72Bacon

Heres my home made CAI / cowl induction



Ebay adapter on AFM, 3" mandrel bent elbow on 3" radius, rubber truck elbow, PRM air filter and a custom air snorkel thru the cowl. The snorkel piece is my design CNC machined and plastic welded. I can't remember what kind of plastic I specified but it's a grade of thermoplastic good to 180 degrees F; I figured since it's got air flowing through it, it should stay cool and it has without problems.

This setup made a noticable difference on my s/c car especially when the temps dropped below 75 degrees. On the chassis dyno the car as you see it here made 8 hp more with the hood closed than hood open. (For you non-thinkers with the hood closed there was no wash of hot air over the intake from the fan in front of the car.) The car has a knock sensor so what's going on is the cold air meant less ping = less timing pulled out = more power.

Pulls like crazy on cold days.

LastClick

BUMP!

I am thinking of making a DIY randall intake. I've read the topic and it seems pretty weather proof, but what about snow? Anyone drove this intake through snow, or after it snowed?

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demoniam

I've driven with this intake through a cat 2 hurricane. It's fine, unless you ride around without a hood. or park in the snow with the hood off.

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Graeter

For the tube intakes... what are good ones vs. bad ones? I could care less about looks, only clean cold air... The cheaper the better too. I know nothing about them.

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95 Miata
Future Track Car

Techsalvager

Is there a known air flow rating for that rpm filter?

72Bacon

I don't know the CFM but when I bought it the guys at PRM said it was good for around 220-250 hp

AMMendes

I had a FM randall intake and now i hava JR SC this gave me an ideia how to cover the hole made for the randall, nice post

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http://img429.imageshack.us/img429/4...adriver8jv.gif
Green air filter, Silenced de-kat pipe, 4-2-1 header, Mx5Parts SS Exhaust
Flyin'Miata Randall cowl intake, Koni Sport Kit

jiggerachi

The ideas in this thread inspired me so I thought I'd contribute my idea.

I bought a cheap enclosed filter off ebay, but couldn't for the life of me find a fitting hose with a good diameter at home depot. I was just about to give up when I passed the...leaf blowers...

Bam! Perfect. I picked up a beat-to-hell leaf blower hose on ebay for dirt cheap so out came the dremel / heat gun and I resumed the project.







Ignore the dirty cluttered engine bay, that's a project for another day. I used half of the stock snorkel off the airbox for the elbow off of the filter. I tested it with and without too see if I would get better throttle response with larger diameter, but couldn't tell a difference. I still may switch this part out later though as it's the skinniest pipe in the system.

Leaf blower hoses respond very well to a heat gun as well.

Sound is slightly louder than stock, but tame untill about 75% of throttle. Pedal all the way down gives a nice grunt, but not rediculous.

Mainly I was trying to cure my summer heatsoak / pinging issue, and hopefully be able to run higher timing again. I was not expecting a power gain, but was actually surprised. Car feels lighter, more responsive in the low end, mid and high end feels a bit stronger as well.

If anyone is looking for a perfect snorkel pipe, leaf blowers is where it's at.

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'94 C-Package Black & Tan | MS3x | USDM Tein Monoflex 10/8k
My 8 year roadster evolution|www.dfwmiata.com|Old Cardomain Page

phantomxrider

They also sell a piece of tubing which is adjustable at Autozone for $20, made by Spectra.

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1990 White - R-lip, ducktail spoiler, Megan coilovers, retro interior, center exit catback, black hardtop, xxxxxxxxxxxr 531s

"You look at the Elan, and you look at the Miata, and both of them have the same look on their face where they're both just kind of like, "What's up? Let's go start some shit."

jiggerachi

^Hmmm...I remember seeing an interesting spectra part when I was buying couplers at Autozone. I don't exactly remember what it was, but I passed on it, maybe it was too narrow or something. Is it an elbow, or the accordian aluminum?

The best part about the leaf blower tube is the flexible accordian seciton is smoothed and about 4in diameter. Enough to not impede airflow at all. Being so fat, it was tough to squeeze around the clutch master cylinder, but that's what the heat gun was for.

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'94 C-Package Black & Tan | MS3x | USDM Tein Monoflex 10/8k
My 8 year roadster evolution|www.dfwmiata.com|Old Cardomain Page

phantomxrider

It's actually just like the accordion aluminum, except it's made out of black plastic.

This is the only good pic I could dig up of it on Google. It's the black tubing attached to the shiny tube.

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1990 White - R-lip, ducktail spoiler, Megan coilovers, retro interior, center exit catback, black hardtop, xxxxxxxxxxxr 531s

"You look at the Elan, and you look at the Miata, and both of them have the same look on their face where they're both just kind of like, "What's up? Let's go start some shit."

Richy

so. I went to have a look & plan this, only to be greated with this.......



So not sure if i can do it now!

Jae_Rex

Great inspirational ideas here. I've been cleaning up my engine and this would be the perfect project to try next.

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"Never trust a big butt and a smile"
94 M-Edition / 91 ED3 Sedan / 96 JDM DC2 / 97 328Ti / 01 AP1

KJMagnum

If you don't drive in the rain then you can tear out that wiper motor and washer bottle like I have. Then you will have plenty of room.

