Intake Update

"Long_Voyager94" (yourenotavalidusername) 03/06/2020 at 07:11 • Filed to: intake, Grand Caravan

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As most of you know, I’ve started into “solving some issues” I have with the new van. The biggest of those is the lack of punch below 4k rpms.

After researching and searching, I’ve found deleting the intake resonator is netting excellent gains on the Pentastar engines, especially in the low/mid range.

So I set out to build something seeings performance parts for the Grand Caravan are non-existent. When I left you last I had the resonator deleted but still had the factory flex pipe in place:

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Since then the rest of my pieces arrived, so now the flex pipe is gone as well.

Not the prettiest, but it’s functional for the moment. Now that I know it gives me the desired result, I plan to get some 4" piping bent up ( anyone know a guy? ) to go from the TB to just inside the air box, where I’ll also remove the garbage factory filter and replace it with a good cone on the end of the pipe.

This should give me the best results as it will be a short ram intake, but it will only pull cold air from the bumper as it will be housed within the stock box.

So far this “mock up” has given me hope.

The throttle response that is always annoying on these is greatly improved with almost zero lag.

There is a noticeable bump in punch from 2500-4k rpms.

More aggressive sound, noticeable but not obnoxious.

Consistent 1.5-2 mpg bump in economy.

Who is the Leader - 404 / Blog No Longer Available > Long_Voyager94 03/06/2020 at 07:33

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Thats a substantial difference! What did they make the factory stuff o ut of? Swiss cheese?

Nom De Plume > Long_Voyager94 03/06/2020 at 07:40

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Delayed first thought: You mean to tell me mini-van’s lack for hard low rpm efforts in favor of quiet launches designed to keep as many cheerios in their container as possible?

Your rough modeling might benefit from some math/ research and checking the dumpster of a local custom racing exhaust welder (if such exists). Guessing air temp is going to come into account here as well. S o a Summer solution may not be apparent at the moment?

Long_Voyager94 > Who is the Leader - 404 / Blog No Longer Available 03/06/2020 at 08:03

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Corrugated tubing and a giant resonator that directs air back into itself to kill noise.

Long_Voyager94 > Nom De Plume 03/06/2020 at 08:10

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Realistically , air temp should stay the same, or be slightly lower. I’m still pulling from factory location (front bumper) and my current piping is thicker walled than the factory tubing.

At this point my plan is to replace the couplers with a solid 4" pipe, which will slide inside the factory airbox, then install a high flow filter on it. The pipe will get heat wrapped as well. That way it’s still protected from engine heat via the stock box/cold air tube, but flows substantially better.

DipodomysDeserti > Who is the Leader - 404 / Blog No Longer Available 03/06/2020 at 08:23

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Pfff, Chrysler ain’t gonna shell out for Swiss cheese.

I like cars: Jim Spanfeller is one ugly motherfucker > Long_Voyager94 03/06/2020 at 08:39

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The throttle body on these is DBW correct? You might also get better throttle response from idle if you flash the controller with a different setup, I don’t really know if there’s anything turnkey like that for the Pentastar. Based on what you told me about the transmission controls in these cars, I would not be surprised if it was impossible.

Sovande > Long_Voyager94 03/06/2020 at 08:46

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Is this an NA or turbo engine? Is the stock intake really 4"? I can’t imagine needing piping that large for a V6 engine. You will reach a point of diminishing returns with a larger pipe as the airflow velocity will slow down as the pipe size increases. Most aftermarket NA intakes max out somewhere in the 2.5" range. 

I would skip the wrap on the pipe - it just ends up looking ratty and I can’t imagine how it would make any impact on the intake temps.

and 100 more > I like cars: Jim Spanfeller is one ugly motherfucker 03/06/2020 at 08:53

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Luckily, the Pentastar is tunable. Not cheap, but there are options for tuning  available. And these engines remain pretty reliable even when pushed. 

Snuze: Needs another Swede > Long_Voyager94 03/06/2020 at 09:12

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Bravo, I think it looks great! I did something similar on my Cruze with similar results. The Cruze resonator sits in the inner fender area, and the airbox sit’s above it. There’s a pipe that connects the 2 with a flange in the middle. I took it out, but the part off below the flange so now it’s just pulling from in the inner fender instead of the resonator. I also put in a K&N drop in filter.

Does it neck down from 4" to whatever the throttle body diameter is? It looks like it does but it’s hard to tell. As someone else pointed out, running 4" all the way through is overkill and could actually hurt airflow as velocity falls off , but a gradual neck down from the airbox (that outlet looks large, I’m assuming that’s the 4" part) to the throttle body would be ideal.

Regarding wrapping it, I wouldn’t. It usually ends up looking ratty. I t doesn’t look like it’s passing really close to an exhaust manifold or other major heat source, so I think it’s fine. 

For some context, your engine is 3.6L (right?), that’s 220 cubic inches. At 2500 RPM assuming 100% volumetric efficiency it’s pulling 160 CFM. A 4" air pipe is 0.08 ft squared, so 160 CFM through that size pipe requires a velocity of 1833 ft/min, or 30.6 ft/sec. If your pipe is 2 ft long, the air spends 0.065 seconds traversing between the airbox and the throttle body. There’s just no time for any appreciable heating to occur. (Also, I know this was probably unnecessary but I like figuring this kind of stuff out).

Finally, you may want to just drop in a high flow panel filter like a K&N. It would be easier than fabbing up a cone filter mount and yield similar results .

Long_Voyager94 > Sovande 03/06/2020 at 10:01

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NA engine. Factory piping is 4.5" necked down to 3.5" at the TB, so I’m already stepping down from factory size.

Long_Voyager94 > Snuze: Needs another Swede 03/06/2020 at 10:14

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It is 4.5" at the air box, then necks down to 3.5" at the TB. So realistically, running 4" necked to 3.5" is already stepping down from factory, combined with smooth pipe it should net greater velocity.

I agree on the intake temps, but it’s something that everyone keeps bringing up.

Where the pipe will enter the airbox should have plenty of room to just mount a filter off the pipe inside the airbox. The factory filter design leaves a lot to be desired as it closes off a good portion of the airbox

Snuze: Needs another Swede > Long_Voyager94 03/06/2020 at 10:28

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Sounds like you’ve thought this out. Very awesome!

Also, WTF is that thing? I mean... seriously? What the hell? Why? I have so many questions for Chrysler engineering.

Long_Voyager94 > Snuze: Needs another Swede 03/06/2020 at 12:16

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It’s been thought over and over. This is just a wayside/test piece for what’s to come.

And yes, WTF!?!?! You’re wasting all that flow potential for what exactly?

If only EssExTee could be so grossly incandescent > Long_Voyager94 03/06/2020 at 14:26

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What a coinkydink. I just ordered a part to delete my resonato r. It turns out to be super simple to do. The 3-series with the same engine as my 528i does not have a resonator d espite having the same intake. Probably to save money or be cause the 3 is sportier. For $13 I ordered the section of intake tube for a 3-series and I can just unbolt the resonator from the back of the airbox.

This is the piece that’s on th ere now. It’ll actually make maintenance easier in addition to the sound benefits . The boot that goes over the resonator pipe is known to split and make a vacuum leak (since it’s after the MAF) and getting rid of the resonator box makes pulling the whole int ake significantly easier because of the way the parts are interconnected.