Does a cold air intake add power on a 4.0?

I believe the stock intake pipe itself is probably sufficient in size for the engine to breathe unrestricted. There exists a sort of a loose formula for flow of a tube or throttle body. It's roughly the cross section area in inches times 100. It's supposed to give you rough CFM. Using that formula the tube and throttle body stock are sufficient for 400 CFM or so. Which is more than the 4.0 can use stock. I think the restriction is the filter and filter box. I did remove the 90 degree velocity pipe off the front of the airbox on one of the pulls and power did go up slightly. I think it was like 2hp or so. Also I looked into the stock air filter panel itself. I contacted WIX filters and inquired about the flow data for that particular filter. They informed me that their filter flows 210 CFM. That is 100 CFM less than the engine can flow. I would only be able to speculate as to why Chrysler would use that size filter, but it probably came down to either cost or size packaging. It's interesting all this discussion and no one asked what filter element I tested.
 
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dbbd1 said:
That fitting should be for sale on the BMB site.
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Not really. All that will do is create 50 different examples of out of control wonky installs using crap like vacuum hose, dryer vent hose and some cobbled together bullshit that disgusts everyone. There's the picture, if you can't do that part, you are going to also suck at the rest of it.

That and I'd have to sell it for 100 bucks to make it worthwhile and that isn't fair to anyone.
 
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Brianj5600 said:
Did you log MAP on your Dyno runs? I'm curious what RPM the stock throttle body becomes a restriction.
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No, but I had HP scanner pulled up the entire time. I doubt whether you could see a discernable difference in MAP with that small of change. The MAP signal is typically pretty noisy also. The stock throttle body is about 3.8 Sq inches which using the 100 to 1 formula would be 380 CFM which the stock 4.0 would be hard pressed to ever reach.
 
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mrblaine said:
Not really. All that will do is create 50 different examples of out of control wonky installs using crap like vacuum hose, dryer vent hose and some cobbled together bullshit that disgusts everyone. There's the picture, if you can't do that part, you are going to also suck at the rest of it.

That and I'd have to sell it for 100 bucks to make it worthwhile and that isn't fair to anyone.
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There are already many different hacked up intakes out there. This could help (maybe) for some people.

Also, there are many options for intake tube, elbows, and fittings on the web. I just cannot fab that bulkhead adapter. Unless you tell me that it's an off-the-shelf part that you modified.

And it might be worth $100 for me to buy pre-made.
 
mrblaine said:
All that will do is create 50 different examples of out of control wonky installs using crap like vacuum hose, dryer vent hose and some cobbled together bullshit that disgusts everyone.
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So true. 🇺🇸

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Seems to me that an easy way to prove that the air filter is the major restriction would be to do two back to back dyno runs, one with, and one without the filter...
 
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Zorba said:
Seems to me that an easy way to prove that the air filter is the major restriction would be to do two back to back dyno runs, one with, and one without the filter...
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Gonna have to be someone else. I don't have any stock TJs left.
 
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mrblaine said:
No, they are a polyethylene or polypropylene type that is difficult to glue.
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I know there's a difference in the 3 materials but from my limited understanding, wouldn't ABS be better suited than the others for our underhood applications because of it's higher heat tolerance?
 
reddvltj said:
I know there's a difference in the 3 materials but from my limited understanding, wouldn't ABS be better suited than the others for our underhood applications because of it's higher heat tolerance?
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Given that I've never seen any heat damage or deterioration in any underhood intake system parts I'm going to say no, or the plastic is a blend of something other than an ABS derivative that handles the heat just fine.
 
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mrblaine said:
Given that I've never seen any heat damage or deterioration in any underhood intake system parts I'm going to say no, or the plastic is a blend of something other than an ABS derivative that handles the heat just fine.
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Not trying to be obtuse. The reason I am asking is, the stock air box, in the Jeep I recently picked up, had been replaced with a Banks intake setup. I know I can find an OEM airbox and tube to put back in, but I'm planning on doing something that is more suited to high clearance fenders, similar to some of the mods that have been done by others in the forum. I already have ABS pipe and fittings readily available, so what I'm asking is, would there be a detriment using ABS over polyethylene or polypropylene?
 
reddvltj said:
Not trying to be obtuse. The reason I am asking is, the stock air box, in the Jeep I recently picked up, had been replaced with a Banks intake setup. I know I can find an OEM airbox and tube to put back in, but I'm planning on doing something that is more suited to high clearance fenders, similar to some of the mods that have been done by others in the forum. I already have ABS pipe and fittings readily available, so what I'm asking is, would there be a detriment using ABS over polyethylene or polypropylene?
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A quick search shows polypropylene melts at 327 and abs at 221. They both get soft way before melting. You'd be better off with some semi-rigid dryer duct.
 
srimes said:
A quick search shows polypropylene melts at 327 and abs at 221. They both get soft way before melting. You'd be better off with some semi-rigid dryer duct.
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Guess I should have done some research in the first place...

Your search resulted in different temps than my search did. Mine shows PP does have a slightly higher melting range, but it's not all that different. Either one will easily hold up to under hood temps. Aside from that, it looks like ABS would be more durable than PE or PP as well as being easier to work with for the average DIYer. The only drawback I saw to using ABS is, it is lesss resistant to certain chemicals. I'll have to look into which chemicals are harmful later.
374° to 518°f for ABS,
464° to 554°f for PP
https://plasticranger.com/melting-point-of-plastics/
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