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Thread: Warm Air Intake - Intercooler as an intake heater

  1. #41
    Moderator Eggman's Avatar
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    Hello foama!

    Quote Originally Posted by foama View Post
    Hey guys,
    let me sum up a few thoughts...

    1) Most enrichment occurs when it is cold. The colder, the more.The longer the car needs to warm up, the more enrichment it gets, and for a longer period. Consequence being, the colder it is, the more fuel gets burned.

    2) With intake air being warmer (just as with coolant being warmer), the mapping is told it needs less enrichment (less fuel). Remember, the ECU receives A) coolant temp info, and B) intake air temp info.

    3) When warming up and warm intake air is needed most, the coolant is cold. So much for a coolant-to-air heat exchanger. Of course after warm-up the exchanger will work and be beneficial, but it has definite limitations during warm-up when it is needed most.
    This is where an engine block heater comes in to complement this idea. The two can work together to get things up to temperature faster.

    As you likely already know, air intake heaters are not a new idea. They have been in use for many years - not for normal operation, but for faster warm-up times. Ones I am familiar with use the exhaust manifold as a source of heat.

    Quote Originally Posted by foama View Post
    4) Take a look at the engine assembly!
    The resonator-box and the air intake snorkel are basically back to front!
    If the snorkel went behind the engine instead of to the front, we would have a very simple, and equally effective warm air intake.
    This would be so much easier if the two were switched... I suspect the length of the intake snorkel acts to help develop a positive pressure at the air box.

    Quote Originally Posted by foama View Post
    What we do not want to change is the resonance frequency (air volume!) of the total airfilter/resonance-box/intake-snorkel assembly, because it would change the torque curve.
    Warmer air will also hinder power development.

    It is my understanding that this experiment is intended to bring out improved efficiency at the expense of a loss of peak power. How much of this trade-off is acceptable is yet to be determined. I would argue that most enthusiasts interested in this modification are not focused on improved power, but improved efficiency in the sense that the 3A90/3A92 develops plenty of power for their needs.

    I am interested in learning more about the resonant cavity of that box. Do you have any info on that, because the Mirage service manual makes no mention of it's use as a resonant cavity (unless I missed it...)

    Quote Originally Posted by foama View Post
    Any ideas how to get the snorkel to lead behind the engine?
    Yep! Take a look at this thread: Warm Air Intake And this post in particular is the source of my curiosity.

    It's been done, and while I dislike it's appearance I admire the performance.

    Quote Originally Posted by foama View Post
    Just for the record, The old thread " ECO Mod: Howto reduce level of enrichment when cold " shows how the ECU programming can be easily oversmarted to reduce enrichment and fuel consumption.
    I remember that!

    The intake air warmer idea may not require electrical modification depending on if the design needs controls to modulate temperature.


    I wish Old Mech was still contributing, as he had some fine insight in these matters.

    Old Mech, if you are out there, I hope you consider chiming in, and that all is well with you.


        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


  2. #42
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    Hi Egmann!

    Quote: "This is where an engine block heater comes in to complement this idea. The two can work together to get things up to temperature faster."

    I agree fully, but you need a power source next to the car, and block heaters are damn expensive in Europe.

    Quote:
    "I am interested in learning more about the resonant cavity of that box. Do you have any info on that, because the Mirage service manual makes no mention of it's use as a resonant cavity (unless I missed it...)"

    The FSM doesn't mention anything else other than the box being a resonator. The theory to this is quite simple: At a certain amount of revs, the engine intake makes a certain noise. If the intake is resonant to that frequency within the noise, more air gets drawn in, and the torque at that particular rev-level increases. So much for theory!
    In practical terms, the resonance is of low Q, meaning it is not so pronounced or high, but rather dampened due to the air filter cartridge and other things. Because it has low Q and a low peak, resonance occurs at a wider frequency range (rev range). Usually resonators are tuned by design to increase torque at moderate revs. Note: The entire intake, from the valves to the end of the snorkel, and everything in between determine the frequency of resonance, which we don't really want to change more than necessary.
    The basically same theory applies to LC circuits (example antenna tuning) in electronics.

    "I wish Old Mech was still contributing, as he had some fine insight in these matters." I fully agree!

    I think it may be worth it to look for an elegant way to get the snorkel to end on the warmer side of the engine.
    Last edited by foama; 10-29-2017 at 02:40 PM.

  3. #43
    Senior Member fifteenwindow's Avatar
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    ...what do you think of as a safe "max' iat value?

    That's a good question. In the thread I referenced above in Post #23, the forum member said his IAT temps were 100 degrees above ambient. That almost seems too hot...especially in warmer months. I would think the engine could be running dangerously lean if the incoming air temp is always something like 150 degrees. You would be running the risk of detonation (in which the ECU pulls timing and you lose power) or potentially overheating. Warm air is good...but I would be concerned about intake air temps well above 100 degrees in the summer.
    Hey, Everybody.

