That Lazy? It's like 10-12 bolts! Yes, Im that fukin lazy. I am always working on something... I like easy access to it. So Mazda was so far ahead of the game that they decidied to put it on only the RX7's ... and only a very small percentage of those at that. They dropped the whole idea on every other car they ever made. (or at least most, not sure on the FD)

I don't buy the other BS your feeding .. I have never seen a Porche, or a Honda with that crap covering their motor, stock. ... Not to say all models don't have it, but I have never seen it ... The other model cars you speak of I have never worked on ... but I am willing to bet MOST if not all the models those other manufactures make don't have it either.

Then lets go back to what i was saying ... it might be on sports cars for aerodynamic purposes... but it's not on all the other cars cause it's not there for cooling purposes! thus sports cars only. It would be on big *** heavy duty trucks long before sports cars if it was a cooling issue.

-Robert

 

None of that increases the oil cooling capacity, only it's flow. You still have less air flowing through it than there should be.
Common sense says you maker the stock system work the best it can before upgrading it. That means keeping everything Mazda put on to make it work better. You have reduced the airflow through the radiator, so you have reduced the cooling system's ability to dissipate the heat all that power has created. This is completely at odds with everything you've just said about taking precautions.
Traps heat? How's it going to do that? Air is supposed to move through the radiator, so the heat goes backwards.
Anything that smooths the flow of air under the body reduces turbulence and drag. Removing and replacing the undertray is a two minute job each way, and how often you you even need to do it?
Every car made in the last 20 years has had an undertray or something similar to ensure air entering the front of the car goes through the radiator instead of under it. This is just basic and obvious engineering.

Keep in mind the tray has to go as far back as the bottom of the radiator, so the RX-7 with it's long, low nose has the radiator mounted further back than most cars and has a longer tray as a result.

I can't understand why you wouldn't want something that improves the efficiency and capacity of your cooling system. That makes no sense.
Sorry man, but that's just nonsense, particularly since the turbo is much further back than the undertray. It's there to improve the cooling system's efficiency.

 

Yo,

I so want the aluminum bit now! Especially since it's on the Infini IV.

Junkyards, here I come!

Kevin
1989 GTUs "More undertray = Mo' bettah!"

 

Ah okay the front plastic panel you are bitching about was on over 180,000 FCs... I guess that is a small percentage...I guess close to around 1/2 of all RX-7 production is a small number...

I guess you have not seen many Front engine rear drive Porsche Products... Seen them on 929s, 951s, etc.

Go look at any new Lexus sitting on a dealer lot and tell me if you can even find one without it.

Hmm, the most reliable cars in the world have them... whats that say???

Trucks don't have packaging issues and are designed to be the cheapest build, most high volumn, products. In addition most trucks are not concerned about aerodynamic issues. So if you don't care what size the package has to be or aerodynamics, but you are concerned with build cost, why would you want that panel?

The plastic panel serves two purposes... it helps air flow for better cooling, and it helps airflow for aero dynamics. The alum panel that this thread was/is originally about only helps aerodynamics. It serves absolutely no other purpose.

You have an upgraded system, that probably would not have needed upgrading with the OEM parts working in correct condition. Seems like you shouldn't even be commenting on another part BS because it does nothing for your non OEM setup right now

 

There's nothing under there that you should need to get to often.
The FD does have one and so does my fiance's 626 and a mate's JC Cosmo. My HB Cosmo had one too. Hell, even my 75 Corolla had one.
Why are you so adament this is BS? We're not making this up just to annoy you. And it's not covering the motor, it's sitting forward of the radiator. Look under any reasonably modern car and you'll see that the manufacturer has used some method to ensure all air entering the front of the car goes through the radiator instead of around it or under it. It makes sense for both engineering and economic reasons to design something to as efficiently as possible, and in the case of a radiator that means pushing as much air as possible through it.
How much?
Answer this simple yes or no question. Do you think the plastic undertray forces the air to go through the radiator instead of through it? If yes, then how is this not for cooling purposes? If no, then please explain why not. If you're gonna argue this, you should at least have some reasoning behind it.
Have you seen where the radiator is located on big trucks? Yep, right at the very front...

