"Warm Air Intake" Apparently increases fuel efficiency?

[Z2TT]

Looks like warm air intake could increase fuel economy, there's even an article on wikipedia about it which mentions it's for a fuel economy.
Don't know if it's a load of shit like Jimmmay said or true.

http://en.wikipedia.org/wiki/Warm_air_intake

[jimmmayyy]

well wiki is written by anybody who cares too submit an article. the fact that it completely flies in the face of well established theories just says blatantly that its crap.

this whole thing where people have been saying that warm air=more throttle=less pumping losses etc...is just crap. if you have to crack the throttle more, its gonna use more fuel, theres no questioning that. as for it having any effect due to less pumping losses...id think that itd be more luck than anything that you may find the sweet spot in the rpm band where torque is at its peak and therefore less effort to make the whole shebang move.

this is totally in contradiction to the FACT that cooler air is more dense and therefore contains a higher partial pressure of oxygen, the only gas in air that is combustible obviously. most EFI engines are quite capable of compensating for any changes in air temp, and that wiki article in my eyes is completely contradictory of itself in the thinking of any petrol powered ICE. if you look at the cited references you'll see that its only particular to THROTTLE-LESS engines...IE diesels.

simply, for a petrol ICE, the less dense the intake air, the less oxygen to burn=less power. therefore you need to crack the throttle further to gain the same amount of forward momentum, thus increasing fuel consumption. this is a long established theory, and really, i dont see any justification to question it, particularly when you see manufacturers doing it...even F1 - the pinnacle of automotive engineering - as well as all other forms of motorsport, use a huge intake directly above the driver's head/or highest, cleanest point for induction.

[woggin]

Jimmmayyy- if this theory didnt actually work why would all the best (fuel economy based vehicles) all run warm air intake systems??

If CAI was so much more economic why dont the most economic cars on the planet use them?

F1 is different, your trying to cram air into the intake, thus producing more power, as for being above the drivers head, its provides cooler air, also increasing more power! they do wat they can to get more air in to make more power...

IF this discussion cant be solved, how bout we send it into mythbusters and we'll see if we can get them to do real life testing??

[kehendo]

actually, this theory is based on simple facts. if cold air is denser than warm air that means that there can be more fuel burnt in each cylinder if we retain the 14:1 afr. taking this information the warmer, less dense air will only burn cleanly with a smaller amount of fuel. so for this to work the car needs to be able to adjust it's own mixture on the go which means the car must be efi.

so in short, cold air = more fuel = less fuel economy + more power
warm air = less fuel = more fuel economy + less power.

to be honest, i think that any gain or loss will be negligible you're better off leaving it the way the manufacturer intended. they spend millions in car design with a team of 20 or so people to design that intake, do you really think you can do better in your own shed armed with information that you got off a forum?

[Duk]

well wiki is written by anybody who cares too submit an article. the fact that it completely flies in the face of well established theories just says blatantly that its crap.

this whole thing where people have been saying that warm air=more throttle=less pumping losses etc...is just crap. if you have to crack the throttle more, its gonna use more fuel, there's no questioning that.

The load sensing system (AFM or MAP sensor+RPM) + feedback from the exhaust gas oxygen sensor when cruising determines fuel requirements. Throttle position is only used for transient throttle fuel requirements (acceleration enrichment) and to tell the ECU that the driver has his foot off the accelerator (fuel cut for over run).

as for it having any effect due to less pumping losses...id think that itd be more luck than anything that you may find the sweet spot in the rpm band where torque is at its peak and therefore less effort to make the whole shebang move.

Induction pumping loss at part throttle represents a very big part of the inefficiencies of a petrol engine. Any thing that can be done to reduce that pumping loss helps part throttle/cruise fuel economy. Exhaust gas recirculation is a good example of a means of reducing pumping losses.

this is totally in contradiction to the FACT that cooler air is more dense and therefore contains a higher partial pressure of oxygen, the only gas in air that is combustible obviously. most EFI engines are quite capable of compensating for any changes in air temp, and that wiki article in my eyes is completely contradictory of itself in the thinking of any petrol powered ICE. if you look at the cited references you'll see that its only particular to THROTTLE-LESS engines...IE diesels.

Nobody is doupting the FACT that cool air is more dense and is better for outright power.

F1 - the pinnacle of automotive engineering - as well as all other forms of motorsport, use a huge intake directly above the driver's head/or highest, cleanest point for induction.

And this would help them to achieve better fuel economy when cruising at 100-110km/hr how?

