Prototype high flow belly pan finished and tested
 

Here it is.
https://www.rx7club.com/forum/attach...postid=1202712
https://www.rx7club.com/forum/attach...postid=1202723
https://www.rx7club.com/forum/attach...postid=1202739 https://www.rx7club.com/forum/attach...postid=1202749
https://www.rx7club.com/forum/attach...postid=1202767
https://www.rx7club.com/forum/attach...postid=1202775

If you have looked at the stock belly pan here are the modifications:
1. The lower lip is extented by 2" and angled more aggressively to scoop up more air.
2. The upper panel is angled to create a larger front opening and to increase the airflow speed via ramming effect.
3. There are now 2 rows of upper panel vents instead of 1. 3 sets of 2 1" vent openings have been extended to 2 sets of 6", 5", 6" vents (more than 5x the original flow x-section). The vent angles are also modified to be near perpendicular to the radiator (increase the flow effectiveness)

The aerodynamics have been tested up to 150 mph. At highway running speeds the average water temp is 8-12 deg F lower. (depending on speed and ambient temp).

looks like you made it outta the same material as the fake vomit people use for gags.

would you be able to extend the sides so that it reaches behind the wheel? i don't know what that might do and how it affects it , but most japanese companys that sell the undersweep have it this way.

luigi

It looks like the first good belly pan besides the stocker. The flat sheetmetal ones are junk.

Did you make this part or have someone else make it? PM me back if you can.

Thanks,
Jeff

That's pretty awesome.
Looks like fiberglass.
What are your plans for production process?

It could be done, but not sure why you would want to. It would be kind of awkward, the sway bar is in the way (check the last picture).

I did the redesign, and a friend (familiar with fg work) did the mold work.

Depending on the amount of interest out there, we will probably run a set of 20 the first go around. The finished product will be shipped fully assembled.

AND the big question, to get cooler tempts it will cost only ??? fill in the blank please. ------------

Yes, what will it cost?? Sounds good to me so far though. I'm interested.

The price should be $120.00 to $160.00 plus shipping depending on the quantity of each run. The time should be around 10 working days from the first determined production.

Just a point of interest. For those who are interested in show car items, we are going to have a carbon fiber (clear epoxy resin finish) version for $250.00

are you able to make one for people with FMIC's etc? or would that be a huge pain considering having to make the another mold. I ask because normall the radiator is in a different position from stock.

Danny

Nice job. Good to see people developing new products/different ideas for our cars.

HAHAHAHHA! What a piece of shit!

It sure is great to know there are some novice engineers (or should I say Profiteers?) that are ready to selll anything to anybody in the name of performance.

I guess Trex, this guy, is smarter than the Mazda engineers..........with their wind tunnels and cad cam stuff - even in 1990. Jeez, Mr. Chin, you really should check this out!

Tested to 150 mph? In your dreams.

If ANY of you guys buy this shit you
deserved to be raped!

HAHAHAHA! Talk about "cobbled"! Best laugh I've had in months!!!

Add me to the list of people interested in purchasing one.

I guess PT Barnum was right.

Ron, I thought you were all about some ghetto mods.
Trex, I can't see that lasting very long. As many times as I've heard something smack or scrape the bottom of my car, that fiberglass will just shatter.

Dood, I AM. But I don't try to pretend they work at 150 mph and then try to sell them to noobs. But hey, it's a free country and god bless all the hacks.

BTW, if you looked at my car, from ANY angle you would never know anything is Ghetto. (OK, maybe the exhaust if you crawled underneath)

I'm not trying to flame this guy, but you need to have somewhere for all of this "extra" air to go to make it work. Although my experience in aviation and laminar flow dynamics is rather limited to 22 years as an Airframe and Powerplant Mechanic and two plans built airplanes from scratch under my belt I still have a lot to learn.

Oh, what the hell. I am flaming him!

