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Discussion Starter #1
I've been thinking about this for a while, and after seeing the recent posting about exhaust temps I decided to put thoughts into action.
I know it's a good thing to have cool/cold air entering the intake. Better combustion and all that. And I've read on here how the spider already has a descent albeit convoluted cold air intake system and the aftermarket systems are a lot of money for not much increased power, just a louder/better? sound.
However, after checking out some of the aftermarket offerings I saw a system by K&M that had a heat shield extension piece that extended the shield up to give more separation of the exhaust manifold heat from the intake. Not a bad idea, I thought.
So, here's what I came up with. I had some scrap galvanized metal skirting lying around that was just the right size. So I fabricated a heat shield extension to see if it helps lower my air intake temps.
This is the side facing the exhaust manifold.
This is the back showing the crude bracing I made to keep the shield extension from flopping around too much.
This is a test for fitment.
And this is the shield installed.
A close up of the hose and O2 sensor wire. I haven't had a chance to test it out yet, but I'll take her out tomorrow and measure the temps and let you know what I find.
 

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Well done.

The real gain from lower IATs isn't the better combustion of colder air. Its that the stock ecu is more aggressive with its ignition timing. This is why your car feels so much stronger on a cold winter day.

For example this is a stock 06 miatas ignition timing retard map:

ECT = Engine coolant temperature in Celsius
IAT = Intake air temp in Fahrenheit.

So if you look at the far right column since thats where a fully warmed up engine would be you can see how every 10 degrees higher IAT results in more and more timing retard.
 

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Discussion Starter #7
I wanted to share the results, so far, of installing my home made heat shield extension. I took the temperatures of my Spyder last week after a short run with some highway driving and found temps. of 357.2 F for the exhaust manifold heat shield and 161.2 F for the air filter box. The ambient air temp was 68 F.I remeasured the temps. after taking a similar trip after installing the heat shield extension and got 354.5 F for the manifold shield and 96.0 F for the air filter box. The ambient air temp was 66 F. That's a 65.2 F difference! Does this change the AIT? All I can say is "it couldn't hurt!"
The manifold temp before,
The air box temp before,
The manifold temp after,
The air box temp after.
 

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I question your original temperature reading on the air box.
I've never actually measured any engine bay temperatures, but I have touched the air box after an extended run, and it didn't feel all that warm. Had it been 160° or so, I'm sure I'd have noticed it (and put butter on my burns).
 

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Discussion Starter #9
I question your original temperature reading on the air box.
I've never actually measured any engine bay temperatures, but I have touched the air box after an extended run, and it didn't feel all that warm. Had it been 160° or so, I'm sure I'd have noticed it (and put butter on my burns).
Well, all I can say is that the little red laser pointer dot was on the top of the air box in both photos. If the temp reading is wrong on the first photo it must be wrong on all of the photos. The first temperature photos were originally posted on a thread about exhaust temps. posted by HCS in the general forum last week.
 

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Nice experiment!
 

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The only way to test it properly would be to use a scangauge type device to recover the IAT from the ECU and compare that before and after driving at a constant speed with the same ambient temperature on both tests.

Stand still temperatures really arent that important because you dont need extra hp at idle. When at speed theres alot of air going through the engine bay so you'd want to get the measurements at the same speed.

Also its more accurate to read the IAT since the temperature of the airbox doesnt directly relate to the temperature of the air comming into the engine (although it does help). The air is flowing quite quickly through the system especially when going hard so even if the airbox is hot, its possible the air isnt even staying in there long enough for it to make a difference.I'd say it would be more important to have a source of cool air comming into the intake system than it is for the intake pipes, airbox etc. to actually be cool themselves.

But hey, every little bit helps, if it keeps the airbox cool enough that its getting the IAT that little bit cooler than its worth a shot. Just be careful its not rubbing on those hoses, wouldnt want it to wear its way though slowly.

On an unrelated note... your exhaust heat sheild looks in really good condition. Its so shiney and new looking.
 

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I have performed various experiments like this one to reduce the air intake temps and I was so successful that I got it down to 5 degrees above ambient.

What I found was that all of the shielding was equally worthless. The effect of outside ambient temps does make a difference like driving on a cold day however trying to simulate the effect by shielding in theory seems like a good idea but did not yield those results.

This leads me to conclude that it really does not matter and cold days are what count not shielding. When the car is in motion there is a sharp decline in air intake temps anyway and even though the piping may be subject to heat the cold air rushing in does not get heated up.

Though my testing I found something that I was not looking for but became apparent which is if you allow the filter to have as much room to gather air on all sides it can then make the most profound difference in the way the car breaths even if it is sucking in heated air.
 