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Project: Laguna Blue 94B w/ HT
Sold: Daily-Driven GT28R Civic

Richy

Can you swap it round?

I can't rip it out. I live in the UK! Its always bloody raining!

KJMagnum

I'm guessing you're out of luck unless you can squeeze it between the two.

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Project: Laguna Blue 94B w/ HT
Sold: Daily-Driven GT28R Civic

Richy

Boo! Might have a squeeze....

95montego

Ok, so did this thanks to the posts here on the forum. Had to trim the hoses 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"



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:





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:




Hopefully you wont have this many rings:



Recently, I've wrapped part of the plumbing closest to the exhaust shield with some insulation. I got it on there kinda loose, since air is an insulation too. What I've noticed is after half an hour of driving, it's not hot too the touch anymore.



Some members said PCV gives of toxic fumes when heated, but I figured I'm not breathing that air from inside the cabin anyways, and also, the PCV is not being melted or burned. I'll think twice if I get hospitalized or starting to lose consciousness while driving

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*!!

99whitemiata

Why is everyone so hesitant about just installing a hood scoop for the forced induction into the air filter. I have done these DIY mods but I am really considering getting a hood scoop and doing it. Any thoughts. PRO and CONS'

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Why are you asking me? I don't know either
I am just going topless

KJMagnum

I personally do not find aftermarket hood scoops aesthetically pleasing (especially since it would be off-centered). This is a less garish solution that doesn't permanently damage the exterior of the car if you decide to change.

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Project: Laguna Blue 94B w/ HT
Sold: Daily-Driven GT28R Civic

99whitemiata

Autozone has various sizes and there is one orange miata here in Pensacola that placed on the driver side. Though when I spoke to the person it was the gf. She said her bf did it with a scoop and then fiberglassed it to make it look like it was built with one. She said it drives fast. Idk

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Why are you asking me? I don't know either
I am just going topless

KJMagnum

LOL, if you want to believe her then go ahead and do it. I personally wouldn't take a girlfriend's impression of her miata being fast after her boyfriend fiberglassed a scoop to the hood.

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Project: Laguna Blue 94B w/ HT
Sold: Daily-Driven GT28R Civic

estabahn

The cowl is *the* place to get cold air. You get high pressure, and it creates no extra drag the way a hood scoop would. Also a CAI into the cowl won't get full of rain/snow while driving.

spitefulcheerio

The cowl might be the place to get cold air on an NA but the bumper is where its at on an NB. Way mo betta

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amptramp

Not so sure about that. If you are stopped at a light, an intake near the bumper may suck in air from the radiator and taking off from a light is when you need the cold air. Also, air near the road is going to be hotter than air two feet above the road. Cowl is the way to go.

Derek86

I'll bump and throw mine in the ring...



In progress, I need to tweak a few things (and clean my engine bay).

Flexible intake tubing (holds shape)
Silicone coupler to airbox
2 metal hose clamps
1 ziptie (to hold the tubing away from the clutch master cylinder)



I've had it on the car for about 3 weeks.

It does not seem the coupler and hose get too much heatsoak from the manifold. I've warmed the car up and done from spirited driving and immediately checked it. I also let it sit and idle until the fan kicked on so there was less air moving through the engine bay to cool the piping. After both instances I could hold the piping right next to the manifold.

I have, however, encountered a high idle situation which I'm not going to immediately correlate to the intake. I have been encountering a ~1,000 RPM warm idle with no load. I have checked the pre-airbox tubing for leaks and it is solid. So, again, I don't know how much it's related to the intake.

Overall I spent less than $40 on the setup. Does it increase performance? Maybe. Does it sound cool? Definitely.

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1990 Miata, SNC 1.6, DIY Randall, R-Package Lip, Overnight parts from Japan.
1979 XS650, far from stock.

leatherface24

lol you guys fail. do it the way i did it and youll be much happier. Maybe even do the cowl style setup on the actual cooler side of the engine.

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1vicissitude

Hood scoop needs to be placed in a high pressure zone or it will end up being an exhaust port, not an intake. I'd also strongly second guess the usefulness of any of those cheap ass scoops. Proper scoops, just like naca ducts and air foils, need to be engineered correctly. I can guarantee you a $10 scoop at autozone had zero consideration for this in its design.

So unless you are aerodynamically savvy, chances are you're just going to make something uselsss and be stuck with a stupid autozone scoop on your hood.

Just putting a hole on the hood doesn't mean its going to draw air from it. The randall style intakes work because that is a known high pressure zone at the cowl and base of the windshield.

A properly designed ram-air setup takes a lot of work and testing. They can be awesome if done right, but don't expect any results by strapping a shitty scoop to your hood.



I don't see a single great position on the hood for a scoop. Maybe at the top middle, right over the back on the cowl. Good luck routing an intake right there lol. Its ram air for your coilpack!

Derek86

I know. What can I say?

~ Derek

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1990 Miata, SNC 1.6, DIY Randall, R-Package Lip, Overnight parts from Japan.
1979 XS650, far from stock.

KJMagnum

Any before/after dyno results? I've always read that you lose midrange torque when eliminating the helmholtz resonator on the stock intake pipe. I'd imagine this randall style is more daily friendly as opposed to the peak power of your design.

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Project: Laguna Blue 94B w/ HT
Sold: Daily-Driven GT28R Civic