Cold air intake vs hot Air intake on FI cars
 

I know this forum isn't very technical or DIY..

but I was hoping to start a discussion or convo about this topic


I come from a strong turbo car background..and i've been thinking about things...

on the R56 forum, ppl bang on about how important it is to have a CAI and how important fresh cold air is etc etc...


but on almost all other turbo cars.. ppl don't bother..

usually it's a filter on a stick.. or a filter on the turbo mouth..
hell alot of times there's no filter at all.. simply a mesh over the mouth to keep debris out of the turbo!

the reason being.. the air will pass thru the intercooler and get cooled down anyway...

sure fresh air is always better.. but at what cost?

with long snorkels and fancy intakes trying to pull air from any nook and cranny it can, it takes "effort" for the engine to try and vacuume this air thru the piping and filter and such

the "hot" air intake basically is the equivilant to a short runner ram air kinda intake..

yes the air temp is higher, the density is lower.. but the VOLUME is also greater...

I wonder, what is the relation between air going into the turbo and coming out the intercooler

for example.. for every 1 degree change of air entering the turbo.. vs coming out of the intercooler...


already the air coming out of the turbo is compressed and super heated to 80-90*C how much diff will another 4-5* make I wonder?


are all the "japanese" guys doing it wrong with a filter on a stick?

or is the whole CAI thing over hyped on the Cooper S?


Compare a fancy CAI such as the Gruppe M unit which is a $1,300 best of the best intake on the market

vs a filter on a stick+ forge performance Front Mount.. $800-900


here are examples of High horsepower cars using nothing but a filter on a stick, to help with the "visualitazation"



http://www.simmers-cousins.co.uk/yar...bbigsingle.jpg
http://image.turbomagazine.com/f/248...rew_engine.jpg
http://www.speedalliance.com/images/...2_EVO_VIII.jpg
http://www.manic-motorz.com/Soar/IMG_0361.JPG
https://www.driftinjapan.com/uploade...ic3-734426.jpg

Dos intake is the best of the best for a mini .

I saw one on here from japan that was a stick with a filter . But it didn't have the maf on it. They moved the coolent tank to fit it in. If you could get the maf on it it looks like a good option . I bet it spools up quick. Can anybody find it on here and post the pic up. The dos unit is a great one but not everybody wants to cut a hole in the bulkhead panel. Plus it's cost over $300. cheap stick and a ic sounds good to me.

I know that my car (06 Supercharged) runs much better in cold weather than it does in hot and the fact that your engine runs about 180 degrees should convince you to run a CAI over filter on a stick. chances are the intercoolers on those cars are big enough or use a water meth injections system to dissapate the heat that comes through them and bring the air temp back down to a usable range. So my answer would be if you go with an intercooler that will make your temps optimal then filter on a stick would be fine. only problem is that when you compare a cold air intake price to intercooler price you aren't just talking a couple of dollars. Don't be afraid to cut your firewall, it's not hard to do and would actually be hard to screw it up.

Cold air is denser and when you draw it from a high pressure zone (front of the vehicle, wheel well, cowl, etc.) you get a large volume of cool air surrounding your filter. If you can increase the pressure around the air filter, you will have greater results on the outlet of the turbo because it will not have to work as hard to achieve the desired result.

FWIW, some DSM guys move their air filter from the engine bay down to inside the bumper where it gets a constant stream of fresh air and they were seeing 1-3mph gains in the quarter mile. There is a reason turbo drag cars put the turbo as close as they can to an open outside air source.

In the end I think it is a small piece to the puzzle to make the car work more efficiently.

Here is a pic of an 8 second gasoline 4 cylinder car and you can see right above the massive Garrett (best around) intercooler, there is an intake snorkel that draws cold air from a high pressure zone on the car.
http://i568.photobucket.com/albums/s...g/img_0457.jpg
Here you can see the opening
http://i568.photobucket.com/albums/s...g/IMG_9942.jpg

BTW the evo engine bay you posted above has an air filter assebmly in the corner of the picture. It looks to be an ARC cold air system. ;)

I don't feel the edge of the windshield is a high pressure area.. the stock hood scoop is a much better choice

yup I know the one ur talking about...

i've considered it myself as well...

i don't have an AFM on my car so it's a viable option... except I feel it's over priced and u could fab one up urself for a fraction of the price.. (perhaps they're selling it as "intellectual property)

http://duell.sakura.ne.jp/sblo_files...e/RIMG1227.JPG
http://duell.sakura.ne.jp/sblo_files...e/RIMG1222.JPG
http://duell.sakura.ne.jp/sblo_files...e/RIMG1181.JPG
http://duell.sakura.ne.jp/sblo_files...e/RIMG1103.JPG


I don't disagree that cold air is better.. (but when it's being sucked thru a mile of tubing... going from the front of the car to the back of the car then back to the front again there's alot of resistance)

but there is also a balancing point.. like my example.. FMIC+mushroom vs CAI+stock IC


as for the EVO yes it has an ARC intake.. but that is not a CAI either.. as that was the point I was trying to illustrate..

