ThePass

iTrader: (3)

VW Corrado maybe?

ThePass

iTrader: (3)

Does anyone have any ideas what kind of temps the diff is seeing in general? I'm looking at how much it might cost to put together a pump/cooler/lines for the diff. The Mocal pump I found is good up to 300 degrees but that sounds low to me..?

-Ryan

sixshooter

iTrader: (12)

I reduced my trans and diff temps significantly just by shielding my exhaust in the sections where they were adjacent. Even the factory exhaust is shielded from the trans, and we are burning twice or three times as much fuel as stock to make twice or three times more power (some of us). That is obviously going to mean more heat. Shielding is a must between the trans and diff unless you are just street driving, and probably a good idea for that also (Mazda thought so).

vehicular

iTrader: (3)

If you're getting over 300F, I think you've about destroyed a Miata diff or trans. Especially with coolers...

ThePass

iTrader: (3)

Good point. I was thinking brake and exhaust temps... had a brain fart and thought 300 was low for oils

concealer404

iTrader: (3)

Audi. S2/RS2 i think.

ThePass

iTrader: (3)

Here's what I have so far, mid-body section is done. It's 6 feet long, begins at the front subframe brace, so the opening in the front subframe around the oil pan is exposed - I think i'll leave it this way so there is some way for engine bay air to get out the bottom, and see how it goes. There's an aluminum section riveted in where the exhaust gets close to the undertray...

I don't see any place to put a NACA duct to get air to the diff - obviously from below it's just a big flat panel so you'd think you could put one anywhere, but the exhaust, trans, PPF etc. are less than an inch from the other side, the only place I can see the top side of a NACA duct fitting is behind the diff - which would only be useful for supplying air to a differential cooler.

Anyways, here's pics:





-Ryan

cordycord

iTrader: (2)

Right now we're trying to push air behind the radiator out the sides of the car--into ducts which haven't been made yet. Our exhaust is routed out the side, so the only thing I'm worried about frying is the bodywork, not the differential. A plate under the engine won't be placed until we have things figured out.

It would be easy to slot out a NACA duct in front of the pumpkin. The Catfish has an open space around the diffuser for releasing air behind the wheels, and it would work well to release heated differential air as well.

GeneSplicer

iTrader: (14)

As much as I hate to say it - I plan on wrapping the exhaust all the way back from the DP - AND adding coolers for both the trans and diff. I was going to do side exhaust until I saw in ST1/2 its a -.4 penalty - screw that, I can live with the extra weight.

I had planned on using aluminum - no plastic for fear of melting, which includes Alumilite - overly cautious? Also, with the GT kit coming, I plan to weld in jacking points that protrude through the undertray as it will extend all the way out to the runners. Anyone ever see an air-jacked miata? - that would be cool - but adds weight - not much benefit, unless I can't get my jack under the points. Sorry, strayed there...

Looking good guys, keep the designs coming!

k24madness

iTrader: (6)

My plans for undercar aero will have the exhaust exiting before the pumpkin feeding hot air into the diffuser. Wrapped exhaust from header back. Running E85 makes for cooler EGT's so hoping that will all work without cooking the exhaust.

I am going to seal the diffuser after the pumpkin and vent the trapped tunnel air through the floor and out the lic place hole.

I will also do trans and diff coolers to lower fluid temps to help service life.

The timing of this thread is perfect as it is my next project to tackle.

dstn2bdoa

iTrader: (18)

Crushers header and exhaust are wrapped to rear axle with DEI 2" header wrap.

ThePass

iTrader: (3)

If dedicated coolers for the diff and/or transmission are the answer, who has found a way to put together an affordable kit?

A small Trucool cooler is cheap: Tru-Cool Oil Coolers
I know it's not as efficient as the Mocal stuff, but I have the 24-row for the engine and it works well enough.

I would probably use AN push-lock lines, since I also use that for my engine oil cooler.

So that leaves the pump - anyone got ideas?

