In the latest issue of Honda Tuning , the did a comparo of 9 different intakes, but what was interesting was they went scientific. They put the various intakes on a flow bench plus they took temperatures of outside, underhood, coolant and Intake air temperature sensor in the intake (via tapping into the OBD-II). The actual numbers aren't that important here, but the conclusions were very interesting (some of which we already suspect, but here it is proven).

1) Any intake whether short ram or CAI is better than stock. Stock is designed to be quiet, not efficient. Too many bends and baffles equal poor air flow volume. (237 CFM)

2) A short ram intake (ie: Franken, Berk) flows more air than a CAI, (avg 345 CFM) easy to install, but because of underhood temps, produce less HP. In the article, with a ambient outside temp of 78 degrees, underhood temps were 110 degrees at 80 MPH. Idle temp would be over 130 degrees. The temperature at the intake temperature sensor would average 125 degrees.

3) A CAI (ie: Place Racing, Injen) flows less air than a ram (325 CFM), is harder to install and more expensive. Average temps at the intake sensor was around 98 degrees.

Power results: The CAI's and ram intakes they tested all produced more HP than the stock intake, but the CAI's put out twice as much power(in this case 9.2 hp vs around 20 hp).

Before you guys flame me for reading a Honda Magazine, let me say first, put your little thing back into your pants and stop having such a myopic view on cars. Two points here, one is always know everything about the competition, whether it is business, racing or even war. Next, I purchased the magazine for this article because it would apply to all cars, not just Hondas.

 

Thanks for sharing this info with us. No flame from me

 

Very interesting info, but no matter what the article said there will still be arguments about the HP gains since the CAI and HAI are both different when it comes to racing off the line and (0-40) and long run (40+). But I guess over all the CAI is a little better, but he difference is not that noticable.

 

No flame from me. I found the article very interesting and posted about it a couple of weeks ago. I was only able to skim the article. Thanks for posting more details about it.

 

Great information for me. Which month is the issue in question? I own a 01 Max. I just recieved a PRCAI in the mail. I have no replies from anyone that has used a Monster Flow filter. This is the filter a included by PR. Have you used or know anyone that has used this filter? I find no info

 

thanks for the info.. I will be posting it in the 4th gen forum..

 

It was from the Oct/Nov issue of Honda Tuning. In the newstands now. My place racing came with a K&N, so I couldn't really say anything about the Monster filter. Something I didn't mention in the original post is they did a quickie compar of the different filters too. Not much difference with a AEM, DC, K&N filter, but the Jackson Racing filter flowed notably higher, so the way to go would be to do a hybrid setup with a CAI and a Jackson Racing filter. Cost? I don't know.

xfirepwr1 : I think you can feel the difference. 10 HP is noticeable. We are always trying to find that extra few ponies and I hear lots of butt dyno's saying a UDP (worth maybe 5 hp) is noticeable (but who knows how accurate butt dyno's are )
Also, the HP and torque graphs from their dyno runs all run fairly parallel to the stock curves only with more horsepower and torque, so people who say they are feeling the power lower or higher in the rev range are probably all in the owners head (that damn butt dyno again).

 

See, this is BS, and it's also why I have little to NO respect for these so-called "tuning" magazines

A friend of mine did this EXACT SAME TEST with a thermocouple on his intake which he wired into his car, and the underhood temp while moving was EXACTLY the same as the outside air temperature. Only while stopped completely did the under hood temps rise, and even then, once about like 5 mph they'd drop down to outside temps in a matter of seconds.

More rubbish.

What kind of Honda gains 20HP from a CAI intake when a Short Ram gains only 10HP. I'm gonna have to stop and look at this mag tomorrow because something is definitely hokey here.

Keep in mind that the whole point of these mags is to sell advertising and to SELL PRODUCTS. Obviously intake manufacturers will want you to think that you're getting your money's worth by paying TWICE as much for a CAI by trying to make you think you'll get TWICE the gains. But I smell a big fat juicy load here...

Maybe to get the "20HP gain vs 9.2" on the CAI, they took the damned filter head off, which is what I suspect they did

Don't believe everything you read, folks...

Anyhow Tai Mai Shu, I'm not flaming you. Thanks for posting this. But there are some definite technical holes in this article, and whadayaknow...it's from a Honda-related magazine. I'll check it out for myself tomorrow, though.

BTW, I just thought I'd add that there has been NO noticeable difference in dyno results between the CAI and Short Ram intakes on Accord V6's with the 3.0L VTEC V6 engine. Both gained about 8-10 fwhp regardless of which intake it was. I don't know where the f!ck this 20 fwhp number is coming from in this article unless they're pulling a fast one.

Does Honda make any 6.0L engines?

 

The only thing im worried about is our 3.0L and even 3.5L motors..tahts almost double the displacement. Would we need double the air?. The CAI is almost Double the piping needed compared to the short ram. Is that piping too much?

 

That does seem to be the consensus experience with HAIs (i.e., hot air intakes, short ram intakes, etc.). CAIs have an advantage over HAIs until the vehicle begins moving. Within a matter of few MPH, air circulation under the hood carries heat away from both the engine and the air intake. At that point, the CAI not only loses its advantage, but the increased air flow attributable to HAIs should begin to consume the CAIs initial performance advantages. If dyno results indicate otherwise, testing methodologies, intake geometries, flow characteristics and other factors should be thoroughly investigated. Obviously, some factor other than air temperature must be at work in producing results that continue to favor the CAI as the vehicle gains speed.

 

No flames from this direction. Actually, you get my compliments for looking for the tech regardless of the source (wider variety is why I frequent a couple of GM-oriented bb's, a Mustang forum, Corner-Carvers, a Honda board, and SCCAforums in addition to this one).

I do have a little direct experience with this particular piece of tech, since I can read IAT while my car is being driven at any time I choose. I'm talking about the Malibu with its aftermarket EFI and the calibration/data monitoring/data recording software here, but the tech doesn't care about make/model (only the specific numbers may vary). I've seen sustained IAT's using underhood air in the 120's and even 130's on an 80 degF day. A cheapie CAI dropped the IAT by over 30 degF (but since I haven't figured out a workable way to attach a filter I'm still stuck with the high temps). On a highway trip if I get stuck in traffic or at a toll booth the IAT goes up pretty quickly but drops much, much more slowly.

IAT is affected by airflow through the radiator/engine compartment vs inlet positioning, heat radiated off the headers (and the rest of the engine), and heat conducted through the intake manifolding. Quite likely even the color of the hood and the directness of sunlight exposure on it have some effect (that's what my observations suggest, anyway).

Norm

 

We're on the same page SteVTEC- I'm sticking with my test results.
http://forums.maxima.org/showthread....hreadid=161964

 

English please.

 

Hey Norm! (Not the same guy from Cheers?) Sorry I couldn't resist. I agree with you concerning underhood temps and the temp reading of the sensor. Even at speed, how could the underhood temp be the same as the ambient temps? The majority of air flowing into the engine compartment is coming throught the radiator , plus like you said, the heat from the exhaust manifolds and engine also contribute. Why do you think early Jaguars used to vapor lock all the time?

As for all you guys who say they were BSing in the article and making up the numbers, I guess you don't believe we really landed on the moon either? (I'm just messin' with ya!)

 

OK so this is what I've gathered from this thread (let me know if I'm mistaken anywhere):

Temperature ramifications aside, CAI, with the longer piping compared to HAI, facilitates a smoother (i.e. less turbulent) stream of air into the intake manifold at lower RPM's.
What this basically means is more air gets into the cylinders at lower RPM's and with less effort. You get more torque down low.

The shorter piping of the HAI allows for a more turbulent stream of air at lower rpms, and thus less torque. But at higher rpm's, ballpark 4500+, then yes in general HAI will allow more air, meaning more torque.

The longer the piping, the lower the maximum air-flow rate and vice-versa. Hoever the longer the piping the smoother the air stream.

But either set-up will be better than stock. And more torque at lower RPM's is certainly what I'm looking for so I'll stick with CAI (just got the Injen today ).

