What happens to the air after it goes through the top mount intercooler?

[fortressofcomfort]

Hey all,
I was about to post this in the Turbo forum but was on the fence and though I'd get more exposure in here. Mods correct me if I'm wrong.

So Gen2s have this hood scoop that forces air through the intercooler; the volume of air going in is based on the forward speed of the vehicle (+/- headwind). What happens to that air after it goes through the intercooler?

Well, it must get heated somewhat, on the order of 10s of degrees F. But it does what aerodynamically, just smash down on top of the engine and its valve cover and spread out in all directions under the hood? I have seen aerodynamic anomalies with the hood when driving at very high speeds (> 130mph), that seem to back up my theory. My hood will start shaking from all sides and eventually the air seems to escape out the cowl side, given enough forward speed and pressure on the hood scoop.

I searched the forums and found nothing related to this.

Now, we don't all drive 130mph all the time, but even at 30mph or 60mph, perhaps we can harness that slightly heated "used" up air to do something more useful than unsettle the hood. What if we could point it at the back of the engine, where the turbo is located, and let it escape underneath the car?

I had some ideas:

1) Simply remove some combination of sealing and or underbody panels to achieve this effect.
2) Design a "plate" that sits on the underside of the intercooler that is higher on the leading edge than the trailing edge, with perhaps a downturned lip at the final edge (pointing air toward the turbo/rear of the engine bay).
3) Perhaps some sort of "spacer" or even just a combination of washers on the underside of the intercooler to give it more space to allow the air to be dispersed at a lower speed but higher volume (note this effect may not help force air to the rear of the engine, but it might lower the pressure of the air as it hits the valve cover, slowing the air down and allowing it to spread in more directions underhood).
4) ???

Am I way off base here? We all know that the rear of the engine, and the turbo etc get very very hot. I know that we need a certain amount of EGT to make the turbo work. But has anyone thought of, or tried to, a way to utilize the air coming in from the hood scoop to do something other than cool the intercooler?

[NCZ13]

I was expecting to open the stupidest thread known to man when I clicked it.. but this is a valid question in a way. Ultimately a plate going underneath the IC to divert air to the exhaust mani is just going to act as a giant hot plate. Since heat rises, its gonna end up heating up cooking and whatevers beneath it (like an oven). So youd end up killing the coil packs much sooner.

[86AmishMs3]

The air in engineering terms is assumed to be ambient...ie there is soo much coming through there that the heat it picks up from the intercooler is considered negligible. Makes life easier...but you're probably right...might be 5-10 degrees warmer. But either way it gets forced out of the engine bay. Its not perfect and you'll have stagnant zones that are hotter...but thats why a lot of us remove the weather stripping. Allows some air to escape upwards.

Don't know what you're getting at about turbine and egt's heat though. You could try to re-route air somewhere else but it's not going to do much.

Solution...unbolt and take off hood.

[MATT DAMOND]

Back when I had my MS6, I was intending to replace the TMIC with a heat exchanger for a LAIC. I had plans of making a plate to sit atop the valve cover, under the HE, to direct air to a hole cut in the hood, similar to a c-class benz:



But then I sold my MS6, and bought a van.


I'd suggest making a panel to fit under the TMIC, testing it out, and seeing if there is any benefit. It's hard to direct hot air around the top of the engine, without finding a quick way for that air to travel... hence M Benz hood idea.

[bislag]

To add to this, I'm curious about how the Corksport ram air intake + FMIC might impact this situation as it pertains to the aerodynamic anomalies mentioned with the hood. Uninformed guesswork would be that the problem would be reduced, since more of the air actually has somewhere to go, but that the problem would still persist to a lesser degree.

Also, wouldn't routing air under the car potentially result in more lift?

[fortressofcomfort]

Originally Posted by bislag To add to this, I'm curious about how the Corksport ram air intake + FMIC might impact this situation as it pertains to the aerodynamic anomalies mentioned with the hood. Uninformed guesswork would be that the problem would be reduced, since more of the air actually has somewhere to go, but that the problem would still persist to a lesser degree. Also, wouldn't routing air under the car potentially result in more lift?

It's ALL going out under the car now right? I mean do we have vented fender flares? Where else would it be going? I had mentioned in another post that at very high speeds (130+ mph) my hood actually dances and flutters around as if there is SO much pressure under that hood that its trying to come out from the cowl side (or anywhere it can). So I don't know if that would be such an issue.

Solution: buy FMIC. Let hood scoop cool engine directly lol. Damn, I wanted a cheap solution to lower underhood temps where they heat up the most (by the firewall).

