Does a cold air intake add power on a 4.0?

Jezza

Jezza

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Answer is yes.

I have seen this question asked and answered before. Typically the answers I see range from very little to none. I had a hard time believing that there was no power to be had, so I did a little test today while I had the TJ on the chassis dyno. I tried to keep it as scientific as possible. I allowed the engine to reach full operating temp before starting and I gave it ample cooldown time in between each pull. I also logged the coolant temp and intake air temp with a scan tool before each run. I did 5 runs with the stock airbox and intake tube, 3 runs with a Edge intake tube and K&N filter, and 1 run with the factory airbox and tube, but with the airbox inlet velocity tube removed. Results.....

Run 1 stock airbox and tube ECT 197 IAT 136 HP 152.3 TQ 193.7
Run 2 stock airbox and tube ECT 199 IAT 141 HP 153.4 TQ 197.3
Run 3 stock airbox and tube ECT 199 IAT 144 HP 153.0 TQ 194.2
Run 4 stock airbox and tube ECT 197 IAT 146 HP 153.1 TQ 194.7
Run 5 stock airbox and tube ECT 197 IAT 139 HP 153.6 TQ 193.1
Run 6 DQ started log late
Run 7 DQ double clicked the start
Run 8 Edge tube and K&N ECT 197 IAT 135 HP 163.1 TQ 201.3
Run 9 Edge tube and K&N ECT 197 IAT 145 HP 163.8 TQ 203.6
Run 10 Edge tube and K&N ECT 199 IAT 152 HP 163.7 TQ 202.1
Run 11 stock airbox velocity inlet removed ECT 195 IAT 143 HP 157.5 TQ 196.9

As you can see the runs are fairly consistent and most are within 1-2HP of each other. Removing the velocity horn from the stock airbox gained around 3-4HP alone. Replacing the stock airbox and tube with the Edge tube and K&N filter was good for a solid 10HP. The gains were most apparent above 4k RPM, but there were small gains below 4k as well. Does a cold air intake add power on a 4.0? Yes, in my testing it was good for around 10HP at the wheels. Is that power worth the money or the possible lack of filtration? I don't know, you be the judge.

Jeep All Runs.jpg


Jeep KN vs stock vs Horn.jpg


Jeep Stock vs KN.jpg
 
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Jezza said:
Answer is yes.

I have seen this question asked and answered before. Typically the answers I see range from very little to none. I had a hard time believing that there was no power to be had, so I did a little test today while I had the TJ on the chassis dyno. I tried to keep it as scientific as possible. I allowed the engine to reach full operating temp before starting and I gave it ample cooldown time in between each pull. I also logged the coolant temp and intake air temp with a scan tool before each run. I did 5 runs with the stock airbox and intake tube, 3 runs with a Edge intake tube and K&N filter, and 1 run with the factory airbox and tube, but with the airbox inlet velocity tube removed. Results.....

Run 1 stock airbox and tube ECT 197 IAT 136 HP 152.3 TQ 193.7
Run 2 stock airbox and tube ECT 199 IAT 141 HP 153.4 TQ 197.3
Run 3 stock airbox and tube ECT 199 IAT 144 HP 153.0 TQ 194.2
Run 4 stock airbox and tube ECT 197 IAT 146 HP 153.1 TQ 194.7
Run 5 stock airbox and tube ECT 197 IAT 139 HP 153.6 TQ 193.1
Run 6 DQ started log late
Run 7 DQ double clicked the start
Run 8 Edge tube and K&N ECT 197 IAT 135 HP 163.1 TQ 201.3
Run 9 Edge tube and K&N ECT 197 IAT 145 HP 163.8 TQ 203.6
Run 10 Edge tube and K&N ECT 199 IAT 152 HP 163.7 TQ 202.1
Run 11 stock airbox velocity inlet removed ECT 195 IAT 143 HP 157.5 TQ 196.9

As you can see the runs are fairly consistent and most are within 1-2HP of each other. Removing the velocity horn from the stock airbox gained around 3-4HP alone. Replacing the stock airbox and tube with the Edge tube and K&N filter was good for a solid 10HP. The gains were most apparent above 4k RPM, but there were small gains below 4k as well. Does a cold air intake add power on a 4.0? Yes, in my testing it was good for around 10HP at the wheels. Is that power worth the money or the possible lack of filtration? I don't know, you be the judge.

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I'd like to see you run the 10hp adder for a month and then test it again.
 
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Gilaguy23 said:
Cool, another pile of shitsky K&N/hot air intake sales pitch. Id guess most pre mini van powered jeeps will likely never will see 4000+ rpm either.
Click to expand...

I can't comment on a 4.0 but I drove my 2.5 above 4K RPM's a lot even with 4.88 gears so and add 10 HP would have been NICE.
 
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Did you custom tune? Because I guarantee a few runs on the dyno with a change to timings and adjusting air/fuel ratioes, you can pick up a good bit of power and slap on any intake you want and call it "gains". I know the 4.0 left a small amount of power on the table which people pick up "canned tunes"

I dont think changing the intake size is gonna make a difference unless the hole is smaller than your actual opening itself(throttle body). You cant just force more air down a 55mm TB by having an (example) 60mm opening on top of it. If the outer opening where smaller (<55) then maybe, but I dont think so.

