Intake air temperature

[Petrus]

Not all thát marginal this time.

I remember several here mention it, @shnazzle in particular. That lower intake temp means more hp.
3 degrees C. lower intake temperature means 1% more power.

Now Toyota did a very ggod job delivering just about the coolest air possible to the engine within other parameters.
Where they hád to accept high temps was with the exhaust simply because of space. The result is that with the OEM install the air filter housing and the rubber connection to the intake manifold does warm up.
Same thing the drip tray and nappies. Noise reduction is a pita. But the bright side is that wé can delete them 

Modifying the exhaust to free it up from a bit to a lot has the added benefit of lowering the under hood temperature  = inlet temp = power. Win-Win.

There is another thing that can be done (with a better flowing system). Opening up the rear so any heat from the exhaust can get out quicker. Deleting the black heat shield and removing as much of the number plate holder as possible is nothing visible but does help.

These things have a neat, in this case literally  cool knock on effect.
Opening up the flow out the back reduces the pressure in the engine room thus will see more air flow in fromm the side vents. That takes out the heat out faster still.
By all means take out the charcoal canister, install a smaller battery of move it up fornt; both will obstruct the flow from the vents less and ... you get it.

Go the whole hog and you will notice that the eyeball scorching whóósh of air rising from under the rear lid after a spirited drive has GÓNE!!! It tells you that the airbox is cooler too. You could also see it in the temp reading from the MAF. Free power 

1% hp per 3 degrees C. and there is considerably more than 3 degrees to be won.
Cool no?!

[shnazzle]

Not all thát marginal this time.

I remember several here mention it, @shnazzle in particular. That lower intake temp means more hp.
3 degrees C. lower intake temperature means 1% more power.

Now Toyota did a very ggod job delivering just about the coolest air possible to the engine within other parameters.
Where they hád to accept high temps was with the exhaust simply because of space. The result is that with the OEM install the air filter housing and the rubber connection to the intake manifold does warm up.
Same thing the drip tray and nappies. Noise reduction is a pita. But the bright side is that wé can delete them 

Modifying the exhaust to free it up from a bit to a lot has the added benefit of lowering the under hood temperature  = inlet temp = power. Win-Win.

There is another thing that can be done (with a better flowing system). Opening up the rear so any heat from the exhaust can get out quicker. Deleting the black heat shield and removing as much of the number plate holder as possible is nothing visible but does help.

These things have a neat, in this case literally  cool knock on effect.
Opening up the flow out the back reduces the pressure in the engine room thus will see more air flow in fromm the side vents. That takes out the heat out faster still.
By all means take out the charcoal canister, install a smaller battery of move it up fornt; both will obstruct the flow from the vents less and ... you get it.

Go the whole hog and you will notice that the eyeball scorching whóósh of air rising from under the rear lid after a spirited drive has GÓNE!!! It tells you that the airbox is cooler too. You could also see it in the temp reading from the MAF. Free power 

1% hp per 3 degrees C. and there is considerably more than 3 degrees to be won.
Cool no?!

Probably not that straight forward I think I mentioned it in thr context of hp drop per 10deg change. 

So, running a turbo without sufficient cooling and hitting intake temps of 70deg or so would make things pretty noticeable. 

I reckon if the engine is at peak happiness, it might gain closer to 2hp per 10deg colder. Offset by optimal operating temperature. So all in all you might be between 2-3hp better off in the summer.

[Dev]

I have done all sorts of intake modifications to lower intake temps. I have eventually got the air intake to match one or two degrees above ambient using clever shielding.
The result was no difference in power.  What does make a difference is when the ambient air is cooler regardless of the IAT reading.

Let's say the MAF IAT temps read the same from two intakes. One has a better way of routing reads at ambient temps by design and the other reads 15 degrees higher than ambient but the outside temps are cooler. The one with the cooler outside ambient temps is the one that can be felt but it's not a big difference.