Matt Damond is on the right track with what I was trying to imagine.

[Tokay444]

The under tray is designed to pull that air down behind the engine and out under the car.

[snailD]

well its a very small thing but have you removed the rear weather-stripping? alot of hot air gets out the back of the hood if you do. just make sure you don't remove the ducting to the i/c, the gen2 scoop is very efficient in cooling compared to the gen1 and ms6 with the ducting on there.

personally i have never noticed the hood bouncing around, but thinking in terms of raising it with washers/spacers isn't the worst idea ever. it will give a tad more room for the air to dissipate around the head, just have to make sure it still clears the hood and the under-hood ducting is still functional

[Alejo_NIN]

holy random quetsion, batman
subbing for updates.

[pzr2874]

^I did this on the past few subies I've owned and they referred to it as tilting to get more air directed to the IC..... Then again, the "unused air" just goes flowing down to the DP area and under the car. Matt's Idea is probably the best out there. Nice post.

A better air splitter/diverter on the gen2 would probably help with the hood bouncing.

[Chimmike]

Originally Posted by Tokay444 The under tray is designed to pull that air down behind the engine and out under the car.

/thread

if you want to design some good aero shit, fab yourself some brake ducts and some ducting to direct air into the radiator and not just into and around it

[Alejo_NIN]

i dunno, but i would't want to "cool off" the exhaust manifold.
remember, that hot gases is what propels the turbo, cooling them down does the opposite.

[forcedinduktion]

It has to do with pressure. Refer to the venturi effect

"When air hits the front of a car it causes a stagnation point, high pressure. So for air to flow across the radiator, there must be an area of relative low pressure on the engine side. The larger the difference in pressures, the more air will flow across. To increase this movement of air across the radiator, it's very important to shroud all edges so that air MUST flow through the radiator instead of around it.

After air passes through the radiator, what happens to it all? Well some of it quickly exits through the under-body, but not much because air flow under a car is slow from all the drag caused by the gearbox, exhaust, suspension, etc... The rest of it stays inside the engine bay and creates a lot of turbulence as it collides with the engine and other components. This is therefore the limiting factor as it creates a high pressure, slow moving air (turbulent), so now the difference between pressures in front and behind the radiator is dramatically reduced. Air flow across the radiator decreases as a result..."

[Koke382]

very good quesion...hmmmm...

[Tokay444]

This is why I feel the companies that build fmic kits should include shrouds that seal to the rear of the front number cover.

[easy]

hood louvers

[bertrand_CX_7]

Nice curiosity.......

Here u go ==>

Mazda MZR 2.3 DISI Turbo Engine. - YouTube

Mazda MZR 2.3 DISI Turbo Engine. - YouTube

[easy]

^ hes talking about the air that cools the intercooler

[Tokay444]

Lol.

[pzr2874]

Originally Posted by Tokay444 This is why I feel the companies that build fmic kits should include shrouds that seal to the rear of the front number cover.

But can't these be fabbed pretty easily?

[Tokay444]

I'm not tooling up a brake press for it.

[dpolseno41]

Originally Posted by Tokay444 I'm not tooling up a brake press for it.

Just to clarify for my tired mind, you mean a shield from essentially the bottom of the mesh grill then attaching somehow to the bottom of the intercooler to create a bottom shelf? Makes a lot of sense if that's the case.

[snailD]

Originally Posted by dpolseno41 Just to clarify for my tired mind, you mean a shield from essentially the bottom of the mesh grill then attaching somehow to the bottom of the intercooler to create a bottom shelf? Makes a lot of sense if that's the case.

that, and when i installed my front mount mazda had plastic pieces that forced the air into the radiator instead of letting it go around, which i had to remove to fit the front mount. i've been thinking of fabbing up new ones so the air thru the grill has to go thru the fmic and not around it. i'll wait til i get the new core in though

[Tokay444]

Everywhere. Top, bottom and both end tanks.

[fortressofcomfort]

@NCZ13: "I was expecting to open the stupidest thread known to man when I clicked it" That's how most of my threads read so no worries.

@86azms3: True, the higher the speed of the car, the smaller the difference between the temperature of the air going into the intercooler (which is just an air to air radiator/heat exchanger) and the temperature of the air exiting the intercooler. So heat soak is still there, correct.

@MATT DAMOND: Your design I like... It is essentially like "taking the weatherstripping off but in a larger and more orderly way. Make it and paint it primer black and I'll test it for ya No really, its brill. If anything we'd see solutions coming from Germany, no?

