So after reading about AEM's new driveshaft dyno in the latest issue it sparked a great (at least I think) topic for an article...do ram air or cowl induction intakes actually work? There was a pretty big post over on miata.net a week or two ago about this very thing, but it basically all boiled down to a lot of math and theories about whether or not it would work because up until now there was no way to truly test it (other than a wind tunnel I guess).
I think it would be a great article topic just to put all the discussion to rest with proof. Do they work and at what speeds do you need to be driving in order to see results?
Can you do an article on this? Pretty please?
I think the topic's been done to death by now over the years...long story short, you get very little to no performance increase from the ram-air effect.
I wouldn't worry about it for anything but a landspeed car.
gh0st
New Reader
4/30/12 9:50 a.m.
GameboyRMH wrote:
I think the topic's been done to death by now over the years...
Exactly my point. It keeps coming up. It would just be nice to see the results backed up with numbers
Cold air and Ram air intakes are the most misrepresented things on the market.
Most do neither/
A true ram air will allow cold air but the ram effect is only at high speed
CLNSC3
Reader
4/30/12 9:55 a.m.
On my SC I built a system that our good friends from down under(australia) created. Called it the BFI or Big berkeleying Intake.Dyno results from that system with new OEM filter made significantly more power than ANY aftermarket option.
It basically takes advantage of the cars OEM intake track, you just seal and smooth it up. Also you open up the area it pulls air from a little more. And it was super cheap!
Link for brainstorming:
http://planetsoarer.com/BFI3/bfi3.htm
In reply to CLNSC3:
That's what I did on my truck. I used a 3" speaker port. Worked great.
I don't know what you guys are talking about, because real ram air works. 1/4 mile times don't lie...
The only way to measure ram air gains is with a wind tunnel dyno or one of those new driveshaft dynos. If it gets more power at speed / with wind than on a regular plain-jane dyno run then it works. Otherwise you can't separate it from intake differences.
With many stock intakes being brought down to the size of a dime at the cone entrance, you can get a bump in performance with any intake that will allow cooler air in faster. Suck air through one straw, then shove ten straws in your mouth and suck. Which is easier? (make sure you take a picture and post it.)
Most ram air is likely getting most of its benefits from cold air.
I don't remember the exact numbers, but I do remember in reading in the evaluation of the Mitsubishi Zero captured in Alaska (Akutan Zero) they made mention of the effect of the ram air on the engine (could be opened from within in the cockpit).
I believe they estimated it at something like 5hp or so. This was on a engine that put out around 950hp and was travelling over 200mph! Your result may vary, but they probably are not going to be huge.
Lowering the inlet air temp most definitely increases power. And like Jav said, real ram air does in fact work. Plenty of systems out there do not work, but the theory is valid.
You guys make the OP's point.
With the new driveshaft dyno we can actually find out what kind of effect the ram air gives.
aircooled wrote:
Most ram air is likely getting most of its benefits from cold air.
I don't remember the exact numbers, but I do remember in reading in the evaluation of the Mitsubishi Zero captured in Alaska (Akutan Zero) they made mention of the effect of the ram air on the engine (could be opened from within in the cockpit).
I believe they estimated it at something like 5hp or so. This was on a engine that put out around 950hp and was travelling over 200mph! Your result may vary, but they probably are not going to be huge.
Yeah, not even remotely close to accurate, man. The Akutan Zeke was never given 100% power for fear of breaking it, and every airplane has ram air. 
carguy123 wrote:
You guys make the OP's point.
With the new driveshaft dyno we can actually find out what kind of effect the ram air gives.
What's wrong with 1/4 mile ET's? Race car, make change, race car, change back, race car, etc. Magazines and racers have been doing it for years. I can tell you from personal experience in a Ram Air equipped AMC (which is a dual system, you can run on normal or pull the lever for the scoop) just running back-to-back-to-back-to-back that the factory ram air was worth a solid 2 tenths over it being closed off. I don't need a dyno to tell me that it made more power to go 2 tenth quicker...
tuna55
UltraDork
4/30/12 11:31 a.m.
carguy123 wrote:
You guys make the OP's point.
With the new driveshaft dyno we can actually find out what kind of effect the ram air gives.
A nearby dragstrip will test that out for like $7 on a test & tune night. I'd still like to see the test, but the dyno thing is a bit extravagant for that.
Javelin wrote:
carguy123 wrote:
You guys make the OP's point.
With the new driveshaft dyno we can actually find out what kind of effect the ram air gives.
What's wrong with 1/4 mile ET's? Race car, make change, race car, change back, race car, etc. Magazines and racers have been doing it for years. I can tell you from personal experience in a Ram Air equipped AMC (which is a dual system, you can run on normal or pull the lever for the scoop) just running back-to-back-to-back-to-back that the factory ram air was worth a solid 2 tenths over it being closed off. I don't need a dyno to tell me that it made more power to go 2 tenth quicker...
