RX8Performance Under Tray Review
 

Ok, I finally got around to getting this mod installed. I had a lot of things come up once I received the tray, within my family, and it delayed being able to install the tray. It is now installed and I am really enjoying it and seeing results!

First off, I received the tray packaged really well. The tray is lighter than I thought it would be with the coolers and fans on it. The material is very nice and the look of the coolers with fans mounted is pretty sweet. There is a notch cut out still for draining the radiator which was something I was wondering if it would have. There is also some vents. The screens on the bottom are nice and cleanly installed to allow air flow to the coolers. The wiring was all shrink wrapped and secured which is a nice thing to know and not have to worry about when driving in the weather or car washes. All hardware was included for the installation as well as new hose for the coolers. The holes for the side trays to mount to the under tray lined up perfectly and worked great!

The install was pretty much straight forward. You just have to decide what you are going to use the coolers for. I used one for a sec aux cooler and the other as a tranny cooler. In the pics below, you will see I had a pretty big tranny cooler in the front of the car. By using one of the coolers on the tray for the tranny, it allowed me to removed the front tranny cooler and allow better air flow into the radiator. The hoses supplied with the tray were more than enough to allow for the routing of these coolers to the parts of the car they needed to be routed to. The hardware also included the fittings needed to attached hoses as well as clamps, screws, etc. Nothing extra was needed to be purchased for this install.

One thing I noticed immediately after the install was the amount of air I could feel the fans pushing...I was impressed that the fans could push that much air for no bigger than what they are. My buddy who helped me with the install was impressed as well at the amount of air they were moving.

I have pics below through the install, the only pic I forgot to snap was one before I put the bumper on.

I have noticed a difference in the temps since the install of the tray with coolers. Before the tray install, on days with the temps in the 80's, I was seeing temps between 195-200 until the fan mod kicked both fans on. Now I am seeing temps in the 180's and havent seen it go over 192 yet. This as well on days with the weather int he 80's. As for the tranny, I was seeing temps in the 170's-185...now it ranges between 145-160.

All in all, the tray mounted up perfectly to every part of the body and side trays. The hoses supplied and hardware was more than enough to get the job done. prepping the car for what I was going to use the tray for and removing the old tranny cooler took longer than the actual install of the tray itself.

Also, I have pics showing the motor mounts I also purchased from RX8performance. The pics show them installed.

Here is the pics!

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Here is the old tranny cooler I removed
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I'm confused.....what are the fans for? Does the undertray block the normal airflow to the radiator somehow?

No, the under tray is under the car, not in front of radiator. The cooler in the pics that is in front of the radiator is the one I removed. The fans on the coolers pulls cold air from under the car up through the coolers.

Seems like you would want push fans. Wouldn't pull fans just pull the heat out of the new coolers and blast it into the stock rad? Push fans would take air entering through the bumper and push it out under the car. Haven't really put that much thought into it but it just seems like a more natural flow to do it that way. But maybe im missing something...

Sounds strange... If those are definitely pull fans, I would probably change them to push fans to give it a try. Even though you are seeing cooler temperatures, the setup probably isn't ideal and the temperature drop might be because of the better heat exchangers.

Can you give us feedback on the motor mounts?

The fans are pulling so that they pull the colder air from underneath the car into the coolers instead of blowing engine heat through them

The mounts are very nice! I used to have a small vibration through high rpms's but now since I installed these mounts, its gone. Also, the engine seems smoother if that makes sense. I am impressed with them!

^^ honestly, from an engineering perspective, I would be surprised if that setup did anything beneficial. First off, you are trying to pull a fluid running parallel to the fans, a fluid that has a velocity as your car speed increases, next, there is so much turbulance generated from the drilled holes under the radiators that it is creating so much pressure between the fan, rad and the tray and that sure as hell doesn't help the air get sucked in. The air will want to flow through the bottom of the car along the ground where there is less resistance.

the fans themselves will be more of a benefit during stop and go/low speed situations. That is usually where our engines could use some help. At cruise the fan will be less useful but just the presence of an extra cooler will be of help. And you are exactly right---at speed the air is flowing faster under the car and that causes a venturi affect that will pull some air through those coolers.
I think its a good product-- I would put a thermostat on the secondary radiator though.

