Remodded my intake
 

Out at hawthorne , i was feeling around the filter part of my K&N Air intake after some of the runs and i discovered that the entire area was very very warm. (and it was only 65 ish out ) I had Nick check it out also. then I noticed that there was a small gap between the K&N 'heat shields?' and where you could see the header/ exhuast manifold type stuff.

....
So flash forward to today

I drove my car over to ansels and i was very very easy on her. i didn't spool up past 0 boost, nor did i go over 3800 rpms. as soon as i got to ansels i popped the hood and we felt the cone air filter, it was a bit warm. warmer then the intercooler. (air temp was about 62 ish out !)

So i pulled out a small peice of sheet metal i bought monday. And with help from rubberbuscuit i bent, folded, tore a peice into shape to complete the heat shield. we even drilled a hole in the sheet metal and reused a factory bolt location. Ansel found a small scrap of unsed weather liner that came with the K&N and sealed up one last little gap.

then i took my lovely stock subaru snorkel. And attacked it with a Razor blade. :D Cut a 'precision air Duct' on the side of it. and fumbled around with the plastic bit i cut off for a little while to try and block the factory outlet of the snorkel. it wasn't really staying in there. :( but Luckly ansel had a box in the trash and i cut a bit of that cardboard up and fit it in nicely to deflect the air flow right towards the K&N Cone. :) I planned to use a bit of Duct tape, on that air Duct later on, but i gave the snorkel a few good shakes and the cardboard is very secure.

then we take it for a test drive. I went to the only 55 zone in tahoe and drove it hard (drove it hard on the way there too) kept it over 4K the whole time. we pulled over in a parking lot and felt the cone. COLD !!! Very cold (the air temp was now 54 ish) but wow was that filter COLD. the outside of the new heat shielding was WARM. and the intercooler was Cool. :D

$3 mod :) gotta love it ! damn tahoe kids ! :lol:

Ansel will post some pics tomorrow.

Some people will say it doesn't really matter if your sucking hot air in since it's all getting heated by the turbo. Who really knows how big of a difference a mod like that will make? Certainly can't hurt and I give you an A for effort. :cool:

the funny thing is i was one of those people who said it shouldn't matter if its hot or cold air .
Mostly it was freaking me out a little bit that the air filter was very warm to the touch.

yo. as promised.

http://i3.tinypic.com/1196yl2.jpg
tools used by profesional fabricators.

http://i3.tinypic.com/1196yaw.jpg

http://i2.tinypic.com/1196wx2.jpg

i am not a mspainter.

oh and about the tempature, i can vouch for the external filter temp decrease. after a soft drive before fabrication the filter was warm to touch. after a spirited drive, after shield fab, filter feels like cold. no scientific temp reading taken, but it should be signifigant.

when the turbo heats up air, it will heat the air coming in. therefore if air is 10* cooler should be approx 10* coming out. theory fucked up? i dont know shit? i don't know. i do know that i'm late for work.

True, if the air into the turbo is colder, the air comming out will also be colder than it might be otherwise. However, your car is intercooled. If the intercooler is properly setup and not heat soaked, it should cool the intake charge to near ambient even if the intake is warm.

For example:

intake -> 100* -> turbo -> 200* -> intercooler -> 80* -> manifold
cold air intake -> 70* -> turbo -> 170* -> intercooler -> 80* -> manifold

See what I mean?

does the turbo's efficiency change if its compressing cold air or hot air ?

And yes, assuming 100% IC efficiency that makes perfect sense. I've read on the Interweb that IC are usually 95% efficient though.

eeeerr wait. Given PV=nRT , if you took 1 liter of air at 2 psi and pulled 100 F out of it, or pulled 130 F. you'll get a larger pressure drop with the more heat you pull out of it (same number of air molecules in a given space) yes i'm using a formula for a contained space, and not flowing air , but i belive its applicable (qualitatively)

I don't believe the efficiency changes significantly with the temperature ranges we're talking about... +/- 30*F isn't really that much.

What does 95% intercooler efficiency mean? It can take out 95% of the heat the turbo put in? It can get within a certain percentage of ambient? I guess my point it, unless you've got a temp probe at the intake manifold and take before and after readings, you don't really know how well the CAI works. I'm not saying it doesn't help, but if it's only 1 or 2 degrees colder, it's probably not reducing your detonation risk at all.

For the record, I used to run a CAI and now I don't, but that's only because I switched to a BigMAF and FMIC. IMO, intakes in the fender are the way to go, simply because they get the filter element out of the dirty/crowded engine bay and into a high pressure area.

