[sg335]

I have read through all the threads and post herein regarding FMIC's from the various vendors and there appears to be some debate as to their efficiency, design shape, placement, and more specifically whether or not they INCREASE heat within the engine, and therefore increase the temperature of the oil and coolant systems. These later two systems are important when tracking the car at a road course and have proven to be the reason why engine shut down, or limp home mode has been observed by some of us.

I have come to understand that IC's, especially aftermarket upgraded units, provide an increase in cooling capabilities in air intake temperatures thus resulting in a denser charge air charge within the combustion chambers of the engine. This cooler air will therefore allow the car to create more power, or power output closer to the designed maximum of the engine's capabilities in simple terms. What is in question here, and what should be a simple answer, is whether or not this more efficient combustion will cause the engine to run "hotter".

So to restate the question: Will any of the FMIC's cause increased engine temps due to increased engine power efficiency, and if so, will they therefore cause increased oil and coolant temps? The question of design (height, shape, thickness, air flow) is secondary as they all will cool the intake air more than the stock unit. Your simple answers are appreciated.

[Neema]

im sure ALL the vendors who know their stuff will chime in and answer this question soon enough, give it like 10-20 mins and your answers will start pouring in

[zenmaster]

Originally Posted by sg335

So to restate the question: Will any of the FMIC's cause increased engine temps due to increased engine power efficiency, and if so, will they therefore cause increased oil and coolant temps?

No because it doesn't work like that. Any cooling of air will give you that much more power (i.e. 7% more with 40F drop), with decreased engine temps. You do not run hotter on a colder day.

Originally Posted by sg335

The question of design (height, shape, thickness, air flow) is secondary as they all will cool the intake air more than the stock unit.

I would not be so quick to say that even if the unit is larger, the question of its thermal efficiency should be answered by measurement. Do the vendors provide these measurements? No. What you want are inlet temp, outlet temp and ambient temp, pressure loss - after car has been running a good 20 minutes on the track. So far I've only seen pressure drop and dyno measurements - these are good of course, but do not represent the complete picture. They are not totally confidence inspiring. However, those that have seen what similar setups provide in other cars might be able to attest to their value on this platform, without needing measurements.

Originally Posted by sg335

Your simple answers are appreciated.

1) Not a single vendor has provided efficiency measurements as compared to stock on the track. Only dynos and pressure drop.

2) There is a question about the placement of at least one of these units possibly restricting air flow to the radiator.

[sg335]

I'll reduce the question further to:

Will an FMIC increase oil and coolant temps?

[1clean335i]

no. cooler air into the engine= better burn= less heat created= cooler temps all around.

[leftcoastman]

Originally Posted by zenmaster

No because it doesn't work like that. Any cooling of air will give you that much more power (i.e. 7% more with 40F drop), with decreased engine temps. You do not run hotter on a colder day.

That is not an apples to apples comparison. On a cooler day, you have cooler air hitting the IC, which could presumably result in more engine heat, all else equal. However, on a cooler day, your radiator and oil cooler are also getting the benefit of the cooler air to enhance cooling efficiency to offset any increased heat from the increased power.

With just a more efficient IC, the engine gets cooler intake air and produces more power but the radiator and oil cooler don't get any additional cooling help.

[zenmaster]

Originally Posted by leftcoastman

On a cooler day, you have cooler air hitting the IC, which could presumably result in more engine heat, all else equal.

I do not understand the mechanism how this could happen.

[BaLLzZz]

Originally Posted by zenmaster

I do not understand the mechanism how this could happen.

+2

[sambonator]

Originally Posted by zenmaster

I do not understand the mechanism how this could happen.

The mechanism for this is that cooler, denser air allows more oxygen to enter the engine, which results in more fuel being burned, which produce more power.

More fuel being burned and more power almost always means more heat being generated by the engine.

[2ABRUPT]

Originally Posted by sambonator

The mechanism for this is that cooler, denser air allows more oxygen to enter the engine, which results in more fuel being burned, which produce more power.

More fuel being burned and more power almost always means more heat being generated by the engine.

+1.

Imagine yourself having more energy to pedal a bike. You take in the richer food, which invigorates you even more, and therefore you pedal faster, which of course, makes you sweat more.

When the pistons accelerate faster because of more power, the oil has no choice but to heat up quicker, which makes the oil breakdown faster. But this is with any power application. There is no way around it if you want more power.