On the exhaust side you don't want to cool it down. You want to keep heat in as this does two things. Scavenging exhaust gases and lowering radiated heat in the engine bay that migrates to the intake if your goal is to lower intake temps.  Using  shielding is the best way to keep the hot side separated from the cold side.  When you remove the shields for weight reduction hot air migrates to the engine bay.

For these cars to perform their best where overheating is not an issue the last thing you want to do is lower the temps. Cars perform best when they are thermally efficient and hot.

[Petrus]

The thermostat keeps the operating temp neatly stable. No need to worry there.

Indeed best keep all the OEM shielding like I did ;-)
Apart from the black one, obviously.

With a free flow exhaust system heat retention is a station past and more so for the 1ZZ with long stroke and modest cam timing.

Whether a particular bum nótices the difference or not, is a not very interesting discussion.
The science is hard: less temp is more density is more hp. This is for turbos, intercooling and n.a. alike. Just more marginal in n.a.
Whether the IAT is lower becasue of lower ambient temp or less heat transfer from the under hood temp is exactly the same obviously. Bottom line is that you want as cool as possible charge at  the intake valves thus the least possible heat transfer.

As to how large the effect is, here is a research table for temp/density. Density ´equals´ hp (within road temp range 3 degrees C cooler = 1% denser)





....and the ´finished´ product on mine





For those inspired with an OEM set up, there was a cool mod by Simca Ralley racers; a vented rear lip:





Ergo conclusio:  The cooler the charge at the inlet valve the denser the charge =  the less heat transfer to it, the more power. 

Whether yoú  will notice the difference and whatever yoú want to do with the knowledge is all the same to me.  Í think it cool :-)

[1979scotte]

You've both got valid points.
Obviously the science is sound everyone knows cooler air is better.

Makes no noticable difference NA but you can defo feel it with a turbo.

[Petrus]

Obviously the science is sound everyone knows cooler air is better.

Makes no noticable difference NA but you can defo feel it with a turbo.

Well... in the small hours of the night, driving through the crisp, cool dry mountain air you só notice the difference in an n.a. 
The ambient air temp about 20 degrees cooler and is breathes so much happier.
Minimum versus max heat transfer from the under hood temp. is about the same.
But yes, as I started out with, it is n.a. scope of things so marginal in supercharged scope of things.

[tets]

has anyone measured the differences with the side scoops?
I'm moving the battery, deleting the canister and the rear crash bar & number plate area for better flow. I've also got rid of the plate under the grill in the rear hood!

By the way, i've been searching leboncoin for one of those Simca's for a few years now - hoping to stumble across a barn find when i'm drifting through the French countryside again!

[Petrus]

Not read any measurements anywhere but the effect must be considerable. It is like sticking out half of your cupped hand in the air flow. Or look at the effect of even the small Mongos.

I for sure would fit a set if they were reasonably priced.

[Dev]

has anyone measured the differences with the side scoops?
I'm moving the battery, deleting the canister and the rear crash bar & number plate area for better flow. I've also got rid of the plate under the grill in the rear hood!

  I have. The side scoops will give you ambient air temps if the filter is well shielded using a short ram intake. Part of this shield is the battery.  If you relocate the battery the hot air will creep into the intake. 

[shnazzle]

has anyone measured the differences with the side scoops?
I'm moving the battery, deleting the canister and the rear crash bar & number plate area for better flow. I've also got rid of the plate under the grill in the rear hood!

  I have. The side scoops will give you ambient air temps if the filter is well shielded using a short ram intake. Part of this shield is the battery.  If you relocate the battery the hot air will creep into the intake. 

Somewhere on here there's a lengthy review of air temps without scoops, with scoops and with scoops with an extra widening. He tested IAT while moving and in traffic/standstill. 


If I recall correctly the conclusion was that the scoops improved IATs at speed but at standstill made it worse. 
The widened scoops (a cone built in to the top of the scoop) added even more cooling effect and improved standstill temps as well.

[Dev]

Obviously the science is sound everyone knows cooler air is better.

Makes no noticable difference NA but you can defo feel it with a turbo.

