Even Cheaper Bastard Cold Air Intake
 

Decided to whip up my own cold air intake modification to my OEM air box. It is even cheaper in that I didn't pay the original Cheap Bastard for his pre-made version. After mocking up with cardboard, I designed the sheet metal in CAD. Then printed out the template, secured to my sheet (light mist of spray adhesive on the template), cut and bent. I used some spray paint to transfer the shape of the opening to the bottom of my air box so I knew exactly where to cut the hole. Then installed with heavy duty weatherstrip and a K&N filter. See pics below. If there is further interest, I will show details on bending up the sheet without special tools and provide the template.

https://www.rx7club.com/attachment.p...d=224786&stc=1

https://www.rx7club.com/attachment.p...d=224787&stc=1

https://www.rx7club.com/attachment.p...d=224788&stc=1

looks good man, quality work there. I wonder how it compares to the original cheap bastard intake mod...

Dunno. I found old threads with some engine bay pictures some time ago, but when I decided to make my own, I just started from scratch. Maybe some OCB (original cheap bastard) owners can comment?

nice,i work in a machine shop and could make that,how about posting that template thanks

Nice work. I did something simular for the bottom part of a custom intake I built.

The other person (CBI) wont tell people what he did for his intake or what it looks like, cause its a patened secret so i cant compare. You can only know if you buy it, instead of just showing the idea and helping the comunity. But you did a great, clean job!!

Details Man!!
 

Thanks for all the positive feedback guys. It really is NOT a lot of work to do this modification once you have this template. I enjoyed the process and I think it is great others might benefit from my efforts. So find attached a PDF with full size template including a pictorial view and some notes on construction. This is an ANSI D Size print which measures 22x34 inches (landscape orientation). If you don't have access to a large format printer, you can take it to a copy shop and have it printed out. The actual template fits on a 12 x 18 inch piece of sheet. There is one small difference to the template versus the way you see it in my photos - a groove in the last face which allows it to be captured by the face that gets bolted down. This is an improvement over having to somehow fasten the two faces together, though you can do that if you want (epoxy, poprivet, snip & fold tabs, etc.)

Below are some more photos showing the bend squence as well as the air box cutout and weatherstrip seal. I used a couple pieces of wood, a large C-clamp and my dining room table to do the bending - low tech but very effective for mild Aluminum sheet. For the box cut out, I just drilled 3/8 inch diameter holes at the corners, buzzed through the plastic between holes with a jigsaw and then cleaned up the edges with a rotary rasp in my dremel tool. I also removed 1/2 inch wide strip of the ribs on the bottom of the box around the opening so that the seal would be tight. Finally there is a spot on the bottom of the box which is not flat like the rest of it - you can see I cut a few wedges of strip to fill this gap on the bottom of the box.

The PDF template itself is linked as an attachement only (scroll past the photos and click on it). Enjoy!! :D -- James

https://www.rx7club.com/attachment.p...d=224841&stc=1

https://www.rx7club.com/attachment.p...d=224842&stc=1

https://www.rx7club.com/attachment.p...d=224840&stc=1

Damn James... nice work! Not exactly the "cheap bastard" way of doing things... it looks excellent... :D

Now thats a write up!!!!!! WOW... job well done :D

Looks nice... gonna give it a try sometime~ Thanks for the post~

damn dude. Impressive.

Certainly not cheap.

well... certainly not expensive though either. with the exception of the CAD software, that intake shouldnt take up more than a few dollars and some elbow grease...

Uh oh, Adam's got some competition :D

competition? doesn't look like anyones trying to sell anything here.

good thinking.......! we need more do it yourself post here

Definitely trying it out soon... Thanks for the ingenuity!

Good job adam. I used your first idea and it was awesome.

What other idea did he have ? Couldn't find it an any post he started ? ? ? ?

Nice work and a great write-up. It beats the hell out of most instruction manuals these days...

0.025 Inch sheet, not 0.040
 

In case somebody is trying this, the sheet I used (which I purchased at Orchard Supply Hardware, also available at ACE Hardware) is actually 0.025 Inch thick Aluminum sheet, not 0.040 Inch thick as I previously stated. It cut VERY easily with simple tin-snips and also bent VERY easily using the scrap-wood & C-clamp technique.

You may see a 1 to 1-1/2 psi increase in boost pressure with this modification and a K &N performance filter. This is very significant! If you have other modifications, make sure you are paying attention to your boost level. Hopefully you have a PFC or other ECU upgrade to allow you to keep your air fuel ratio safe.

You will also notice some increase in blow off valve noise. The OEM setup routes the output of the BOV's into the air-box. In order to do this upgrade, you need to remove your rock guard (if you use the spray paint air-box cutout marking technique). With this modification and particularly with the rock guard off, the PSSSSSHHHHHT sound from the BOV's operating when you boost then let off the accelerator is much more apparent than before the modification. This is nothing to worry about, but I thought I would mention it so you will know what to expect.

FYI, I bought my K&N filter from this outfit: http://www.cardomain.com/item/KNN332017 Best price I found $47.95, no CA sales tax, and free shipping! Got my filter very promptly. Doing this modification with the OEM filter will probably help, but for maximum increase in free flow, you need this K&N filter upgrade too.

-- James

I meant that it wasn't cheap as in quality not price....

OH HELL!LOOKY LOOKY I SEE YOUR SORRY ASS IS STILL COMEING AROUND
tell us who you are! scammer shane willis
GUYS CAUTION WITH THIS GUY!AS I MYSELF HAVE BEEN WARNED BY SOMEONE WHO HARDLY MISSES

Looks very good! I will surely be trying this myself, i am just in the process of making my own system for the car, ducting for the radiator, new battery box etc all out of 0.7mm sheet stainless. The only thing i have left to work out how to do is my cold air intake and you just did it for me!

Great job!

Hi BobfisH.

I hope the template is of some help to you. I too need to fabricate some radiator and intercooler ducting. I would love to see some pics of what you have done so I can get some ideas!

Since that original template, I have put in a Koyo racing radiator. The fitment seems to be tighter than it was originally. For now, I tweaked my existing duct to fit. Basically I squeezed it at front and aft ends so at the front it looks like < and at the back, it looks like > which makes it thin enough to slip between the radiator/fan assembly and the chassis like it did originally. I'll post a pic tonight.

I am thinking I would like to redesign it to have a longer thinner opening next to the radiator, instead of the simple rectangle going straight down. And maybe a bit larger opening to the air-box. Will post back here if/when I get around to it.

-- James

cool, your very lucky to have CAD facilities. The metal i am using is quite difficult to bend so i am being forced to use a hammer on it to get a small radius bend. I was too lazy to get a piece of wood so the install looks a little shabby, plus i havent used a tape measure once, since i started building it. I will go and take some pictures now for you since im bored and i dont have any yet!

back in 15 with pictures.

Ok so i just took some pictures. The quality of workmanship is not great but im in a rush for an event and i always say function over form... (because im lazy :P)

here she is :)

Attachment 719477

and my new seats, for good measure...

Attachment 719478

Heres a picture of how the cars laid out, the intercooler is quite large so you may have more space to play with:

Attachment 719479

the panel infront of the intercooler i fabricated, more on that later - its the duct. i also fabricated to battery box on the right for a PC680 odysee battery. Ive done a lot of searching on this battery and have seen some bad stories, but ive had no problems so far. Never fails to start the car, however i do drive it probably every 2-3 days and the battery has only seen 2 months of use. Heres some more detailed pictures:

The box was made of a net that i drew up out of cardboard, i basically folded carboard around the battery, made sure it fitted nice and then cut out the metal and did the same.

Attachment 719480

I riveted out from the inside to hold the whole thing together, the top layer under the rivit is an extension of the long side panel. I have pictures of the carboard net i made if you want to see them.

This box is then riveted to a single piece of sheet that i cut to fit into the existing two bolt holes on the chassis rail for the original battery box base. This piece was then riveted to the bottom of the battery box itself.

Attachment 719481

Attachment 719482

The top right of the box is cable tied to a solid point on the inner wing to stop the bottom sheet flexing with cornering.

as for the intercooling ducting, the AC bottle thingy got in the way of my duct. The lines are pretty stiff and supportive so ive removed the bracket from it and cable tied the lines to some of the loom of the car. The ic duct is comprised of 4 bits of sheet shaped to be conical. I had to do a bit of funky bending to get this lot in, and its not perfect, but it needs more tweaking im not finished yet.

Attachment 719483

Intake elbow side of engine:
Attachment 719484

exhaust port side of engine:
Attachment 719485

i have no photos of the bottom piece, but its a large piece i have bolted to the crossbar just above the steering rack. There will be plenty of spare holes there if you have removed the stock airbox and IC. The whole lot is riveted together:

The front will then follow the path of the stock IC duct out the nose of the car, although i am going to expose a large portinon of the duct through the bumper )possibly 1/3 of whole hole in front bumper)

this part isnt done yet, but the plan is to build it to be removeable, i plan to do this by shaping the end of the duct so that it slides over the end of what ive got above, im then doing to weld some captive nuts to the inside of the existing duct so i can drill the new piece in the right place and insert a bolt through into the captive nut to hold it.

More pics of this when im further along with it, car has to be done by april 19th sooo...

Cool Bob, thanks for sharing that!!

I have a Greddy SMIC and I plan to do something similar to your IC duct. I kind of wanted to pull out the stock duct altogether, but it is nice the way it catches the incoming air in front. I think I am going to start with that part and work backwards to the IC itself.

I also have an Odyssey battery. I bought their "billet aluminum mount" and had a small plate welded to the chassis to hold it down. Here's some shots:

http://www-eng.lbl.gov/~osborn/rx-7/...Images/402.jpg

http://www-eng.lbl.gov/~osborn/rx-7/...Images/403.jpg

http://www-eng.lbl.gov/~osborn/rx-7/...Images/404.jpg

http://www-eng.lbl.gov/~osborn/rx-7/...Images/431.jpg

http://www-eng.lbl.gov/~osborn/rx-7/...Images/432.jpg

Very nice! i was looking for those style terminals for mine but could not find any.

I will not be using the stock plastic front piece of the IC, it will all be sheet stainless. I am just going to follow the lines of it.

They sell the battery with optional metal jacket (add MJ) and terminals (add T). I bought the PC680MJT, so it included the metal jacket (painted red) and the terminals. The terminals are brass and have a stainless socket head cap screw captured inside them. These just screw onto the non-terminal version of the battery like yours using an allen wrench. I'm sure you can order the terminals direct from Odyssey http://www.odysseybatteries.com

Not shown in my pic (hidden beneath the red rubber boot) is a brass marine terminal I bought at a local Kragen. This has a larger offset then the stock positive terminal and includes a post/wing-nut configuration that acts as a quick disconnect. This terminal allows me to install the stock fuse holder unit aft of the battery.

Edit: Uhhh, here's a pic showing the terminal (but not the wing nut!):

http://www-eng.lbl.gov/~osborn/rx-7/...Images/434.jpg

Bob I think some weather stripping would go a long way for your intercooler duct. It will stop the duct cutting up your intercooler when the engine torques and it will seal much better. As we can see the bottom of the duct has a large opening.

On a side note, I am planning to do some FRP ducting myself. Making a good mold out of metal is going to be the hardest. Also since FRP doesn't go great on corner I will have to fill the corners and round them to the best of my abilities.

It is nice to see something like this, a simple mod which improves performance nicely.

I will try the same. I think I'll stick with Aluminum. It is light and easy to bend. :)

Off-topic, but the way you've ran those shoulder harnesses is extremely dangerous and should be addressed immediately.

I don't know much about racing seats and harnesses rynberg. What's wrong with that setup?

Shoulder harnesses need to be run within 15-20 deg of horizontal in order to provide proper restraint, otherwise, they will cause severe injury. I also can't tell how they are bolted in, so can't comment on the safety of the mounting point either.

Aside from that, 4-point belts are dangerous because of "submarining". A 5-point is better, with a 6-point being ideal.

So here's two pics showing how I squeezed the end which sticks down between the radiator and the chassis. I left the upper portion as is to mate with the cutout in my airbox.

https://www.rx7club.com/attachment.p...hmentid=232567

https://www.rx7club.com/attachment.p...hmentid=232568

yeah i know, i need to get some - its not finished yet; but thanks for the suggestion; its on my shopping list :)

My IC Duct
 

I finally got around to doing the duct for my IC. I used the same method as the intake duct that I started this thread about. First I mocked it up with card stock, then modeled in CAD, printed out the design, spray-glued to aluminum sheet, cut, bent and pop-riveted it together. It turned out great. For the final touch, I painted it crinkle black and made a custom bracket out of 1/8 aluminum plate.

You'll notice also that all my aluminum parts have a sparkley glow to them - they are all bead blasted and clear coated. This makes for a nice clean uniform appearance for those who are not into the polished look. Pictures of all this start here:

http://www-eng.lbl.gov/~osborn/rx-7/Page48.html

You can also see I blocked off the stock intake to the oem air box. I used high temp gasket sealant to glue a piece of aluminum sheet over the hole, then cleaned it and painted that crinkle black too. I like that crinkle black - it looks cool! :D

i dont see how it works? its like a little rectangel thing that goes to nothing.

Uh, which part are you referring to? Sounds like you are talking about the intake duct which started this thread? Yeah it goes to "nothing", namely cold fresh air from below the car, next to the radiator. The stock setup has this restrictive plastic box that takes some air from the inter-cooler duct, and transfers it over to the oblong hole on the front of the air box (the one I sealed closed and painted crinkle black).

The whole idea with the cheaper bastard intake modification is to provide a more direct free flowing intake path of cold air to the bottom of the air box. You could just cut the box open wide on the bottom and forget the duct, but then you would be drawing hot air from the the engine bay and downstream (hot) side of the radiator in particular. Hot air intake is undesirable for performance and reliability.

A ram intake would be even better. Some guys have mounted flexible pipes which take air from the front of the car and direct it to an opening in the bottom of the air box. But space is tight. And all this would really do is allow your turbos to work less hard. They already are capable of over-boost and so the lack of ram intake is not limiting performance. If you had ram intake, it would just mean less effort by the turbos to reach maximum boost before the boost control kicks in. I don't think it would result in any significant performance gain though.

Nice work! I like the look...

Did you consider removing the duct piece from the airbox, and then seal the side of the airbox itself?

That would not be hard to do. Actually I'm now thinking of something more custom to replace the oem air box. My original idea on leaving the oblong projection is that I can install the factory plastic transfer duct. I had to cut away some of the plastic on the bottom side so that it would fit over my inter-cooler. It is strictly cosmetic now, but it results in a VERY stock look which I hope will allow me to pass CA smog inspection without hassle. See this page for a pic with the transfer duct in place:

http://www-eng.lbl.gov/~osborn/rx-7/.../Image546.html

I'm glad I don't have to deal with the hassle of Ca's smog inspections anymore.

Just seeing has any of you guys tried installing this shield on a Series 8?

Seems to me that the radiator mounts and some other bracket is blocking the shield from sliding down into position. Even if i did get it to slide down it looks like the undertray is in the way also.

Collapsed...
 

I built one of these and it worked pretty well, but I did have one problem. To fit it in between the radiator and chassis (maybe because of aftermarket radiator) I had to crease the ends a bit, like rxcited2 shows above. No big deal, but it may have lead to the bigger problem that it collapsed at high flows! For a while I thought I had a turbo transition problem because after the transition, the boost dropped to around 6 psi. But after pulling off the bottom tray for something else, I noticed that the sides of the duct were bowed in towards each other. I took it out to straighted it and noticed that there were actually witness marks on both sides where they had been hitting each other. So besides straightening the thing, I added a brace between the two sides. I just made a square-U out of a strip of the sheet aluminum about 1/2" wide. I put a slight V crease in the middle part to stiffen it, and riveted the two ends through the duct sides. Works like a charm now.

Other slight modifications were to extend the bottom of the duct to custom fit it around various braces, and I needed to "adjust" the mounting bolt hole closer to the duct.

Ha ha ha!
 

I had virtually the same thing happen to me. In my case though, my mechanic had "leaned" on the airbox. Because I had an aftermarket SMIC, I had to remove the driver's side airbox support, so leaning on it caused the even cheaper bastard to collapse just like yours!

The brace is a very good idea. In my case, I found I really didn't need to crease it; I was able to square it up and jam it back in there even though I too have an aftermarket radiator. After this I didn't have anymore problems.

Now I am onto a completely new "rich bastard" or maybe you'd call it "typical bastard with friends who are good welders" version. This is a custom set of hard-pipes for both primary and secondary turbos, and a new rigid aluminum airbox using K&N cone filters and a cold air duct like the cheap bastard, but is welded, made of thicker material (of course), and includes a "ram intake" scoop feature at the bottom. Basically the rock guard will be cut away so the cold air intake can get down below the guard, and the duct will include a scoop pointed forward to get the air.

Will try to post some pics when it is all done.

Great mod... may do this myself
Thanks for the pdf and info

Here's a pdf of the intake duct that started the thread. This is separated onto 4 letter-size pages that can be taped together (with overlap) to allow you to print the design at home
Might save someone 20 minutes

Thats really good work. No crinkles in the metal or anything. Top notch

Uploaded the wrong file :lol:
Here's the one I meant to upload... too big to host on rx7club
http://www.multiupload.com/YE1Q3RMJMK

Thanks @rxcited2 for this.
I just did this yesterday and it works pretty good!

I have a KOYO rad and had to squeeze the duct to be thinner so I can get it in between the frame and rad.
Spool is definitely quicker with only a minimum of boost increase ... slightly less than 1 psi. I currently have dp and massive catback; still have main cat.

What I've noticed is the car doesn't loose steam up top now. Before, it would have power drop just after 6200 RPM but now it pulls till 7000 rpm. Stock airbox/duct a limitation?

While doing this, I sealed the air feed from the IC duct to the intake box so all the air goes to the IC .... so I don't know if i cleared the restriction of the intake box or better airflow to the IC that gave me better top end. (If I don't close this feed, I can see air flow between diverted from the IC)