Heated air in the airbox for cooler weather efficiency...?!?

[The Dark Shadow]

Okay, so here's one I've been thinking about.

I live in Nova Scotia. Cool temperatures. Our car (and my motorbike) get better MPG in the summer than fall/(winter)/spring.

So, cold air is more dense, containing more oxygen, but still it seems that warm air will aid the explosiveness of the air/fuel mixture and hence require less fuel, resulting in better fuel efficiency.

Sure, denser air means greater drag, but even in the city where air drag is nominal, the MPG goes way down in cold weather.

So, I was thinking of a crazy idea of putting a heater inside the airbox, with thermostat and controller, to heat the air before it enters the engine in temperatures below 15 to 20 degrees Celsius.

Does anyone have any thoughts...? I've done some reading. Sure, colder oil means more viscosity means greater drag. But, the engine gets warm to operating temp pretty quickly and maintains the same operating temperature whether ambient is 5 degrees or 25 degrees Celsius. So I don't buy this "extra drag" hypothesis.

Also, if tire pressure is adjusted correctly, there would presumably be less friction/drag from tire surface to road surface. So I don't buy this hypothesis either.

If indeed a warmer air intake helps fuel efficiency, it seems like a heated air filter would be awesome!

 

[SMSW]

Carb heat in small planes reduces power available, but since the heat prevents carb icing and subsequent engine shutdown resulting in a crash (rapid unplanned disassembly) all small planes have this.

Your reduction in fuel economy comes mostly from the engine running a rich mixture because it senses cold air. There is a gadget out there that fools the engine into thinking its colder in order to force a richer mixture resulting in more power, lower mileage, and smoother running. It was the subject of another thread and was derided as being a solution in search of a problem. If you could fool the sensor into thinking the weather is warm, you would get a leaner summertime mixture, rough running (maybe in cold weather), and perhaps other problems. Think starting an ice without a choke in the winter - the engine stumbles, refuses to run smoothly, and has low power until it warms up. The rest of the engine is cold, so 'fooling' it with warm air in the carbs will probably be unsatisfactory. Fuel injected bikes similarly might be upset - I don't know. Putting anything in the airbox - like a heater - might also upset the tuning of the intake pulses that Honda designed into the bike.

My opinion is you can save even more on fuel by not riding the bike in cold weather. Where would you get the energy for this heater? Maybe a long extension cord?

 

[flyfisher]

Does Nova Scotia have winter fuel mixtures? We do in Minnesota and the mileage goes down because of it and of course enrichened fuel mixtures because of cold starts(choke)

 

[CruSTy]

Winter fuel blends contain lighter molecules to aid in fuel vaporization. The lighter molecules contain less BTU and cause reduced MPG as well.

 

[Kevcules]

Internal combustion engines will always be harder on fuel in our winters. (NB) There are many factors like, the engine takes longer to reach operating temperature, the rolling resistance of the vehicle is higher (frozen bearings), gearboxes with molasses until the fluid warms up, low air pressure which is not often checked in the cold weather, all contribute to higher fuel consumption.
I'm not aware of the thought that heated air somehow generates less fuel consumption in a warm environment. Never know.
Engines seem to run more crisp after they get to operating temperature on a chilly fall afternoon, or maybe it's just the seat dino that's a little off.

 

[dwalby]

Given the airflow rate, and the temperature rise required in a very short time interval (because cold air is constantly flowing in) you'd need a very powerful heater, I think this idea isn't even practical in the first place.

 

[rwthomas1]

Interesting topic. The only thing I've ever read on the topic was using partial carb heat on a small aircraft engine to improve atomization, resulting in less mixture variation between cylinders. This then allowed the engine to be run very lean, thus saving fuel. It was interesting but not widely practiced, and a moot point on injected engines. Hot air usually causes a decrease in power, decrease in power is less efficiency, is it not?

If you were going to pursue this there is no need for a heater in the airbox. Aircraft use a simple heat box around an exhaust pipe, and then draw fresh air through that to heat it, and duct it to the intake/airbox.

I can assume you have a 1300? The fuel injection system is a speed/density system is it not? No mass airflow sensor? If its a speed/density system the computer is looking at the MAP, engine temp, throttle position, etc. and metering fuel based on that. It may be possible to tweak those fuel maps, but you'd need to find someone who really knows what they are doing. Is there an O2 sensor on a 1300? If there isn't you are truly flying blind when you start messing with fuel maps.

 

[Slydynbye]

Maybe putting a partial blanket on the radiator like Truckers use would be a better idea.
I'm thinking the warmer engine would be more efficient.

 

[Jethro]

My 1984 Ford f150 had a choke stove to aid warm up.It rotted off,and l never noticed any difference.Ride your bike for Pleasure& be happy .