Ottoman, As you already know, two things can usually help,

1. colder air is better
2. more air available the better

I think what you show in your pics is pretty good. :thumbsup:

the only thing missing to make that a true cold air intake is a heat shield. the hole in the above picture is drawing air from outside the engine bay. If you look that EVO engine has a heatshield and I wouldn't be surprised if it draws air through a scoop on the hood or though a headlight housing. But like I said before it costs more to go the route of matching a new intercooler to a stick than it does to buy a true cold air system.

I was comparing a $1,200 gruppe M intake (the best intake for the Mini IMO)




to a $7XX FMIC+ a cheapo filter on a stick...


as for ur example.. of course ur car runs better in cold weather.. because the IC is getting colder air as well as the intake.. so its compounding..
and the engine bay doesn't heat soak as easily..

ambient temps play a big role

if it's 40*C ambient.. even with the worlds best intake and IC ur only going to have a 40* AIT at best...




sure if money was no object i would choose an FMIC AND this intake:

ironically even with the amazing build quality and such.. it's still cheaper than the m7 equiv. which isn't anywhere close to this..



https://www.gruppem.co.jp/onlinestor...am/fri0317.jpg

Get some software
 

and measure. The math is easy... PV=nRT, and watch knock sensor data as well. But cars with either a T-MAP type sensor or a MAF sensor can be logged to see what pulls more air in.

A lot of turbos with a simple horn under the hood are pushing so much HP that the owners don't care about what's lost to hot intake air density losses. those who race will take the time to route cold air in, cause it's not that hard to do and the benefits are real. And when you're racing, it matters.

Matt

I was thinking of buying a Blitz R-VIT i-Color

so that i could watch exactly the things u were talking about

but at 700 bux it's a big bullet to bite.. just to see the numbers...

If the base of the windsheild does not work why do nascar,arca,scca and nhra racers use cowl induction?

By the way GM proved you are wrong back in the 60s

Do you have anything by a reputable source that is published on this? Thanks.

Well the MAF is going to make just about everything null and void. In reality I would run a screen over the turbo and no piping. There is nothing restricting the air flow. In a street driven car running a regular intake or running a CAI. There are intakes on the market that say that it is a CAI but, it is a RAI. A true CAI would have the filter located somewhere outside the engine bay. I wish MINI would have reversed the motor with the turbo in the back toward the center of the car and the intake toward the front. I would have made some things better and easier. Once the ecu is cracked and easier to program or someone runs a stand alone ecu then it might be possible to run filterless.

It is DEFINITELY a high pressure area....

I think you'd be surprised at how little air comes in the scoop vs the cowl...

Stick a sheet of paper at the edge of the windshield/cowl and see where it goes.....no where. :thumbsup:

The DoS style intake is the best on the market....period. And yes I run an open "hot air intake" DDM, and don't mind it at all. But if you want to talk about the best, most functional design on the R56.....DoS wins that hands down. In reality though, I think people spend too much time getting hung up on things like intakes...when the stock one actually works pretty darn good, and the JCW being one of the best. I only have mine for personal sound preferences.

:confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused: :confused:

To respond to your first response, this is a thermal image of surface velocity of a Tesla electric car which is nothing more than a modified Elise body.
http://i168.photobucket.com/albums/u...rodynamic2.jpg
Why would this matter? Well being that it has zero reason to need proper aerodynamics for an efficient radiator or good/decent air intake, they look to move the car through air with as little resistances as possible. You will notice that there are a few problem areas as far as pressure build up which are a problem for every car unless it is an open wheel or a true race car. The blue areas are spots where air is moving slower and pressure is building. The base of the wind shield and the wheel wells are both areas that stick out to me. These are natural high pressure zones on a car and exactly why cowl induction works so well. The faster you go, the more air pressure is being built there and the more you can attempt to keep the turbo fed with a nice amount of cool air.

Also drawing air from the cowl isn't much more of a distance than drawing the air from the back of the engine bay like the one you posted.