 

Alright - here's my dyno plot overlay. You'll find both the CAI w/ Catback & WAI w/ Catback. Torque is nearly the same, the big dif is HP.

http://24.198.13.132:3385/Maxima/CAIvsWAI_Dyno.jpg

The torque numbers on the right do not reflect my peak torque, as that was 236, but that number is the torque at the point of peak HP.

 

I don't see a big diff in HP til after 5.5k.

 

Right - but that big difference ranges between 4 - 14 HP!

There's not much of a difference in the torque except between 2.2 & 2.7. Otherwise it's all pretty comperable. But answer me this - there's not much of a HP difference until you hit 4.6k - but when actually applying the power of the car - are you shifting @ 3k? NO - your up around 4k - 6.5k which is where the difference matters.

 

I rarely go over 5.5k. I mean rare.

 

no flame...good info to share..

one thing tho...i don't know what car the test was conducted on, but i'm guessing it's a Honda. If you compared Cheston's numbers(his Stillen short ram vs. Place Racing CAI), the SI laid down more on top, while the CAI laid down more on bottom end.

 

good post, i'll have to pickup that mag and read further

one main thing you all are forgetting is aerodynamics. a honda may or may not have better under hood air flow. that would be why the numbers for the IAT and under hood AT are so much different from a max. that alone could make the final numbers so much different.

 

That's precisely the results one would expect. Once the vehicle starts moving and ambient air begins to circulate under the hood, the advantages of a CAI disappear quickly. Dyno result after dyno result prove this point.

 

Not so, As you can see from their readings, the ambient outside temp was 78 degrees, but at 80 mph the underhood temp was still at 110 degrees. Most of the air flowing into the engine compartment comes thru the radiator and the air conditioning compressor. So you aren't getting ambient air temps going in. And dyno results do not truly measure the positive effects of a CAI because, in the dyno room, the ambient air temp goes up from the heat of the engine. Anyone with a ambient thermometer on their Maxima knows that if you are idleing for any amount of time, can see the ambient temp go slowly up. I've seen it at 110 outside on a summer day.

 

Hmmmm. Let's see. Underneath the engine is a HUGE hole. In front of the engine is a brick wall (aka radiator). Now I don't know much about air circulation, but it seems to me that more air will come through a huge hole than through a brick wall. Then again, I could be wrong about that . . .

 

any more folks have their dynographs available for HAI vs CAI? Great post!

 

The radiator is a rather porous brick wall, and all the air that comes into the engine compartment has to find a way out somehow. At the risk of gross oversimplification (since I don't have the airflow study either), I'd say that down has to be out for the hot air.

Norm

 

As much as I respect your opinion, Norm, hot air still rises.

If I remember my high school science courses correctly, gases and liquids flow along the path of least resistance. If that's the case, more air should enter from under the engine compartment than through the radiator. If anything, air pressure in front of the radiator should be greater than air pressure behind the radiator because the radiator introduces a barrier to air flow. That would tend to create something of a vaccuum behind the radiator drawing air from around and underneath it.

Does that make sense?

 

The whole picture is far more complicated. Keep in mind that flow is determined far more by the influence of a pressure differential than by convection currents that exist due to temperature differences. Given that the air dam acts as a flow splitter, you get some flow that goes up and through the radiator and some that goes under the car. The pressure drop for the air that goes through the radiator is greater than that for the air that goes underneath, so, yes, there is some tendency for air underneath to get drawn upward. But in order for a finite amount of air to do so involves a pressure drop in the mass of air flowing underneath, which acts to keep the underneath air downstairs. Net effect? Probably a little bit of air moves up, most likely immediately behind the radiator/radiator support.

You still have to let the air get out, or else the underhood conditions are stagnant, the engine compartment would be slightly pressurized (greater tendency to keep the undercar air out), and the engine will ultimately overheat. In the absence of hood louvers, huge hood gaps (in the right places) or other oddball air extraction routing (i.e. into the wheel wells), the only place for radiator air to go is down (behind the possible small upward flow noted above). Obviously, some air will make the tortured journey up over the engine and transaxle, which will help cool the back side of the engine and its exhaust. But off the top of my head, the pressure drop involved to accomplish that is somewhat greater than that required to obtain downward flow in front of the engine, so I still expect that the bulk of the radiator airflow simply goes down. Obviously, the space at the bottom of the radiator is a zone of turblence.