 

when i was a little younger I worked at an oil change shop for a couple years. I saw the underneath of probably 60 cars a day 5 days a week. I would say, aside from trucks. at least 65-75% of the cars had some sort of underbelly pan. And even some trucks have them incorporated to skid plates. Late model blazers have them, 4runners have them. My old accord had one that I broke twice, My buddies Infiniti has one. Even crappy GM's have them. Alot of the times they are trashed, but there is usually something there in the form of underbelly pan.

 

I must not be the only person in the world that thinks this underbelly traps more heat then it helps to remove;

"NOTE:...Our radiator brackets attach to the same points as the original RX-7 radiator, but move the bottom of our radiator forward to a vertical position. The right and left brackets are almost mirror images of each other, except that the driver's side bracket has a wider wing seal on it's lower outward side.
...Part of the plastic underbelly tray below the radiator should be removed between the steering rack and the bottom of the radiator. This modification more area for the hot air exiting the radiator to escape the engine compartment." - Taken from a proven RX7 racing site.



"None of that increases the oil cooling capacity, only it's flow. You still have less air flowing through it than there should be." - NZ

You and I both know thats bullshit, anytime you increase the flow through a device that is air cooled, you increase the cooling. It's based on a principal of surface area.

You guys do what you want, I'll do what I want... I don't have the time to dispute your comments one by one.



-Robert

 

AS far as other cars not having the trays, this is not true. I have worked on miata's (mazda) and been under an m3 (bmw) and a corvette (chevrolet) a couple times, they all have it. The rx-8 also has one. If it didn't have the slits in it then I would think that it would trap heat but it has slits in it, works the same way as smoke in a tube, it will come out slowly on its own, but blow across the top it comes out much more quickly.

 

They are there for a reason!
They not only keep water spray off of the hot engine and componenets they force the air to flow through the radiator, intercooler and oil cooler. This is accomplished whether it is plastic tin or aluminium or carbon fiber. Its desing is simple aerodynamics by making on side low pressure and the other high pressure the air will always follow the low pressure path!

 

All the cars you mentioned are sports cars.. I am not disputing that sports cars have them (once again read above) That just reinforces my point that they are for aerodynamic purposes, not cooling .... If they helped cooling, all cars, trucks, mini vans etc. would have them. Not just sports cars .. (for the most part)

-Robert

 

Ahh jesus... now you guys are telling me this piece of plastic **** UNDER the motor is helping my intercooler on TOP of the motor? If anything it is hindering it by keeping much higher engine bay temps in the bay, thus read above the clip of the race shop that removed most of it to allow the bay to run cooler.


Crack=Bad

-Robert

 

And of course .. you guys do know I just like to argue with you fuggers sometimes. It adds a little bit of entertainment value.

Here is a question for you;

When you dyno your car do you do it with the hood open or closed, and why?


-Robert

 

It was a general term for any vehicle that my have a front mount intercooler it was added because of course because of the low pressure area caused by this pannel the air would be forced to go through the cooling devices listed above. Air would not naturally like to flow through there as there is resistance caused by the fins and such thus making it a high pressure area but if the area behind it is of low pressure then the air will want to go throug these cooling devices to get to the low pressure area even if there is resistance before it, because it's only other option is the high pressure area below it(if plate is there) and it won't go there!

By the way life does have it's entertainment value even without arguments... it's called BOOST!!!

 

iirc this aluminum pan is on EVERY european FC, or atleast was on every i have touched

 

"You and I both know thats bullshit, anytime you increase the flow through a device that is air cooled, you increase the cooling. It's based on a principal of surface area. "


Not quite true. The cooling medium is the air. Assuming that you don't change the heat exchanger, the cooling capacity is limited to the quantity of air and the temperature difference achieved by the air flowing over the heat exchanger. In other words - more air or colder air will increase your cooling. Not putting more hot oil through the exchanger.