It would create the venturi effect only if the fans are in a push (through rads) configuration, not if they were pull (through).

edit:

let me rephrase, it could produce the VE if the fans were on pull, but it would really only happen if there wasn't a mesh drill pattern under the rads, unfortunately the turbulence caused by that configuration would prevent any flow at speeds. Now if that mesh pattern wasn't there then yes, i could see a significant flow being pulled up through the rads, but for obvious reasons they cannot leave that exposed.

With the fans in a push configuration, during speeds you would expect the fluid air to flow around the car top and bottom, but also some air would get fed into the 'mouth' of the bumper where it would then get pushed through the rads then accelerated through venturi when the air meets with the air passing through the bottom of the car.

but regardless, like you said, it's benefits will be shown when at a stop so these assumptions are moot.

I have noticed cooler temps significantly when driving and also when sitting in traffic. We can all sit here and say "well if it did this...or if it had that...or whatever" but the proof is in the pudding...and the pudding being the temp differences shown on my scangauge of the water and tranny temps of before and after ;)

you haven't really proven anything except that these two radiators in particular have better cooling capacity than the oem one. If you want actual proof of how effective everything is, remove the fans and drive ... I bet you that while you are driving the temps are going to be no different than when you had the fans installed.

edit: and by "remove fans" that doesn't mean simply disconnect them from a power source.

If you think about it...whether it is push or pull you will effect the airflow over the radiator...you either push air through the coolers that came in the front...or pull air in from underneath that will be heated a bit..and then go through the rad...either way there should still be a net increase in heat leaving the system.

From my perspective the fans will provide lots of extra cooling when stopped...and likely not do as much when driving. If there was an easy way to do it...turning them off when moving would likely be a good thing

Paimon...then with what you are saying...the fans running or not running when driving down the road makes no difference and the fans running when at a stop helps. So why are you complaining about the fans again??? The tray is working great for me and if you want a tray but dont like the fans, then guess what bud...you can order it without the fans ;) As for my setup, I am very pleased with it and its staying like it is.

Likes to complain ;)

Got ya ;)

thats my point too--the fans aren't usually on while you are cruising down the interstate.

Dont under estimate the effectiveness and importance of the stock cooling fans for at speed cruising. Dont believe me, just try disconnecting or removing them. I have and the car overheats, even in mild tempuratures and loads.

As far as this under try with cooling fans, I would like to see them push and have louvers on the bottom side to smooth out and improve the air flow. I am sure the fans inturrupt the radiator air flow a little, but the stock cooling fans keep the air moving in the right direction.

If someone gets this without fans, you should use louvers on the bottom and some sort of scoop on the top.

Thats my 2 cents. As the OP says, it works great for him and he is very plessed. To be honest, unless you test the different setups with fluid dynamics computer research and or wind tunnel testing, we are all just guessing at what the airflow will do and what is or isn't best.

I got to see one of those panels with the fans last time I was in Tampa at Scott's shop. How did you wire the fans? Did you set them up to always run?

I just read the product description it says they come wired plug and play. Can you elaborate on that? I wonder how well they would work as an intercooler since most block flow to the radiator.

It has nothing to do with complaining, first off I have no reason to complain and could care less either way. No need to get uber defensive, but why bother posting a "oh this works" thread if you cannot handle when someone questions the actual effectiveness of a product.

I am not going to get in a shit throwing debate here, but I suggest taking some time to read a bit on fluid dynamics and what is really happening in that particular system.

I am not at all saying hte product works, doesn't work, was worth it, wasn't, etc, so lets chill out out for a second and actually read what I am saying:

What PART of this setup is actually providing the benefit. I can GUARANTEE you that the tray provides ABSOLUTELY no benefit to the setup, and is actually HINDERING the true performance of the radiator and fan setup. Why? The drilled mesh holes on the bottom of the tray. What I am saying is that consider what is really happening when you are at a complete stop and the fan is running ... do you guys really believe that you are getting efficient flow of air through those holes? do me a favor and take that tray, turn it upside down, place a garden hose over it, and turn on the water .... turn on the fans now .... tell me what happens and you will figure out exactly what I am talking about.

you are happy with the product that is awesome, and I am happy for you.... some of us throw parts in our car and assume that each piece of it provides a benefit and nothing can be improved in that system ....

......You don't obviously know what the "holes" the rad sits on are. They are not some small round holes drilled in the undertray. They are holes that basically are the full size of the auxillary rad with a mesh screen to protect the rad fins.....there is very little resistance to airflow introduced by this...so you are "GUARANTEE"ing something you don't have a clue about

You also seem to forget that in the real world...results trump theory. If you actually understood what you were looking at...you could even get your theories to align with the facts. Where do you think all of the theory came from in the first place. From observations of the real world

Really...all that counts is that there is airflow over the radiator..the direction and even to a small extent the temperature of the air is secondary to the delta in temperature

So unless you have access to a lot of very high end modelling software, a very powerful computer...and a ton of money......the empirical observations are as good as it is going to get

yall are forgetting one major thing. The coolant that this set up uses is NOT coolant that goes through the oem radiator. It is coolant that is supplied by the heater hose which bypass's ever going through the oem radiator. Its it fed back into the coolant system at the thermostat housing. That means if your coolant is for example 200F at the top radiator hose--it goes through the radiator and is cooled to for example 180F--right? BUT, then it mixes right before the water pump with hotter coolant for the heater supply( 200F unless the heater is on) which adds heat back into the coolant that is being circulated through the engine. So ANY cooling of that heater curcuit coolant is of big help.

Paimon, I am not getting into a pissing contest with you either and didnt mean for it to come off as if I was. And I know when you post something up, you have to expect people to try and blow holes in it. I welcome that and its fine. Like I said...the numbers dont lie and I am pleased with the product and I have seen instant results. If someone thinks the fans are hurting something, then they can always order the tray without the fans. To each his own. I know I like the tray, love the results and not changing a thing about it :)

yes the fans are plugged into a fuse in the fuse box and kick on when the car is on. The wiring took literally 5 minutes to connect, easy as pie :)

Might also help keeping the interior cooler by reducing temps in the heater core. (If the aux radiator is put on the inlet side of the core.) :boink:

So Highspeed, how were your transmission temps during the Texas8?

My tranny temps were very nice. Last year when I ran stock, my tranny got so hot that the car was put into limp mode. This year, this never happened. My tranny temps, when being pushed really hard up hill with me paddle shifting and keeping the gear in 2nd for the climb and through turns, the tranny temps ranged from 205-230. Only once did it go above that, not by much at all, and that is because I was up the butt of another car, uphill, in 2nd gear about 6KRPM's and pushing it hard.

The temps on the car in all were a lot lower this year and not once had to back off or slow down or anything else to prevent overheating. I am VERY impressed with this tray and the cooling it provided. Would buy it a second time if ever needed :)

How do you figure that's very nice? Opinions vary but Typically anything above 220F and you are damaging the internals. So if you are exceeding 230F I would say that's not good.

I am hammering it to the floor and running through the heat, up hill, in second gear the whole time...yeah those temps are good. Now yes, anything on the water temps over 220-230 is bad...but we are not talking about coolant levels, this was tranny temps and on the auto, anything above 250 is bad. For my coolant temps, The highest I saw was 223 and that was only once...the rest of the time they were in the low 200's :)

Last year when I ran it, my car shut down in limp mode due to excessive heat in both coolant and tranny temps. This year, she ran strong the whole time and did great :)

As for cruising temps day to day...temps for coolant stay between 180-192 and the tranny is about 160 average. They both used to be a lot higher before the tray

Where are you getting your data from as far as what is good or bad for tranny temps? Just because you were not going into limp mode doesn't mean everything is ok. In the towing world on much more robust transmissions anything above 220-225F is damage territory. But if it ran good then that is freakin' awesome.

Thanks sir :) It was a blast and we had a good group. Missed the rest of you guys from down south. Hoping you make it to the next one :) Did you get everything in line and going good for the turbo setup? Is she alive yet?!

Good to know the system shows positive results.

For what it's worth, I think the fans are blowing in the right direction. Here's a thought process of why.

a) First, the only reason air will move through the main (or any other) radiator, is because of a higher air pressure on the inlet side than the exhaust side. (Fans help this airflow because they reduce pressure on the exit side.)

b) The stock undertray helps cooling by preventing the higher pressure air from getting to exit side of the radiator without going through it.

c) Removing the stock undertray reduces cooling at speed by lowering the pressure difference across the main radiator.

d) Suppose the rx8perf tray were installed with the holes, but without the fans or aux radiators. Net cooling loss as in (c).

e) Now suppose the fans are installed (without aux radiators), but with the speeds set to exactly counteract the air pressure from the plenum above, to the lower pressure air under the car. Net effect = zero.

f) Speed up the fans. The pressure in front of the main radiator increases, flow through it increases. Net effect = plus.

g) Now insert the aux radiators. The pressure in front of the main radiator remains the same. The air is somewhat warmer. Where is that heat coming from? The main radiator! The hotter the aux rads (and and consequently their exhaust air), the cooler the main radiator is. Net effect = plus (still).

h) Additionally, the aux radiators are mounted to a large piece of aluminum exposed to fresh air, which adds both convective and radiative cooling not present in the stock system.

Would the low pressure under the car be enough to counter the "suction" of the upward blowing fans? Eventually, but I suspect at speeds higher than reasonably achieved. However, cooling problems usually don't happen at high speed but rather at a stop or in tight twisties or steep inclines where power output is high and (air) speed, low.

Finally, I'd propose, rather than do an install w/o the fans, do one w/o the radiators and just the fans. I suspect that there'd be a noticable improvement in cooling from both the added air pressure in front of the main radiator and the added 'help' the airstream gets in turning the corner around the bumper to reach rather shielded upper part of the radiator.

YMMV

I recently installed Rx8 Performance's aluminum undertray also, but I was just replacing my factory one that had gotten all torn up and was providing NO airflow to my radiator.

The version I got has no fan and is just the aluminum sheet, weighs somewhere around 5 pounds (Way less than the GT spec) and I got it for a price that is less than the stock plastic one.

I was just curious on everyone thoughts? Do you think just the aluminum undertray by itself provides an noticeable gains over the plastic version? I have thoroughly enjoyed it so far though, definitely and upgrade from no undertray, :yelrotflm

Omfg! I'm starting to hate this forum. The amount of unresearched uniformed garbal. It's Fraken insain! Do any of you know s$@@, is this just a place to post what you think may sound educated to others beacuese someone who is cool said or did it,trying to get some street creed.

I joined this group and, really at first I thought a lot of people were d@&ks.
I now know this is not the case. Some are the same jackA$/ that rev at a light.
Was your last car an Acura.

See above^iPhone still suck

Maybe the nut on the iPhone should be adjusted.

If things are that bad just go away and quit complaining. We obviously don't meet your standards.

Ideally it would be tied to a speed sensor just like the radiator fans and only run them below some minimum speed when airflow is not sufficient on it's own.

For a rotary engine auto trans those temps are pretty decent You might be surprised how hot the manual trans and diff oils get in the same scenario if you ever took the time to measure them.

Yup, my last car was an Acura, how did you guess? If you have an issue with the information here, state the specific information you think is questionable, or get out of this thread.

Sometimes I think some people join this forum just so they have someone to bash on or talk trash too cause their life is pathetic. They try to be "hard" or acting like they are better than everyone else here to compensate.

Seph, glad you like the tray, its a great product. I have the tray with the coolers and fans and I am nothing but impressed and loving it. Good buy sir and thank you for posting up about it!

where did you get the undertray?

because i know that the mods dont like us linking the vendors page, i will try and spell it out for you lol...


are + ex + eight + performance.com

or even

"We drive a Mazda" ___ (performance.com)

...





I can spell out this one too:

Gee Oh Oh Gee Ell Ee Dot See Oh Em

Ronnie, just get an OEM tray, don't waste your money on that BS.

LOL :rollingla

lol see thats what i tried to avoid

why, it's what this entire thread is about?

yea, and its blatantly in the title lol