@bislag: "Also, wouldn't routing air under the car potentially result in more lift?" I would have to think so.

This brings me (us) to the point of what is the problem we're trying to solve?
a) reduce hood flutter at high speeds
b) gain performance across the powerband
c) help car stick to the road by reducing lift.

As far as I'm concerned, B is the concern I'm trying to address. I rarely go REALLY fast, and the two times I've had the car to indicated 146mph (probably 140mph really), it stuck to the road like glue. Obviously things happen quickly and you have to be smooth, but that's what driving racecar is all about. In other words, I did not notice any "lift of the car, front or rear" anomalies, just hood flutter. And I know all about lift of the car. Try riding in an early 90s Toyota MR2. Here's a car that they put all their money into the styling and engine (at least the turbo engine) but none into the stick to the ground factor. My buddy had a NON-turbo MR2 and as we struggled to hit triple digit speeds, the front end became so light that I about shit myself. That rarely happens. I mean car turned into airplane. It changed lanes by itself. The MS3, even at 140mph (nearly 2squared or (2*2) ) was generating 4 times the aerodynamic trends and is still stuck to the road. Like I said, SOME attention was paid by Mazda to the aerodynamics of this car, but its like they ran out of money lol.

@snailD: I have heard that many people remove their rear (cowl side) hood sealing. This would apparently allow more of the air that comes in the front of the car (the hood scoop, the radiator area, etc.) to escape directly our the cowl of the car, but a little less would be diverted under the car (maybe a good thing?).

@Tokay444: derailed the thread just a little in post #15 (although truly it began to go astray on post #5 by bislag) by changing the topic from TMIC to FMIC. I understand your concerns with the FMIC, but let's stay on topic here since most of us still unfortunately have a TMIC. Much love though Tokay444

@pzr2874: Not addressing what I'm asking, but this is another modification that we could apply to the hood scoop. Basically you are saying, the subie guys make the *hood scoop better*.

@Alejo_NIN: Point well taken. The turbo is driven by the Exhaust Gas Energy. This consists of both the velocity of the air and the heat in that (volume of) air. At best we could cool off the turbine housing a few negligible degrees, with a better air flow under the hood, resulting in a negligible difference. But what about keeping the intake side of things cool? Or where your intake sucks in air? For example, I've noticed that my IATs are always 10*F higher than ambient, even if I'm driving 40mph or more. Why is that? Must be a pocket of slightly hotter air up at the front battery side of the engine compartment. IATs must be measured before the turbo right? So let's cool that pipe. That's kind of my idea. The overall reduction of heat will outweigh any changes we could possibly make to the turbo's performance.

@forcedinduktion: Understood. This is obviously not an MS3 specific chart so its kind of useless. But its good for showing folks why manufacturers test cars in wind tunnels these days. You'd be surprised at how much difference a little panel here, a little panel there, can make to the performance/aerodynamic abilities of the car. Do we know if a similar "wind tunnel" flow chart exists for the MS3? (yeah right).

@easy: Not a bad idea. Obviously they would need to be located behind the hood scoop (between the hood scoop and the passenger compartment). Might make GenPu look better? How about SMILEY LOUVERS ??

@bertrand_CX_7: Other than giving us a little better sense of the external dimensions and shape of the engine, that video is not related to the discussion at hand.



**** SUMMARY SO FAR:

Lots of good ideas...

- It seems that we need to define our/my goals better. I'm saying, for this thread, that reduced, and reduced more quickly, under-hood temps is the goal for those of us with TMICs. The more I think about it, the more it all comes down to heat-soak. I mean look at the FMIC guys all trapping 110mph+. Show me one K04'ed TMICed car that can do that on K04/93 only. If we don't have the $1,000 it takes to put a FMIC on our cars, then what do we do? I think what we do is GET THE AIR OUT OF THE ENGINE COMPARTMENT AS FAST AND QUICKLY AS POSSIBLE. I want to see IATs equal to ambient. As soon as I start moving I want more of the air that has stagnated under the hood for the last 2 minutes waiting at a stop light to get the hell out of my engine compartment.

- It seems that removing the rear cowl insulation is an easy way to let more air "out of the engine compartment" thus hopefully allowing us to move more (cooler) air INTO the engine compartment. But at what cost to lift disturbances at high speeds, I don't know. Also, like @snailD eluded to, why not just raise the entire rear of the hood, maybe doubling the "gap" made by now not having insulation back there ?

- I did personally, physically look at the factory setup and there's not much room under the factory TMIC to put *anything*. Spacers looked like a more complex idea than I originally thought.