It's always funny to see idiots come to life on this forum. First of all, I do not claim to be smarter than the Mazda engineers, but then again, it's the same engineers that made the plastic ast that breaks apart and a precat that acts like a turbo heater. That been said, I'm sure there will be plenty of people with nearly a decade of experiences on the FD who will love to support your devotion to the perfect Mazda engineers. Oh have you also told Pettit how stupid their aluminum ast is yet, or Greddy for their rediculous one piece elbow. Is
The stock air channels in the belly pan was designed to provide sufficient airflow for STOCK configuration and nothing more. As anyone who have done the fmic mod will tell you, there is sufficient increase in the airpath resistence that the stock radiator position will no longer provide enough heat dissipation. Therefor, one common solution is to move the radiator to a vertical position, as required by all FMIC kit manufacturers (Apexi, Blitz, Greddy etc.) or are they all stupid as well, since they are tell you to move your radiator, contrary to where the Mazda engineers have placed them? For those people who prefer to leave the radiator in the stock position the reduced air flow is now a problem. The solution, increase airflow from below the radiator.
By the way, I hold a BE EE from MIT and MS comp sci from Princeton and currently working for Honeywell as a senior software control engineer, so don't tell me about "their wind tunnel and cad cam stuff", what is your almighty engineering background in making such a rude and crude rebuttal to the novice engineer?
I welcome any constructive criticism in my design modifications. That is how things get better, that is also why there is always an engineering team working on a design. Read through the original post and agree or disagree with each of the modification points, provide logical reasoning for the disagreement. But refrain from making juvenile comments on something you know nothing about.

I will answer your question. First, I had the car up to 150 mph, so has many others. I had to take the car up to that speed to make sure that there is no adverse lifting effect caused by pressure build up. And as you so fondly pointed out, I don't have a wind tunnel in my garage.
Second. If you bothered to read through the original post (line item 3.), the larger opening that collects the "extra" air is redirected through the larger (and extra) vents which are 5x larger in surface area than the stock vents, toward the radiator (isn't that the whole point of the exercise?)

As I have already stated, this is a PROTOTYPE, it has not been prettied up. There is such a thing called paint.

What does an Airframe and Powerplant Mechanic do? Design & engineering work, or is it the airplane equivalent of a general car mechanic?

Not sure what you run over. The prototype have been on my car for over two months and 1800 miles. I have driven over everything from the interstate to gravel. Given the direction of travel (since velocity is a vector, x being the horizontal running along the direction of travel, and y being perpendicular to the road surface) any object with enough force to crack the belly pan would have to come from extremely high velocity impact (lower velocities cannot create enough kinetic energy to inflict such damage). At normal highway speeds ~ 70-80mph the vertical velocity would be no more than 10~15 mph, that is not near enough force to crack the belly pan. I will however, concede to scraping, that is unavoidable. I have studied my own stock belly pan and I can assure you, there are plenty of scraps.

Although I applaud your efforts, I am always leery of mods that are done which may adversely effect the aerodynamics of the car at speed.

Driving the car at 150 MPH and noticing no changes in the steering or handling may give the impression that the car is safe with the mod at speed but what would really convince me is if you had some numbers on lift. I do not believe to measure lift a wind tunnel is required but it would require a fifth wheel with a device which can measure downforce(I am not sure what the name of the device is or how much it would cost to rent or buy).

[QUOTE]Originally posted by Trexthe3rd
[B]

I will answer your question. First, I had the car up to 150 mph, so has many others. I had to take the car up to that speed to make sure that there is no adverse lifting effect caused by pressure build up. And as you so fondly pointed out, I don't have a wind tunnel in my garage.
Second. If you bothered to read through the original post (line item 3.), the larger opening that collects the "extra" air is redirected through the larger (and extra) vents which are 5x larger in surface area than the stock vents, toward the radiator (isn't that the whole point of the exercise?)

Look man, I don't begrudge anyone doing prototypes of anything - it's all good fun. But just exactly what is the exercise here, more cooling? You can only "ram" so much air through the radiator fins, and then they cavitate and become less efficient.

Flow dynamics is a tricky and strange science, even with a wind tunnel and super computers.

I guess my problem is that you are quoting prices for your finished "product" already, and you are sucking along lots of guys in the process who think this will make them go faster, run cooler and be cooler - for a price.

But, like I said, I've got a lot to learn.

There is nothing but road construction, and chopped ass roads wherever I drive these days. When my car was new to me, I went over a few speed bumps that caught me off gaurd, and smacked the hell out of the frame rails. Everything was alright, but that would have been enough force to crack fiberglass.

I do not have the pressure roller for testing the down force differences between stock and my modifiec belly pan. I am also wary of the adverse effects on the aerodynamics of the car, that is why I could never agree with any of the other belly pan mods that have come along. I took the car up to 150, and felt no steering degradation. I have had slight wheel misalignments and caused the car to be wobbly at 120. This may not be the be all and end all prove, but for me (not planning on making too many 150+ runs down the interstate, not sure how many of you are?) it is sufficient.

I would have to say that all the track guys (and I thought you were one of them) are interested in any ways of keeping the engine temp down. All the road race guys see at least 140+ regularly on long straights.

To simplify, I can rebuild ANY airframe or powerplant, and re-certify it to the manufacturer's specifications or beyond along with any modifications. Airplane repairmen - "mechanics"- report to me and I sign off on repairs that are exceptionally technical or any thing out of the unusual. When you crash your plane and tear off both wings and motor, I sign the paper after it is repaired that says you can fly it again, with paying passengers on board.

I also consult with engineers and designers on the PRACTICAL aspects of modifications and structual components that they dream up.

I also fly their ideas to see if they work as they predict. They usually don't.

That's why airplanes look pretty much the same as they did 50 years ago.:cool:

[QUOTE]Originally posted by RonKMiller
[B]Please read through my post completely and understand it first before posting a question that is already answered. The modified belly pan is not ramming more air through the radiator, it is ramming air through the vent holes. It's primary function is there to makeup for the loss of airflow created by the installation of the FMIC. If you already moved the radiator to the vertical position then you donot need the modified belly pan. The increase in air flow from the modified belly pan is no where near the amount of air flow needed to cavitate the fans (think about it, a vertically oriented radiator can travel with more than 160mph air flow when a car is traveling at top speed). Again, the air is redirected at the radiator so there is less efficiency to begin with. If you are familiar with vectors you'll realize the resultant airflow (even with enlarged vents) are still much less than direct perpendicular flow.

Where did I say this thing is going to make anybody go faster? Please find it, and I will make a public apology and go hide in shame. The fact is simple, there are bigger air vents directing more air to the radiator, what do you think the result is?? I did quote a price for people who asked for it, they can and will purchase a product that has been tested if they want to.

I beg to differ, ever heard of the hopeless diamond.

I usually hit 120 max on the 1/4. The highest track speed for me was 158, I quess I'm just a pussy. Seriously, I wouldn't feel comfy with anything over that without a roll cage.

Yeah, but you wouldn't want your momma to fly it if the computer went down!:D

Hey look, like I said, I like prototypes and fun stuff like this, and maybe one day you'll make a buck at it, and good for you.

I don't care how many degrees you have from what institutions, or your level of schooling, what you have presented here is pure conjecture, subjective reasoning and hype.
It's not backed up by any of the science that you seem to revel in.
I just call 'em like I see 'em, and I've seen literally thousands of "improvements" on wing and airflow design that just don't cut it in the real world. Well, ok, vortice generators work, I put them on my planes.

Ya gotta' back it up with some real world evidence, and all I see here is another worthless ricer mod.

Sorry if I hurt your feelings, I really do think it's a great effort, and I applaud anyone who tries to come up with a better mousetrap. BTW, you really should consider vacuum bagging, it's quality is awesome and would be a perfect application for your design if you go into production.

I'm outta here - good luck.

I do believe that the temp reduction numbers were given in the very first post.

:confused: Sometimes I wonder if people ever read anymore.
What conjecture? I have been running hot since I installed my FMIC and left the radiator in the stock position. After I installed the belly pan my temp now runs 8-12 deg cooler (~190-195, was ~210). I tell you what, I'll take a picture of the danm temp gauge just for you.

How is this not scientific (Hypothesis, experimentation, results)? And what would you call "real world evidence"?

How is this a rice mod?? Is anyone else confused as I am?

This mod/enhancement does pretty much the same as airshields (temp drop wise I mean). You should make integrated airsheilds in to the final design and perhaps the temp might go down even more. It's really not that hard, I put airsheilds in my car in about 30 mins with out my car in the air (which was pretty good i think since my car is dropped pretty low, with the car in the air, i probally could have done it in about 10 mins). I made them out of scratch (just a couple of sheets of cheap ass sheet metal). Personnly I have seen a 20 degree F. drop in temp in my car so that with my stock radiator, I can maintain about 180 degrees all the time. The temp of course drops if I cruise faster then 60mph, usually it drops another 5 degrees or so.

In the finnal production version, how many layers of fiberglass will be used?

It's going to be two layers of fg.
I'm not certain of the air shield you are referring to. I have heard of people taping up gaps around the radiator to force more air through the rad instead of around, is this what you are referring to?

