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View Full Version : NA DIY Randall Intake w/detailed instructions!!!



95montego
01-15-2013, 08:10 PM
So you've probably heard about the Randall intake which takes air from the high pressure, sealed off area before the windshield. A lot of members use accordion type piping since it's easier to manipulate the thing. But accordion piping have the ridges and is not optimal for smooth air flow. I chose PCV piping and had to trim the pipings a bunch of times, so I figured I'd put together somewhat of a detail write-up. Save some time for future DIYers. Of course I wont be responsible for any damages done following this guide.

Tools and Parts used:
- 90* 2" elbow (3)
- 2ft 2" PVC pipe (1)
- 2" rubber coupler, no hub, with heat shield (1)
- 3/8" rubber hose (used to line the hole in the firewall)
- PVC hand saw, super easy to cut PVC pipes
- 2 1/2" bi-metal hole saw w/arbor and drill bit
- shop vac was VERY useful for clean up, you'll have lots of metal and PVC shavings all over
- Eyes and ear protections for when cutting the firewall

Note: the Randall intake I followed mentioned PVC cement to seal the junctions of the pipes. I did not use any, it's easier to disassemble if they're not fixed together permanently. Also I found the other 2" coupler found at the hardware store was too long to be used with this particular application, it's probably would be a better choice since the rubber is a lot thicker.

First, disconnect the OE intake snorkel, I also took off the 2 bolts and 1 nut that hold the intake box to chassis, so it's easier to manipulate everything. Then cut the 2ft pipe into 4 segments, as follow (yes, you'll have a lot extra):
#1 - 3 1/2"
#2 - 2"
#3 - 4 1/4"
#4 - 1 3/4"

http://i580.photobucket.com/albums/ss245/gaccount86/Miata/intake.png

Assemble everything with the exception of segment #1. Just so you can see where the hole needs to be. Make sure you cut a hole so that the plumbing wont put stress on the clutch reservoir. Here's a pic for idea:

http://i580.photobucket.com/albums/ss245/gaccount86/Miata/100MEDIAIMAG0082.jpg

http://i580.photobucket.com/albums/ss245/gaccount86/Miata/100MEDIAIMAG0085.jpg

After the hole is cut, you can apply to paint to prevent rust. Also, a Dremel or file can be used to remove the burs after the hole is cut. Then, cut a slit in the 3/8" hose and use it to line the hole. #1 segment will take some elbow grease to get in the hole, it's a snug fit. But, being #1, it can get into any damn hole it wants to. Finished product:

http://i580.photobucket.com/albums/ss245/gaccount86/Miata/100MEDIAIMAG0087.jpg
http://i580.photobucket.com/albums/ss245/gaccount86/Miata/100MEDIAIMAG0086.jpg

Hopefully you wont have this many rings:

http://i580.photobucket.com/albums/ss245/gaccount86/Miata/100MEDIAIMAG0083.jpg

Results: nice throaty rumble near and at WOT, notice hesitation during acceleration is gone, throttle is more responsive. Have fun!

Next up: advance timing by 14*!!

Heyitsryan
01-16-2013, 09:39 AM
Looks pretty sweet, how much did this entire set up cost you?

psulja
01-17-2013, 12:51 AM
Great write up; thanks for posting this up here!

95montego
01-17-2013, 07:29 PM
Hmm lets see...

hole saw ~$15
pvc saw ~$5
pvc piping/elbows ~$20

way cheaper than an actual CF Randall intake pipe, which is around ~150, or the JR intake, which is around the same price if not more

79rx7
03-20-2013, 05:04 PM
I like this
Will be doing it this weekend

The Driver
08-31-2013, 10:05 AM
I like this even better than the other Randall CAI thread! Sweet deal!

mrdos
01-22-2014, 07:11 PM
Can you post a pic of the entire bay? Want to see what the entire set up looks like :D

BoBo
01-23-2014, 06:34 PM
^ Same here, I have an FM Shock Bar but can't use a Randal Cowl. I want to see if it looks clean, I was thinking about using an ebay shock bar and racingbeat intake as an alternative.

finnthehuman
04-08-2015, 01:01 PM
Great write up.

I am however just wondering,

How did you attached the larger bore pipework to the stock airbox which only has a small inlet?

Many thanks