Cold air intake - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 03-29-2014, 03:48 PM   #1
Jeeper
 
Hogosha's Avatar
 
Join Date: Mar 2014
Location: South Africa
Posts: 31
Images: 6
Cold air intake

Evening friends, I want to get some ideas on how to improve the inlet system of my TJ to breathe cooler air for better performance. The engine seems to choke from 4000 revs upward and I suspect it is starving from enough air.

Hogosha is offline   Quote Quick Reply
Old 03-29-2014, 05:41 PM   #2
Jeeper
 
TXST8tj's Avatar
 
Join Date: Jan 2007
Location: Katy, TX
Posts: 1,933
Send a message via AIM to TXST8tj
The factory air intake system is one of the most free-flowing OEM designs I have seen on any vehicle. It think that is why when you look at result charts from CAI setups, the results are nothing spectacular.

You might look into the condition of other aspects like the O2 sensors, cat, and/or muffler.

__________________
- Patrick
TXST8tj is offline   Quote Quick Reply
Old 03-30-2014, 09:48 AM   #3
Jeeper
 
Hogosha's Avatar
 
Join Date: Mar 2014
Location: South Africa
Posts: 31
Images: 6
I have recently free flowed the exhaust and chipped the vehicle, and now have 105 kW on the wheels but it feels like it is gasping for air at high revs. I was thinking of fitting a safari snorkel, which reduce the intake temperature by about 10 degrees, but at engine inlet on the articles I have read, now substantial improvement is achieved.
Hogosha is offline   Quote Quick Reply
Old 03-30-2014, 02:41 PM   #4
Jeeper
 
00tj2's Avatar
 
Join Date: Aug 2011
Location: Westchester, NY
Posts: 1,285
Just curious as to what your KW at the wheels was before the chip and exhaust? 105kw translates to 140 hp so that a 50hp loss to the wheel right there and that seems kinda high. Wondering if something else might be going on?
__________________
I know a lot of things, most of them are only correct in my own head...
Better to be judged by twelve then carried by six. I'm sure this is going to get me in trouble down the line
2000 sport, 5speed, 1-1/4 body lift, 3" zone, metal cloak front fenders, metal cloak control arms, 4.88, 35" cooper stt.
00tj2 is offline   Quote Quick Reply
Old 03-30-2014, 06:44 PM   #5
Jeeper
 
jherrington's Avatar
 
Join Date: Jan 2012
Location: Baton Rouge
Posts: 2,025
Quote:
Originally Posted by 00tj2 View Post
Just curious as to what your KW at the wheels was before the chip and exhaust? 105kw translates to 140 hp so that a 50hp loss to the wheel right there and that seems kinda high. Wondering if something else might be going on?
25% drive train loss? That sounds about right.
__________________
98 TJ sport 4.0L I6 356,000 miles.
No Engine, axle, tranny, or t-case rebuilds.
Check out my 5.3 swap in progress here!
jherrington is offline   Quote Quick Reply
Old 03-31-2014, 01:13 PM   #6
Jeeper
 
Join Date: Oct 2012
Posts: 99
If you are trying to rev a 4.0 above 4000 you are wasting your time. The 4.0 is a tractor motor not a ricer.
RedRubicon is offline   Quote Quick Reply
Old 03-31-2014, 01:16 PM   #7
Jeeper
 
turnbull's Avatar
 
Join Date: Jan 2013
Posts: 291
Quote:
Originally Posted by RedRubicon View Post
If you are trying to rev a 4.0 above 4000 you are wasting your time. The 4.0 is a tractor motor not a ricer.
My 4.0 has no problem reaching 5k.

To OP, I would check your O2 sensors as well before installing an intake.
turnbull is offline   Quote Quick Reply
Old 03-31-2014, 01:33 PM   #8
Jeeper
 
Junky_One's Avatar
 
Join Date: Sep 2013
Location: Highwood
Posts: 503
Without a fancy cam, full free flow exhaust and a true tune, (can't flash a jeeps computer). You might as well take the top off and let the wind take your money. Not gonna see any difference in the seat of your pants with a 4.0, and anyone that claims that you do is probably just convinced by the new grumble the hamsters making under the hood.
__________________
Jeeps never get stuck or broke. Just parked in odd places for an indeterminate length of time.
Junky_One is offline   Quote Quick Reply
Old 03-31-2014, 01:38 PM   #9
Jeeper
 