Yep, although im using metal plates.

Sounds like a fun job. I hope they ask you to test out some stuff that makes the jets *quieter* as they go in and out of my local airport :)

Here's a question for you-- occasionally while working on the car, I've been known to, uh, break certain fasteners. Let's assume I broke one of the bolts used in the suspension. Now, I figure that as long as I am replacing the part, I'd like to use something that is stronger and at least as corrosion resistant as the stock part. Lots of places sell "aerospace" or "mil-spec" fasteners, but can you suggest any suppliers that are reliable and would stock pieces that we may typically use on these cars? Is there any reading material that you'd recommend on the subject of fasteners, automotive plumbing, etc., that has good advice and is accessible to the layman? People often refer to one of the Carroll Smith books, but are there other useful materials on the subject? Thanks.

OK here's the problem I see in the pan. It looks from the pics that there is a gap between the front of the car and the pan. This means that the huge amount of air going through the nose of the car is going to flow out of that gap and go un used. The stock pan is made to force air comming in from the nose through the rad.The vents in the stocker are there for water to escape out of the pan, Thats why they are backwards facing.

Before you finalize it I have a suggestion!!!!! Its something I was thinking of doing to my stock belly pan but couldnt figure out a way of doing it that didnt look ghetto.....with the stock pan

With you building a pan from scratch it would be possible to build brake ducts into it!!!

Now that would REALLY serve a purpose and if you can build some good functioning ducts for the brakes into I'll prob buy one.

I was going to use the "excess" air that is routed out the back of the duct and basically just reroute it to the brakes, it lines up almost perfect to do this when its mounted to the car.

Just a suggestion

STEPHEN

A machinary's handbook should have the answers you need on fasteners.

I got the same (actually better) reduction in coolant temps by blocking the gaps between the frame rails and the radiator using the stock belly pan.

I won't poo-poo the design at this point but I hope you can buy them by the dozen because those things will be cracked constantly on the street, especially with all these guys on coilovers and lowered cars.

The book you are looking for is "Prepare to Win"; it has some metallurgy and failure analysis in it. I believe you can even get it from amazon.com. He also has a title specifically on nuts, bolts, fasteners and plumbing; just search with him as author. I think it's just Carroll Smith's Nuts, Bolts and Plumbing Handbook.

I would buy every book that man has written, I know I have :D They are written just for you, not over your head at all.

RonK: I'm considering buying this because my bellypan is ripped to shit.

Trex: I'm interested in the CF layered version.

And this one will last better???? Get a stocker. Carbon fiber, fiberglass, kevlar, I don't care. Not the right material to use.

www.aircraftspruce.com. Free catalogues and basic advice on fasteners. AN (aircraft grade) is over kill unless you are building a dragster or LeMans racer.
I like stainless stuff that you can buy at any specialty nut and bolt shop and often at your local hardware store.

Let's see if I can clear this up once and for all. The front edge of the upper vent plate is at the same location as the stock, the reason why it looks to be further back is because the lower lip has been extented by 2". There is more air being forced through the modified belly pan than the stock.
Last but not least, the vents in the lower panel is not there for water to escape out of. Those are negative pressure vents that exists elsewhere (the metal pan futher back) that creates a low pressure pocket due to the Bernoulli effect to draw out excess air build up and create down force.

An interesting suggestion, I have looked at the overall location of the belly pan with respect to the brakes. Here are the problems (technical difficulties):
1. If ducting is created to divert flow from the pan it will dramatically decrease the airflow to the radiator.
2. If the ducting can be created without reducing the airflow, there is more structural support mounting point for the duct (due to the relative proximity to the suspension components)
At this moment I can not see a solution to these two problems, if you can, please let me know. It would be an added benifit, but at this point I find engine temperature to be a much more critical issue than break temp.

Ummmm, yes and no. By stuffing or taping the gaps surrounding the radiator will force more air through the radiator no doubt. But I prefer not to go that far home made. The temperature changes are recorded with 90+ ambient conditions and wot runs (it was done in August). Not sure about you, how many people with FDs are running below 190 with a fmic and stock radiator location? With current ambient temp of 58deg F, my temp gauge is reading 175 under hard runs. If you can get this type of results, hey more power to you, stuff and tape away. There certainly would be a lot less complaints about over heating during the summer.

