For the same reasons ugly women buy beauty creams. They dream of being beautiful but nothing that cheap is going to make any difference whatsoever.
Air intake mod question
- Thread starter Jay MacLeay
- Start date
Hey Jerry, I'm a fan of the stock box myself as it flows fine, my goal is colder outside air.
What I had thought about doing was adding a tube to the trumpet and running the tube to a spot (don't know where yet) to pull air into the trumpet from a protected outside the engine compartment air source to lower the air temperature to the motor.
I would include a bend so that any splashed H2O would run back out and the tube entrance would be about the same height as the stock trumpet, it would only be moved forward about 6 to 10 inches at most I figure.
Thoughts?
What I had thought about doing was adding a tube to the trumpet and running the tube to a spot (don't know where yet) to pull air into the trumpet from a protected outside the engine compartment air source to lower the air temperature to the motor.
I would include a bend so that any splashed H2O would run back out and the tube entrance would be about the same height as the stock trumpet, it would only be moved forward about 6 to 10 inches at most I figure.
Thoughts?
Not to sound rude but it would be a waste of time and just congest the engine bay. That time could be more wisely spent somewhere else.
My thoughts are is that while colder air can make a difference in some (!) situations and it definitely makes sense in theory, all that would be a complete waste of time & effort where the TJ is concerned. Where a Jeep is concerned, cold air won't make a noticeable or significant difference even if it was really cold. Unless you're racing it at the dragstrips where a .1 second difference at the end of the quarter-mile is important to you.
You won't feel any difference on the street or trail with a CAI.
TJRick
TJ Enthusiast
Jerry gets really defensive and pissy when it comes to the stock air intake, Chief. I apparently committed a cardinal sin by asking this same question only a couple of weeks ago, but I am now satisfied that the stock air intake is a pretty good design:
https://wranglertjforum.com/threads/why-didnt-the-tj-get-a-stock-cold-air-induction.37454/
I am from South Carolina myself. What part do you live in?
If you want to characterize someone explaining why it doesn't help/why it's more of a waste of time & $$$ than it's worth where a JEEP is concerned as "defensive and pissy" then I don't know what to say.
Maybe you'd like it better if I was supportive of any and all such ideas as new Jeep owners show up wanting to do them because of the ads they read in catalogs like Quadratec or automotive magazines?
And it's absolutely true that SOME engines benefit greatly by replacing the factory intake with a less restrictive design, since some intake systems are either designed to be restrictive (true) or just aren't good designs. The Mustang 5.0 and Camaro Z-28 being two examples of engines that will pick up significant performance gains with nothing more than an intake air system replacement. The TJ's air intake system, on the other hand, was well designed and it is absolutely non-restrictive. James Repp, sr. Jeep engineer who was also the creative force for the Rubicon, confirmed to me in a phone conversation years ago (yes, that is true) their goal for the TJ's air intake was for it to be non-restrictive.
Could you measure your banks system for me? I will be doing a cowl mod one of these days when I get time off and wanted to see if there is a box that can fit in the cowl area to muffle the air intake noise
TJRick
TJ Enthusiast
You said it all right there. Most of us in here - me included - did not get the luxury of talking to the Senior Jeep Engineer on the phone about the stock Jeep Wrangler TJ air intake. Seeing as it how SOME engines can pick up "significant performance gains" by replacing the stock air intake system with a less restrictive design, I think it is a rather logical idea to question the unusual design of our stock air intake system.
After all, YOU wondered enough about it to ask James Repp. Right?
What is “colder” outside air going to do? Absolutely nothing, I guarantee it.
Please don’t take this as me being an asshole, it’s truly not my intention. I am just trying to smash this myth that air intakes, cold air induction, or whatever nonsense people want to call it will NOT make any difference whatsoever on your TJ, period.
This is basically the same as trying to use a band-aid to cure cancer.
Now if you had a Hellcat engine, then maybe you’d be onto something.
Our RPM and engine needs are different. For sure. Unless you are compressing air, which will benefit from colder air for obvious reasons, it won't apply much, unless you start changing your fueling and timing maps and exhaust.
TJRick
TJ Enthusiast
Well Chris, "colder" outside air is typically MUCH cooler than the hot air that is generated under your hood from an engine that is designed to run at over 200 degrees.
The design of the stock air intake on the Jeep Wrangler TJ has it sucking in hot, underhood air.
Cooler air is denser than hotter air.
Cooler, denser air has more oxygen and generates more power than hot underhood air. That is what it does. And cold air intakes typically draw in outside air from the front of the vehicle, which also creates a bit of a "ram air" effect.
The Jeep Wrangler YJ used a cold air intake on their 4.2L carbureted engine and their 4.0L fuel-injected engine.
The Jeep Cherokee and Jeep Grand Cherokee used a cold air intake on their 4.0L engines.
So it's not such a dumb question to ask why our TJ doesn't have a cold air intake on its 4.0L engine.
If a cold air intake does "absolutely nothing," then that means the Jeep engineers and accountants are idiots for using a cold air intake on their 4.0L engines in their Cherokee and Grand Cherokee lines. In fact, ALL of the car engineers and accountants from the last 50 years are idiots:
The Ford Pinto used a cold air intake on their 2.3L engine.
The Ford LTD Country Squire station wagon used a cold air intake on all of their engines.