RPW has a diff fluid pump for $179, but I don't know how capable it is, and it has a small in/out (3/8 NPT) - they have a beefier version for $295. I'm sure it's not the case for everyone, but $500+ for a diff cooling setup is not in my budget..
Differential Cooler Pumps- Oil Scavenge Pump- Oil Circulation Pumps

Also, I'm assuming you just get an adapter fitting for the threaded drain and fill holes already in the diff to convert to AN. No drilling/tapping the pumpkin right? Just looking for confirmation on that.
-Ryan

ChrisGriffin

The Tilton Engineering pumps have been run on every pro race car I worked on. They do occasionally fail but not very often. There does not seem to be a better alternative. The pumps are noisy.

ThePass

iTrader: (3)

I'm actually pleasantly surprised by the Tilton's price. Expected $350.

Which model to go with? the 40-527 seems right - BUNA diaphragm for normal fluids, and designed for continuous use.. $195

This as well as some other pumps I've seen have 3/8 NPT threads - and all the coolers I've seen are 1/2" NPT. Obviously you can just use an adapter fitting, but are the coolers I'm seeing mostly for engine oil? Are there small differential-intended coolers with 3/8 threads?

-Ryan

jacob300zx

Dont forget to attach some tires spats to direct air away from those brick wall of tires, some garden edging would be flexible when it bottoms and it would eventually just self clearance. I think the key to a flat under skin is to keep the air under the car where you can manage what it does. Maybe try some rear spats that direct air away from the rear tire and channel into the diffuser. I think you could also see some benefit by attaching some plastic to the bottom of the a-arms. I believe Emilio had good gains the farther rearward he ran the splitter under the motor, would sealing it off not increase the efficiency of a cooper scooper? What would happen if you attached some 1.5 inch spacers to the bottom of the front fenders to create a gap allowing air to pass through and out near the leading edge of the door?

ThePass

iTrader: (3)

Directing the air away from the rear tires is definitely a good idea. I'll probably be adding spats like you suggested.

On the front tire I seem to see conflicting ideas out there; one is to do spats that extend below the splitter and block the air from hitting the front tires. The other version seems counter-intuitive to me: making the rear edge of the front splitter in front if the front tires actually curve upwards, channeling air into the front wheel well. I am still trying to figure out which is better.

On the front fender vent subject here is what mine look like now (I'm doing a lot if aero changes this winter):

But, I don't know how much engine bay air can make its way out of the front fender.. Im sure the hood vent definitely becomes more effective as the bottom gets more closed off, but I'm just worried about having a large enough combined area for evacuating the air coming out of the radiator...

-Ryan

exST165

slightly offtopic but: GeneSplicer, do you have any pictures or details on how you plan to do this? My rockers have rusted out so I'm interested in how you would structurally attach to the jack points.

Thanks,
Thomas

GeneSplicer

iTrader: (14)

Either weld in short tubular stubs down off the pinch welds, or come in from the side using jack pads as below - in either round or square inserts...

What are you guys using as fasteners for the undertray? Zeus fasteners?

ThePass

iTrader: (3)

I think that the best solution is weld nuts. I just did weld nuts in the rocker for my new sideskirt design and they are rock solid. Way better than a bracket. But, I went with L brackets for now just because they were easy to make and I didn't have to crawl under the center of the car with the welder. Currently using metric button head stainless allen bolts. I think I'm going to countersink each hole and switch to countersunk allens for the final version.

Most of my track bike is held together by Dzus quarter-turn fasteners, and I just don't feel confident in using them up-side down for the undertray, I worry about them backing out.. I did my brackets with a pretty big surface area on them so that I could switch to Dzus stuff later on if I wanted.

Here's the brackets that run down the center. It also mounts to two of the existing front subframe points, and brackets that I made on the rear subframe.:



-Ryan

gtred

This is how I managed my under-body and ducting on my old SPO car. I used a Tilton trans and diff cooler and ducted them from NACA's in the side windows.

I will advise that you use caution when using the trans/diff coolers with a sealed bottom, as I ran into problems with venting; the trans and diff overflowed and then dripped onto the inside of the sealed underpan. This eventually found the exhaust which was similarly placed and I almost burned her up!

Be sure to vent all possible leaks clear of the pan, consider a bulkhead/drainage for the fuel bladder should it rupture in a crash, and be sure to put in access panels to clean/ wipe down seepage should it occur around the trans/diff and cooling lines.