OH
yes an IC efficiency is rated by how much heat is reduced in comparison to the ambient air. so if its 80 out at Stead and your turbo adds 100 F with a 95% rate you get this .

air 80 -> Turbo 180 -> [95%] IC -> 85

Okay let's use that math:

ambient = 70* -> hot intake -> 100* -> turbo -> 200* -> 95% IC -> 76.5* -> manifold

vs.

ambient = 70* -> CAI -> 75* -> turbo -> 175* -> 95% IC -> 75.25* -> manifold

Looks like a CAI that reduces intake temps by 25* over a hot intake on a 70* day reduce intake manifold temps by 1.25*. Assuming the 100* we're picking for heat added by the turbo is realistic, but even if that number changes, the overall result still remains true: due to the intercooler, a CAI has only a very small change in actual intake manifold temps.

Exactly, so with an IC that works below 100% efficiency there would be a measurable (but small) Temp Differance in the intake manifold. 1.25 F in your example. :) Will i notice ? i bet no, but Clearly its worth the $3.50 in parts :)

it sure did bug me that on a 65ish day my filter felt over 100 though. (wild guess, maybe Nick has a better idea)

FYI i have about a 12 X 24 ish sized piece of sheet metal left over if anyone needs it for , well who knows what :)

Wait, what? 1.35* isn't going to make any difference in the performance of the motor (go ahead and try to re-tune the car for 1.25* colder intake temp)... so your $3.50 in parts is clearly worth nothing.

I'd think it would help keep the IC cooler if cooler air is entering it through the intake. IC heat soak is the real enemy.

The air from the turbo is going to be hotter than ambient no matter what, so there is no way it can "reduce heat soak", assuming you're defining heat soaked as 'the state in which the intercooler it hotter than the ambient air temperature'. Besides, the amount of air flowing through the IC from the hood scoop is *far* more than the amount of air flowing from the turbo, even at relatively low speeds.

If you want to fight heat soak, just drive the car > 10 mph, and spray down the I/C when it's stopped to get it near ambient.

CAIs are primarily about flow, not air temp on Intercooled engines. There is a great thread on this over at corner carvers. Go look for it.

And any mod <$25 and makes you feel good = 5Hp minimum, just like SECCS stickers.

Well, heatsoak usually only occurs when the car is not moving so there would be no air coming in through the scoop in that scenario. What heats up the IC? A combination of heat from the the turbo/exhaust/engine and the intake.

I surmise cooler air going through the intake on the TMIC (on a stationary car) would slow the rate at which the IC heatsoaks.

So the tempature of your charged air has NO (absolutey Zero) affect on engine performance :?: Why does nearly every turbocharged car have an intercooler then ?

Oh well, at least i only wasted $3.50 intead of the cost of a FMIC :lol:

lol double post

Here is a cool calculator for you guys to play with. The site has a metric buttload of turbo information.

Link

Steve

You surmise incorrectly. Heat increase on the inlet side does not result in a linear increase in heat on the discharge side, nor does that temperature affect intercooler heatsoak at all. The heat rising off the engine black (and blowing back from the radiator) is what does it.

Cool!

You sure you understand my post? I didn't say anthing about Heat increase on the inlet side affecting heat on the discharge side directly.

So you don't think 200*F+ air entering the IC inlet affects heatsoak on a stationary STi?

So I used Scott's example from earlier and ran it through the calculator from the link.

From the actual calculations. (Stock Boost of 11.5 psi up here)

Hot intake of 100° --> turbo --> 253° --> 95% IC --> 79° Intake Temp

CAI --> 70° --> turbo --> 215° --> 95% IC --> 77° Intake Temp

IC efficiency is more like 85% I think. I have been wanting to set up an experiment to measure temperatures on the IC for a while, maybe I'll borrow some TC equipment from work this weekend ...


Steve

Intercoolers are heat exchangers. They don't know anything about direction. they will try and make the air on the inside equal to the outside and vice a versa. So when stopped, intercooler output temp pretty much = underhood/intercooler temp since there is littel air flow besides convection on the outside.

Yes, the Intercooler will heat the intake charge.

I understand a great deal pertaining to the contents of this thread, but I simply don't have the energy or inclination to explain what I know for the 27th time on the internet. Here's the cliff notes: Cold air > warm air. Intakes that affect airflow in any way should be tuned for. Intakes that don't affect the airflow in any way are worthless.