Rob

 

They are on sports cars because logically sports cars create more heat than a "regular" car.

 

with the type of power you're putting down?

excuse me but power has nothing to do with it. It's effected by how fast you are traveling. That's the only thing that matters.

 

Please, do yourself a favor; Open the garage door a little wider when warming up your car.

You may now jump off the bandwagon.. ..

 

They obviously have a better grasp of this than you do. They quite clearly state that only the section of the undertray that extends past the bottom of the radiator is removed, leaving the rest of the tray in place for proper ducting to the radiator and oil cooler. Your example has proven what I've been saying.
No you don't. Simply moving a fluid faster doesn't increase heat transfer, and in fact it can decrease it because less time is spent in the cooler. You mention surface area, but you haven't changed the surface area of anything. Without changing the oil cooler itself, the only way to increase oil cooling capacity is to push more air through the cooler. You've gone in the other direction by allowing air to bypass it.
Hey, that's cool. You can do whatever you want to your car, and if you have no problems that's great. But you can't just start saying "the undertray doesn't affect cooling" and not even offer any sort of explanation for your thinking, especially when there are so many examples that prove you wrong. All I really wanted from you was a simple yes or no to my question and a reason for your answer.
The RX-7 has one so this is just for sports cars? Don't you think that's a huge leap in logic? Like I've already said, all modern cars have been designed to push as much air as possible through the radiator. Due to the shape of the RX-7's nose, quite a large tray is required to do this. Cars with higher noses that have the radiator mounted closer to the front may not need something quite as big, but there will be something there for this purpose. This is not a sports car thing.
Ever heard of a front-mount intercooler? They go at the front...
Do you drive along the road with your hood up? No, so if you want a realistic power reading you should dyno with the hood down. But most people don't want a realistic reading; they want the highest they can get. In most cars (especially modified cars with open pod filters) opening the bonnet will give a higher power reading because of the lower intake temp. There's no reason why the hood has to be up for power runs. The dyno's fan should easily provide sufficient cooling for a few runs. Tuning obviously takes much longer so the hood needs to be up to stop heat soak from causing inconsistent results.

Not that that has anything to do with the undertray...

 

My point here is that the intercooler is just like a radiator (more or less) except for air instead of coolant right? well. I compare the hood to the undertray. Both cover the motor, one from one side, one from the other.. with me so far? Your undertray you claim forces the air into the radiator, instead of around it .. for optimal cooling. Well compare that to the scoup in the hood on a TII, forces the air into the intercooler for optimal cooling. Yet, you are telling me bigger HP numbers, and a cooler intake charge are achieved with the hood up??? damn, imagine that .. the same type of item for the same purpose .. on oposite sides of the motor, but one is better to have open, the other is not?

I'm lost in your logic.

-Robert

 

If i didn't open the garage door i'd be dead in 30 seconds. My seven isn't stock.

Just admit you're completely wrong about aero and we can all move along.

 

Yeah!



What an awesome thread. No I'm not postwhoring here. I want to build a one piece panel to replace both of these panels. Who's with me?!? Maybe a sheet of fiberglass made from one layer of mat . . a 1-2 pound sheet to replace both stock ones.

Oooooh, and maybe another one to cover some other holes under the car . . mmmmm.

 

My comments were clearly about all cars, not FC's in particular. Any car with a TMIC is difficult to dyno consistently because you don't get proper airflow through the core with the hood up or down.

But since you brought it up, the hood scoop does work in a similar manner. Imagine what would happen if you removed the rubber seal between the hood and the IC. Air would leak around the IC instead of going through it, and intercooling would suffer. Same principle with the undertray.

That's the second example you've provided that proves me right.

 

Great idea. It'd be difficult to mount a completely flat sheet under there (the stock ones are heavily shaped to reach mounting points) but there's no reason it can't be done. I wouldn't use fibreglass though; it's not durable enough. Aluminium sheet would be better.

 

NO, you can't comapre that little strip of rubber to the entire plastic undertray ... that's not even a remotely decent comparison