Phil you are right in theory, but..
Vizard suggests (p118, HTMYM) that for maximum power a Mini engine likes to be 12.5-13.0:1 f/a ratio. I agree this is pretty rich- but whaddaya want- power or economy?
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| Author: | 1380 yellow devil [ Fri Jul 09, 2004 5:31 pm ] |
| Post subject: | Air Fuel Ratio |
What is the Best air fuel mixture for Power and economy Mine runs at 13 pouds of air to 1 pound of fuel on all rev ranges up to 5000. |
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| Author: | Anto [ Fri Jul 09, 2004 8:23 pm ] |
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I've heard it's about 13.8:1 Air Fuel ratio for a mildly tuned motor. So it sounds like your in the ball park. |
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| Author: | PhildoD [ Fri Jul 09, 2004 9:53 pm ] |
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Most efficient Fuel:Air ratio is 1:15(+/- 0.1). Always has been, always will be. Most economic Rev range for a piston engine is between 2100 and 2400 RPM. The major improvement in fuel economy in modern cars is the constant monitoring keeping the mixture at the optimum ratio. Edit...... Those figures are universal for reciprocating piston engines running pump petrol. |
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| Author: | drmini in aust [ Sat Jul 10, 2004 7:51 am ] |
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Phil you are right in theory, but.. Vizard suggests (p118, HTMYM) that for maximum power a Mini engine likes to be 12.5-13.0:1 f/a ratio. I agree this is pretty rich- but whaddaya want- power or economy?
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| Author: | a_man_a_dog_and_a_mini [ Sat Jul 10, 2004 10:38 am ] |
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we want both.. don't MAKE me stamp my feet and hold my breath....!!! And these ratios are achieved by needle selection? |
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| Author: | drmini in aust [ Sat Jul 10, 2004 12:07 pm ] |
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I think with a bit (lots!) of needle experimentation you can get it a little rich at full throttle for power, and still have a lean cruise. But there are limitations- too lean and it'll have flat spots. |
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| Author: | PhildoD [ Sat Jul 10, 2004 3:41 pm ] |
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as I said, the most EFFICIENT for power versus economy is 1:15. Running slightly rich is a good safety measure for when you accelerate hard. Since SU's dont have an accelerator pump of any form, until the piston steadies itself into cruise condition again, it will be running lean. That means every time you put your foot down. Piston engined aircraft have a mixture lever, which allows adjustment for different times. Full rich is used for takeoff and landing, but it can be leaned out for cruise at altitude, espcially since less fuel is required when higher up. For that reason they all have an Exhaust Gas Temperature gauge. |
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| Author: | 1380 yellow devil [ Sat Jul 10, 2004 9:38 pm ] |
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Thanks Guys. Silly me i should have look in My vizard book first I will look next Time. |
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