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f1anatic 08-06-2013 09:35 PM

DYI CAI for the 3.6L V6 engine
10 Attachment(s)
I have recently completed my DYI Cold Air Intake project for my 2014 Jeep Grand Cherokee. I was disatisfied with both the price and/or performance of some of the products on the market. To mention just a few of my concerns with some of the products (in no particular order)
  • some products replaced the plastic intake tube with a metal unit (aluminium). Metal is a better heat conductor than plastic. This condition could potentially increase the Intake Air Temperature (IAT) due to increased heat soak.
  • some products used a cone filter which was positioned in such ways that the air being "sucked" in the engine was from inside the engine compartment. This condition could potentially increase the Intake Air Temperature (IAT).
  • some products were priced just too high.
  • some products moved the location of the sensor.
From my experience with Subaru turbo engines, heat is an enemy. And colder air is ..."for the win" OF course with Subaru, CAIs are very much frowned upon, and the standard solutions include a combination of solutions such as: a larger inter-cooler, water/methanol injection, water spray and front-mounted inter-coolers. Not applicable to normally aspirated Jeeps - until I will supercharge it some day.

So this is what I did:

  • OEM Resonator (P/N 68194974AA) for ~ 63$
  • AFE Pro Dry S (Dry Media) (P/N 31-10218)~ 55$
  • Vacuum Hose (Home Depot)
  • 2 x 3 inch diam. Rubber Couplers
  • 3 inch PVC pipe (Home Depot)
  • 1 x 1.25 inch diam. Rubber Coupler
  • OEM Snorkel Intake Duct (P/N 68022213AB) ~ 41$
  1. Disassembled the OEM intake assembly (duct with resonators, air filter box, snorkel intake duct)
  2. Cut one of the ends of the OEM Intake Duct
  3. Connected snorkel intake duct to the vacuum hose using the 1.25 inch diam. Rubber Coupler
  4. Ran the Vacuum Hose through the opening behind the driver's side tow hook
  5. Reassembled the snorkel intake duct and air filter box (with the new AFe filter)
  6. Using a DREMEL or other precision tool, I cut out the resonators from the spare OEM intake duct.
  7. Plugged the holes in two areas (smaller resonators)
  8. Using the two 3 inch couplers and the 3 inch PVC pipe, I filled the gap left by the larger resonator.
  9. Improvised a little scoop which I connected to vacuum hose end by the driver's side tow hook. I am still looking for the perfect scoop but it works.
Sure it makes sexy sounds under acceleration but what I am concerned with is the fact that theoretically, there is MORE DENSER (colder) AIR going into the engine. Yeah, the filter has to be cleaned more often and damn it I can no longer ford rivers and streams deeper than 1.5 feet without first using a Phillips screw driver, but I think I will be just fine in the jungles of Chicago.

There are ways to quantify the effects and I do have access to the the instrumentation needed, but it is beyond the scope of my little project.

padgett 08-07-2013 08:00 AM

Re: DYI CAI for the 3.6L V6 engine
2 Attachment(s)
I did something similar but just cut/blocked (1.5" rubber freeze plug) the tube to the furnace and left in the small resonator box. The rationale was to keep the spacing of the tube over the passenger cam cover and wiring and to keep the forward mount for the engine cover.

That said it seems to make little difference in long term cruise temp, more is how fast it comes down from a hot soak. The long tube inside a 200F engine compartment is the problem.

To be effective we need a 180F-185F fast opening thermostat but as yet I have not found one.

ps keep in mind that I live in a hot climate. YMMV.

f1anatic 08-07-2013 12:40 PM

Re: DYI CAI for the 3.6L V6 engine
Great minds think alike.
Try the addendum - the little hose and scoop which is bringing in colder ambient air forward of the car.

Ahujadaddy 08-07-2013 01:09 PM

Re: DYI CAI for the 3.6L V6 engine
props to both of you. I read the post, and was like wow padgett will want to see this... scrolled down and of course he was the first reply.

somedaycts 08-11-2013 01:58 PM

Re: DYI CAI for the 3.6L V6 engine
How much noisier did your engine get? I'm looking to do similar, and like you, can't justify the cost of aftermarket options. Good job on this project!

GCLimited 08-11-2013 02:36 PM

Re: DYI CAI for the 3.6L V6 engine
I agree with your list of "Cons" when it comes to aftermarket CAIs, but that's way to much work for just a noise maker.

I just dropped in a aFe Pro Dry S filter into the stock CAI and called it a day.

f1anatic 08-11-2013 03:36 PM

Re: DYI CAI for the 3.6L V6 engine
The engine is only slightly noisier in the upper rpm range. Unlike most other so called CAIs out there, mine does bring in more air at a colder temperature. A similar commercial product is sold by BANKS POWER: Banks Super-Scoop.

It is rather easy to calculate the air flow entering the little scoop: cross sectional area x speed of the vehicle = air flow per unit time. And there is a formula out there for those interested to calculate air intake into the engine, at a given rpm, per unit time. But any supercharging effects are negligible.

More importantly, engines are exothermic, they give off heat. Which by conduction and convection will heat up everything else in the engine bay. The coldest air available to an engine is at ambient temperature, which is exactly what I am doing.

It is not a mere noise maker. But what can be proven, is the added benefit of colder air and that of a smoother air flow through the intake duct. Which is idiotically long. The intake air filter box should have been on the right side of the car to start with. I will try and calculate it, in my spare time.

What a dyno generally cannot pick up about a CAI adding extra air, an acceleration test can. For me it is enough proof. This project reminded me of the good old debates about light weight pulleys and flywheels. You cannot measure any improvements in peak power/torque on a dyno but you surely can rev up the engine quicker which makes the difference on the racetrack.

It is a lot of work so... For most people seeking instant gratification and impressive gains, this project is not it.

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