2.0L Custom Cold Air Intake

DarkLight

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This has been a long time coming, as I’ve spent the better part of 2 years ironing out the best solution for a high performance intake system.

I was becoming frustrated with the poor performance of aftermarket short ram intakes; they suffer badly from heat soak, cause tuning issues, and are not long enough to be resonance/pulse tuned in a useable rev range.

What I’ve come up with is fairly fool-proof and simple, with none of the MAF/fueling/heat soak issues that come with aftermarket intakes.

077026F5-B589-4C54-94CE-719EC8AAC7E1.jpeg


Before I just stuck a cone filter in the fenderwell and coupled some pipes together, I measured the length of the intake in the OE airbox because I wanted to resonance tune the intake for the best performance possible. It was about 30” from inlet to MAF. While examining the box, it seemed like Honda tried to make the length of the intake as long as possible, which yields higher intake air velocity.

I then made some other simple calculations, measuring the length from the intake valves, to the throttle body, and finally to the airbox.

Basically, I wanted the intake to resonate at 3.5K rpm’s so I plugged the numbers into a formula and figured the length needed to be roughly between 32-36” from inlet to MAF in for this to happen. I wasn’t exactly sure about my math, but I used trial and error and settled on 32.5”. In addition, I wanted to use as few bends as possible to limit restriction.

I initially had some difficulty fitting this specific length of piping so I had to remove the aluminum airbox bracket to get it to fit. I also had some trouble with hanger mounting points, but I used the radiator airbox mount and removed the bracket, held by (2)10mm bolts.

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I’ve been running this current configuration for about 5 months/ 8K miles and this intake is what I always hoped it would be. The power increase is felt basically in the entire rev range but beats everything out there for torque under 4K rpm’s. In addition, I’m getting 34 mpg’s without ever using econ mode.

At 3.5K rpm’s, the engine produces a nice torque spike and max acceleration occurs from there on to the limiter. It’s good enough that I can overtake and even merge on the interstate in 6th gear.

A short tutorial so you DIY’ers can get started:

First step is removing the MAF housing from a donor airbox lid:

1A34BDAC-5878-4CFD-BA60-1DFD35FD87D3.jpeg


Then, it will be necessary to get some 2.75” aluminum piping/bends:

(1) large radius 90* bend
(1) 12” straight section
(1) tight radius 80* bend

I used HPS and Vibrant piping.

Then you’ll need:

(3) 2.75” couplers
(1) 2.75” cone filter
(1) HPS 2.0 silicone elbow
+Hose clamps and 18 gauge sheet metal for hangers.


More to come...





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DarkLight

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Myx

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Friggin' beautiful! Love these kinds of posts. Thanks for sharing this.
Kudos bro. Love the work. Will stay glued to the results. :headbang:

I am VERY interested in your resonance tuning formula that you used to calculate the length of the pipe. Do you mind sharing that with us? Read a lot on this but the numbers I needed to use to find the proper length boggled my brains so never utilized this while N/A. I just knew I wanted the sound harmonics to reach the intake valve at a specific rpm.
 
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Here’s the papers I used:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.612.5295&rep=rep1&type=pdf

http://web.iitd.ac.in/~pmvs/courses/mcl345/mcl345-20.ppt

https://www.sae.org/publications/technical-papers/content/2009-01-0302/

https://www.jstor.org/stable/26308359?seq=1#page_scan_tab_contents

As I said previously, I’m not entirely sure I did the math properly, but what I made seems to work, and in my own simple tests it outperformed the stock and AEM intakes I had, both in performance and efficiency.

I’m not finished with this intake either. There’s still a few more things I can do to extract more power, and I’ll share the details once I’m finished.
 

Myx

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Here’s the papers I used:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.612.5295&rep=rep1&type=pdf

http://web.iitd.ac.in/~pmvs/courses/mcl345/mcl345-20.ppt

https://www.sae.org/publications/technical-papers/content/2009-01-0302/

https://www.jstor.org/stable/26308359?seq=1#page_scan_tab_contents

As I said previously, I’m not entirely sure I did the math properly, but what I made seems to work, and in my own simple tests it outperformed the stock and AEM intakes I had, both in performance and efficiency.

I’m not finished with this intake either. There’s still a few more things I can do to extract more power, and I’ll share the details once I’m finished.


Wow.....great info and links. Also the Power point as well. I'll have to read up on those this weekend while I'm off. Actually excited about it in a nerdy kind of way.
In the meantime, I'll share some articles that I've used while making intakes for my Toyota RAV4 and Honda Fit.

Analytical Investigation to Predict the Intake Pipe Diameter in Naturally Aspirated Internal Combustion Engine

Fundamentals of Intake Design

Influence of Intake Pipe Length and Diameter on the performance of a spark ignition engine


I have just one suggestion on your project. Going from your maf sensor to your air filter, on each bend, increase the piping size by .5". I did a test with this on a dragstrip, changing my intake a few times at the dragstrip and found a measurable difference in my 1/4 mile trap speed (power). Here's an old thread I posted about it. Intake Diameter Observation - Dragstrip

Can't wait to read your links so thanks. Good luck on the project. Will stay glued to the thread.
 
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Losgar

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I had just came across this thread today (10/22/19) and am currently blown away and wondering if there are currently any updates to this build as i would love to try and replicate it.
 

treasures

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I admire the effort put into this and its documentation, great job! also the added input about increasing diameter, I wonder if anyone has anymore input or experience with this design?
 
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How did you end up getting that pesky intake resonator out?
I ended up taking mine out for my CAI from FKXRacing. It's a super big pain in the ass and took me the longest out of any mod. Long story short you have to cut it in half and remove 3 or 4 10mil (I think) screws holding it in.
 
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NSaneeee

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I ended up taking mine out for my CAI from FKXRacing. It's a super big pain in the ass and took me the longest out of any mod. Long story short you have to cut it in half and remove 3 or 4 10mil (I think) screws holding it in.
Same my lord I was borderline tears but I got it out 😝
 
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Romeoridgee

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Do you think this setup is better than a k&n drop in filter with throttle body spacer? The aem cai is an eye popper, but don’t want to lose the low end torque. Some dynos don’t use a blower to simulate driving which explains heat soak. Would love to see dyno numbers between stock and your intake setup.
 

Myx

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Here’s the papers I used:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.612.5295&rep=rep1&type=pdf

http://web.iitd.ac.in/~pmvs/courses/mcl345/mcl345-20.ppt

https://www.sae.org/publications/technical-papers/content/2009-01-0302/

https://www.jstor.org/stable/26308359?seq=1#page_scan_tab_contents

As I said previously, I’m not entirely sure I did the math properly, but what I made seems to work, and in my own simple tests it outperformed the stock and AEM intakes I had, both in performance and efficiency.

I’m not finished with this intake either. There’s still a few more things I can do to extract more power, and I’ll share the details once I’m finished.


@DarkLight
So what few more things have you done to extract more power? I am about to work on my 1989 Subaru XT6s intake by applying the math in the links for intake resonance (My Civic seems to be forever in a shop). Before I get started, curious to see what else you have in mind. Don't want my overconfidence in making intakes to give me tunnel vision. Need to keep an open mind. :p
 

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