[Slithering_Joe]

Originally Posted by TDmaster

Exactly! Seems that everyone here convinced me that CAI is worthless, so instead, I went with the SDS (Supercharger Drive System) from RIPPMODS...picked up over 100 whp on my 3.8L JK

That'll do it! Vortech!!

[Robert J. yates]

Originally Posted by Unlimited04

actually on the TJ, at WOT, i believe its the exhaust ports in the head. for the TJ's 0331 head casting, the exhaust port shape was changed to make them more restrictive. they did this to cause the Cat's to heat up quicker for emissions purposes. now any time other than WOT, you're completely right, thats the purpose of the TB - to meter the air coming in

a bigger TB does help a little bit with throttle response , mostly 1/2 to WOT transition when merging and such. I highly doubt theres much HP improvement (2% at 4500rpms maybe?), definitely no mileage improvement....i've been running one for ~2 yrs.

The exhaust ports (and valve size for that matter) are not a huge issue for making power. The real issues are restrictive factory OBDII programming and a severely retarded cam. The cam is easy (and even moreso with a Hesco AL head) and frees up an honest 15-20RWHP that you can actually feel as opposed to hearing it and then thinking you feel it as happens with a CAI.

Why folks would want to spend hundreds of dollars on a CAI thinking it will get them real HP on a 4.0 is beyond me. Anyone with any dyno experience knows that the advertising supporting CAI's is all within the margins of error for most dynos not to mention that it is somewhat difficult to get comparative back to back dyno runs to be able to say one way or another that a mod delivered a consistent HP and TQ gain.

[adam728]

Originally Posted by Robert J. yates

Why folks would want to spend hundreds of dollars on a CAI thinking it will get them real HP on a 4.0 is beyond me.

Because it takes 5 minutes and a screwdriver to accomplish. Sure a cam will make a far greater difference for the same cost or less, but it's a lot more work than 99% of people aren willing to do.


My 2 cents on the subject? Listen to everyone saying "save your money". I have a Fram Boost (AKA - AEM Brute Force, which was even picured in the Fram instructions). It did nothing but give a different sound. HP feels the same, and fuel economy picked up 0.3 mpg, right at the same time stations went from winter to summer blend gasoline (which usually nets me a small mpg gain, so I'm saying the intake was a wash).

Was it worth it? Yea.
Why? Because I got it free when Fram was doing their big advertising campain before releasing them for sale.
Would I ever buy a cold air intake for a Jeep

[Ridin' Around]

Originally Posted by Firekite

Nice. Any idea which one fits? :P

PM sent with some more details

[Deacon]

Probably wouldn't hurt to post it here, though. It's not a secret, is it?

[Ridin' Around]

Well.... I was gonna give you one of the Top-Secret pixie dust oil recipes, but since no one on here has a magic oven to cook it in, nobody could copy it anyway.

The Amsoil cone filters are available in many sizes. I sent Firekite the size chart & product chart with images of each filter.

[Baldlobo]

Found a calculator that could be of help to this cause. It shows hp relation between spacers, cold(outside) air temp minipulation(spelling?), and throttle size

Throttle Body Sizing Calculator | REVTRONIX

[Unlimited04]

Originally Posted by Baldlobo

Found a calculator that could be of help to this cause. It shows hp relation between spacers, cold(outside) air temp minipulation(spelling?), and throttle size

Throttle Body Sizing Calculator | REVTRONIX

Nice find. Interesting to play with the numbers. According to that calculator, the 4.0L's stock throttle body is not a limitation - even at WOT, and is capable of supporting more than the stock engine itself is even capable of making.

Assuming 80*F intake temps (175*F) as a worst case scenario:
- At 5200RPM, with the stock 58mm throttle body you get 319.53 CFM and 196 HP.
- At 5200RPM, with a 63mm throttle body you get 319.53 CFM and 196 HP

Assuming 20* F intake temps (68*F) as a best case scenario:
- At 5200RPM, with the stock 58mm throttle body you get 319.53 CFM and 236.2 HP.
- At 5200RPM, with a 63mm throttle body you get 319.53 CFM and 236.2 HP

The 4.0L itself is rated at 190 HP - thats measured on a dyno, at the crank, in a lab! This math confirms no matter what throttle body you have, you get the same power. It also confirms the Jeep's intake capable of supporting more power than the engine itself is even capable of making.