That being said, I really like the one that you posted. If you built a semi large box around the filter and sealed it only allowing air to come from the opening that the pic was taken from, that would probably be ideal. I say that because the pipe is shorter and straighter, but I still feel that a cold air source is better than a hot air source even if it has to make a couple of bends. I would venture to bet that that opening sees quite a bit of air given that that is where the factory air box feeds from and engineers with wind tunnels aren't stupid. You could run a decent size velocity stack which should help fill every part of the straight gentle tapered pipe with air without a stagnant boundary layer.

All that we would need to run a setup like this would be a maf pigtail extension, a box, and a pipe, though I suspect you would need a little tuning if you move the maf closer to the turbo.

Also if you look at that white car I posted and notice his intercooler end tanks, I think you will notice that he understands how air moves. His car is what got me thinking and researching cold air intakes. If a really fast stripped car like that is adding weight for something like that, it has to be something worth considering.

Not the best of ideas....

If you like hood scoops, then go all the way and stick a Cragar chromed beastie jutting up through your hood... LOL

No, cowl induction works very very well. The DoS CAI seems intuitively the right way to go.

First off I just wanna say keep it comin guys!

at no point am I claiming to be an expert or anything.. (I do have an tendency to play devils advocate tho)

but I would like to see more of these kinds of discussions vs the usual cosmetic/aesthetic and troubleshooting threads...


now back to our regularly scheduled program:




the reason I thought our base of the windshield wouldn't work is because I thought to myself.. doesn't our beltline divert air away from that area? the edge of the mini bonnet almost seems like a Ramp
effectively "pushing" the pressure area higher up the windshield, and make a lower pressure area behind the ramp aka the scuttle area the DOS intake draws from



http://i17.photobucket.com/albums/b7...rometrimII.jpg




that link is interesting.. but how effective is it going to be on our cars? we don't have a giant bulge running up the center of the bonnet with a big offset gap...

is the idea behind this theory.. the highpressure turbulent area provides a denser more oxygenated place to pull air from? or is air bouncing off of the windshield and "into" the duct so to speak...

bearing in mind.. in those days u had carbs and were sort of limited to where u go put ur intake...

do u think the cowl is better than a hood scoop?

gruppe M makes an intake for the EP3 using this area for an intake
and it still makes it like a scoop.. rather then just a flush piece to pull air..


http://i341.photobucket.com/albums/o...p/Gruppe-M.jpg

http://defendersofspeed.com/store/im...2-thickbox.jpg




(on a side note I wonder if something like this could work on the mini)





isn't an RAI by nature a CAI as well? i.e. an RAI can be a CAI but a CAI doesn't necceseraly means it's an RAI

as for putting the turbo in the back.. trust me u don't want that.. the VAG cars put it back there.. and it makes ANY work on the exhaust (i.e. downpipe) or turbo upgrades etc a real PITA...

N/A cars.. sure I agree move the intake to the front, makes it shorter, and the exhaust shorter...

what makes u say the DoS is better than the Gruppe M? because of the cowl principle can feed more air than the RAI+CAI of the gruppe M?



i was having the same thoughts... rather than a filter on a stick.. have some sort of air box ala the ARC.. that butts up against the stock feeding hole and seals the intake from the engine bay at the same time.... shortening the path the air has to travel before making it's way to the turbo can't be a bad thing...


btw your link on the tesla doesn't work so I can't see what ur talking about :(

Neat to watch this discussion develop . . .
 

This design is actually quite effective for cowl induction because it has a lip right at the edge of the hood and a decent air gap before the apron panels that sit at the base of the windshield.

Air is smoothly flowing over the hood until it hits the windshield. When it hits the windshield, a high pressure area is generated. Air, like many liquids, seeks the path of least resistance. When you place a duct or vent at this area of the car (a low pressure area) the high pressure air is able to easily find a path to the cowl vents. Some of it tumbles at the windshield, but it doesn't 'bounce' into the vent.

But the duct is facing the wrong way in the image above for most effective induction at the cowl.

MINI places the stock air inlet at an area of high pressure, the grille. It is one of the most vertical surfaces on the front fascia of the R55, R56, & R57, so it makes sense to put it there.

DoS is not into the idea of placing an air inlet duct over the turbo. It removes a potential location for turbo cooling & venting, so we left it alone.

Best,

-Clint

here's an interesting article on pressure areas and ways of testing them:

after ppl read it we can do some more discussing :D

http://autospeed.com.au/cms/A_111111/article.html

good thread

Pic is fixed :thumbsup: