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Wiltron 06-14-2011 12:06 PM

Which CAI should I get?
I can't decide between these two models.

One gives the metal tube, which would look nice for those looking in my engine bay, while the other claims a higher HP gain at 4800RPM (a line I rarely cross).

I'm more interested in the sound of the engine, as well as the higher air flow, rather than the marginal performance increases they give.

K&N 77 Series for JK
K&N 63 Series for JK

77 Said lower HP Gain, but colder air due to metal piping, so likelihood of higher MPG savings. 63 is reported to give a higher HP, at the cost of being less functionally sound for the fuel savings.

Only interested in K&N, have used them on every vehicle I've owned, I trust their products.

jeffk42 06-14-2011 12:12 PM

Neither will have any effect on HP or MPG, so just get the one that you think looks the nicest.

Wallygator 06-14-2011 12:15 PM

The cold air intake will have no effect on performance and very little on mileage. They are designed for high revving motors. So yeah go with the one that looks nicest

Wiltron 06-14-2011 12:22 PM

How can they give no increase? Everyone I've talked too, including mechanics who work on SUV's and larger trucks, as well as all the reports online all said it increased responsiveness as well as fuel econ?

jeffk42 06-14-2011 12:27 PM

There are no benefits to putting an intake on a vehicle unless that vehicle has restricted airflow from the factory (many do), which the aftermarket intake alleviates. The Wrangler's airflow isn't really restricted.

All the mechanics that you talked to should be agreeing on this point.

MTH 06-14-2011 12:35 PM

Ran a "title" search in the JK section for the word "intake" and got 43 hits. This gets asked all . . . the . . . time.

But the basics are--as Jeffk42 stated--that the stock intake provides, for the most part, all the air the engine will use during normal operation as currently configured.

Hence, you get only marginal performance increases from simply adding a new intake. While the dyno sheets published by the CAI manufacturers are not fabrications, even they only show three or four more horsepower at common RPMs. Maybe a shade more gas mileage, though I rather doubt that one.

To really capitalize on the whole "air" thing, you'd have to do the whole engine front to back -- new intake, new throttle body, new headers, and a new exhaust. The dynos published by the guys at Ripp show similar set ups netting 20+ horsepower. Might be able to tweak out some more with a custom tune of the computer to capitalize on the extra airflow.

The problem is that's not a very cost effective way to put 20 more hp on the ground. You could regear for less and create more hp at a given speed.

That said, you stated that you're really only interested in the sound. I have an AEM Brute Force along with a viper throttle body and the engine sounds FANTASTIC. It feels as if it's given me a few more horsepower--I'd say less than 10, but that's just a guess.

Here's my intake review and here's my throttle body (*not* a throttle body "spacer") review.

Mr. Sinister 06-14-2011 01:15 PM

Let's approach this logically and scientifically:
The factory airbox, by it's design, is a CAI. The inlet and filter are contained in a box, cut off from underhood heat, right? Right.
An engine only pulls in enough air it needs to operate efficiently, right? Right.
To flow more air, a filter must also allow more dirt to pass, right? Right.
If you increase the diameter of the inlet pipe by using a CAI, you still bottleneck at the throttle body, right? Right.
Metal is an EXCELLENT conductor of heat, right? Right.
If you bring more air into an engine, you need to flow more air out, and increase fuel delivery to compensate for the added air, change your timing, etc. right? Right. There's a little wiggle room on all 3, but like you have seen, in most cases it's peak power, not over the entire powerband. This is why you can't just throw a big honkin' set of headers on a stock motor. You'll lose power by slowing velocity, because the potential volume increased dramatically, without velocity. Velocity is just as important as volume to power and fuel economy. This is why you see longer intake runners used for factory applications, to keep volume and velocity where they need to be on a stock engine, to produce the most useable torque. Your air inlet (CAI) is essentially just an extension of the intake runners. Shortening the intake track raises high rpm power, and also raises the entire useable powerband. There are limitations to both, however. Your runners can be too long or too short, but we won't get into that.

Increasing airflow on an engine that doesn't really need it by increasing the flow through the filter and increasing the diameter of the inlet pipe will net you very little gain, and in fact, may RAISE your peak power rpm, by providing a larger hole to draw air through, slowing velocity and altering your torque curve. Think about how often you're seeing RPM above 4000 on a Wrangler. The couple HP a CAI may provide are not nearly as important as the affect it will have on torque, which is most likely negative in the 3.8's case. Even if you gain a couple ft/lbs of torque, unless it's average and not peak, it's basically useless in our Jeeps.
Higher performance engines often benefit (more so, but still not typically dramatic) from a CAI because the factory air inlet was designed to keep noise down, not make the most power. The 3.8 has been around long enough and used in enough different applications that it's pretty much been optimized. It produced 150hp originally, and now makes 202 in our Wranglers. That's a 52hp increase, while still having to maintain Federal standards. I'd say that's pretty much optimized for a fairly low performance V6.
The most powerful things about these CAI kits are their marketing teams. Until you NEED the added flow, you're basically just wasting money. You might pick up a couple of peak hp, maybe a real 1/2mpg, and a little added noise. So you have to decide if allowing more dirt into your engine and possibly altering your useable powerband is worth the "benefits" and the price.
There are many, many variables here, but basic engine operation is the same.

MTH 06-14-2011 01:25 PM

I hear this is a "drop-in" way to increase horsepower and torque significantly. More airflow and such . . . . :D

cremaley 06-15-2011 06:53 AM

I added a K & N 77 Series along with MBPR performance exhausts and Superchips tuner and got more power and better gas mileage. With 33x12.5 Khumo tires on 17 inch wheels before adding the above MPG was 15.1 After the above mods, MPG is now 18.7 and lot's more power as well.

Wallygator 06-15-2011 11:10 AM

Probably due more to the exhaust and tuner. My biggest gain was from putting an a better exhuast. Intake did next to nothing. Sounded nice tho.

Ol Tex 06-15-2011 02:55 PM

I added a Banks CAI to my Jeep and it is great and really fits into the stock location. As for added power, maybe a little. It does sound good!!!! I did change the oiled filter element for a dry AEM element. There are many experts on here who quote dyno results and really talk the CAI down as a waste. Well, it was my money and I am happy. I dont care what the Einsteins think!!! I would do it all over again!!!!! Have a goodun!!!!

Djstorm100 06-16-2011 07:48 AM

Increase air flow does not mean increase or decrease in MPG. Air is a dependent variable soley based on the amount of oxygen that is in the air (giving the humity, elevation, and temperature)

thenorsepole 06-16-2011 08:03 AM

I got the 66 and, performance-wise, I see no substatial difference based on "seat of the pants" technology. I do, however, reset my MPG tracker between oil changes. Prior to the 66 I was averaging 17.3 MPG, Over the last 1500 miles or so I am averaging 18.0.

Is it because of the intake? Oil type? I can't say for certain, but I can say that it does sound much better than with the stock set up.

Even though the intake may not make a significant difference in performance, I don't feel as if I pissed away my money in buying and installing it either.

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