Originally Posted by pmd from ozfoz

pete and i did some measurements a long while ago of inlet air temp, underbonnet air temp close to the i/c outlet throttle body inlet, and the core temp of the i/c on both inlet and outlet sides.

Pete's mods at the time (green demon - my01 auto... Td04, mbc@12psi, resonatorectomy with 90mm cai, silicon hose kit, standard i/c with no tilt, pmd splitter, standard scoop.

The measurements were done using thermocouples, and whislt we couldn't measure the actual air temps, there should be a good correlation between the temps we measured on the core of the i/c and the air temps inside. The measurement points were air intake (actual air temp), the i/c tube temp at inlet side of i/c, i/c tube temp at outlet side of i/c, and underbonnet temp about 2" above the i/c to throttle body hose.

Some of the results........

Ambient temp during tests was 21 dec c

1. Heat soak measurements.

Car warmed up with some normal driving, then pulled over and left idling.

Initial - air inlet 22, i/c temp 26 in 22 out, 35 underbonnet

1 minute - air inlet 38, i/c temp 40 in 33 out, 57 underbonnet

2 minute - air inlet 36, i/c temp 44 in 38 out, 65 underbonnet

3 minute - air inlet 45, i/c temp 46.5 in 43.5 out, 71 underbonnet

5 minute - air inlet 45, i/c temp 50 in 48 out, 68 underbonnet

2. Car then driven off "normally"

after 10 sec's - air inlet 29, i/c temp 39 in 26 out

20 sec's - air inlet 28, i/c temp 29 in 23 out

30 sec's - air inlet 28, i/c temp 28.6 in 23 out

40 sec's - air inlet 27. I/c temp 35 in 24 out (short acceleration with boost)

50 sec's - air inlet 25, i/c temp 33 in 22 out

60 sec's - air inlet 24.5, i/c temp 30 in 22 out

after another minute of driving, the inlet air temp stayed arounf 21 - 22 deg c (came as ambient), and the i/c in temp varied from 25 deg c (coasting/throttle off) to 44 deg c (at the end of 5 secs of hard boost). During this time the i/c out temp stayed pretty much around the 22 to 23 deg c mark, even during hard boost.

Noticed that slight breeze that was around affected underbonnet and air inlet temps by +/- 5 deg c (had less effect on i/c temps).

Was surprised by consistancy of the i/c out temp under different driving conditions (coast, normal constant speed, normal and hard acceleration)

heat soak temps come down pretty fast once moving.

Hope this is of some value

cheers

john

Originally Posted by robbks from ozfoz

i had a probe in the tb->tmic coupling in my fozz.

I noticed the worst thing for heat-soak was a closed throttle.
As pmd showed, ic and air temps would go up to about 50 degrees.

But sitting at traffic lights with no airflow through the core.
If i held the throttle open slightly say ~1300rpm the air temps would drop down to ~35 degrees.
That's a 30% drop in intake temps just from airflow through the intake system.
Because you're drawing in sufficient ambient temp air to actually start to cool the ic and intake piping from the inside.

So if you're worried about temps like that, just rest your foot on the throttle to keep the throttle butterfly open before giving it a bootful
this is useful at motorkhana's/ drags for getting off the line.
Especially if you've been sitting idling in staging lanes for a long time.
My last time at the drags, i was trying to move the car up to the staging line using some throttle to promote the airflow but with my foot heavily on the brake to keep the speed down.