Junky_One's Avatar
 
Join Date: Sep 2013
Location: Highwood
Posts: 503
And as far as ca intakes go they suck. The best I've ever seen was frankensteined from Wind star intake components and ducted into the firewall above/behind the glovebox. Up higher then stock but still higher then the 100s of other nuances that need to be addressed to make a trustworthy deep water crossing jeep. But if it's intake temperatures your looking for buy a supercharger/inter cooler. Or just take the trim rings off the headlight bezel.

http://www.jeepforum.com/forum/f9/co...ir-box-566973/
__________________
Jeeps never get stuck or broke. Just parked in odd places for an indeterminate length of time.
Junky_One is offline   Quote Quick Reply
Old 03-31-2014, 06:38 PM   #10
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
The Windstar intake will keep your intake manifold at about 40*F above ambient air temps. Whereas air from any intake that pulls from the engine compartment will be at about 190-200*F.

On a 0 degree day, I have seen 40* intake temps. On a 90* day--130*. I can't tell you if it really makes the Jeep any faster. Maybe... I know I seem to get slightly better gas milage than many on the forums among those who pay attention to such things.
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 03-31-2014, 06:49 PM   #11
Jeeper
 
turnbull's Avatar
 
Join Date: Jan 2013
Posts: 291
Quote:
Originally Posted by jjvw View Post
The Windstar intake will keep your intake manifold at about 40*F above ambient air temps. Whereas air from any intake that pulls from the engine compartment will be at about 190-200*F.

On a 0 degree day, I have seen 40* intake temps. On a 90* day--130*. I can't tell you if it really makes the Jeep any faster. Maybe... I know I seem to get slightly better gas milage than many on the forums.
Unless the Jeep somehow defies the laws of physics, that cooler air will absolutely make it faster. Whether the difference in speed is noticeable is questionable.
turnbull is offline   Quote Quick Reply
Old 03-31-2014, 06:53 PM   #12
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
Quote:
Originally Posted by turnbull View Post

Unless the Jeep somehow defies the laws of physics, that cooler air will absolutely make it faster. Whether the difference in speed is noticeable is questionable.
Well, that's great then. I will say that it is just barely noticeable. I don't like to overstate the reality of the gains. Here is the bigger, better Windstar thread. I go into better detail in the later pages.

Also, driving a Jeep around at 4000rpm is doing it wrong.
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 03-31-2014, 07:22 PM   #13
Jeeper
 
UnlimitedLJ04's Avatar
 
Join Date: Aug 2010
Posts: 7,528
Quote:
Originally Posted by Hogosha View Post
Evening friends, I want to get some ideas on how to improve the inlet system of my TJ to breathe cooler air for better performance. The engine seems to choke from 4000 revs upward and I suspect it is starving from enough air.
Quote:
Originally Posted by Hogosha View Post
I have recently free flowed the exhaust and chipped the vehicle, and now have 105 kW on the wheels but it feels like it is gasping for air at high revs. I was thinking of fitting a safari snorkel, which reduce the intake temperature by about 10 degrees, but at engine inlet on the articles I have read, now substantial improvement is achieved.
neither the exhaust nor the chip do anything worthwhile. they won't add power, no matter how much you wave your magic wand.

the engine breaths just fine with the stock intake, even at higher RPMs. if you look at the efficiency numbers, the stock throttle body and intake both flow more air that the 4.0L can use.

the restriction is in the head & valvetrain itself. if you want more power out of the 4.0L, you need to either add boost or do stroker/cam/big valves/head work...or both....then do a dyno tune with a piggyback ECU like SplitSecond FTC.
__________________
Suggested Tech Readings
UnlimitedLJ04 is online now   Quote Quick Reply
Old 03-31-2014, 07:34 PM   #14
Jeeper
 
Majnoon's Avatar
 
Join Date: Apr 2013
Location: Springfield Missouri
Posts: 3,150
I've seen ricers at track day sticking bags of ice on there intakes and pushing there cars to the line. Like physically pushing them lol. To prevent heat under the hood. The larger bore cars smoked them no matter how cold they made air. I say goofy stuff some times but this really happened. Not joking.