-M

[zenmaster]

Originally Posted by 2ABRUPT

Imagine yourself having more energy to pedal a bike. You take in the richer food, which invigorates you even more, and therefore you pedal faster, which of course, makes you sweat more.

When the pistons accelerate faster because of more power, the oil has no choice but to heat up quicker, which makes the oil breakdown faster. But this is with any power application. There is no way around it if you want more power.

But the RPM is certainly not changing for the added power.

[zenmaster]

Ok I have thought about this.

Say you are cruising at 90MPH with intake manifold temp at 100F @ 3000RPM, maybe at 250HP.

I'm thinking that the same 90MPH with intake manifold temp at 140F would require like, say 3100RPM to make the same 250. That is because at 3000 RPM with 140F temps, you are making something like 240HP.

I think the lower intake temp change gives you more power, at a lower RPM, for the same speed. This reduction in RPM reduces engine heat. (there is no "peddling faster")

[2ABRUPT]

Originally Posted by zenmaster

But the RPM is certainly not changing for the added power.

No, but the derivative of the rpms does change. Velocity doesn't change, but acceleration does. It's this acceleration that causes a more rapid change in temperature.

-M

[2ABRUPT]

Originally Posted by zenmaster

Ok I have thought about this.

Say you are cruising at 90MPH with intake manifold temp at 100F @ 3000RPM, maybe at 250HP.

I'm thinking that the same 90MPH with intake manifold temp at 140F would require like, say 3100RPM to make the same 250. That is because at 3000 RPM with 140F temps, you are making something like 240HP.

I think the lower intake temp change gives you more power, at a lower RPM, for the same speed. This reduction in RPM reduces engine heat.

No.

[zenmaster]

Originally Posted by 2ABRUPT

No.

Why not?

[zenmaster]

By reducing the air temp, you are increasing the compression. That means more power at lower RPM. I'm not sure what you are saying no to.

[2ABRUPT]

Originally Posted by zenmaster

By reducing the air temp, you are increasing the compression. That means more power at lower RPM. I'm not sure what you are saying no to.

You are NOT increasing the compression. That is constant unless you modified the bore and stroke of the engine.

Reducing intake air temp increases the volumetric MASS of the air. You'll get more power period (not just at low rpms) since the motor will burn more fuel/air charge per compression stroke and the power stroke will be more explosive which will cause the piston to move downward faster than before (more torque=more horsepower). This will increase friction which of course, causes more internal heat on the oil that is supposed to reduce friction. I hope you are starting to understand now..if not, let me know.


-M

[hotrod2448]

In my experience larger/denser IC's increase coolant temps not so much by increasing HP but, by limiting airflow through the radiator and raising the temp of the air passing through the radiator. This is what I would be concerned about not, the extra 5 hp you might pick up.

[sg335]

I somehow knew this would not be a simple answer!

[2ABRUPT]

Originally Posted by hotrod2448

In my experience larger/denser IC's increase coolant temps not so much by increasing HP but, by limiting airflow through the radiator and raising the temp of the air passing through the radiator. This is what I would be concerned about not, the extra 5 hp you might pick up.

Very true. Depending on the size of the intercooler and how thick it is, I have seen this cause heat problems with the RX7 Turbos (I used to own one). They could only do 1 or 2 top end runs before the coolant temps were sky high. The remedy for this would be to put a large electric fan behind the radiator and a colder thermostat. Sometimes this wasn't even enough.

-M

[hotrod2448]

Do you notice a difference in coolant temps (once up to operating temperature) from when it is 50 to when it is 65 degrees outside? Not really.

Now try putting some painter's tape or cardboard over the front of your grill...

[zenmaster]

Originally Posted by 2ABRUPT

You are NOT increasing the compression. That is constant unless you modified the bore and stroke of the engine.

Yes, the compression ratio is fixed. I meant higher pressure.

Originally Posted by 2ABRUPT

Reducing intake air temp increases the volumetric MASS of the air. You'll get more power period (not just at low rpms) since the motor will burn more fuel/air charge per compression stroke and the power stroke will be more explosive which will cause the piston to move downward faster than before (more torque=more horsepower). This will increase friction which of course, causes more internal heat on the oil that is supposed to reduce friction. I hope you are starting to understand now..if not, let me know.

But what I was saying is that this faster piston acceleration also allows you to reduce the engine movement for the same amount of road speed, which means less heat generated.