Watch This Space

[mad082]

here's the story. when my mate finally gets his r33 on the road i am going to put an air temp sensor in the intercooler pipe after the intercooler, and 1 in the pod to finally see how much of a difference a heat shield makes. plenty of people have done this just seeing the temp at the air filter, but not once it has been heated up by the turbo then cooled by the intercooler. i personally don't think there will be much difference. i know from personal experience with firends cars with aftermarket ecu's that have an air intake temp sensor that don't have heat shields have had intake temps at or below ambient air temp.

my personal theory is that on a turbo car with no intercooler a heat shield will make a difference, but on a car with an intercooler the difference will be very small, if any. the reason i think this is that the air gets heated up above ambient by the act of compressing it, then is cooled by the intercooler. so if you have an efficient intercooler it will cool the air to ambient temp no matter what temp it starts at.

i am going to do this thoroughly. i will test at different speeds and test multiple times to rule out any heat soak or anything like that. so watch this space.

[WogsRus]

I have already done this to my car, need to dig up the files, but i found mainly the differance was in town, the heatsoak in the car was dramatically reduced, and i do mean dramatically. My box is preatty well insutaled with thermo foam, do a search.

can't remember all the temp details, but it does help.

Good luck looking farward to your results.

[djr81]

This may save alot of time for you:

Blue is the air filter temp.

Pink is the compressor outlet.

Yellow is the I/C outlet.

Cyan if the throttle body.

Car was a skanky RX-7 with a Chinese front mount & an unshielded air pod. Note the bad arsed heat soak on the I/C when the car is at a standstill last in the test. Not good for drags or hillclimbs.....

Conditions: Ambient 15 deg. Drive down hwy at 100 k's, brake and accelerate from 2nd gear throught to 8000 rpm in 4th, cruise for about 30 sec and the accelerate from 3rd gear to 8000 rpm in 4th. Stop and idle for about 45 seconds shortly after.

Temps at 8000 rpm in 4th for first test:

air filter 48

after turbo 117

after I/C 45

throttle body 51

Temps at 8000 rpm in 4th for second test:

air filter 47.3

after turbo 122.6

after I/C 45.9

throttle body 53

Temp at air filter after stationary at idle for about 45sec was 84 deg! Thermo fans switched on and filling engine bay with hot air obviously.

So, based on the above results for the second test lets to some 'what if' scenarios based on different inlet temps to see what effect they have on the after I/C temps.

Intercooler efficiency = 71 %. Temp rise across turbo = 75.3 deg. Using these figures some calculated and an ambient temp of 15 deg, after I/C temps are:

Assumed inlet temp/Calculated after I/C temp

15/ 36.6

20/ 38.1

30/ 40.9

60/ 49.5

80/ 55.3

So if I can get the inlet temp before turbo down to 20 deg (allowing for 5 deg pre turbo piping heat soak above ambient), I should get a reduction in after I/C temp of 7.8 deg. Which is not that big a deal for high speed driving (ractrack), but I'll still be sorting out an out of engine bay filter location given that most events I do have a standing start followed by a lot of slow speed (2nd and 3rd gear) work.

Edited April 12, 2007 by djr81

[MBS206]

here's the story. when my mate finally gets his r33 on the road i am going to put an air temp sensor in the intercooler pipe after the intercooler, and 1 in the pod to finally see how much of a difference a heat shield makes. plenty of people have done this just seeing the temp at the air filter, but not once it has been heated up by the turbo then cooled by the intercooler. i personally don't think there will be much difference. i know from personal experience with firends cars with aftermarket ecu's that have an air intake temp sensor that don't have heat shields have had intake temps at or below ambient air temp.

my personal theory is that on a turbo car with no intercooler a heat shield will make a difference, but on a car with an intercooler the difference will be very small, if any. the reason i think this is that the air gets heated up above ambient by the act of compressing it, then is cooled by the intercooler. so if you have an efficient intercooler it will cool the air to ambient temp no matter what temp it starts at.

i am going to do this thoroughly. i will test at different speeds and test multiple times to rule out any heat soak or anything like that. so watch this space.

The only way you'll get to having intake temps BELOW ambient is if you're cooling by another means, such as dry ice.