(Keeping this short so that AOL doesn't boot me off)

Norm

 

Do you guys realize the volume of air that the VQ is pumping in and out every second at full throttle?

With a 3.0L engine at 5000rpm and 100% throttle, you are bringing in 1.5L of air every revolution. 5000rpm = 83.3 revolutions per second.

1.5L x 83.3 rps = 125L/s

Now where do you think this air comes from? Is it all just loitering around the radiator and engine block taking its good ol time to get nice and warm and cozy before it makes its way into the intake? Or is that air zipping from the outside, through whatever underhood path it takes, and into the intake tract so quickly that it doesn't even have time to heat up much, if anything, beyond outside air temperatures at all.

Yeah, if you're loitering through town at NIL throttle there is very little air flow and I bet intake temps would be higher. But then you're not too concerned about making power are you, because your foot isn't even on the gas. But if you stomp on it, all of that hot air nestled under the hood is going to be displaced by fresh air from the outside in a matter of no time with a flow rate of 125L/s.

 

Thanks for your feedback, Norm.

Yes, it is complicated. And you obviously have a better grasp of the dynamics involved than I have. I guess the proof is in the pudding. The only way to properly test this would be to take a vehicle to the drag strip with a WAI and a CAI and conduct several runs with each installed. You'd probably want to do a quick reset of the ECU before each run to try to keep the computer settings as neutral as possible. Short of that, the WAI vs CAI debate seems unlikely to abate any time soon.

 

I would go for the 20 hp up!

 

So we're back to the only meaninful difference in the two intakes is the actual geometry/air flow dynamics of the longer CAI tube vs the shorter WAI. Correct?

 

That's pretty much what I'm saying, yes

EDIT: And if my theory is correct, those with WAI's don't even need to worry about hot stagnant air on power launches if you just blip the throttle firmly a couple of times just before you launch to flush out the hot air from under the hood and replace it with some cooler fresh air from the outside.

I think this would be a neat experiment to try. I'll do it after I get my intake installed. Already have all the equipment I need to test it (thermocouples) from the lab at work

 

Haha 2 pts if you can name that movie.

So which should I get? Some one please just tell me what CAI to get that will be easy to put in and give me 10whp or more.

 

Both a CAI and a WAI will give you similar gains in torque. The difference is that with a WAI, it will hold the torque up to higher RPM's better than a CAI, which in turn gives you more horsepower. Horsepower is a function of torque multiplied by RPM.

The longer the tubing, the more restrictive it will be at high RPM's. So a CAI will give you the poorest top-end peak horsepower gains, and the power will fall off faster than with a hybrid (medium length tube) or POP (short length tube)

On the otherhand, for low-RPM power, you actually *want* some restriction, so a CAI will actually help you with low-end. A short POP intake has the shortest length so it will give you the highest top-end (horsepower) gains, but the poorest low-end performance.

http://forums.maxima.org/showthread....hreadid=161964

 

where did you get the 1.5L number? cause the mixture between gas and air is closer to 14:1, under perfect stoich, but by going by a 1.5L figure that would be a 1:1 mixture.

 

4-stroke engine. Only half of the cylinders are taking in air for each revolution. It takes TWO revolutions to complete the 4-stroke cycle on each cylinder. So if you have a 3.0L engine at WOT, it's bringing in close to 1.5L of air each revolution.

No engine is 100% volumetrically efficient, though, but I'm not trying to be precise here. Just illustrating a point that the engine is moving A LOT of air at full throttle and that any air under the hood isn't going to be staying in once place for very long

 

As always, you come in with an intelligent and informative reply. Great work

 

Have you estimated the air volume flowing through the radiator? At 30 mph every square foot of radiator as seen in front view swallows 44 cubic feet of air per second. That's ~1250 liter/second. The radiator is bigger than one square foot, but offers restriction. Conservatively calling it a wash means that the engine digests at most 10% of the air coming into the engine compartment.

Norm

 

Thank You Norm!

Even if the VQ swollowed as much air as he proposes, the replacement air is still heated from the flow from the radiator, not from the cooler outside air.