mazdaexe

Thought I'd share.

Back in Feb 07, I was down at a track event. It was my first time down at a track with the air duct on.

About after 4-5 laps on the track, I noticed my thermostats started to go up. It went more than the half way point. So I slowed down and it dropped back to normal. Then whenever I pushed the car again, it started to creep back up.

I've been to the same track before, but did not have the air duct back then and it was during Oct 06. Weather was similar to the Feb event.

I went down to the same track again last weekend, weather was probably slightly cooler than it was in Feb and here are the things I did to the car.

1. Took out air duct
2. Replaced coils
3. Cleaned Revi air filter
4. Cleaned throttle body.

No more signs of overheating.

Thanx

eviltwinkie

Dont know if it was the duct...I was out on a "spirited" drive this past weekend pushing her really hard and I know she got pretty damn hot. It was about 80F outside and sustained 80-90mph avg speeds w/ rpms between 6k-9k...short bursts of 120-135mph depending on distance of straights and visibility...all for about 2 hours or so...at the end...the total drive was approx 6hrs total, however there was a lunch break so I did not count that in as the car got a chance to cool whilst we ate...

I didnt get anything "wierd" on the temp or oil gauges...but I noticed that towards the end of the run...wot would have a small hesitation for about 1-2 secs before power delivery started...on the cool down drive back into civilization I noticed that idle started doing something wierd...it would idle at 1k...drop to 500...start to stall...jump back up to 1k...over and over...about 30 min later of very easy driving on a highway (for cooling)...she was back to normal and idle was restored...

I have the AP pulley and I heard something about water pump cavitation at high rpms so I thought perhaps the underdriving would help prevent cavitation or instead was not flowing enough for adequate cooling...

I am starting to think that it may be time to get a new hood with some vents to dump some of that heat...

based on where the ram duct is, I would find it highly doubtful that it would cause any restrictions of airflow over the radiator...there was a discussion about an RX in australia that had heating issues with it on during a sustained high speed run, but it was also a single oil cooler version so I think its the limited cooling capacity of that car and not really the duct...

I also know a friend who takes his to the track who also uses the duct+revi and hasnt reported any heat problems...

mysql101

I don't know how it would cause the car to overheat... it shouldn't be blocking your radiator. I have an intercooler completely in the way of my radiator, and I don't overheat ... though I'm not tracking my car right now, so it's not a legit comparison.

Anyway, if it's not blocking the radiator, how would it be the cause of your car overheating?

eviltwinkie

One of the running theorys was that it changes the pressure dynamics of the car...so the high pressure zone that is created at the nose is changed due to the ram duct reducing the pressure and therefore limiting how much air is being routed in...again it was a theory from the aussies and while I could maybe see the logic its still a pretty hard sell for me...

Nemesis8

iTrader: (3)

I had an old front grille thread somewhere... Here it is, but does not have much info about airflow.

TeamRX8

iTrader: (25)

just FYI

your radiator gets it's cooling air from the lower center grille, not the upper center grille where the inlet duct is located

sosonic

There is another ram air intake duct from Odula

http://www.odula.com/page/frame.htm
(2nd type wide duct)
(2nd type wide duct)

It would not block your radiator if you think that's the problem. It was designed to fit with the stock air box though... An earlier version of the duct was tested, there are 2 versions of it--

https://www.rx8club.com/australia-new-zealand-forum-37/taka%92s-review-odula-ram-intake-duct-58857/ (Taka's review)

Odula type 1 as tested by Taka



Taka saw good results with the old version, so I would think the newer wider version would show more improvement.

If you really think its the RB duct, than its something to look at.

sosonic

I don't understand this theory. Please elaborate on this more.

The stock VFAD was sucking up hot air close to the engine for one thing. ..

I also don't understand how a high pressure zone in the nose is being created, with the stock (VFAD) system. Especially since the VFAD is like split into 2 parts and restrictive...

I thought that it being under the hood that it was in fact a lower pressure zone than what a ram air duct would provide. The hood/nose would be deflecting air and the stock system would just be sucking up multi-directional hot air which came in from the front grill, mixed with hot air over the engine, and swirling around in various directions.

I thought ram air intakes like RB and Odula would increase the speed and pressure of incoming air and focus it. Thus the whole point of their existence....

Note- Another interesting thing done by Odula was come out with a different nose design that could help the VFAD system get more fresh air....


They put "holes" in the nose so that more fresh and colder air could get to the stock ducts. Regular RX-8 noses don't have this.



The Mazdaspeed nose, may be a little more helpful with general air flow. But you can see the advantage of ram air ducts or the Odula modified nose. You can also see how Odula makes it hard to mount fog lights too...Hehehehe....

N10S

Here is the other thread that opens the questions about the RB ram air duct and possible overheating issues.

https://www.rx8club.com/showthread.p...heating+intake

I don't really have a position one way or the other at this point, but this is another similar example in question.