- We didn't talk much about improving the design of the factory hood scoop.

- What about, not only taking the rear cowl insulation off the car (so there is a gap), but making this gap bigger, as big as possible.

Anything else? I would certainly give up a bit of high speed instability (and lost wiper blades) for a car that heat soaks less and is like 10*F cooler under the hood, even in the "pockets" at all times, wouldn't you?

Can someone get us an "underbody" shot of a GenPu? Maybe while its up on a rack?

Can someone who has removed the rear cowl insulation post some pictures here? Has anyone added washers to the rear hood hinges in an effort to gain a couple more millimeters of clearance at the cowl side?

Now what?

[anavrinIV]

Originally Posted by fortressofcomfort **** SUMMARY SO FAR: Lots of good ideas... - It seems that we need to define our/my goals better. I'm saying, for this thread, that reduced, and reduced more quickly, under-hood temps is the goal for those of us with TMICs. The more I think about it, the more it all comes down to heat-soak. I mean look at the FMIC guys all trapping 110mph+. Show me one K04'ed TMICed car that can do that on K04/93 only. If we don't have the $1,000 it takes to put a FMIC on our cars, then what do we do? I think what we do is GET THE AIR OUT OF THE ENGINE COMPARTMENT AS FAST AND QUICKLY AS POSSIBLE. I want to see IATs equal to ambient. As soon as I start moving I want more of the air that has stagnated under the hood for the last 2 minutes waiting at a stop light to get the hell out of my engine compartment. - It seems that removing the rear cowl insulation is an easy way to let more air "out of the engine compartment" thus hopefully allowing us to move more (cooler) air INTO the engine compartment. But at what cost to lift disturbances at high speeds, I don't know. Also, like @snailD eluded to, why not just raise the entire rear of the hood, maybe doubling the "gap" made by now not having insulation back there ? - I did personally, physically look at the factory setup and there's not much room under the factory TMIC to put *anything*. Spacers looked like a more complex idea than I originally thought. - We didn't talk much about improving the design of the factory hood scoop. - What about, not only taking the rear cowl insulation off the car (so there is a gap), but making this gap bigger, as big as possible. Anything else? I would certainly give up a bit of high speed instability (and lost wiper blades) for a car that heat soaks less and is like 10*F cooler under the hood, even in the "pockets" at all times, wouldn't you? Now what?

If you're willing to do work you can build a fmic setup for ~$400. If not, that's where the big money comes in.

As far as a plate under the intercooler, I wouldn't suggest that. There's not a ton of space under it (as you found) and if you put a plate to direct air there's a good chance you'll decrease the flow across the intercooler and raise your BATs.

Matt Damond had the best idea IMO, venting the hood behind the IC to allow air to escape. It's the same theory as the weather stripping/hood spacing.

Your best bet is the FMIC if you want to really lower under hood temps.

[Printman]

Damn @fortressofcomfort you should be writing a novel or something because you really enjoy typing, JK

Always love your posts/threads because I always learn something and you are informative but makes my head hurt. Condense your thoughts a little more for easier reading.

[fortressofcomfort]

OK, so what are the negatives of having a big gap at the cowl side of the hood?

- Less air going under the car, maybe that's a good thing?
- More wiper blades flying off?
- Does water get down into the engine compartment during heavy rain? What gets messed up?

I always like to question the design as it stands, so to those who have weather stripped/hood spaced, what problems have you run into?

[fortressofcomfort]

Hey isn't Matt Damonds idea similar to what they did to the 2000s Firebird WS6? Didn't they combine a hood scoop with louvers? Why weren't those louvers "smiley?"

Originally Posted by Printman Damn @fortressofcomfort you should be writing a novel or something because you really enjoy typing, JK Always love your posts/threads because I always learn something and you are informative but makes my head hurt. Condense your thoughts a little more for easier reading.

I am the tl;dr king.

I like people to see my thought process, that's all.

[Chimmike]

Originally Posted by Tokay444 I'm not tooling up a brake press for it.

All you need is a small brake, some thin aluminum, rivet gun and 2 sided tape, honestly. I've been contemplating doing this on my car for a while, direct air straight to the fmic.

[pzr2874]

I have the stripping off and hood raised 1/4 of an inch,, helps,,, but nothing in writing.

Gen1 as well

[fortressofcomfort]

I dunno if its pic worthy, but if so, @pzr2874 can you show us the "gap" with the hood closed.
More importantly, any issues like electrical, or wipers flying off?
How'd you "lift the back of the hood? Unbolt hinges, put some washers, I guess 1/2" in between, and bolt back up? I guess if you do one at a time then no alignment should be necessary.
Awesome, thanks. I will respect your result without numbers or metrics lol.

