e10(or e15), especially if you've got a high performance engine running on the edge. Curios to hear other's thoughts and experiences.
Bob Lloyd
Full Throttle Marine
Bob Lloyd
Full Throttle Marine
02-26-2011, 09:32 PM
#2
Registered
iTrader: (-1)
Join Date: Mar 2010
Location: Cowichan Station BC
Posts: 491
Likes: 0
Received 0 Likes
on
0 Posts
Thought I'd throw this out there to generate some discussion. Seems now that everyone is being forced to run e10, there are some tuning factors to consider. Everyone knows that it takes more fuel to generate the same amount of power with e10. What we're seeing is a need to run the A/F about .4-.5 richer than with pure gasoline to get peak power on the dyno. I can see this being an additional evil of e10(or e15), especially if you've got a high performance engine running on the edge. Curios to hear other's thoughts and experiences.
Bob Lloyd
Full Throttle Marine
Bob Lloyd
Full Throttle Marine
02-26-2011, 10:28 PM
#3
Registered
Join Date: Jul 2003
Location: North Las Vegas, NV
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
If you're going to monitor A/F ratio, which would be the best option, simply find a gauge that will display Lambda instead of air/fuel ratio.
Air/fuel ratio is always dependant on a known stoichiometric value for the fuel being burned. Because we don't always know this value, Lambda is a better way to measure.
Lambda = 1.00 at the stoichiometric point for any fuel. The wideband O2 sensors on the market today are actually Lambda sensors, and the box or gauge they connect to are programmed for the stoich point. If you have a gauge for gasoline, it's probably programmed for a 14.64-14.7:1 stoich point. When you run E10, the difference in stoich point now makes the gauge read wrong.
If you were looking at Lambda, the Lambda stoich point is always the same, as is the burn. For instance, if gasoline has a stoich point of 14.7, and you want your engine tuned for 13.0:1, then you're really tuning to Lambda = 0.88 (13.0 / 14.7). Because the Lambda value is constant and not calculated based off a set stoich point, if you watch your gauge for 0.88 all the time, you know if it's running lean or rich compared to your target.
Air/fuel ratio is always dependant on a known stoichiometric value for the fuel being burned. Because we don't always know this value, Lambda is a better way to measure.
Lambda = 1.00 at the stoichiometric point for any fuel. The wideband O2 sensors on the market today are actually Lambda sensors, and the box or gauge they connect to are programmed for the stoich point. If you have a gauge for gasoline, it's probably programmed for a 14.64-14.7:1 stoich point. When you run E10, the difference in stoich point now makes the gauge read wrong.
If you were looking at Lambda, the Lambda stoich point is always the same, as is the burn. For instance, if gasoline has a stoich point of 14.7, and you want your engine tuned for 13.0:1, then you're really tuning to Lambda = 0.88 (13.0 / 14.7). Because the Lambda value is constant and not calculated based off a set stoich point, if you watch your gauge for 0.88 all the time, you know if it's running lean or rich compared to your target.