ZoomZoomH

iTrader: (1)

i have the RB air duct and the REVi intake, in 2 years' worth of track and daily driving, no overheating problems whatsoever

sosonic

Interesting point was combination of RB ram duct with stock box. The Odula ram duct was designed to work with the stock box. The RB ram duct was designed to work with the RB intake. The RB duct came out after the RB intake was made and was made to match their intake and not the stock box. In fact you have to do some "workarounds" to get the stock box and RB ram duct to work together.

https://www.rx8club.com/showthread.p...highlight=duct
( RB Ram Air Duct with stock air box )

Razz1

The CAI duct is not causing overheating.

Mazurfer

+1

eviltwinkie

OK heres what I know and how it relates. You get a high pressure zone "think air bubble" where the air smacks into the nose and is either deflected upwards and over...or down and under. The factory nose creates a bubble which splits the air such that you have a certain ratio of air flowing up and down. Obviously too much air being forced down and your car tries to get airborne, too little and not enough air is availible for cooling.

I believe that the aussies postulated that the introduction of the duct changed the zone "changed the shape of the air bubble" by subtracting pressure in the area...the duct fundamentally uses the high pressure air and routes it to the intake. This change in effect forced more air to go up and over the car reducing the amount of air availible for cooling.

This was the "theory" if I remember correctly discussed both on the thread and via PM.

Personally I dont believe that the duct would create such a difference as to actually change the high pressure zone in front of the vehicle enough to do anything. What also needs to be taken into account should be the speeds we are talking about and all the enviromental variables.

Your probably going to encounter heat soak or underhood temp issues well before the minimal change in the pressure zone is going to actually affect anything.

[Asbestos On Now...]

eviltwinkie

BTW, I just finished reading an article on that whale that exploded in taiwan a few years ago and how lots of people went to see the whale to "experience" its 5ft dong...

Those ducts sure do look similar to the pictures in the article haa haaaa....

RX-8 Whale Dong Duct....EXPERIENCE it!!

chickenwafer

iTrader: (9)

that's an...um....interesting duct. I personally think the inlet is too small

eviltwinkie

What I would like to see instead of this duct stuff is a hood which had louvers or a duct on it which routed air traveling over the hood down and into a thermally isolated box....

Punch a couple of vents towards the back on the left and right to get some underhood suckin goin...

Damnit...where's my dremel when I need it?!?!

ZoomZoomH

iTrader: (1)

that's what she said!!

rotarygod

I guarantee if you put a pressure tap to monitor air pressure at the front of the car that you won't see a difference either way.

One thing that street cars almost never do (unless you are Lotus) is to properly duct the radiator. Sure cars have large grille openings and the collers are behind them but we don't really have a true sealed air duct as race cars do. On my friend's RX-7, she had an aluminum duct made that completely sealed the area between the grille and the radiator. The 3rd gen RX-7 is notorious for overheating in city traffic. She is a driving instructor at a driving school. She can now track her car in the summer and not overheat. All because of that duct! When the fans are on, you can stick your hand a couple of feet in front of the grille and feel the air being sucked in. It works. I think more people should look into proper ducting. You'd be surprised at what it can do. The Mazsport cooling fan mod also works well at keeping temps down.

zoom44

the stock temp gauge in the cluster doesnt creep up. there is band of temp after operating temp it doesnt even show. then once it gets over a certain point(which i dont feel like looking up right now but i have posted it before- i think the band is a hundred degrees or so) it pops up and starts climbing again.

when the temp started climbing did you turn the heat on to see if htis would bring the temp back down?

that the temp was coming down by slowing down make sme think two things- something was blocking the radiator (paper/plastic etc) or more likely that something was blocking the oil coolers. of course you could have been experiencing the water pump cavitation but i would bet on oil cooler blockage

mazdaexe

I have heat turned on when I noticed the overheating, but it didnt help. Had to slow down.

Cant say that I took a careful look for any blockages, but from quick look at the grills nothing was blocking the radiator or oil coolers. and its not likely that paper/plastic blocked it for one session then fell off, cuz it happened to all my sessions for that day.

Thanx

sammytcl

iTrader: (1)

Hi Steven, get the mazsport cooling fan mod, it helps. The intercooler in my car sits lower than the RB duct. When I was tracking my car last Dec (without the cooling fan mod), it didn't overheat in any section. I was running 10psi all the time. With the cooling fan mod, I haven't track the car yet, but from daily traffic drivings, the water temp is lower 10-15 degrees. Let me know when you are going to track day next time.

Sammy

Edit: I forgot to mention that I have a Koyo rad.

CoupeM

I am on koyo rad and my water temp still hit 112 deg on my 3rd lap round sepang(malaysia f1 track)..had to back off for awhile. No revi duct installed yet.

ZoomZoomH

iTrader: (1)

^that's 112degree CELSIUS correct?

mazdaexe

Hey Sammy, im thinking about the cooling fan mod and also the racing beat flash.

Or does the racing beat flash already do the same/similar thing?