Throttle body spacers - you can play with the throttle body bore depth to see the possible pressure difference due to throttle body length. You get the same value - 0.22 psi @ 20*F - for 1", 2", 3" and even 10" with the stock 58mm throttle body. For 80*F, the result is a 0.18 psi pressure drop, regardless of intake length. With a 63mm throttle body you get 0.16 @ 20*F for 1" and at 10" you get 0.16 psi. For 80*F, the result is a 0.13 psi pressure drop, regardless of intake length.

This shows what most here already know - throttle body spacers are useless, whether the TB is 1" or 10" high!! It does show slightly less pressure drop with a 63mm vs stock 58mm TB, resulting in 1.2 hp less drop in power - @ 5200 RPM with 68*F intake temps.

So best case scenario - a 63mm TB will allow you to save 1.2 hp @ 5200 RPM, assuming you have 68*F intake temps.

[97goobTJ]

Great thread guys, and thanks to all contributors. Alot of different opinions and theories out there. I'm not sure which airbox mod I'll do. Some of you have valid points and some not, but very informative. And thats what this is about right?

[Boobah]

Wow... some very strong opinions... wouldn't it make a difference on where you live? Meaning, altitude, temp during the winter and summer months...what may work for someone in CO or the upper east coast may not work for someone who lives in the south or even on the west coast?

[Unlimited04]

Originally Posted by Boobah

Wow... some very strong opinions... wouldn't it make a difference on where you live? Meaning, altitude, temp during the winter and summer months...what may work for someone in CO or the upper east coast may not work for someone who lives in the south or even on the west coast?

well there are three constant items in case you weren't paying attention.

1. Dust - open element air filters allow a lot more dust into your engine
2. The stock intake flows plenty of air - it was specifically designed to be non-restrictive.
3. an open element air filter under the hood sucks in the same air the stock intake does.

[coldbeer52]

I installed the Banks on my TJ late spring, and have had doubts all
summer. The summers here in the Vegas valley are a pizza oven.
I know, that big opening on the filter housing is just sucking in a lot of
extream heat and all trails out of here are heavy dust.
good thing I still got the original air system, I'm putting it back.
See how she runs. Live and Learn.

[groundhound]

I scanned through this forum pretty quickly so my apologies. Has anyone considered or tried making there own CAI? Has anyone tried to use the stock airbox and just add a reliable hose from the airbox to the front of the jeep? I seen an interesting DIY Kit online. Check it out

http://cold_air_intake.koken.org/

[Unlimited04]

Originally Posted by groundhound

I scanned through this forum pretty quickly so my apologies. Has anyone considered or tried making there own CAI? Has anyone tried to use the stock airbox and just add a reliable hose from the airbox to the front of the jeep? I seen an interesting DIY Kit online. Check it out

http://cold_air_intake.koken.org/

see post #1.

Originally Posted by Unlimited04

Better, True CAI & Snorkel Write ups:
Buick/Hummer snorkel #1: http://www.jeepforum.com/forum/f9/tj-hummer-intake-write-up-buick-airbox-473981/
Buick/Hummer snorkel #2: http://www.jeepforum.com/forum/f27/write-up-hummer-cold-air-intake-326040/
Low buck Buick airbox: http://www.jeepforum.com/forum/f9/buick-airbox-installation-557152-post5204961/
Homemade Cowl CAI #1: http://www.jeepforum.com/forum/f9/my-final-word-cold-air-intakes-578437/
Homemade Cowl CAI #2: http://www.jeepforum.com/forum/f9/cowl-induction-snorkle-write-up-541004/
Mustang Air box CAI: http://www.jeepforum.com/forum/f9/mustang-gt-air-cannister-737236/
Homemade Aluminum Snorkel: http://www.jeepforum.com/forum/f9/homebrew-aluminum-snorkel-810246/
Another cowl intake: http://www.jeepforum.com/forum/5483830-post49.html

[groundhound]

oh I forgot the heat sheild. This one does't actually seem safe or deflect heat that much. These are off of different vehicles but I am talking about the concept.

http://www.nloc.net/vbforum/gen-2-lightnings/36744-3-95-diy-heat-shield-cold-air-intake.html