Otherwise, the intercooler will actually begin attempting to HEAT the intake air up.

An intercooler is just a heat transfer, it transfers from the warmest, to the coldest, as the two temps get closer, the rate of change in temperature with respect to time, becomes significantly less. Hence, the best air intake temp you can get through an air to air intercooler, is ambient.

[Roy]

As others have said. Plenty of holes in your thinking. The real question is woudl the differences be negligible?

In my eyes it doesnt really matter. Heat shields are so easy to do it makes sense to run one as any reduction in inlet temps will provide you with a lower manifold temp post intercooler.

If you can work out how to get the inlet charge lower then ambient then we can make a fortune in my industry. Reality is i dont doubt you have seen it on a hand controller of an ECU. The thing is it means the calibration table for the probe used top measure the temps is way off, so reads way of

[MANWHORE]

As others have said. Plenty of wholes in your thinking. The real question is woudl the differences be negligible?

In my eyes it doesnt really matter. Heat shields are so easy to do it makes sense to run one as any reduction in inlet temps will provide you with a lower manifold temp post intercooler.

If you can work out how to get the inlet charge lower then ambient then we can make a fortune in my industry. Reality is i dont doubt you have seen it on a hand controller of an ECU. The thing is it means the calibration table for the probe used top measure the temps is way off, so reads way of

I sort of disagree with you there matey. See, the idea with a pod filter, why it flows so muhc more than a factory airbox, is because of the surface area of the filter. Before any of you jump in and say oh, but i didn't notice anymore power, i'm talking cfm test on a pod and an airbox alone. If you didn't see more power, it's because the airbox wasn't a significant restriction at your power level.

Anyways, back to what i was saying, by putting on a shield, you are essentially creating a restriction as air can only come from around the shield. That might not lose power (airbox v pod argument as above - is it a restriction at your power level), but at some level of power, it would be a restriction.

Putting a shield on it is basically putting you closer to the stock airbox - may as well just run that?

I think of it as a slider. On the one side, you have a completely exposed pod - flows the most, lots of heat. Other side - stock airbox - flows not as much as the pod, less heat. You can go anywhere from one extreme, to the other, or anywhere in between

[mad082]

I sort of disagree with you there matey. See, the idea with a pod filter, why it flows so muhc more than a factory airbox, is because of the surface area of the filter. Before any of you jump in and say oh, but i didn't notice anymore power, i'm talking cfm test on a pod and an airbox alone. If you didn't see more power, it's because the airbox wasn't a significant restriction at your power level.

Anyways, back to what i was saying, by putting on a shield, you are essentially creating a restriction as air can only come from around the shield. That might not lose power (airbox v pod argument as above - is it a restriction at your power level), but at some level of power, it would be a restriction.

Putting a shield on it is basically putting you closer to the stock airbox - may as well just run that?

I think of it as a slider. On the one side, you have a completely exposed pod - flows the most, lots of heat. Other side - stock airbox - flows not as much as the pod, less heat. You can go anywhere from one extreme, to the other, or anywhere in between

that is sort of what i think. with a sealed box you may get colder air, but at high rpm you might only be getting 90% of the air that the motor could use. this isn't the sort of thing that you could really tell by seat of the pants. if you put 2 dyno graphs side by side they would slowly seperate. at low rpm they may be the same, but once you get up in the rpm you may be suffocating the motor.

in my opinion if you are going to have a heat shield you should just have it run from front to back in the engine bay, and leave the back open, then have a good feed from the front bar. this will feed cold air, and blow any warm out out of the box. but even with the box you are probably getting hot air radiating off the hot intercooler piping.

[djr81]

I am particularly glad no one bothered to read my first post.

There are several things to consider.

1. For a turbo motor the higher the pressure ratio that the compressor is running at the higher the temperature will be at the outlet. So what the hell does that mean? Means that if you inlet air is less dense because of flow restrictions the turbo needs to work at a higher pressure ratio to flow the same mass of air which in turn means the air entering the intercooler is hotter. Airflow restriction bad, no flow restrictions good.

2. The circumstance in 1 is no where near as bad as running you pod in hot engine bay air in the first palce - see my first post.

3. The amount of air being shoved around the engine bay through the radiator both by the cars motion & the fans will be more than that going through your cold air intake. So seal the cold air intake from the engine bay gases.

4. You will get heat soak even with a good intercooler on a hot day. Have a look at the attachment. Compare the blue lines - the second of the two shows acceleration falling of only when the I/C gets hot.

Edited April 13, 2007 by djr81

[psi]

I've had the pod filter/ air box discussion before!

Everybody talks about the surface area,

BUT, have you thought of this..

The pod filter flows more because of its shape!

the air box is a bad design, and having no air filter in the box seldom even comes close to the flow of a pod.

Sure the underbonnet heat is a huge issue when considering the horsepower side of the equation,

but just for flow, think more about shape! do you have a square exhaust pipe? No, it doesn't flow well!

Cheers

Aaron

[psi]

As for intake temps,

I plugged into the intake manifold, and drove the car for 4 weeks. The average intake temp once operating temp was reached was 77deg. that was highway cruising only. then stop and hit the turbo timer for 5 min, the temp JUMPED 20+ degrees in under 30 seconds! That was a stock engine.

Then (because I live in tropical queensland) i removed the throttle heater pipe. That dropped the average intake temp to 49 degrees while cruising. Different thermostats will give different results. Its because the factory uses engine heat to heat the intake manifold through the throttle body.

Remember, that was inside the manifold! thats the actual temp of the air that the engine injests.

Hitting boost to pass a car on the highway gave an average increase of only 4 degrees in the manifold. It stayed at that temp for about 30seconds after the bosst stopper. But I think that was because of the stock intercooler giving up the heat it just absorbed.

Cheers

Aaron

[WogsRus]

Well it sure seams to work fine on my car, but here in Tas our temps are a lot lower. What insulation do you guys run on your boxes. I have my box fully sealed, with thermo foam, and a piped inlet from the outside.

All i know is that the temperatures of teh car running arround town, and sitting in trafic, have made a hudge differance.

I am also about to reroute my IC piping, so the turbo pressure air goes accross teh top of the radiator, and then back across the fornt, and into the intake througha short run, ie: reverse the flow of the IC, i have a hybrid one.

The pipes will also be double skined with an air gap inbetween, and this makes a hudge differance, trust me on that, i am a mech engineer that is what i do best.

I belive that the system works.

[djr81]

I am also about to reroute my IC piping, so the turbo pressure air goes accross teh top of the radiator, and then back across the fornt, and into the intake througha short run, ie: reverse the flow of the IC, i have a hybrid one.

The pipes will also be double skined with an air gap inbetween, and this makes a hudge differance, trust me on that, i am a mech engineer that is what i do best.

I belive that the system works.

Yes it works, but I would question whether or not it is actually worth the effort of putting in a double skinned pipe. It you do a quick calculation on the flow rate & then work out the heat transfer difference between the single & double pipes I suspect you will get pretty close to sod all difference. If you are worried about it (particularly where it goes over the radiator) just wrap it in tape.

Also, by reversing the flow of the I/C you will be getting a larger pressure drop across the system. Simply because the hot gas goes further in your set up.

Just some things to think about.

[DivHunter]

The only way you'll get to having intake temps BELOW ambient is if you're cooling by another means, such as dry ice.

Otherwise, the intercooler will actually begin attempting to HEAT the intake air up.

An intercooler is just a heat transfer, it transfers from the warmest, to the coldest, as the two temps get closer, the rate of change in temperature with respect to time, becomes significantly less. Hence, the best air intake temp you can get through an air to air intercooler, is ambient.

Assuming the intercooler and pod/airbox intake are affected exactly the same by 'wind chill' or that the vehicle is stationary :sorcerer:

[djr81]

Assuming the intercooler and pod/airbox intake are affected exactly the same by 'wind chill' or that the vehicle is stationary :sorcerer:

I am sorry, but I don't understand that at all.

[khunjeng]

lol at this thread.

[AndrewD]

lol at this thread.

Im with you on this one.

I love some of these interpretations! Hilarious

[Pauly33GTS-t]

We aren't ever going to see any results are we? lol, not that it looks like they make a whole lot of difference now.