    In using the big burrito WAI from the other thread, I used 190 degrees F as an upper IAT limit in driving. The reason I picked 190 degrees was because the coolant thermostat opens at 195 degrees, so I thought that might be a safe temperature. I used an old bicycle brake cable to lift the end of the WAI about a half an inch off the exhaust manifold if the IAT got above 190 F.

    Anybody here in Florida or California with a scanguage? Could you tell us what the IATs get up to when you are stopped in traffic or gridlocked on the highway in July? I suspect if you are at operating temp, idling in 100 degree F ambient temps, your engine breathes in some very hot air, especially when your radiator fan kicks on, at 220 degrees F.

    I am excited to see where this conversation leads. Thumbs up, folks.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage DE 1.2 manual: 53.1 mpg (US) ... 22.6 km/L ... 4.4 L/100 km ... 63.8 mpg (Imp)


  4. #44
    Moderator Eggman's Avatar
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    Quote Originally Posted by foama View Post
    In practical terms, the resonance is of low Q, meaning it is not so pronounced or high, but rather dampened due to the air filter cartridge and other things.
    I would expect the air filter would essentially eliminate any resonance. I would also expect the resonant chamber would be more effective if located between the air filter and the throttle body, or even between the throttle body and the intake manifold.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


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  6. #45
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    Quote Originally Posted by fifteenwindow View Post
    Hey, Everybody.

    In using the big burrito WAI from the other thread, I used 190 degrees F as an upper IAT limit in driving. The reason I picked 190 degrees was because the coolant thermostat opens at 195 degrees, so I thought that might be a safe temperature. I used an old bicycle brake cable to lift the end of the WAI about a half an inch off the exhaust manifold if the IAT got above 190 F.
    Pictures of the cable please! Are you still using the burrito?

    Quote Originally Posted by fifteenwindow View Post
    Anybody here in Florida or California with a scanguage? Could you tell us what the IATs get up to when you are stopped in traffic or gridlocked on the highway in July? I suspect if you are at operating temp, idling in 100 degree F ambient temps, your engine breathes in some very hot air, especially when your radiator fan kicks on, at 220 degrees F.

    I am excited to see where this conversation leads. Thumbs up, folks.
    My OBDLink LX features data logging. Too bad I didn't track intake air temperature like I was tracking coolant temps for the past seven months of use... I am tracking it now.


    With the Big Burrito approach, I see fast response coupled with low cost & complexity - an easy modification.

    With the Hot Tamale approach, I see an ability to control the peak temperature using a valve. This could even be automated. Also, it all can be contained within the air filter box.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


  7. #46
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    Quote Originally Posted by Eggman View Post
    I would expect the air filter would essentially eliminate any resonance. I would also expect the resonant chamber would be more effective if located between the air filter and the throttle body, or even between the throttle body and the intake manifold.
    The air filter will dampen resonance, not eliminate it. It does that because of the restriction to the air flow. Dampened, resonance also occurs at neighbouring frequencies, albeit at much lower amplitude.
    Were the resonance chamber located between air filter and throttle body, the resonance would have a higher Q (= higher peak) and thus be much more pronounced at resonant frequency, but almost nill at neighbouring frequencies. Frequency here translates to rpm.
    This is more or less the same behavior as displayed by parallel L / C circuits. There is lots of literature on that.

  8. #47
    Senior Member MightyMirageMpg's Avatar
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    Foama,

    Your explination has me puzzled.

    The air waves travel back and forth but The resonator box only works under very certain rpm window, when the pulses would force more air thru the open valve, correct?

    This would increase power, but lower fuel economy due too increased fuel? Or would it increase fuel economy, because of significantly less pumping loss?


    Eggman do you have any pictures of The inside of The magic box?

  9. #48
    Moderator Eggman's Avatar
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    Quote Originally Posted by MightyMirageMpg View Post
    Eggman do you have any pictures of The inside of The magic box?
    I should be able to get some for ya.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.6 mpg (US) ... 21.1 km/L ... 4.7 L/100 km ... 59.5 mpg (Imp)


  10. #49
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    Quote Originally Posted by MightyMirageMpg View Post
    Foama,

    Your explination has me puzzled.

    The air waves travel back and forth but The resonator box only works under very certain rpm window, when the pulses would force more air thru the open valve, correct?

    This would increase power, but lower fuel economy due too increased fuel? Or would it increase fuel economy, because of significantly less pumping loss?
    1. Correct. Resonance occurs only at a/the resonant frequency.
    2. It would increase max possible torque (power) at resonance.
    If you for some reason that power is not enough, you would have to shift to lower gear. The resonator helps a bit to avoid this.
    Of course you can not expect wonders from the resonator, especially with the comparatively small mirage engine that needs to rev if it has to deliver any elevated level of power.

    I personally don't need very much power the way I drive, I rather try to drive economically.
    Last edited by foama; 10-29-2017 at 07:45 PM.

  11. #50
    Senior Member MightyMirageMpg's Avatar
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    Whats the actual projected impact this little thing has?

    I always viewed it as something you throw in the trash if you feel like



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