Sure, but the question is: Is it faster because it has a direct supply of cool air vs sucking in whatever hot garbage from the bay when closed, or because there's a fraction of a fraction of a psi gain in pressure because of the air being "rammed" in once you're going a certain speed?
I'm inclined to believe that the gains from "ram air" systems are really just because it's a more efficient intake system, not because it's actually introducing enough pressure to make a power difference.
I've got $50 that says that if your AMC hadn't been equipped with the ram air system and you put a good cold air intake on it, you would have dropped those same 2/10ths.
SVreX
UltimaDork
4/30/12 11:49 a.m.
It sure worked on my car, even if it doesn't work! 
SVreX
UltimaDork
4/30/12 11:55 a.m.
I think ram systems are improperly named.
The point is having sufficient fresh air, and it helps if it is cooler.
If you put a household fan near a wall so it's intake side is partially restricted, you can hear the fan work harder.
You are not going to increase the psi with a little bit of "ram".
However, you are going to permit a sufficient supply of fresh air so the motor is capable of pulling as much as possible in (just like the fan).
The volume of air an engine pulls in is significant. Any restriction or hindrance to the airflow is a loss of hp. Smoother and more direct passageway, larger tubes, fewer bends, and scoops, etc that position more air at the mouth of the intake are all benefits, regardless of what they are called.
tuna55
UltraDork
4/30/12 11:57 a.m.
92CelicaHalfTrac wrote:
Javelin wrote:
carguy123 wrote:
You guys make the OP's point.
With the new driveshaft dyno we can actually find out what kind of effect the ram air gives.
What's wrong with 1/4 mile ET's? Race car, make change, race car, change back, race car, etc. Magazines and racers have been doing it for years. I can tell you from personal experience in a Ram Air equipped AMC (which is a dual system, you can run on normal or pull the lever for the scoop) just running back-to-back-to-back-to-back that the factory ram air was worth a solid 2 tenths over it being closed off. I don't need a dyno to tell me that it made more power to go 2 tenth quicker...
Sure, but the question is: Is it faster because it has a direct supply of cool air vs sucking in whatever hot garbage from the bay when closed, or because there's a fraction of a fraction of a psi gain in pressure because of the air being "rammed" in once you're going a certain speed?
I'm inclined to believe that the gains from "ram air" systems are really just because it's a more efficient intake system, not because it's actually introducing enough pressure to make a power difference.
I've got $50 that says that if your AMC hadn't been equipped with the ram air system and you put a good cold air intake on it, you would have dropped those same 2/10ths.
That's interesting. Run the tests in both configurations and then put a pressure/vacuum gauge in the inlet tract.
Shaun
HalfDork
4/30/12 12:03 p.m.
There was an article in racecar engineering a few years back on the subject and IIRC- in whichever car under whatever the F1 spec was at the time a development cycle on the "ramair" inlet was worth 8-9 hp at 150 mph at some stratospheric rpm. Which of course is significant in F1. Positive pressure on the inlet side decreases pumping losses which means more powah irrespective of air temp so it makes sense to me. Is my civic making more powah because of the snorkel I plumbed out to the grill? I seriously doubt it.
92CelicaHalfTrac wrote:
I've got $50 that says that if your AMC hadn't been equipped with the ram air system and you put a good cold air intake on it, you would have dropped those same 2/10ths.
It's kind of hard to do a "cold air" intake on a carburetor equipped car without doing Ram Air, but yes more than likely the majority of the power gain is from the "colder" ambient air as opposed to the hot underhood air, but how much comes from each is a who knows? This would be an interesting effect to study on an EFI car that has a regular intake tract, a "CAI", and then add a ram air scoop of some sort. Still don't need the driveshaft dyno though...
It doesn't have to be "ram" air either.... The old Malibu SS had cowl induction... the pressure @ the base of the windshield is rather high, so when the cowl opens, it provides some pressure on the air charge and helps in cylinder filling - abundance of air
bravenrace wrote:
Lowering the inlet air temp most definitely increases power. And like Jav said, real ram air does in fact work. Plenty of systems out there do not work, but the theory is valid.
Most gains on "ram air" or "cold air" intakes is a result of colder, denser air charges and less restriction in the intake flow tract.
For an example, here is the stock intake on a Coyote 5.0 V8. It pulls air from near the ground and even says "cool air induction" on it. It is one of the best factory intakes I've seen.
AEM makes an aftermarket intake that is marginally better. It smooths out the bends and eliminates the "crinkly" portions of the intake. Note that the lower part (pre-filter) is the exact same as the factory piece
The gains with this intake are only 8 horsepower at 5,000 RPM, on a motor that makes over 400 horsepower stock. A gain of less than 2% sounds like it could be little more than a rounding error to me. The main advantage of AEM's intake is increased throttle response, however.