[Cuts]

vote 1 mythbusters testing

the lack of throttle plays a significant part in a diesels effeciency, so any reduction in pumping loss in a petrol engine should help, but your probably only talking about a couple of degrees less angle on the throttle plate, which i wouldnt think would be enough to notice a difference.

[foamy]

Kind of like that old survival trick. Drinking warm water saves your body from having to use energy to heat cold water up. In this instance it's warm air and saves fuel.

[AdrianS]

Pumping losses are a major cost (efficiency wise) at partial throttle. This is one of the reasons that vvt engines use some non-intuitive valve timing/overlap at light throttle - by allowing some exhaust gas to remain in the cylinder, they reduce pumping losses by breathing less air with a larger throttle opening. Direct injection engines do this to an even greater extent, which is one of the ways they get improved fuel economy.

but - why think or research, when you can just post opinions ?

[AdrianS]

Maybe all the boyz with a huge un-shrouded pod filter in the engine bay are chasing economy ?

[Billzilla]

If you want a bit of an interesting journey, for better or worse do some research on Smokey Yunick's Adiabatic Engine.

Ahem ....
Really guys, there's a lot of good and no-so-good reading with his idea.

[Z2TT]

Thanks for the input everyone

Woggin what do you mean all the most efficient cars use Warm Air Intake? I see that they all use cold air intake with a scoop going near the front of the bonnet or headlight.

So what i get it is that when the air is warmer, the throttle plate has to be open more to suck a given amount of air in, so this reduces pumping losses because the throttle is less of a restriction to the engines efforts to suck the air in because it is wider open, so the engine can suck that air in easier giving it better fuel economy? Yes.

Then shouldn't all the economy orientated cars be using warm air intake? Like Yaris, Echo, Getz?

And also, have you ever wondered why so many people have said that their fuel efficiency has gone real bad after putting a pod filter on... and people blame that because it's sucking hotter air in from being unshielded, isn't that argument null and void because hotter inlet temp = less throttle lossses = better efficiency. So I don't understand why pod filters decrease fuel economy that many people have reported.

[Duk]

And also, have you ever wondered why so many people have said that their fuel efficiency has gone real bad after putting a pod filter on... and people blame that because it's sucking hotter air in from being unshielded, isn't that argument null and void because hotter inlet temp = less throttle lossses = better efficiency. So I don't understand why pod filters decrease fuel economy that many people have reported.

Probably from repeated attempts to feel the massive increase in performance that they didn't get .

[jimmmayyy]

The load sencing system (AFM or MAP sensor+RPM) + feedback from the exhaust gas oxygen sensor when cruising determins fuel requirements. Throttle position is only used for transient throttle fuel requirements (acceleration enrichment) and to tell the ECU that the driver has his foot off the accelerator (fuel cut for over run).

yes, i know that. fuel consumption is always at the highest during acceleration to cruising speed..if youre making less power, you'll need to accelerate longer/harder to achieve the same cruise speed thus using more fuel.

Induction pumping loss at part throttle represents a very big part of the inefficiencies of a petrol engine. Any thing that can be done to reduce that pumping loss helps part throttle/cruise fuel ecconomy. Exhaust gas recirculation is a good example of a means of reducing pumping losses.

yes. however exhaust gas recirc is for emissions reduction, not charge heating.

woggin, i can't say i know of any vehicles youre referring to that use a WAI...could you name a couple?

[Duk]

fuel consumption is always at the highest during acceleration to cruising speed..if youre making less power, you'll need to accelerate longer/harder to achieve the same cruise speed thus using more fuel.

Sounds like you've given that 1 a lot of thought

yes. however exhaust gas recirc is for emissions reduction, not charge heating.

Exhaust gas recirculation adds an inert (non combustable) gas to help partly fill the combustion chamber during an induction stroke. Thus reduced induction pumping losses.
A vacuum gauge on an engine with EGR will show noticably lower manifold vacuum when cruising.
Yes the initial use of EGR was probably emmissions based, but improved cruise ecconomy is a secondary bennefit.

[oldcorollas]

EGR is very simple...
an engine works by expansion due to temperature.
with EGR, you have more gas to expand with the heat generated by the combustion process, so you get more power for a given amount of fuel, and thus, increased efficiency... as well as reduced pumping losses.

this is also the theory with "lean burn" cars for increasing efficiency at cruise

i was looking for some proper research to assist with the discussion, bu tmost has to do with diesels..
for them, the ideal intake temp increases as BMEP decreases.. say from 40C at full load to 100C at low load..

still looking for good papers on SIC..