Heat Shield - The Benefits!

[Mr Morse]

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.

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.

[marcus]

Thats all good mike..............but there must be a better way off keeping it cooler, yea what you have done keeps it cool but it dont look that good mate ;) do you have a pipe from the front off the car to give your filter COLD air, like dave & adie has on theres..........and not only that you say the temperature! is way up there when you are going slow but drops alot when you pick up speed, well lets face it you not going to be raceing around at slow speeds are you so as long as "temperature" drops when you pick up speed thats all that matters

But like i said there must be a better way off keeping the intake air cooler than doing what you have done, could you not put a cover over the Fan to stop it from blowing Hot air to the intake :winky:

But ha if you are happy with it mate then go with it :D :winky:

[Mr Morse]

It wasn't a project with aesthetics in mind Marcus.....it was done to show the benefits of insulating the intake from the manifold and radiator fan heat, which is what has been achieved here. And I have yet to see a commercially available or off-the-shelf heat shield which goes any way close to providing the level of insulation and shielding that I have done here.

and yes....the fan is shielded from the intake

I am an engineer, not a designer, but if anyone would like to work on a design based upon my results I will be happy to work with them.

Likewise, I will also be pleased to run this same experiement on any of the aftermarket or off-the-shelf heatshields as a comparison.

[marcus]

i under stand what you are doing it for mike, and like you say there is not one you can buy off the shelf heat shield.........not that i know off anyway ;) so all in all you could well be on to something here :winky:

This is why im doing this ventted bonnet, to let all that hot air out :winky: with the Turbo things get very hot in no time ;)

[Nick The Greek]

following on from this, i was surprised just how hot the induction tubing for the supercharger gets....

erradicating this can only be a good thing! Our engine bays certainly run on the warm side

[aido]

Impressive work Mike :D

I'm a little slow today due to excessive alcohol consumption but is that basically saying that with the coating on the difference between ambient and engine temperature went from a maximum of 40 degrees down to a maximum of say 3 degrees?

[Mr Morse]

Impressive work Mike :D

I'm a little slow today due to excessive alcohol consumption but is that basically saying that with the coating on the difference between ambient and engine temperature went from a maximum of 40 degrees down to a maximum of say 3 degrees?

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Essentially, yes Aido. The greatest dT (pre-insulating) was at low speeds where temperatures up to 40 deg C were recorded between ambient and intake. Once the speed was increased to 70 mph the IAT temp reduced, but far more slowly than with the insulated intake and was never lower than 5 deg C dT.

[Jiberjaber]

What difference does this make and does it actualy make it worth while ? i.e. is this looking like a 100 quid mod for a 0.1% power increase ?

[Fargo]

be interesting to do some comparative tests, ie with a manifold heatshield, and/or filter cold air box.

i have a filter air box that came with my intake if you want to borrow it, dave also has my old manifold heatshield somewhere.

Also may be an idea to insulate my shields to see what effect that has, as imsure this would be more pleasing to the eye..

[Mr Morse]

What difference does this make and does it actualy make it worth while ?  i.e. is this looking like a 100 quid mod for a 0.1% power increase ?

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The SAE J1349 relative horsepower calculation shows how air density alters the power output of a properly tuned engine. For example, at 85 deg F, 30.14 in-Hg barometer reading, 40% relative humidity and 5000 ft altitude, the engine only produces about 81.1% of the rated horsepower.

For the SAE J1349 relative horsepower calculations, the standard reference conditions are: Air temp 77 deg F (25 deg C), 29.235 Inches- Hg (990 mb) actual pressure and 0% relative humidity.

The air density is the actual weight of a given volume of air. This is a key parameter for engine tuning.

The relative air density is the ratio of the calculated air density to the air density at sea level using the ICAO standard reference conditions.

The density altitude is the altitude in dry air that would have the same density as the input conditions. The ICAO standard conditions for zero density altitude are 0 meters altitude, 15 deg C (59 deg F) air temp, 1013.25 mb (29.921 in-Hg) pressure and 0 % relative humidity.

Today's static values: 39.9 in Hg, 90% relative humidity, Altitude 100ft

Using today's temperatures:

15degC (59degF) relative HP = 148%

20degC (68degF) relative HP = 144%

25degC (77degF) relative HP = 142%

30degC (86degF) relative HP = 140%

35degC (95degF) relative HP = 136%

40degC (104degF) relative HP = 132%

Want me to plot these on a graph for you?

[Mr Singh]

Wow, full marks for effort!

Won't this work?

I mean after all this work, why not just get another IS300 Cold air box, as the car comes with std. and mod it to except a induction filter.

edit: like this, http://www.prolexperformance.com/prolexper...atshield_04.jpg

Used on race car.

[Jiberjaber]

...stuff...

Using today's temperatures:

15degC (59degF) relative HP = 148%

20degC (68degF) relative HP = 144%

25degC (77degF) relative HP = 142%

30degC (86degF) relative HP = 140%

35degC (95degF) relative HP = 136%

40degC (104degF) relative HP = 132%

Want me to plot these on a graph for you? 

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Nope dont need a graph myself being an engineer an all that ;) Do you realy think that the real vrs hypothetical gains stack up though (given you have driven the car with and without the mod) ??

[Mr Morse]

Nope dont need a graph myself being an engineer an all that ;)  Do you realy think that the real vrs hypothetical gains stack up though (given you have driven the car with and without the mod) ??

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With the decatted pipe and the shielding the car certainly FEELS better, but this is only a qualitative conclusion.

The only way of proving the theory would be with a car on a RR and flowing air of different temperatures through the intake.

What I'm trying to show here is that there IS a huge difference between temps in unshielded and shielded intakes, especially at lower speeds and combined with the theroretical RHP% figures, the result I have shown are all the proof I need in my own mind to show it to be a benefit.

BTW the total cost was about £6 - for a tube of silicone sealant plus some leftover insulating! :D

[6Speed]

All I know is this:

Lower intake temperature = more power

Higher intake temperature = more chance of detonation

These 2 rules are even more so important on turbo cars.

To sum up if you want to look after your engine, keep the intake temp down.

Well done Mr Morse!

[Dave-Ellen]

All I know is this:

Lower intake temperature = more power

Higher intake temperature = more chance of detonation

These 2 rules are even more so important on turbo cars.

To sum up if you want to look after your engine, keep the intake temp down.

Well done Mr Morse!

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Completely agree !

Excellent work Mike.

I have a cunning plan...........

[6Speed]

I too built a custom airbox/heatshield for my calibra turbo. Didn't look that impressive but you could definately feel the difference.

[Dave-Ellen]

Cold air to an engine is like an ice cold lager after a long day at work :D

[jasestu]

Awesome to see a methodical scientific approach was taken. Clearly you have an engineering background. :) I did the same with my old Primera, using four thermocouples and a datalogger. It's sad, but I enjoyed crunching the numbers. I don't have a copy of the results anymore, but they're on a couple of Primera/G20 forums...

I've also done it on the Altezza, looking at the temperature difference when that flap in the intake opens above 4500 rpm.