[Vansquish]

Originally Posted by chimmike /thread if you want to design some good aero shit, fab yourself some brake ducts and some ducting to direct air into the radiator and not just into and around it

Originally Posted by Tokay444 The under tray is designed to pull that air down behind the engine and out under the car.

These guys have it.

During the testing for the MZR 2.3L engine, there was a lot of difficulty in getting EGTs low, and the whole line of engines (both the DISI and the MZR 2.3 N/A) were delayed by several months after it was discovered that the insulation that was being used to reduce heat soak in the engine bay and passenger compartment was discovered to be inadequate.

How do I know? I have a relative who worked on this issue.

As we all know, there isn't all that much room under the hood, and in particular, the exhaust manifold doesn't get much air movement around it. That being said, it apparently gets a lot MORE now than it did at the beginning of the design process.

What am I getting at?

Well...basically, while I think it's an interesting experiment to see if we can reduce EGTs and heat soak issues (and possibly high-speed hood movement), it may be quite challenging to make real progress without making some very serious compromises for those of us who have daily-driven vehicles.

I'm not sure why this hasn't been brought up before, or has only been hinted at, but there is something else we should be considering here. Hood flutter is likely caused by a pressure differential between the under-hood area and the air moving across the surface of the car. This is a little different than saying that there's and excess of air pressure under the hood. Moreover, if we divert more air up and over the car, the likelihood is that we'll eventually begin to see minor issues with high-speed stability. Basically, I'd like to see us figure out a way to channel more air UNDER the car. The higher the rate of flow beneath the car, the less lift the car will generate. Moreover, if we can channel air from the front of the car through the engine-bay, and then down past the exhaust manifold, we'll be able to lower our EGTs a bit and the expansive nature of hot air will help accelerate the flow of air beneath the car even further. As an added benefit, the pressure differential between the under-hood area and the air flowing across the surface of the car will be less significant, meaning there will likely be less hood flutter.

TL; DR --> Mazda/FoMoCo spent a long time working on airflow through the engine-bay; if we're changing this, we should try and push more air through the engine bay and then out the BOTTOM of the car, NOT up through the cowl.

[vrspeed10]

will post pics tomorrow. What i did. Removed cowl weather stripping, raised hood 1/2 inch, removed iner tmic ducting, fabed up a diy heat shield that goes under the tmic to help slow heat soak, raised tmic about one inch off the motor. this way there is more air movement across the top of the engine and less direct heat exposed to the bottom of the tmic.

[snailD]

Originally Posted by vrspeed10 will post pics tomorrow. What i did. Removed cowl weather stripping, raised hood 1/2 inch, removed iner tmic ducting, fabed up a diy heat shield that goes under the tmic to help slow heat soak, raised tmic about one inch off the motor. this way there is more air movement across the top of the engine and less direct heat exposed to the bottom of the tmic.

do you have anything to monitor bats? because i believe removing the ducting will sacrifice the cooling of the tmic a bit.

[Tokay444]

And here I was accused of thread derailing.

[Tokay444]

You don't want any MORE air flowing under the car. That will create drag and lift.
You want the air flowing under the car already, to be faster than the air flowing over the car.

[Chimmike]

Originally Posted by vrspeed10 will post pics tomorrow. What i did. Removed cowl weather stripping, raised hood 1/2 inch, removed iner tmic ducting, fabed up a diy heat shield that goes under the tmic to help slow heat soak, raised tmic about one inch off the motor. this way there is more air movement across the top of the engine and less direct heat exposed to the bottom of the tmic.

if you removed the tmic ducting, but still have tmic, you fucked yourself. Your BATs are guaranteed to be higher. The motor is water cooled, it does not need your help in creating more airflow in the engine bay. the TMIC, however, needs that ducting to function and not be a giant heat sink!

[Snap Off]

Originally Posted by fortressofcomfort Hey isn't Matt Damonds idea similar to what they did to the 2000s Firebird WS6? Didn't they combine a hood scoop with louvers? Why weren't those louvers "smiley?"

No the 1998-2002 WS6 hood only had ram air. Just gave the engine cooler air but didn't vent any heat out.
Anyone try ceramic coating the valve cover reduce the heat being transferred into the TMIC?

[Matt]

Somebody needs to build an undertray/skidplate that reduces engine bay pressure as much as possible. That's the best solution for moving more air through the IC and evacuating the hot air out of the engine bay. Problem solved.