Granted I dont have a dyno, I was able to drop my IAT over 100+ degrees from the stock box, and was able to have a significantly larger opening than the stock horn, and noticed absolutely nothing. Interesting results nonetheless.
https://wranglertjforum.com/threads/the-cold-air-intake-thread.57569/
 
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mrblaine said:
I'd like to see you run the 10hp adder for a month and then test it again.
Click to expand...
I already took it off and installed the factory airbox for the last pull. If I had to guess you are implying that the lack of filtration will have negative results long term?? I can't speak to that besides to say that this is the intake that came on my 2002 when I bought it and it runs fine. I have no knowledge how long it was on there or what types of conditions it was operated in. The engine still has good compression and doesn't use oil.

DylanM345 said:
Did you custom tune? Because I guarantee a few runs on the dyno with a change to timings and adjusting air/fuel ratioes, you can pick up a good bit of power and slap on any intake you want and call it "gains". I know the 4.0 left a small amount of power on the table which people pick up "canned tunes"

I dont think changing the intake size is gonna make a difference unless the hole is smaller than your actual opening itself(throttle body). You cant just force more air down a 55mm TB by having an (example) 60mm opening on top of it. If the outer opening where smaller (<55) then maybe, but I dont think so.

Granted I dont have a dyno, I was able to drop my IAT over 100+ degrees from the stock box, and was able to have a significantly larger opening than the stock horn, and noticed absolutely nothing. Interesting results nonetheless.
https://wranglertjforum.com/threads/the-cold-air-intake-thread.57569/
Click to expand...
It is still the stock tune. It would however be interesting to do a dyno comparison with and without a tune to see if there are quantifiable gains to be had with only a tune. I didn't have anymore time for that. The factory airbox has a intake tube on the front of it that looks like a horn. I should have taken a picture of it. The hole in the center of that is considerably smaller than the throttle body. Just by removing that it picked up power. If I had to guess most of the restriction is in the paper filter.
 
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Jezza said:
I already took it off and installed the factory airbox for the last pull. If I had to guess you are implying that the lack of filtration will have negative results long term?? I can't speak to that besides to say that this is the intake that came on my 2002 when I bought it and it runs fine. I have no knowledge how long it was on there or what types of conditions it was operated in. The engine still has good compression and doesn't use oil.


It is still the stock tune. It would however be interesting to do a dyno comparison with and without a tune to see if there are quantifiable gains to be had with only a tune. I didn't have anymore time for that. The factory airbox has a intake tube on the front of it that looks like a horn. I should have taken a picture of it. The hole in the center of that is considerably smaller than the throttle body. Just by removing that it picked up power. If I had to guess most of the restriction is in the paper filter.
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Not at all, we tend to see the programming adapt to the power adder and eventually return it back to the stock power level. I'd like to see if you found a way to circumvent that.
 
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mrblaine said:
Not at all, we tend to see the programming adapt to the power adder and eventually return it back to the stock power level. I'd like to see if you found a way to circumvent that.
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Ahh I see. That is a possibility. Someone else will have to test that as this Wrangler is getting a turbo kit installed in the next few weeks.
 
Having tuned literally thousands of F150’s with and without aftermarket intakes, exhausts, forced air induction, naturally aspirated, yada, yada, yada one thing I can guarantee.
When used together and properly tuned, each component will add power. Typical 5.4 Triton Ford will pickup 30-40 rwhp, which is noticeable to most. If it’s spiritedly driven, power will remain constant, however if the same vehicle is babied the pcms adaptive strategy will effectively degrade the vehicles performance. When this has occurred the quickest way to “regain” the performance is to clear the pcm by disconnecting the battery.
That being said, I wouldn’t waste the time nor money to attempt the same on my 4.0 TJ. Just doesn’t make good sense. Your average driver will never notice a 10-15 rwhp gain.
 
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Trod286 said:
Nope.. it does however keep you from buying filters, as ya just clean the k&n oil it again and run it again.
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Understand that a K&N doesn't begin to start filtering even decently until it's dirty/packed with dirt. Its filter openings are too coarse to filter well when it's clean and oiled.

Read the last sentence in the below chart of filtration abilities, it came from the ISO lab test results. A K&N air filter is absolutely the worst filtering air filter of them all.
K&N Chart with Text.JPG



I cluelessly installed a K&N 21 years ago and kept it clean and oiled on a regular basis. Then a buddy saw it and suggested we remove the air intake from the throttle body and look inside. He knew what was coming, I did not. I was frigging shocked how much dirt and crap was inside the plastic tube and inside my throttle body. I was pissed. I ended up installing TWO prefilters onto the K&N trying to get it filtering at least decently. I couldn't go back to the stock filter box because I had installed a York compressor for an OBA system.

This is the K&N air filter I stupidly ran until 22 years ago.

K&N.jpg
K&N1.JPG
K&N2.JPG
 
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Jerry Bransford said:
Understand that a K&N doesn't begin to start filtering even decently until it's dirty/packed with dirt. Its filter openings are too coarse to filter well when it's clean and oiled.

Read the last sentence in the below chart of filtration abilities, it came from the ISO lab test results. A K&N air filter is absolutely the worst filtering air filter of them all.
View attachment 318446


I cluelessly installed a K&N 21 years ago and kept it clean and oiled on a regular basis. Then a buddy saw it and suggested we remove the air intake from the throttle body and look inside. He knew what was coming, I did not. I was frigging shocked how much dirt and crap was inside the plastic tube and inside my throttle body. I was pissed. I ended up installing TWO prefilters onto the K&N trying to get it filtering at least decently. I couldn't go back to the stock filter box because I had installed a York compressor for an OBA system.

This is the K&N air filter I stupidly ran until 22 years ago.

View attachment 318448View attachment 318449View attachment 318450
Click to expand...
Why is that I have a York and still run the stock air box ?
 
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