Well... in the small hours of the night, driving through the crisp, cool dry mountain air you só notice the difference in an n.a. 
The ambient air temp about 20 degrees cooler and is breathes so much happier.
Minimum versus max heat transfer from the under hood temp. is about the same.
But yes, as I started out with, it is n.a. scope of things so marginal in supercharged scope of things.

Just to reiterate I have noticed the difference on a cold morning or a colder season as the car is less sluggish than on a hot day however from my observations trying to simulate that by lowering intake temps was not the same thing. I think there is a lot more about air density, atmospheric pressure and humidity than just lowering intake temperature to do the same thing. 
These were my observations when I was of the belief that I could get better performance by lowering my IATs but it just didn't translate to something I could feel so I removed all of the shielding. 
Your observations might yield you something different but I was disappointed.

[Petrus]

A fundamental difference Dev is that the abient temps can differ almost binary whereas reducing underhood temp nearly always is a process.

The crux is that 20 degrees cooler at the inlet valve is 20 degrees cooler regardless of whether that is from cooler ambient temp. or less heat exchange from the engine room.

Now anóther one to ponder about:
The larger the difference between ambient air temperature and the underhood temperature, the more heat transfer there will be to the intake charge.
It is not a given rate. It is like water pressure difference.
A cooler engine room will see you enjoy a cool ambient temp móre more   

[1979scotte]

has anyone measured the differences with the side scoops?
I'm moving the battery, deleting the canister and the rear crash bar & number plate area for better flow. I've also got rid of the plate under the grill in the rear hood!

  I have. The side scoops will give you ambient air temps if the filter is well shielded using a short ram intake. Part of this shield is the battery.  If you relocate the battery the hot air will creep into the intake. 

Somewhere on here there's a lengthy review of air temps without scoops, with scoops and with scoops with an extra widening. He tested IAT while moving and in traffic/standstill.


If I recall correctly the conclusion was that the scoops improved IATs at speed but at standstill made it worse.
The widened scoops (a cone built in to the top of the scoop) added even more cooling effect and improved standstill temps as well.

I'm sure MR X did a load of research. 3d printed several different types of scoop.

[Dev]

has anyone measured the differences with the side scoops?
I'm moving the battery, deleting the canister and the rear crash bar & number plate area for better flow. I've also got rid of the plate under the grill in the rear hood!

  I have. The side scoops will give you ambient air temps if the filter is well shielded using a short ram intake. Part of this shield is the battery.  If you relocate the battery the hot air will creep into the intake. 

Somewhere on here there's a lengthy review of air temps without scoops, with scoops and with scoops with an extra widening. He tested IAT while moving and in traffic/standstill.


If I recall correctly the conclusion was that the scoops improved IATs at speed but at standstill made it worse.
The widened scoops (a cone built in to the top of the scoop) added even more cooling effect and improved standstill temps as well.

I did testing between the stock side scoops and then with the C1 style scoops and there was not much difference. All that matters is having a consistent pocket of air to draw from.
  I have also tested two other cars. One that was bone stock and the other with the AEM intake that goes to the back. I was the passenger with an ODB monitor but for my car I had ODB monitor built into the dash which I was able to observe for years.

  My observations are:

1. Stock intake keeps IAT well under control and more stable better than the other two aftermarket intakes at idle however it gets saturated with heat and the IATs are generally 20F degrees higher than ambient varying little at idle or in motion with a long time for the IATs to come down as you are traveling. The OEM intake is pretty good with drawing its air from the area behind the battery at the area of the side scoop.   

2. The AEM type or those that are routed to the hot end of the car are the hottest. They can have IATs as high as 40F above ambient. This drops rapidly down to 20F when moving. Even so that really high IATs don't really translate into something that is sluggish.

3. The short ram which is what I have does increase IATs at idle rapidly but it also lowers them very quickly as the car takes off from a stop. There is creep but not as bad as the AEM intake as that is the worst as far as IAT and I would call that more of a hot air intake but still it doesn't exactly translate to a sluggish car. 