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Discussion Starter #13
I have performed various experiments like this one to reduce the air intake temps and I was so successful that I got it down to 5 degrees above ambient.

What I found was that all of the shielding was equally worthless. The effect of outside ambient temps does make a difference like driving on a cold day however trying to simulate the effect by shielding in theory seems like a good idea but did not yield those results.

This leads me to conclude that it really does not matter and cold days are what count not shielding. When the car is in motion there is a sharp decline in air intake temps anyway and even though the piping may be subject to heat the cold air rushing in does not get heated up.

Though my testing I found something that I was not looking for but became apparent which is if you allow the filter to have as much room to gather air on all sides it can then make the most profound difference in the way the car breaths even if it is sucking in heated air.
Interesting. What did you do to "allow the filter" to have more room to breath? I assume that you're referring to the stock air filter box, correct?
And Ben88, I recently had the heat shields off to clean the engine and decided to remove the rust, sand them down and paint them. I used a high temp paint from Auto Plus called Brite Beauty BH206 High Heat Aluminum.
 

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Discussion Starter #14
Interesting. What did you do to "allow the filter" to have more room to breath? I assume that you're referring to the stock air filter box, correct?
And Ben88, I recently had the heat shields off to clean the engine and decided to remove the rust, sand them down and paint them. I used a high temp paint from Auto Plus called Brite Beauty BH206 High Heat Aluminum.
Dev, since I didn't hear anything back from my question, are you talking about drilling holes in the air filter box? I saw something about this on Youtube but it wasn't clear if it was a good idea or not.
 

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Discussion Starter #15
Nice experiment!
Thanks. All I'm doing is experimenting. I have no idea if anything I try will have any importance. I'm just intrigued by the potentials.
 

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heads up, the airbox is a resonance chamber, and works to create a positive pressure effect at a certain engine speed. I believe it is called helmholtz resonance. On bikes it boosts low-end torque noticeably, although the effect is less profound on a less high-strung motor.

You don't want to drill holes in it, normally.

heat shielding is good, but as dev says, it is the airtemp (IAT) that really matters. The beauty of plastic intake, is that plastic is a terrible conductor of heat. So, even though the outside may be very hot, it will not transmit as much heat to the air inside.

Makes you wonder why they used an aluminum manifold on the 2zz *shrug*
 

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Makes you wonder why they used an aluminum manifold on the 2zz *shrug*
Because while it will heat up quickly, once air is flowing through it will also cool down quickly. Besides, plastic intake manifolds are rubish for anyone who wants to modify a car. they dont like high boost, and you cant really modify them. eg. with an aluminium intake you can cut and weld it to make an ITB manifold or to modify the plenum chamber etc etc.
 

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Dev, since I didn't hear anything back from my question, are you talking about drilling holes in the air filter box? I saw something about this on Youtube but it wasn't clear if it was a good idea or not.
Sorry for the late reply. I would never consider drilling holes in the air filter box.

I am just suggesting that if you have an aftermarket intake you should not place too much shielding around it.
 

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heads up, the airbox is a resonance chamber, and works to create a positive pressure effect at a certain engine speed. I believe it is called helmholtz resonance. On bikes it boosts low-end torque noticeably, although the effect is less profound on a less high-strung motor.

You don't want to drill holes in it, normally.

heat shielding is good, but as dev says, it is the airtemp (IAT) that really matters. The beauty of plastic intake, is that plastic is a terrible conductor of heat. So, even though the outside may be very hot, it will not transmit as much heat to the air inside.

Makes you wonder why they used an aluminum manifold on the 2zz *shrug*
That's not what I am saying. The IAT does not make that much of a difference in any perceivable horsepower gains as one would think. What I found makes the difference is when the ambient temps are lower in general. I do not know what accounts for this phenomenon but the air is much better and it does yield a better result.

In regard to plastic intakes and or manifolds it is a misconception that they heat up the air less.
When fresh air enters the system it will not mix with the hot air molecules lining the intake tract so it does not matter.

The goal here is to do what you can but don't obsess with trying to get a lower intake temperature because you are not going to perceive any difference in power and you will only be adding more weight which is counter-intuitive.
If you want real power cheap get a Camcon unit.
 

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ah I think Russell mentioned the drilling.

I hear what you're saying about ambient temps, I'm coming from tuning on turbo cars so I'm more used to heat soaked intercoolers which is a different matter!

I agree that the difference is minimal. Air that is a few degrees cooler will make hardly any difference to air density, and thus power. Any knock resistance gained would be barely noticeable.

using the old rule, air + fuel + spark = torque, torque x rpm = power

it's pretty clear cut from this how you should be going about making more power
 
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