 

[rwthomas1]

Maybe putting a partial blanket on the radiator like Truckers use would be a better idea.
I'm thinking the warmer engine would be more efficient.

That is a bad idea. Diesels are a whole different animal. If you want higher engine temps, a different thermostat is the way to achieve that.

 

[jfheath]

My bike always runs much better in cold air. I love those cold high pressure early mornings in late summer, when the temperature inversion has not yet gone land the colder air is closer to the ground and the sun is just getting up above the surrounding hills. The air is concentrated, hasn't warmed up yet, so each litre contains more oxygen. Beautiful smooth power. But the OP commented on this is Post #1.

Aparently early motorcyclists used to spray a water mist into the intake to get a similar result. I don't know how they achieved it and it might be a complete fabrication and I've heard it third hand, - but I believe it - because the same behaviour is true on misty mornings and misty evenings. Or is that introducing steam engine technology to a petrol engine combustion chamber ??

 

[Igofar]

Before you start overthinking ideas, perhaps you should consider replacing the t-stat, syncing the TB, changing the plugs to the correct heat range of your riding climate, and maybe cleaning your pair sensor screens etc.
Just a thought

 

[Roger]

I've had cars with summer/winter settings on the air intake that you had to swing around yourself. Summer air came from up front somewhere beside the radiator - winter air came from next to the exhaust manifold. One vehicle had an automatic valve that did the job for you. Another motor had no adjustment at all and the intake was from near the exhaust manifold - and in summer it suffered from vapour lock when the fuel boiled! I fixed that once I found out what it was. ...And I had a carb. freeze up running on the summer setting in winter! ...Anyone remember water heated intake manifolds? All these things done to get the engine up to - and keep it at a stable operating temperature - as quickly as possible.

 

[The Dark Shadow]

Does Nova Scotia have winter fuel mixtures? We do in Minnesota and the mileage goes down because of it and of course enrichened fuel mixtures because of cold starts(choke)

I do not know, but I'd expect so.

 

[The Dark Shadow]

Carb heat in small planes reduces power available, but since the heat prevents carb icing and subsequent engine shutdown resulting in a crash (rapid unplanned disassembly) all small planes have this.

Your reduction in fuel economy comes mostly from the engine running a rich mixture because it senses cold air. There is a gadget out there that fools the engine into thinking its colder in order to force a richer mixture resulting in more power, lower mileage, and smoother running. It was the subject of another thread and was derided as being a solution in search of a problem. If you could fool the sensor into thinking the weather is warm, you would get a leaner summertime mixture, rough running (maybe in cold weather), and perhaps other problems. Think starting an ice without a choke in the winter - the engine stumbles, refuses to run smoothly, and has low power until it warms up. The rest of the engine is cold, so 'fooling' it with warm air in the carbs will probably be unsatisfactory. Fuel injected bikes similarly might be upset - I don't know. Putting anything in the airbox - like a heater - might also upset the tuning of the intake pulses that Honda designed into the bike.

My opinion is you can save even more on fuel by not riding the bike in cold weather. Where would you get the energy for this heater? Maybe a long extension cord?

If I don't ride when it's "cold", I'd only be riding about 1 to 2 months a year. It's up to a balmy 13 degrees Celsius today...

 

[SMSW]

Before you start overthinking ideas, perhaps you should consider replacing the t-stat, syncing the TB, changing the plugs to the correct heat range of your riding climate, and maybe cleaning your pair sensor screens etc.
Just a thought

Don't be silly, Larry, It's more fun to ruminate on what might be possible than do routine maintenance. (I'm speaking from personal experience.)

 

[thekaz]

winter blends are definately different then summer
intake heaters are super common on modern diesels as preheaters until operating temp.
intake heaters & coolant heated intakes were a thing on some carbed applications that had icing problems.

BUT have never heard of an ST1300 with an icing problem ?

 

[CruSTy]

Intake air pre heat is primarily there to prevent carburetor icing. Icing happens at the Venturi where the drop in air pressure and the introduction of low pressure fuel cause a temperature drop freezing the moisture in the air onto the Venturi nozzle. The ice acts as a choke blade causing rich mixture and reduction in air flow. A small amount of pre heat will prevent this. On the ST 1300 With fuel injection there is no Venturi to cause the pressure drop, the fuel is injected at relatively high pressure onto warm surfaces near the valves. Pre heat would be a detriment by reducing air density and increasing chances of pre ignition in the combustion chamber.

 

[Capital]

15-20C is The Temperature in Europe to go out and ride. Up & down the whole continent - because it is perfect! The last thing to care is MPG details. How we came to being so complicated?

 

[SMSW]

How we came to being so complicated?

Some folks just have too much time on their hands.