Need cold air intake ideas for V8 - JeepForum.com
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post #1 of 37 Old 10-20-2018, 07:39 AM Thread Starter
Waternut
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Need cold air intake ideas for V8

So I've got my LS installed and it runs great but I have a sneaky suspicion that I'm losing power and possibly fuel economy due my air filter basically being a hot air intake.

On a 70 degree morning, my intake temperature is around 130-135 degrees cruising on the highway. Anything past 85 degrees ambient, my intake temps are 145-150+ degrees. I'm not trying to extract every pony out of this thing but at those temperatures, I suspect the ECU is probably trying to back off the timing to prevent knocking.

Here are the two places my air filter has been positioned and the first picture with the filter over the headers is actually 5 degrees cooler on average so I'm thinking most of the hot air is probably coming from the radiator and less about the exhaust.

Some considerations I'm looking at.... I still want to be able to lower the windshield when I'm offroad so the Humvee style snorkel is likely out unless it's really low profile. I don't have the HVAC box in the cab but I can only imagine that the noise in the cab would be horrendous but I can use that area for something if needed.

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post #2 of 37 Old 10-20-2018, 08:21 AM
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Most guys stick it just behind the front cowl next to the radiator. You should have a hole there that lets fresh air in.

Otherwise, going external is about the only way to get cooler air.


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post #3 of 37 Old 10-20-2018, 08:54 AM Thread Starter
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Originally Posted by ddawg16 View Post
Most guys stick it just behind the front cowl next to the radiator. You should have a hole there that lets fresh air in.

Otherwise, going external is about the only way to get cooler air.
Thanks. My fresh air port is on the drivers side but just getting it beside the radiator may help a lot. I'll give that a shot. With the air filter that far forward, I might be able to cut an inconspicuous hole in the fender forward of the tires as well but I hope to try all other options before I start cutting.


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post #4 of 37 Old 10-20-2018, 09:09 AM
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Thanks. My fresh air port is on the drivers side but just getting it beside the radiator may help a lot. I'll give that a shot. With the air filter that far forward, I might be able to cut an inconspicuous hole in the fender forward of the tires as well but I hope to try all other options before I start cutting.
Well....if you're going to cut into that fender....maybe it's time to think about tube fenders?


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post #5 of 37 Old 10-20-2018, 09:27 AM Thread Starter
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Well....if you're going to cut into that fender....maybe it's time to think about tube fenders?
The thought has certainly crossed my mind but I'm pretty much there already with the cut stock fenders...just no tubes.
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post #6 of 37 Old 10-20-2018, 10:26 AM
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The thought has certainly crossed my mind but I'm pretty much there already with the cut stock fenders...just no tubes.
I like it


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post #7 of 37 Old 10-21-2018, 04:23 PM Thread Starter
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So far this solution is working alright but it's only 65 degrees outside right now so it's not a perfect comparison. I also put an extra 1/4" spacer between the hood and the grill to let more fresh air in. At highway speeds, I'm hovering around 100-105 degrees intake temp. If I had a fan shroud or a plate between the radiator and the filter, that would probably help since it appears all of the heat is coming from the radiator. The intake temp stays just a few degrees warmer than ambient for the first 4-5 minutes. As soon as the thermostat opens up and fluid flows through the radiator, the intake temp jumps up to 100 in a less than a minute. A smaller air filter may help as well since it would be further from the radiator.

Maybe fuel economy will go up as well but I'll need to burn through this tank to find out.
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post #8 of 37 Old 10-21-2018, 07:13 PM
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Why not use a factory YJ air box that has the duct that pulls the intake air from in front of the radiator already?
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post #9 of 37 Old 10-21-2018, 08:02 PM
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Originally Posted by fishadventure View Post
Why not use a factory YJ air box that has the duct that pulls the intake air from in front of the radiator already?
This. This is the only way you're going to get colder air without a snorkel. Your other option is to use the stock air box and cut a hole in the side of the hood and suck air in from there. Most of your problem is that silly huge omni-directional air vacuum you have under the hood.

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post #10 of 37 Old 10-21-2018, 09:24 PM Thread Starter
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Originally Posted by fishadventure View Post
Why not use a factory YJ air box that has the duct that pulls the intake air from in front of the radiator already?

Because I A) don't own one, B) don't have the space for one on the drivers side even if I did, and most importantly C) the tubes in the stock air box are smaller than the stock throttle body on this engine.


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post #11 of 37 Old 10-22-2018, 06:38 AM
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Made my own box, getting air from the hood louvers.
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post #12 of 37 Old 10-22-2018, 07:04 AM
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Because I A) don't own one, B) don't have the space for one on the drivers side even if I did, and most importantly C) the tubes in the stock air box are smaller than the stock throttle body on this engine.
FWIW ‘89 and earlier 2.5 airbox lowers are shorter. And they have a shorter top. And they being plastic can be easily modified. This let me go forward, move left, and up to fit under my CJ hood.

Maybe a similar approach would let you adapt a junk yard YJ airbox with bigger inlet and outlets (I think summit has ‘hard’ flex hoses) and still intake through the grill with an enlarged opening?

I think the reason that the Jeep retail supply stream doesn’t offer something like this readymade for YJs with V-8 swaps it’s mostly because there is always a degree of custom work. The “manufacturers” want to sell a part number that won’t result in the /average/ everyday buyers clogging up their customer service phones because they can’t wrap their minds around something that isn’t plug’n’play.

Lots of “stuff” here, prices are silly on hoses and such: https://www.summitracing.com/search/...t%20Components

Or you could hit the junkyards and if there’s pull-your-own in your area I’m sure some pkups and full size SUVs would be more than willing to donate their hoses.

I wish we had places that sold used junkyard parts around here. (Nowadays it’s all just part numbers at “x%” -usually 50%- off new price.)

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post #13 of 37 Old 10-22-2018, 07:21 AM
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Donaldson.
Everything else is substandard when it comes to filtration.

Most of those are not a cold air intake.
My stock air cleaner sucks air from the grill.

I guess randomly taking air from under the hood is considered "cold" in 2018.
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post #14 of 37 Old 10-22-2018, 09:57 AM
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...sucks air from the grill. I guess randomly taking air from under the hood is considered "cold" in 2018.
Only to the uninformed catalogue peruser.
People today don’t realize the point of hood scoop snorkels on 1950s drag cars- and cowl induction hoods on 60s muscle cars- has a lot less to do with forcing air in than it had to do with optimizing air density.
A little restriction on intakes has less of an effect on horsepower than intake air density, even if through a freer flowing path.
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post #15 of 37 Old 10-22-2018, 11:39 AM
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Honestly I don't believe that you'll have any noticeable increase in MPG from cold air vs underhood. If you really want better MPG drive it like there's an egg under the accelerator pedal.
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