What I felt made a difference is making sure there are no obstructions around the air filer so it has plenty of air to draw from.

[Petrus]

I'm sure MR X did a load of research. 3d printed several different types of scoop.

Not familiar with that; will have a search. Thanks.

My son would be most happy to print some.

[shnazzle]

Obviously it's concentration of oxygen. Car doesn't car much about the other crap in the air. It doesn't play much of a role in the chemical reactions with petrol.

There's only 21% oxygen in the air. We can't increase that in any way. Think it's a bit less actually at sea level.

I don't think any of these little scoops or anything do anything to changing that level of oxygen we take in. All we're doing is changing the effect the environment has on our car's sensors, which makes it feel either more spirited or dull

[Dev]

A fundamental difference Dev is that the abient temps can differ almost binary whereas reducing underhood temp nearly always is a process.

The crux is that 20 degrees cooler at the inlet valve is 20 degrees cooler regardless of whether that is from cooler ambient temp. or less heat exchange from the engine room.

Now anóther one to ponder about:
The larger the difference between ambient air temperature and the underhood temperature, the more heat transfer there will be to the intake charge.
It is not a given rate. It is like water pressure difference.
A cooler engine room will see you enjoy a cool ambient temp móre more   

Is there a difference, probably but I did not notice it. Maybe it is better appreciated on larger displacement engines and those that are forced induction. A cold morning is a cold morning regardless of what intake is on this car opposed to trying to chase it by routing the intake to lower it by 20 degrees. From my observations it just did not add up to the same thing as the IATs did not correspond to appreciable performance that you should be able to feel. After removing the shielding I was much happier with a cleaner engine bay and an intake that I can hear again.
  I felt the same way with wrapping the exhaust manifold and using a muffler blanket to mitigate heat in the engine bay which it did. Im sure there is something there as well but it did not translate to actually feeling it.

[shnazzle]

Oh oh....he mentioned exhaust wrapping... RUN people RUN! Petrus is about to blow 
Hahaha

[Petrus]

  

[Mr2paul]

Does the 1zz have a heated t/b?? I no from my other cars that a t/b bypass is an option to reduce intake temps. It worked for me without a problem.  You can't get lower than ambient temps as we agree on. The heated t/b is ok for such as Norway but in uk it is not needed.

[shnazzle]

Does the 1zz have a heated t/b?? I no from my other cars that a t/b bypass is an option to reduce intake temps. It worked for me without a problem.  You can't get lower than ambient temps as we agree on. The heated t/b is ok for such as Norway but in uk it is not needed.

It has a heated idle air control valve to make sure that doesn't freeze.

[1979scotte]

Does the 1zz have a heated t/b?? I no from my other cars that a t/b bypass is an option to reduce intake temps. It worked for me without a problem.  You can't get lower than ambient temps as we agree on. The heated t/b is ok for such as Norway but in uk it is not needed.

You can.
I'm sure people have used AC to that effect. Perhaps in conjunction with a charge cooler.

[Petrus]

You can't get lower than ambient temps as we agree on.

You can.
I'm sure people have used AC to that effect. Perhaps in conjunction with a charge cooler.

Tricky though as the volume of air taken in is HÚGE ans also has the airco sapping power from the engine.
Would need a ´bit´ of calculation to see if it would be worthwhile to even trý.

[Petrus]

The heated t/b is ok for such as Norway but in uk it is not needed.

Well, even in the UK it is not all a luxury as moist in the charge can drop the temperature of metal surfaces considerably by ´extracting´ evaporation energy.
It is as wet skin cooling from air passing over it.

Mind it is not by fár as bad as in carburettor days or even single point injections systems as the gasoline evaporating is no longer an issue.

Good point though.

[Dev]

 I did see a kit a long time ago in the early part of the century where it would spray liquid C02 to cool  a bulb in the air intake. They claimed 20hp difference. Like most things of this sort it wasn't popular probably for good reason.

 Here it is if you are interested in trying it out. Probably a cheap way to go about it.

  https://www.designengineering.com/air-intake/