Quote:

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I won't poo-poo the design at this point but I hope you can buy them by the dozen because those things will be cracked constantly on the street, especially with all these guys on coilovers and lowered cars.

---

Again with the cracking issue. I have a 1.5" drop on Tein HAs and had it on for almost three months now (driven on everything from highway to gravel roads). There are some minor scratches on the bottom of the pan but no structural damage at all. I cannot speak for every possible situations that can happen out there, so I can only provide my own experiences. The epoxy resin we used is surprisingly strong and flexible to a certain degree, not as flexible as the stock plastic but is holding up quite well up till now.

Nope, no stuffing or taping. Built metal baffles that actually seal from the sides of the hole in the nose to the radiator sides, mush more efficient than "stuffing or taping" as the air never has a chance to go anywhere but through the radiator. In effect there is now a duct leading from the nose inlet all the way to the radiator core.


But I prefer not to go that far home made.


Are you implying that the thing you built looks like a quality finished product??? It is functional, sure. It looks like someone overlayed a stocker with tin foil and some cardboard patterns which they then laminated and butchered. Maybe I was looking at the wrong pics?


Not sure about you, how many people with FDs are running below 190 with a fmic and stock radiator location? With current ambient temp of 58deg F, my temp gauge is reading 175 under hard runs. If you can get this type of results, hey more power to you, stuff and tape away.


I don't have a fmic, but do have a stock radiator and race constantly here in Texas with 100+ degree track temps along with daily driving over 20K miles a year. 58 deg ambient is chilly, hell no you won't have cooling issues. Especially during hard runs. Don't gloat until you have tested when it's hot outside. Most people would consider hot at least 80 degrees, you know, when you have to wear shorts instead of sweaters.


Again with the cracking issue. I have a 1.5" drop on Tein HAs and had it on for almost three months now (driven on everything from highway to gravel roads).


Picture this. Lots of guys have stock belly pans beat to hell. How did they get that way? Probably from running into things on occasion, not on purpose, but it happens. A fiberglass replica is going to be the savior in this case? I would love to see that thing stand up to the abuse a stocker can handle, but fact is it cannot. I think your pan would be entirely useful on a tracked car, but for daily use on roads? Not going to make it.

DamonB
When you read my post please read the the entire content before responding.
As I have indicated in the previous post, the tests began back in August. Temps in GA range 10 the high 90's to over 100 (on one of the days tested it was over 104). The relative humidity is typically over 70%. The running temp under these conditions are from 180-190deg F.
As I had suspected you do not have a FMIC, which means there are no obstructions to the horizontal air flow path, so in that case it is a different scenario. In either case, you are certainly welcome to give out your design specs and instructions on making the baffle work.
The prototype is not pretty, and again as I had indicated in earlier posts, the finished product would have a better finish ready for paint.

The final analysis:
You must have been on a debate team before. You have a knack in selectively ignoring the entire argument, but concentrate on attacking the part you see fit.
I have already conceided to the fact the the stock meterial is much more flexable than the material we are using, and at no time did I claim our product can withstand more abuse than the stock (the savior?). I am simply stating my experiences in the testing period, period! Take it for what you will, the horse has been dead for days.
As someone have so politely pointed out in one of the earlier posts, by obstructing the airflow path and forcing more air through the radiator will achieve better cooling but will change the original aerodynamics of the car. I will stop here because it's just going to turn into a useless debate.

Hey boys and girls! This is rich.........You called ME an idiot in a previous post which I decided to ignore since personal attacks are childish and frowned upon by everyone on this forum including the Mods.

Yet a guy who went to MIT AND Princeton, (BTW, Princeton is the number one school in the country for academics, hands down) has an engineering degree and now works for Honeywell (probably as a janitor) can't spell three COMMON words in ONE sentence? I doubt if you even finished high school, let alone scored high enough on the SAT's to get into a community college:

"conceided" - you meant conceded.
"meterial"- you meant material.
"flexable" - you meant flexible.

Oh yeah, it must have been a typo on your part.

BTW, I never personally attack anyone, I just let you hang yourself, Mr. Rocket Scientist.

Did I say that I igonored your previous personal attack? UNITL NOW:

I contend, sir, that YOU indeed are the idiot, a liar, and lousy "engineer" to boot. Like I said, your "product" (the profit motive creeps back in again) is just another worthless ricer mod that will fall off in a couple of hundred miles.:bsmeter: