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Discussion Starter #1
Here’s one for the techhies amongst you:

After the decatted manifold & Y-pipe were fitted to my car, two problems were apparent:

1) The induction pipe was being heated by the manifold.

2) Hot air was being blown towards the filter head by the radiator cooling fans.

The result of this was that at lower speeds, the IAT was as much as 40°C above the ambient (outside) air temperature. It was not until speeds of 60-70 mph were achieved that the difference in temperature (ΔT) was reduced to below 10°C. These temperatures were recorded using a diagnostic meter plugged into the OBD2 port. Ambient air temperature (AAT) was read directly from the dash thermometer.

Following Boyle’s Law, the effect of the intake drawing in hot rather than cold air is therefore to reduce engine performance.

In order to isolate the induction from as much hot air as possible, I made the following modifications:

Using a roll of aluminium foil coated insulating mat, I made a double thickness heat shield between the manifold, radiator fans and the filter. I also wrapped the induction pipe in a layer of foil, doubling on each wrap to ensure maximum coverage. In order to further insulate the induction I then fully covered the induction with the exception of an opening for the air scoop before taking readings The foil was secured in place using ordinary bathroom silicone sealant.

THIS IS NOT MEANT TO BE PERMANENT AND "SCRAPHEAP CHALLENGE COMMENTS ARE WELCOME!

To quantify the effect of the insulation, a thermocouple was installed into the intake pipe close to the MAF sensor and connected to a digital readout located inside the vehicle.







For the stationary readings, the car was warmed up to full operating temperature and driven until the IAT stabilized. The car was then parked with the engine running and readings taken every 15 seconds. After the final temperature had stabilized, the car was again driven for a short period until the temperature stabilized and the test repeated.

For given speeds of zero, 20, 30, 40, 50, 60 and 70 mph, temperature reading of AAT and IAT were recorded at 15 second intervals over a 5 minute journey. For accuracy, each test was carried out 3 times, with 1-2 mins between runs. The engine was running at a temperature of 25° at the start of all of the tests and a constant speed was achieved by setting the cruise control (not possible under 30mph).

An average for each of the 3 tests for each given speed was calculated and graphs were plotted for ΔT.

The results are as follows. For low speeds up to 40mph the IAT took as long as 2 minutes to stabilize to 2-3° ΔT. For higher speed, the ΔT dropped very rapidly and stability occurred within a minute, and only 1° ΔT.

So, in conclusion, the benefits of insulating the intake with a heat shield are overwhelming.



 

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Great post, I noticed the +40 ambient temp also I wondered if it was just me.
 

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Good job!

A 40 degree C temp difference is huge... I've done similar tests on my own car but have never seen anything that high.

Would be interesting to have tested insulation of the intake pipe vs routing of "cold" air seperately... my observations and tests around insultating the pipe itself have showed almost no difference in AITs... it seems the air just doesn't stay in the pipe long enough to pick up any heat. The temperature of the air entering the pipe is probably the most important thing.
 

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Ahh, the 35 degree diff was recorded with the car stopped but engine running... thats makes more sense now. I was going to say, I've neve seen diffs that big while driving.

Question on the tests @ speed: Did you instantly accellerate to that speed? Where does the data logging start? at 0mph when you started accellerating to the speed? after you had already reached the speed? This is very important to the test results...

Also, as a follow up test, it would be interesting to watch the car in real-world situations... ie I'm cruising on the freeway, temps are already stabilized... so between a non-insulated and insulated system you're only looking at 1-2 degrees difference... hardly enough to produce any real performance gains.

Also of importance is how quickly the car heat soaks after coming to a stop... then recording the temp change as you take off again (ie driving in traffic, stopping at a light, then going again).
 

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Great post! +rep

The data in your charts show good evidence to support your claim. However, since you've got multiple measurments it would be nice to see error bars around your estimates. Also, a test to show statistically signficant differences between the AAT and IAT would be straight forward.

These are just details on a great write-up. I'm glad to see more and more science showing up on this board.

One question though, why don't you measure IAT using the same instrument with and without insulation? It seems like this could introduce bias.
 

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Good post man, I know in Korea they do the same thing, and it looks well ghetto but works :lol:
 

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rtp300 said:
. I'm glad to see more and more science showing up on this board.
I second that, wish i had more time for some tests like this, but glad some people are starting to experiment w/ these things! ... even if it does look like you have a window shade shoved in your engine bay! ;)
 

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Discussion Starter #11
dasgalloway said:
Question on the tests @ speed: Did you instantly accellerate to that speed? Where does the data logging start? at 0mph when you started accellerating to the speed? after you had already reached the speed? This is very important to the test results...

Also of importance is how quickly the car heat soaks after coming to a stop... then recording the temp change as you take off again (ie driving in traffic, stopping at a light, then going again).
For the tests at speed, the car was parked with the engine running. As soon as the IAT showed 25 deg C the stopwatch was set running I accelerated to the specified test speed, so the test started at 0mph with hot air being drawn in.

Your second point - yes this is something we could take a look at doing.
 

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Discussion Starter #12
rtp300 said:
Great post! +rep

The data in your charts show good evidence to support your claim. However, since you've got multiple measurments it would be nice to see error bars around your estimates. Also, a test to show statistically signficant differences between the AAT and IAT would be straight forward.

These are just details on a great write-up. I'm glad to see more and more science showing up on this board.

One question though, why don't you measure IAT using the same instrument with and without insulation? It seems like this could introduce bias.
What I should have done was to run the test without insulation first, but I was a bit too keen on trying to solve the problem.

It had originally been observed by the technicial who was testing the car after the new manifold had been fitted - using a diagnostic meter plugged into the OBDII port and looking at the parameters as the car was being driven. He had written down AAT and IAT for a number of situations but had never tabulated his data. It was something for me to start with anyway.

When it's time for this lot to come off I'll try and find the time to repeat the test, without insulation in order to establish a baseline.
 

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On my car I heat wrapped the intake pipes. While IAT stayed low longer they eventually rose up to the non wrapped temps. at cruising speed i routinely see +20 - 30.
 

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Hey whyd you relocate your ABS? I did also you have any issues with it? Shit and MC.
 

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Discussion Starter #17
IMPRIMIS said:
Anti-lock brake system
Yeah that's what I thought!

I couldn't figure out what ABS has to do with this topic :confused:
 

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LOL nevermind you are in the UK duh
 

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