Edit. I think my snorkel helps on the high way. It forces air. Stick your hand out the window where it goes. It doesn't increase airflow it makes pressure. Of corse it does nothing going slow or on a dyno. It's not like having a turbo or very noticeable at all but it's forced air. Not sucked. Don't think temp matters.
Majnoon is offline   Quote Quick Reply
Old 03-31-2014, 07:48 PM   #15
Jeeper
 
DoubleOught's Avatar
 
Join Date: Feb 2014
Location: Nashville GA
Posts: 1,182
You didn't say what motor you have but I have found on both of our 4.0 6 cyl TJs that simply removing the air horn (elbow) from the front of the stock air filter box helps. Some people say that causes you to bring in hot air but if you measure the size of the horn at the smallest part and do the math, it's slightly less than half the area of the throttle body. I say a little hot air is better than not enough air. It won't make it burn rubber but you should feel a little more response from a dead stop. Also, we picked up about 1/2 mpg on mostly highway trips in both Jeeps. Doubt you will see much difference in the city. We keep the elbows with our trail gear so we can put them back if it looks like we might have a deep water crossing when we wheel. Also just running stock paper element filters. I have also found that opening the spark plug gap to about .048" instead of .035" helps low end response and gas mileage but it will hurt your high rpm response. If you haven't, might want to check your plugs too. I like running the gap wide but if you want to twist it harder, keep it at the .035 factory spec.
DoubleOught is offline   Quote Quick Reply
Old 03-31-2014, 09:49 PM   #16
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
Quote:
Originally Posted by turnbull View Post

My 4.0 has no problem reaching 5k.

....
Mine can easily get to 5k as well. The point is that peak HP/Torque on the 4.0 is somewhere around 3800rpm. There isn't much point spending time above that level. Around town, I tend to keep mine between 1500-3200rpm depending on the need at the moment.
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 04-01-2014, 11:59 AM   #17
Jeeper
 
turnbull's Avatar
 
Join Date: Jan 2013
Posts: 291
Quote:
Originally Posted by DoubleOught View Post
You didn't say what motor you have but I have found on both of our 4.0 6 cyl TJs that simply removing the air horn (elbow) from the front of the stock air filter box helps. Some people say that causes you to bring in hot air but if you measure the size of the horn at the smallest part and do the math, it's slightly less than half the area of the throttle body. I say a little hot air is better than not enough air. It won't make it burn rubber but you should feel a little more response from a dead stop. Also, we picked up about 1/2 mpg on mostly highway trips in both Jeeps. Doubt you will see much difference in the city. We keep the elbows with our trail gear so we can put them back if it looks like we might have a deep water crossing when we wheel. Also just running stock paper element filters. I have also found that opening the spark plug gap to about .048" instead of .035" helps low end response and gas mileage but it will hurt your high rpm response. If you haven't, might want to check your plugs too. I like running the gap wide but if you want to twist it harder, keep it at the .035 factory spec.
I agree that the horn is very restricting. It has a small opening and an unnecessary 90 degree angle, which means it will require more work to move the same mass of air.

Quote:
Originally Posted by jjvw
Mine can easily get to 5k as well. The point is that peak HP/Torque on the 4.0 is somewhere around 3800rpm. There isn't much point spending time above that level. Around town, I tend to keep mine between 1500-3200rpm depending on the need at the moment.
Yes but the OP says his engine "chokes" above 4k, and then someone responded that above 4k is "a waste of time." My point was that there is something wrong with their engines if they cannot go above 4k.

Obviously for regular driving, you would not rev the engine that high. But if you need to accelerate quickly, then that is the reason you would want the RPMs that high. Many engines start to lose power before red line, but that doesn't mean reaching red line is useless because it has more power near red line then it does when you shift to the next gear (usually).
turnbull is offline   Quote Quick Reply
Old 04-01-2014, 02:23 PM   #18
Jeeper
 
sm31's Avatar
 
Join Date: Jan 2012
Location: Casper, WY
Posts: 192
Also, bear in mind that HP is never "free".

If you do the head work & valve grinding necessary to increase flow (the TB & intake are quite large enough already as stated multiple times), then bear in mind that what you gain in high end power you will also lose in the lower range.

Aside from cleaning up some of the major issues (most stock heads have a few) to increase efficiency throughout the rev range, the rest is pretty much a waste. Enlarging intake ports, cam lobes, etc. all come at a cost in the form of decreased intake charge velocity and decreased compression (due to increased valve overlap). Really good head work minimizes the decreased velocity to an extent, but it still happens at lower revs.

IMO, this motor (& most really...) should be left stock unless major upgrades are planned. And if those major upgrades don't include some sort of forced induction then you're looking looking at truly minimal gains unless you dramatically increase displacement and compression.
sm31 is offline   Quote Quick Reply
Old 04-01-2014, 04:59 PM   #19
Jeeper
 
jgorm's Avatar
 
Join Date: May 2010
Location: San Diego
Posts: 1,918
Here is the data. The horn is worth 1.2 hp

Condition Avg HP Avg TQ 3SD HP 3SD TQ
stock 140.92 177.49 2.79 3.68
No Horn 142.12 176.69 3.73 6.06
Tire pressure 146.96 181.20 2.07 10.54
No Intake 151.72 183.12 2.46 5.54
Cowl Intake 149.32 185.71 5.57 5.75
Jeep Wrangler 18 dyno pulls for CAI testing - Trick Tuners Forums
__________________
my 06 LJ rubicon
2.5" SL, 1" BL, DIY highline, 35s with double beadlocks.
jgorm is offline   Quote Quick Reply
Old 04-01-2014, 07:48 PM   #20
Jeeper
 
UnlimitedLJ04's Avatar
 
Join Date: Aug 2010
Posts: 7,528
Quote:
Originally Posted by jgorm View Post
Here is the data. The horn is worth 1.2 hp

Condition Avg HP Avg TQ 3SD HP 3SD TQ
stock 140.92 177.49 2.79 3.68
No Horn 142.12 176.69 3.73 6.06
Tire pressure 146.96 181.20 2.07 10.54
No Intake 151.72 183.12 2.46 5.54
Cowl Intake 149.32 185.71 5.57 5.75
Jeep Wrangler 18 dyno pulls for CAI testing - Trick Tuners Forums
the horn isn't worth 1.2hp because your standard deviation is larger than 1.2hp.

But apparently pumping your tire pressure up is worth 6 hp

Or if you know anything about statistics, then you know all of those runs are statistically insignificant because the standard deviation spans the entire spectrum...meaning there is no real difference between any of the runs.
__________________
Suggested Tech Readings
UnlimitedLJ04 is online now   Quote Quick Reply
Old 04-01-2014, 08:08 PM   #21
Jeeper
 
Sheklikak's Avatar
 
Join Date: Apr 2012
Location: Arizona, southwest
Posts: 527
Send a message via Yahoo to Sheklikak
I may be assuming a lot here, but isn't your TJ motor more on the tired side anyway? I mean, mine has 180k so in my opinion throwing intake, exhaust, and a chip/tune would be like giving grandma new shoes and a nice breakfast and telling her to run up a mountain.

What TXST8J said is true also, so with all of the $$$ you'd put into it, how far would you be from just installing a fresh stroker? Gives you a bit over 200hp. I'm not sure if you can still run regular gas thought.
Sheklikak is offline   Quote Quick Reply
Old 04-02-2014, 12:38 PM   #22
Jeeper
 
Hogosha's Avatar
 
Join Date: Mar 2014
Location: South Africa
Posts: 31
Images: 6
Thanks for all the feedback. The exhaust chip mod added about 20% more power at the wheels. I since the posting fitted a K&N filter and the breathing seems a lot smoother - the revs increase better beyond 3500. I am going to toy around with the inlet temperature to see how that affects the performance and also with the inlet configuration. Most research indicates that a better supply of cool air aids the higher rev ranges and lifts the drop off in power beyond 3500.
Hogosha is offline   Quote Quick Reply
Old 04-02-2014, 12:57 PM   #23
Jeeper
 
sm31's Avatar
 
Join Date: Jan 2012
Location: Casper, WY
Posts: 192
Quote:
Originally Posted by Hogosha View Post
Thanks for all the feedback. The exhaust chip mod added about 20% more power at the wheels.
I am not doubting your results, but I can't imagine how a chip & breathe mods could possibly add that amount of power (or even 2%)... unless something was quite severely wrong to begin with. It would be great if we could discuss this as objectively as possible because I am curious to know what's going on.

Unfortunately, your post is likely to bring on a lot of "I call bullsh*t" types of responses. Hopefully we can filter through those to get some useful information...
sm31 is offline   Quote Quick Reply
Old 04-02-2014, 12:59 PM   #24
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
The first question is how did you determine the 20% increase?
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 04-02-2014, 01:44 PM   #25
Jeeper
 
00tj2's Avatar
 
Join Date: Aug 2011
Location: Westchester, NY
Posts: 1,285
Quote:
Originally Posted by jjvw View Post
The first question is how did you determine the 20% increase?
^this, because without dyno sheets to prove it it is complete, well, it's just not possible. I'm not trying to flame the OP but 20% of 100hp=20hp, to the wheels! Unless your exhaust was blocked beyond belief and the engine was unable to rev and produce stock power because of it, that could be a possability. but Having owned 2 mustang 5.0's which are probably the easiest engines in the world to add Hp to getting 20hp to the rear wheels can not be accomplished by a chip and cold air intake, and they actually do something to those platforms. I mean really, 20% to the wheels in a straight 6 4.0! Was that a April fool joke or something?.
__________________
I know a lot of things, most of them are only correct in my own head...
Better to be judged by twelve then carried by six. I'm sure this is going to get me in trouble down the line
2000 sport, 5speed, 1-1/4 body lift, 3" zone, metal cloak front fenders, metal cloak control arms, 4.88, 35" cooper stt.
00tj2 is offline   Quote Quick Reply
Old 04-02-2014, 02:36 PM   #26
Jeeper
 
