Air box vs open to engine bay cone filter....

[Fourdoor]

Hey guys,

I finished building my sheet metal air box today, then took it out of the car to do some "back to back" temperature testing.

With 75F ambiant temps and the car starting out "ice cold" I let the car idle for 15 min. Looking at the data log temperatures were very stable until the radiator fan started. At that point air temperature rapidly start to climb. After the 15 min of idleing I did some 1,2,3 pulls at 27 psi of boost. With air temps starting at 102F after the 15 min idleing temperatures droped to 95F in 1st gear, climb back to 100 in 2nd, and hit a peak of 107F at the top of 3rd gear. Then I did some cruising around to see what temps would do. Temperatures stabalized at 91F while cruising at 65 mph. I then came home and let the car idle for another 15 min. Over that period of time air temperatures rose to 120F.

I am letting the car cool down right now so I car re-instale my home made air box, and then I will do the "after" testing.

Keith

[turbolarry]

What metal did you use for the box? I had higher temps with a stainless steel heat shield vs. with out it. Go figure? I think I'll try aluminum next time.

[Fourdoor]

Generic steel, probably stainless. Didn't have much description on it at Lowe's

Keith

[Fourdoor]

Lets see how much I need to resize these pics.....

Keith

PS: I hate out file structure! My camera on lowest resolution takes 768 x 1024 pictures... our system has a max size of 800 x 1000

[Fourdoor]

Here is how I was set up befor the air box.

Keith

[Fourdoor]

Here are the parts.

Keith

[Fourdoor]

And here is a piece by piece installation of the box.

Keith

[Fourdoor]

The box usees the stock intake scoop as well as being open at the bottom as the sources of cool air. Now for the testing!

Keith

[Fourdoor]

All that effort, and not much to show from a performance stand point. Ambient temperature is about 77F for the second set of data, and most of the data shows temperatures 2F higher than they were without the box.... just like the rise in ambient temperature! The only time it showed a difference was cruising at a steady speed. Temps then were only 4F over ambient rather than 6F over ambient without the air box.

The only real benefit I gained from all my efforts was to make the car significantly quieter. I no longer have the turbo whine compeating with the radio when doing a gental acceleration like I had without an air box.

Keith

PS: The rise in ambient temperature also effects intercooler efficiancy, and all of my test data is post IC temperatures in the upper IC pipe... so there probably were some benefits, but they are most likely negligable.

[evomrguy]

Thats a shame it didnt show better numbers with the heat shield on.

[nothere]

thanks for the data. So it might be that the air filter area doesn't see that high a temp when the car is moving. Do you have the stock bumper?

I'd like to see a temp sensitive film of the hood vent while the car is moving. It is a low pressure area so it might be drawing a great deal of heat out. With the bumper intake side scoop there may be a steady flow of outside air towards the turbo.

[Fourdoor]

OK, instead of sealing the open end of the box to the hood I added another wall to the air box and did some more data logging.

Main thing I noticed was that temperature rise takes longer now than it did befor, so that shows a significant benefit.... if you are idleing in the staging lanes at the track, the longer it takes your intake air temps to rise the better, so with the fourth wall the air box is actually effective from a performance stand point rather than just from a sound stand point.

Here is the test data:


Start temp..........5 min....................10 min........................15 min

Baseline no airbox idle for 15 min
75.2...............77.0..(+1.8).............80.6.. (+5.4)...............98.6..(+23.4)

Box sealed to hood idle for 15 min
80.6...............82.4..(+1.8).............86.0.. (+5.4).............105.8..(+25.2)

Now with extra wall idle for 15 min
73.4...............73.4..(+0.0).............77.0.. (+3.6)...............98.6..(+25.2)


I did multiple high boost pulls to heat load the engine and then did some more idle testing.


After heat loading engine No box 15 min idle
93.2..............111.2..(+18.0)........116.6..(+2 3.4)............118.4..(+25.2)

After heat loading engine Box sealed to hood 15 min idle
100.4.............114.8..(+14.4)........122.0..(+2 1.6)............125.6..(+25.2)

After heat loading engine extra wall 15 min idle
93.2..............105.8..(+12.6)........113.0..(+1 9.8)............114.8..(+21.6)

Later,

Keith

[evomrguy]

Interesting to see that the air temp gets hotter when sealed to the hood even compared to an open filter. Do you think its heat transfer from the hood itself? Its nice to know that the top being closed off helps out. I just did an install of one of the apexi filters and induction boxes. Its sealed on top, so now I dont feel so bad putting it on the guys car now knowing it will actually help.

[Fourdoor]

I don't think it is so much a heat conduction issue as it is a matter of difficulty sealing to the complex shape of the underside of the hood. There were probably gaps that let in air, and since hot air rises the areas with the gaps would be the areas with the hottest available air to leak into the filter area. It is a trade off though, I could add a bottom panal to the box so that it is compleatly sealed other than the snorkle, but that would defeat the purpose in having a large cone filter in the first place. The best option for cool air AND free flowing design would be to extend the back wall further down, but that would require a complex shape to try and seal around where the upper IC pipe passes through that area. It was a royal pain in the @ss to do the panel that goes around the intake pipe itself, and I am not willing to go to the trouble of making one that seals around the upper IC pipe.

Later,

Keith

PS: I think that a none heat conductive material would be better for an air box. The low air flow at idle seams to allow a lot of convection heating of the air inside the box over a long time sitting at idle.

[evomrguy]

Yeah, if you had the money, cf would be the best material to make it out of. Getting the box 100% sealed would be a major pita, but beneficial. Also a helpful idea, one I will most likely try out, is to run a snorkel from the front bumper to the filter. You have just enough space to run a tube from the drivers side opening in the bumper straight up to the filter. That, along with the sealed box should help with lower intake temps.