Spark ingnition efficiency with ambient air temperature
Spark ingnition efficiency with ambient air temperature
(OP)
Does anyone know how spark ignition ICE efficiency would be expected to vary with ambient temperature?
I have a Toyota Prius and notice the MPG suffers ~10% drop in cold weather even after warm-up. This could be due to many factors, but just wondered if the above could be one of them.
[My own guess, not being an expert, was that colder air having higher density would need more heat input to achieve the same pressure rise. Also, since the same volume of colder air contains more oxygen than warmer air, perhaps higher pumping loss in the throttle is inevitable at low output powers]
Geoff
I have a Toyota Prius and notice the MPG suffers ~10% drop in cold weather even after warm-up. This could be due to many factors, but just wondered if the above could be one of them.
[My own guess, not being an expert, was that colder air having higher density would need more heat input to achieve the same pressure rise. Also, since the same volume of colder air contains more oxygen than warmer air, perhaps higher pumping loss in the throttle is inevitable at low output powers]
Geoff





RE: Spark ingnition efficiency with ambient air temperature
RE: Spark ingnition efficiency with ambient air temperature
To compund the problem with the Hybred, the batteries do not work as efficient and you do not have the full potential for work and your engine will make up for it. I'll stop short on the physics of hybred's and effiency because the facts get in the way. I drive a 1.8 liter 2ggze Toyota engine and it gets better overall milage than their Hybred.
RE: Spark ingnition efficiency with ambient air temperature
Contrary to the analysis provided, I must say that subjectively, I always feel like I have more performance during the summer months compared to winter. This could be either
1) In summer I have less HP but this more than outweighed by even less drag
or
2) It's sunny outside, so everything seems better anyway.
Thanks,
Geoff
RE: Spark ingnition efficiency with ambient air temperature
harveygp,
Take a look to thread108-138154 and thread71-72284.
There you can find answers to your questions from another angles.