Coldside Intake Isolator

- Removed: 11/2005 -
The Coldside now lives with Dan at Run-Down.com


I really enjoyed the intake isolator I had installed on my N/A intake and had wanted to do something similar for my new Coldside supercharger. With the experience of three revisions to my old airbox on my side, I began working to create something that would help keep intake temperatures down while not greatly increasing the amount of labor necessary to work on my car. That's where my N/A box failed - it worked very well at keeping temps down, but it was incredibly difficult to work around or remove.

Intake isolator prototype test fit for Supercharger
Cardboard prototype #01 of the Coldside isolator box.

The area around the filter is pretty simple and seems easy enough to make an isolator box for. One 90* angle vs. the crazy angles on the hotside make it easy. The only problem is the wiring harness seen near the fender, which I can't really route around the box without alot of extra work.

Miata coldside cardboard intake test fit
Cardboard prototype from the top.

The choo-choo and supercharger bypass actuator look safe for now. Making the box seal tightly is problem #1. Not tearing parts up is problem #2. And finally, problem #3 is working around the box once it's installed...

Completed ABS intake isolator for BRP Coldside superchargers
Completed Coldside intake isolator box - rev 2.0.

The intake isolator box was made out of ABS plastic sheeting (1/4" thick) instead of aluminum. I've used ABS before in the creation of air splitters, gauge pods, and radiator shrouds. Why not the intake isolator? Out came my heat gun and dremel. Compaired to two sheets of JB Welded aluminum, ABS is the easiest, most forgiving stuff in the world to work with. I spent much time and several sheets of cardboard getting the fit as exact as possible. The design and placement allowed me to get a tight fit without actually bolting the shield down. It's held in by pressure and removes as a single unit for easy servicing. Notice the insulation at the bottom of the box as well as at the top.

Coldside airbox showing a tight fit on all edges
The isolator box as seen from above.

This top-shot details the tube going through the 90* bend in the airbox quite well. Getting a tight fit involved more trial and error than anything else. I measured to get the center line of the tube, and then just removed little circles of material at a time. Also, you may notice that there's no wires or vac. hoses running through the box dispite Cardboard Prototype 01 above. I took the time to rewire, rerun, and enlarge the harnesses that needed it. My beefy headlight wires were able to be run between the motor actuator and the headlight frame.

Isolator box from the engine side
The blower side of the isolator box.

The filter placement required a bulge be created in the side of the isolator box wall. The heat gun and a large screwdriver handle made quick work of that. I then had to put an inverse bulge below the filter bulge to allow the S/C bypass enough freespace. I decided to wrap the edge insulation around the front of the airbox just to make it look as clean as possible. That insulation actually goes down and makes a tight fit on the bottom frame rail.

Back side of box showing the TEIN damper
The backside of the isolator box.

This angle shows not only the nice texture of the ABS plastic, but the angle of the top of the box. Through the use of playdoh and duct tape, I mapped the top of the hood. I then trimmed away plastic millimeter by millimeter to get a tight fit without lifting the hood excessively. The result is pretty nice and didn't take much time to create. ABS was just much easier to work with than aluminum. I can't believe I didn't think of using it sooner.

NACA duct feeding filter isolated by ABS box for Miata engine
Air sees this before it gets sucked in, compressed and heated, sprayed with fuel, and lit on fire.

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