turnbull's Avatar
 
Join Date: Jan 2013
Posts: 291
Quote:
Originally Posted by sm31 View Post
I am not doubting your results, but I can't imagine how a chip & breathe mods could possibly add that amount of power (or even 2%)... unless something was quite severely wrong to begin with. It would be great if we could discuss this as objectively as possible because I am curious to know what's going on.

Unfortunately, your post is likely to bring on a lot of "I call bullsh*t" types of responses. Hopefully we can filter through those to get some useful information...
20% does seem pretty steep. At the same time, he was pretty vague about the exhaust. He said he "free flowed the exhaust." That could mean that he replaced the entire exhaust system (headers, cat, muffler).

Most people I see only replace a muffler or headers. If you replaced all 3 (the cat being the most restrictive aspect of exhaust) plus chipped, I could see it increasing the HP by a number close to 20%.

For comparison, the Edge Trail Jammer kit claims 20% increase (probably closer to 12-15% realistically) with just an air intake, chip, and larger throttle body, but I feel like one should experience better gains by improving the exhaust system instead.

Of course, this is all just speculation. I'm still skeptical about the 20% increase, but at the same time, I am not going to call someone a liar without proof.
turnbull is offline   Quote Quick Reply
Old 04-02-2014, 02:46 PM   #27
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
Quote:
Originally Posted by turnbull View Post
...
Of course, this is all just speculation. I'm still skeptical about the 20% increase, but at the same time, I am not going to call someone a liar without proof.
The general consensus is that nothing the OP did to his 4.0 will amount to any meaningful gains. Many informed and intelligent people on the forums (Unlimited being one of them) will argue this. The stock intake is not restrictive and the stock exhaust is not restrictive.

Frankly, the burden of proof is squarely on the OP to objectively demonstrate how and why his engine is responding differently to these "upgrades" than other 4.0s do.
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 04-02-2014, 03:05 PM   #28
Jeeper
 
turnbull's Avatar
 
Join Date: Jan 2013
Posts: 291
Quote:
Originally Posted by jjvw View Post
The general consensus is that nothing the OP did to his 4.0 will amount to any meaningful gains. Many informed and intelligent people on the forums (Unlimited being one of them) will argue this. The stock intake is not restrictive and the stock exhaust is not restrictive.

Frankly, the burden of proof is squarely on the OP to objectively demonstrate how and why his engine is responding differently to these "upgrades" than other 4.0s do.
I realize that is the general consensus, but he is claiming that it did amount to meaningful gains. So you have 2 sides to the story. I think it is a bit impulsive to completely disregard someone's claims to increased performance based solely on speculation, as it is also impulsive to confirm their claims based solely on speculation.

I don't know a whole lot about the exhaust system, but having 3 catalytic converters is definitely a restricting factor on the engine, so there is room for improvement there. Also, I own a stock intake as well as a CAI, and until recently I had a 2nd CAI. I compared all three and it is plain as day that there are certain restrictions on the stock intake.

I don't understand why OP should demonstrate why his engine is (supposedly) responding the way it should. This is the only engine I have heard of that doesn't (supposedly) see significant HP gains from mods that most other engines would see gains from.

Just trying to keep an open mind here.
turnbull is offline   Quote Quick Reply
Old 04-02-2014, 03:27 PM   #29
Jeeper
 
jjvw's Avatar
 
Join Date: Oct 2013
Location: Denver, CO
Posts: 775
I'm not speculating and my mind is open to evidence. You say you realize the general consensus, but then you argue that a minority dissenting claim is not required to prove it's legitimacy with evidence. You cannot have it both ways. Extraordinary claims require extraordinary evidence.
__________________
2003 Rubicon
jjvw is offline   Quote Quick Reply
Old 04-02-2014, 03:34 PM   #30
Jeeper
 
Junky_One's Avatar
 
Join Date: Sep 2013
Location: Highwood
Posts: 503
Maybe his 4.0 was in limp mode before he tricked the computer. I can see a 20%gain there albeit not over stock

__________________
Jeeps never get stuck or broke. Just parked in odd places for an indeterminate length of time.
Junky_One is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Download our Mobile App

» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 07:44 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC