IC Duct for Greddy SMIC - Design
 

I recently installed my Greddy SMIC and was debating on what to do about the excellent "IC ducting" provided with the Greddy IC :rlaugh: . If you bought one, you know what I mean!

Having been a aerospace engineer (in a previous life), I decided I could design something better than what was provided (well, so could a 2-year old if you've seen what Greddy provided).

Here's my the design concept. My plan is to get an STL model made up to test the fit and then have the actual part made out of carbon fiber. I'll be adding a flange on the top of the duct to mate with the two threaded holes provided on the top front of the Greddy unit. I'm also thinking about extending the "sides" of the duct to wrap around the side edges of the IC (about an inch).

Here are some concept pis of the design so far. This took about an hour of my time this evening. Let me know what you guys think.

It would be good if you can design an extension to the opening to make it larger and get more air like the one that comes with the ASP...Looks very good BTW:bigthumb:

The opening of the stock IC duct is roughly 10.6" wide and just under 2"high (outside dimension). I designed this one to have an opening of same width (10.6") but 2.5" high. One of the largest "air flow" contraints is the location of the radiator/fan assembly. If you have an aftermarket radiator (and I do) you have to adjust for the additional thickness of the radiator. I checked the cross section of this design by using a cardboard template to ensure the clearence was correct (hopefully). The STL model should verify this.

Anyway thanks for the input.

The snout part that goes into the nose above the radiator is a real pain in the butt to get right. You could make it a little smaller I suppose and have it fit nicely, but then you're losing air. It's a good idea to make one though, you could actually sell a fair number of them if it's done well. At one time I even thought about modifying one of my existing molds to mate up with the Greddy as they don't really have one and there are quite a few of them out there.

Your snout part looks a little long, I doubt you'll actually be able to get it to slide down into the nose.

Mind if I ask what you're paying for an STL? That's a pretty big STL no less.

Kevin T. Wyum

Make sure you let me know once you make them. I'd like to get one :bigthumb:

If your design fits properly with an aftermarket radiator (I am a fluidyne), what would you think of having multiples made ;) because I would definately be interested in buying one :D

Don't listen to clud9! Make one that will fit perfectly with KOYO Radiator. :D

I got a pal in the "business". He actually sells the STL machines. One of the reasons for doing the STL is I can check for fitment issues prior to actually getting it made. Again this is a prototype. Once I get it test fitted I'll post some pics. It will probably be a couple of weeks. My work schedule is pretty tight this time of year.

I believe on Rob Robinette's site he said that he used a pettit duct and slightly modified it to work with his greddy intercooler. You may want to consider that route if your prototype has fitment issues.

Good stuff! I think you'd have a good seller if you can get that made up.

Gotta love the mechanical engineers around here! :)

Dale

Good work, on a product deffiently needed.
I am also ducting a Greddy witha Fluidyne Rad

I am making a C/K duct (had the material) and the red Kevlar matches my car. But have used the trial and error cut and paste method. Built mold from carboard templates and chopped up OEM ducting .. then foamed a plug, and reworked and reworked. Still not ready to throw $100 of C/K cloth at it. If I was not so far down the road, I would have jumped in on your project.

Regarding Pettit, the new style Pettit duct does not fit up to the Greddy and they do not have any stock or desire (I think they told me that they got rid of the molds) to make any more of the old style

Looks good. I'd recommend rounding the corners more so at the inlet to the duct. Different radiator combinations make it a tight fit in the corners sometimes.

Can you do variable rounds in Autodesk?

SIGN ME UP!!!

I'm running the Greddy IC and a really crappy duct. My air temps could be much better.

Please give us a rough estimate of when these could be available and a cost.. I'm thinking 100-150 because most ducts are around $100 or so, but this one is CF.

Yep... You can in Inventor (I'm using a beta version of our next upcoming release). Good idea on the inlet corners, right now they're at .25", maybe go to .50"? I'll run a couple more variations and post a couple more pics. Besides, I forgot how much fun this was :)!

Right now it's still in the concept phase and depending on the unit cost it maybe cost prohibitive for most people. My original plan was to make it CF, but there are cheaper alternatives regarding materials.

Once I get the mockup made and test fitted I'll start shopping around for a place that deals in making CF parts.

Looks good at this point, Richard. Nice work. How did you fashion the cardboard template, and how did it work out as far as clearance to the radiator fan bracket? I'm just curious if you had any clearance problems with the Greddy IC itself (I imagine not, since you didn't mention it). When I installed a PWR radiator, its additional thickness caused clearance problems with the Greddy IC; the front lower leading edge of the IC was contacting the fan bracket, which prevented the radiator brackets on the lower portion (part of the stock anti-sway bar mount) from seating properly. No amount of IC repositioning (what little ability there is) could solve the fan bracket binding problem.

On that same design point, I'm wondering about additional clearance for the radiator fans, as far as spacing from the bracket to the bottom of the duct. The Greddy's additional thickness, plus the duct, blocks off significantly more area behind the radiator than the stock IC duct setup. Have you thought any about that aspect? Probably not a problem, just wondering if perhaps it may be something to think about and discuss.

Thanks Kento. I have given quite a bit of thought to the radiator clearance issue. I have Ron Davis radiator (Mazda Comp) which is 1.5" thick (compared to the stock which is about 1.0") That effectively moves the fan assembly .5" "into" the location for the IC ducting. I took this into account when designing this duct. The cardboard template was done the old fashion way, cut, test fit, cut, test fit. It took about an hour or so until I felt I had it they way I wanted. Then a just digitized it and used it in my design concept model.

The big question is, there appears to be some interest in putting this project in to a limited production run and unless everyone is using the same radiator (as in thickness) there could be some potential fitment issues with the bottom of the IC duct and the fan assembly. I suppose if I had the cross sectional "templates" that would represent the bottom curve of the IC duct for both Koyo and Fluidyne I could make the bottom curve of the IC duct fit the worst case senario. Then the IC duct would fit all three radiator fan assemblies.

I'm open to any design suggestions that would make this project a value to everyone with a Greddy SMIC. As you know there is a lot of variances between how people install things. I have seen posts/pics of the Greddy SMIC (in terms of location, angle of the IC, etc.) installed different ways. This creates a major problem when trying to design an aftermarket product, in this case the IC ducting, to solve a particular problem.

And besides, design by comittee is always fun. Just look at the former Soviet Union... it worked for them didn't it? :D

i'm not really familiar with the Greddy IC so forgive my ignorance... would it be possibel to make new mounting brackets that would move it further away from the radiator/fans assembly and increase the volume of the little "bell" in the duct where it meets the IC... or what about a little fan unit that mounts to the back of the IC in order to constanly be pulling a minimum amount of air throught the IC even when sitting still???

just spouting off stupid thoughts here.

Check out BATMAN's Greddy SMIC duct.

https://www.rx7club.com/showthread.p...ht=greddy+smic

Last I checked with him he was getting temp readings of high 20'sC - low 40'sC on the freeway at 50F - 60F outside temps.

Here is a pic of it installed in the FD:

http://www.illstreet.com/image/batman/engine.jpg

Looks good! I saw this post when I originally did my search for an alternative duct. I decided I wanted do something alittle different for my car.

Updated Design for IC Ducting
 

Here's version 2. I included suggestions made by turbojeff (variable radius, i.e. larger radius on the "nose" section). I also included long tabs to overlap the sides of the Greddy to help seal it. I also incorporated the top mounting flange to mate up with the two existing holes provided on the top front of the IC.

Comments are welcome ;).

I wonder where u got that top flap idea from? ;)

Yeah... I know... I know... it's pretty much the best thing about "their" design! Besides the holes are already there. :bigthumb:

I also have a m-comp rad (1.38" core) and Greddy smic. The rad was a very poor fit, as fan bracket no longer nested against the core, and stand-off was excessive. Called Davis to alert him about it. I had to machine down the upper mounting stubs, and cut off the lower plates that hold the bottom of the rad fan bracket pins, to move the fans close to the core. Also mod's fan bracket. If your m-comp rad was also like that, I'd fix those first. Basic problem was mc core was less that 12 x 24", as stock oem one was.

I like the idea of a real duct for this IC. i have a butchered Pettit. The carbon would be just show, larger market would be FRP or abs ... KTW may have some suggestions for vendors. I aslo think tilting the rad down, at the upper mounts as koyo guys often do, would allow an even deeper slot. Goal would be to hit about 40% of gross core frontal area.

Good luck.

I had the same problem with my Fluidyne rad. The rad is thicker but the main problem with IC duct fit was the fans were held off from the rad core by ~3/8-1/2" due to higher than stock mounting bosses on the top side. The bottom side mounting tabs also held the fans higher than the stock position.

Once I lowered the height of the mounting bosses, the IC duct fit much better.

I met with my buddy this afternoon. He has one of those new STL machines that use ABS material. So the first prototype will be ready by the middle of next week, with the test fitting next Saturday. I agree with you that ABS makes better sense as a material.

With regards to the Davis (MazdaComp) radiator install, mine was a snap! No problems what so ever. I bought mine just before xmas so it maybe part of a newer batch (with mods already incorporated)??? Anyway fitment and craftsmanship were first rate, at least for me :bigthumb:.

Version 3 Update
 

Well I spent some more time discussing the design options for the ducting with my "STL fabrication house". As I mentioned in one of my earlier posts, the STL machine we'll be using for this project uses ABS as the material (I even have a limitied choice of colors). So this prototype will be functional. With a wall thickness of .125" the ABS material should stand up very well to the heat/vibration/abuse of engine environment during the course of "regular" driving.

We did a 1/4" slice of the cross section (length wise) to double check for possible clearance issues. Found a few small problems with the underside curve of the IC duct. Revisions were to the design and now we're ready for the first full run. Interestingly the envelope of the STL machine is 8x8x12 so the duct will be made in 3 pieces and bonded together during final assembly. Since it's ABS the bonds will be as strong, if not stronger than the material itself.

Here is the final design prototype based off the most current revisions. As always your comments are welcome.

Looks really good. I'm shopping to replace my stock IC and this might just make the difference for me in going with the Greddy SMIC.

My one comment is in regards to the inlet design. The stock inlet has a center reinforcement which I have heard is required to keep air pressure at normal driving speeds from flexing the ABS and reducing the overall intake area, disrupting air flow, etc. A section of a Bic pen shaft and two screws would be the poor man's fix. But for such an elegant design as yours maybe you could come up with something better.

Hmm, I have a hard time believing that air pressure at normal driving speeds could flex the ABS plastic of the stock duct; too many holes in the stock setup for the pressure to bleed off at. The plastic is fairly thick in that area as well. I'm thinking they did it to keep the components on top of it (various wiring, supporting the AC receiver/drier, etc.) from collapsing it over time. As long as the ABS plastic is rigid enough, I don't think deleting the center support would be an issue, since it won't be supporting the AC receiver can and piping.

I still have my stock IC ducting and used it as a reference for my design. If you look closely to the stock duct you'll see that it is an assembly of 3 pieces of plastic (ABS??) riveted together. The upper and lower pieces that make up the section that matches up with the stock IC are a thickness of roughly .062", while the nose section is roughly .120-.125" in thickness. My design by comparison is .125" thick ABS throughout the entire design. This uniform thickness should add additionalrigidity to the overall design. I don't anticipate alot of flexing of the intake opening during even highspeed driving. Once the prototype is completed I'll double check to see what amount of flexing will occur by simply seeing how much force is required to actually flex the center section of the air intake (by hand of course, very scientific :p:).

I'll report back my findings. Thanks again for your input!

my mod'd PFS FRP duct inlet did start to close in the middle, due to general pinching and perhaps some residual molding stress, not aero loads. I did bond in a center brace from some plastic sheet.

By the way how do you guys with Greddy SMIC's deal with the cooling/insulation of the battery and AC condensor?

Jon

Most likely the stock IC duct is made from either PP or PE, both resist fuels and oils very well. ABS doesn't fair so well under those chemicals.

An interesting note, in 94 Mazda kept the same or very similar IC duct design but it was converted to a 2 piece rather than a 3 piece design.

If you mean the can like ac component with sight glass, I wrapped it in foil backed insulation from hardware store. The 51R battery sits in a turboJeff tray, with a yellow "batt-mat' as an insulator. My underhood temps are far less than stock, so no need for a fully ducted battery.

I ported the lower inlet to the greddy, and freed up about a measured 1/2 psi drop at 10 lbs boost. This is not a high flow IC, like the PFS or ASP/M2.

any updates?

I need a duct for my greddy SMIC

I would like to add my 2cents here, I am an Industrial Designer (specializing in product and furniture design) and I have a few questions, concerns about the ABS plastic in addition to what turbjeff mentioned.

I have some experience in vaccuum forming ABS plastic parts, and it was said that the ABS should hold up fine under normal driving conditions. Please correct me if i am wrong!
With a wall thickness of .125 [1/8th of an inch] (given there is no load or stress on the duct, which we know!) the heat factor in the engine compartment will still pose a significant problem with warpage regarding the duct.

Discuss amongst yourselves!

You have to keep in mind that fresh, cool air is going to be rushing through the duct keeping the temps down. Also the duct is mostly down in front of the bumper, theres just a small portion actually in the engine compartment. The small portion thats in the engine compartment is also a ways away from the motor, so it won't get near as hot as the motor.

-Alex

That's true, but during traffic when heatsoak occurs the plastic could reach some significant temps. Not to mention that the duct is in contact with the intercooler itself which has hot compressed air fresh from the turbos going through it.

I guess the real question is at what temps does abs plastic warp and will the intercooler duct reach these temps?

Even then, i'm sure it won't get hot enough to warp it. If its attached to the car it will somewhat help keep it from warping out of shape. The duct would get no where NEAR the temps of the motor. You could also put some sort of bracing inside of the duct to keep it in shape. It's not like it would get hot enough to melt. What is the stock duct made out of anyways?

-Alex

Is there an update? Was the first fab successful?

Sorry for not updating the status of this project, but I've been traveling quite a bit lately on business (damn work always get's in the way of my fun :)).

Anyway, I had the prototype made and did a test fit. That's where I ran into some fitment issues (you'd think after all these years I'd have learned to measure correctly :D, reverse engineering is so FUN!). The A/C bracket (the mounting tab portion) hits the side of the new duct and does not allow a good fit, that and I actually wanted to open the fuse cover that is mounted on the front cross member. That along with the mounting angle of the IC itself caused an additional issue. I have since modified the design to take into account these problems. Since my plan is to still use the STL version as a working prototype I decided to add some internal stiffeners to addreess some of the concerns raised here about the possibility of the part deforming due to heat soaking. The ABS material being used has a thermal deflection temperature of 210 Degrees at 264 PSI and 230 Degrees at 66 PSI (well above the loading expected for the part, since its primary fuction is to direct air to the IC and not be a load bearing support).

I should have the new part next week sometime. But I'll be on the road again, so it will probably be a few weeks before I can report anything. I'll let everyone know how it works out.

Whenever you make a finished product. I want one. just tell me what to write on the check.

I am also an owner of the greddy smic. the stock ducting sucks. i have been watching this thread for awhile and cant wait until you finish. please let me know.
Thomas

Thanks. I'm also working on a another version fabricated in aluminum. This will undoubtly be much cheaper to make and it has the added benefit of being able to polish it :D!

If I go that route I'll make the plans available to anyone that wants them free of charge. That way you can have it made locally and pick your own material/finish. The issue with the prototype I'm making now is that to actually manufacture it would require molds be made and as you can see this not exactly a simple part. You would to make quite a few of them just to recover the cost of the tooling and that in turn would make the actual part cost prohibitive (which probably explains why Greddy made such a cheap version of the IC duct in the first place).

Anyway I'll keep everyone informed as to the progress of this project via this thread.

cool man well whatever it costs you to get made. i got the cash so let me know

thomas

if not i will make it out of sheetmetal or whatever to your specs

any idea for what pricing is going to be? are you making fiberglass, carbon fiber, aluminum??

I'm looking at buying this IC, so if you come up with something, I'm in.

Suggestions:

Use the final prototype to make a cheap fiberglass female mold, for making a fiberglass duct, with external gelcoat. Could epoxy in a brace after molding.

Should be able to sub it out for production (might get a contact from KTW). Limited run of "cosmetic" (no vacuum bag or autoclave) carbon fiber ducts could also use same mold.

Make sure initial opening is at least as big as oem.

Slide on door gasket below flange would also be nice, and make for a more forgiving fit. M' Carr # 12335A42

Don't give up on the molded FG or CF version. You can do it without tooling molds.
I made one using a temporary male plug mold out of a combo of foam, sheet plastic and balsa wood fit it to the IC and covered all in waxed plastic. Laid 2 ply’s of CF/Kevlar - epoxy over plug. This worked out giving very smooth interior and grainy but good exterior -- final cap ply covered top and sides for aesthetics. I had problems with duct growth beyond my original master templates, but I was crude in cutting cardboard templates and guessing skin thickness tolerance. I also needed to destroy my plug to get it out, but I would think with preplanning and CAD you could design a breakdown plug for reusing. Someday I will post photos of my duct ... fit to Greddy with Fluidyne rad. An advantage of plastic (epoxy), final fit up can be made with a little blow torch heating to reshape interference zones.

Fab Notes:
- I flanged my top and bolted to Greedy top face, used alum bar as backing bar which also formed a strut to car top frame.
- Used double sided tape around perimeter to mate to IC, (advantage of molding to actual IC (behind plastic) is a perfect fit up.
- Did not put strut in opening, has not closed up, lower lip extends well pass opening (air would push this down and thus open)
- Heat soak does not melt or soften, I just can back from first test run this weekend BBORR race; 118 miles at 140 mph in hot West Texas.
- Had to relocate IC a bit; about 3/8 in back and ¼ toward battery tray. I drilled new bolt hole in trans. sub-frame. No big deal, watch out for hoses underneath and engine pulley clearance.
- CF/red Kevlar was purely for looks .. I had the cloth. But it is as light as a feather. About half weight of OEM duct and more than twice as big.
- Without vacuum bagging, this piece is still as strong as hell. A 2 layer composite is nothing fancy to make, and this thing does not hold your life in its hands.
- Use VERY GOOD epoxy, I use WEST System. The real stuff! for high performance boat building.
- If I did again, I would try to lay some heat shield material (mat/foil) into the bottom layers to reduce rad. Heat input .. but this will take another 1/8in out of the duct internal size, which is already very tight over the fans.
- Would cut down my rad fan support bosses to get more space

Sorry for long story, but the product is in the details

any update on the duct or the pricing?

None at this point. Sorry guys I've been traveling way too much for business (and personel) reasons lately. It looks like this project is going to be on the back burner for awhile longer :mad:.