The Chevrolet C10 pickup used a cold air intake on all of their engines, and that includes their 4wd models.
The Smart Fortwo uses a cold air intake on their 1.0 engine.
The Dodge Challenger Hellcat uses a cold air intake on their 6.2L Hemi engine.
So again, it's not such a dumb question to ask why our TJ doesn't have a cold air intake on its 4.0L engine.
Thanks to this forum, I have learned that the Jeep TJ is different in that is uses a unique trumpet on the end of the air intake that creates a venturi effect on the incoming air. Unless you talked to James Repp (or Jerry Bransford), you probably wouldn't know that.
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The TJ does use a cold air intake. At least my 2006 does. The intake is pointed up and located in a cool air spot behind the passenger side head light. There are rubber grommets on the fenders and hood that keep a gap between the hood and the fenders/grill. When the Jeep is moving cold air can flow through the gap in the hood and over the intake located higher off the engine and up by the hood. Moving the inlet to the front bumper, wheel well, or hood likely wouldn't lower the temperature at all if the Jeep is moving. It's already getting cold air blowing through the engine bay.
It's also likely another reason why the firewall, floor, and shifter area is so hot. Cold air is flowing over the engine and pushed down under the Jeep as it's moving.
For those of us who get frozen northern temps for months on end, cold air is the least of our problems as we get excessive amounts of it. Sometimes cold enough that we block off the front of our cars to compensate.
As noted, many other cars benefit from CAI, but are really not part of the conversation unless you swap their engine into a TJ.
It's also likely another reason why the firewall, floor, and shifter area is so hot. Cold air is flowing over the engine and pushed down under the Jeep as it's moving.
For those of us who get frozen northern temps for months on end, cold air is the least of our problems as we get excessive amounts of it. Sometimes cold enough that we block off the front of our cars to compensate.
As noted, many other cars benefit from CAI, but are really not part of the conversation unless you swap their engine into a TJ.
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Fab up an intake that takes "cold air" from outside the engine. Before installing it, do a dyno, then do a dyno after installing the "cold air intake".
Let me know what results you come back with
You may think I'm being an asshole, but I promise you, I'm not trying to be. I'm simply trying to squash the idea that ANY sort of aftermarket intake will provide any meaningful gain on the 4.0.
The only way it's ever going to happen is if you get a bigger intake manifold, bigger valves, port the head, etc. In other words, open up the entire engine, then you can open up the intake and benefit from more air (though it likely won't be any "colder").
I didn't call him, he contacted me to talk about a problem I had posted in forum or two about misfires occurring with new 97-98 4.0 engines, my '97 Sport was misfiring like crazy. Jeep engineering was working on the issue and after we chatted, they sent me a big box of things to try. New PCM, new injector wiring harness, injectors, spark plugs, clockspring, and a half-dozen other parts. We talked several times about my progress over a few weeks, none of those parts helped.
It was just after a few of those conversations I asked about the air intake when our conversations widened beyond the initial misfire problem. It was then I found out he was Jeep's most senior engineer and had been around since the CJ days. It was later when Rubicon rumors started flying that he would call me me with occasional leaks of Rubicon info like how the lockers had been tested, brand-name, etc. to help keep the rumors under control. It was very cool once I figured out just who I had been talking to. Really nice guy, Google him. Jim Repp, the actual father of the Wrangler Rubicon. It was all his idea. https://jeepblogs.azurewebsites.net...ew-jim-repp-jeep-brand-engineering/index.html
Oh, the misfire problem on those early 97-98 engines turned out to have been caused by a bad batch of valve springs the factory received from the vendor.
TJRick
TJ Enthusiast
Fab up an intake that takes "cold air" from outside the engine. Before installing it, do a dyno, then do a dyno after installing the "cold air intake".
Let me know what results you come back with
I already said that I am satisfied with the stock TJ air intake. The unique design of the trumpet is what makes the difference.
And I am trying to help you understand why so many people asks about the stock TJ air intake assembly, and why you (and Jerry) probably shouldn't completely dismiss their intellectual curiosity.
But it looks like we might can find some common ground. You originally guaranteed that a cold air intake does "absolutely nothing," and now you are saying it won't provide a "meaningful gain" on a 4.0. I can go along with your revised position, as long as we are talking about a 4.0 that uses the stock TJ air intake.
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Rock Toy
TJ Enthusiast
Anyone want to buy a K&N Air Intake System? I have one that I am selling . I took it off because it was too loud for my liking...
. I took it off because it was too loud for my liking...
And BWTM- in California (thank you for your condolences) a vehicle with a CAI will not pass the bi-annual smog check.
I think a more accurate statement about all of this is that the intake piping and airbox on a stock TJ is not a significant bottleneck in the stock system and the miniscule gains (if any) to be had by swapping it out are not going to be measurable in the part of the rpm range most TJ drivers are in 99.9% of the time. It's just not a worth while mod for some every TJ driver out there.
Only dumbasses that try and squeeze a bunch of power out of our straight 6's for some crazy reason would spend the money on other mods to make the intake worth upgrading. And who the hell would care how fast our TJ's can accelerate anyways? Crazy people, that's who
Only dumbasses that try and squeeze a bunch of power out of our straight 6's for some crazy reason would spend the money on other mods to make the intake worth upgrading. And who the hell would care how fast our TJ's can accelerate anyways? Crazy people, that's who
