Since the right side oil cooler does not exist in the 4AT RX-8, can that spot possibly used to funnel ram air to the airbox somehow?

Perhaps a poor man's CAI or long-ram mod of some kind?

Thoughts?

...alright, not an appropriate place to open it up, but why is everyone so stuck on the idea of "Ram Air"?????

it doesn't do anything. there is no "ram" effect. without being in top gear at the bottom of the rev range can i imagine air coming into the "ram" oriface faster than the engine needs to suck it in anyways...

where does this myth come from?? who invented that stupid term?? 'cause there really REALLY is no ram effect.

what was happening in Formula cars of the late 60's and early 70's was that they were being used as the rear quarter of the car (bearing load, having the suspension mounted directly on them), and weren't being covered in fairings leaving the intake trumpets open to the air. the reason they didn't have fairings was the same as why formula cars started (and stayed) open wheel: to save weight (and it's only been recently, with the application of aerodynamic engineering and super-strong materials to racing cars that the open wheel configuration has been a significant detraction).

anyways, these trumpets, with little more than a screen stretched over them to keep small birds and stones and the like from getting into the carbs, weren't able to suck air into the engine as efficiently as they were designed to.
the reason for this was that the air they were rushing through was what they were tryign to suck in. because what moves the air is pressure difference, having the most positive amount of pressure at the mouth of the trumpet would help ingest the most air.

but while the engine was flying through the air at condsiderable speed, the pressure at the mouth of each trumpet is considerably less than ambient, because the air (basically) rushing overhead has its effective pressure reduced, and the faster the cars went, the bigger this effect becomes.

enter: the airbox. a huge "settling" chamber for air to reach near-ambience immideately above the engine to create that highly positive pressure difference. with the inlet small, forward facing (into oncoming air) the effect of air getting "squished" into the airbox is very very very small, with most of the benefit coming from decelerating the air inside the airbox to form an artificially ambient atmosphere right above the engine.

this is how they've worked from the 70's, and the way they still work.

Pontiac's "Ram Air" induction system i suppose would be a big culprit in spreading this term, where their system is nothing more than a cold-air induction system, just like all the other hood scoops from the muscle car days.

same deal with Acosta's gaping hole in the front: no ram air effect at all, it's just a low-temp air induction inlet.

so, don't bother yourself with the "ram" effect. if anything, just try and get the mean tempurature of the air your engine is ingesting lower.

sorry i rant on like this, i can only take this kinda stuff for so long.

That's fine. Find your happy place. ;-) Btw, I am NOT mocking you at all. You have a valid point. I used to work on ram air systems for on-board aircraft APUs.

Ok, removing the "ram air" part of it, I was thinking that the Rotary Extreme or K&N intakes gather their still air from the engine well, next to the engine. Nice and hot.

I was thinking that intake air could be gathered from the right hand side oil cooler intake, via dynamic pressure effects and drawn to the airbox. I don't want to dump the air directly into the airbox, but the area around it. Wouldn't that improve thermal dissipation effects?

Try and find pictures or diagrams of the stock intakes for both the 6-port and the 4-port engines, they already are very well designed Cold Air Intakes, with "ram-air-like" designs. Look for Canzoomers threads and others that have looked into the intake, they all agree that's very optimized and using cold air from the front nose.

Thanks neit_jnf. Yeah, I read those. But, I'm one of those "can't leave well enough alone" type of people.

Also, have to support my fellow 4AT owners, eh?

I also was thinking of the samething......

If you noticed the stock intake is closed off from the engine bay and is getting air from inside the bumper.

For a "real" cold air intake system you will need to place the cone of the intake outside of the engine bay and then run the pipe all the way back to the throttle body! Also you will need to put a "Water Waste Gate" somewhere along the pipe about 7"-10" away from the cone. So you don't suck up water into your motor.

This will give you a much cooler air to the motor, which will increase your hp.....

And yes I know that the K&N intake cone is to large to use..

But you can make the right modifications to make this work!

nose

Main Intake (Both Engines) 1

Main Intake (Both Engines) 2

Main Intake + Fresh Air Duct Above 5500rpm (6-port engine only)

As you can see, the stock intake draws cool air from the front where there's no hot components.

Nice Photoshop'ing! Very cool.

Is it really true that the intake is at 90 degrees from direction of travel? The other posts on this forum didn't mention that.

Thanks again!

Those are some preety cool pictures!

Wakeech: Thank you for bringing that up. I agree absolutely. Too many people out there have been brainwashed by GM and their damn "ramair" TA's.

Many people don't realize that a big funnel for air to enter isn't effective at all. In fact it hurts airflow. The funnel acts as a high pressure region since all of the air is trying to be crammed in. this causes alot of air to reverse and go around this inlet. A reverse cone would be better and this is why a chamber behind the inlet helps. What happens is that now the intake is a low pressure zone which helps force more air into the pipe from outside. As the air enters the pipe and expands into a reverse cone, chamber or whatever, it slows down. This slowing down pressurizes it to high pressure which is what the engine now ingests. This system will make more power than a simple straight tube to the front of the car from the throttlebody with a funnel on it. If you look at the design of the intake scoops on the bodywork of race cars such as formula 1 or Indy cars, they have a small opening that expands in area as it gets toward the engine. This opening is just placed in a spot that has unobstructed airflow to it. This allows the low pressure region to be at the mouth and the high pressure to develop behind it. Even the big hood scoops on the old muscle cars are shaped like this. Lots of people have it backwards. On race cars, a NACA duct doesn't even start to "ram" air into the engine until speeds of over 300 mph. Not even a Formula 1 car can do that. That is something that we only see in drag racing or land speed racing.

Not to be too offtopic, but I remember my ZX11 Ninja had a air intake on the front under the headlight slightly off center, and according to Kawasaki, at over 50MPH caused a ram effect for the air intake.

Why do I mention this? NO reason. Just rambling :D

That reminds me. Since the A/T does not have a right side oil cooler, why didn't Mazda put an A/T cooler its place?

those pictures were taken from a video/animation in the Mazda RX-8 Tech Highlights CD that I downloaded from this forum!

As for the A/T cooler, most manufacturers incorporate that inside the radiator.

Funny thing about those "Ram Air" TA's - my dad was a Pontiac saleman for a while and I believe that GM said the system only added like 5 hp at 120mph

Same goes for the 550 Marenello, but Ferrari claimed like 15 hp.

I posted this question in the turbo kit postbut I didnt see this one so I moved it to here instead. Do you guysthink that installing a turbo charger onto our automatic Rx8s would be redundant?

I would loveit if I could get the horsepower of my Rx8 up to the level of hp onthe 6speed stick Rx8s. While weare talking about mods for the automatic Rx8 I am wondering what if anything can be done for significant performance gains of at least 25hp w/o something expensive like a turbocharger or nitrous system.

Your best bet would be high flowing exhaust, a/f/ignition tuning and maybe a lighter flywheel (make sure it's specified for the 4-port engine). Wait for someone to come up with a piggyback like Canzoomer's or do it yourself with something like the Greedy E-Manage.

Originally posted by neit_jnf
Main Intake + Fresh Air Duct Above 5500rpm (6-port engine only)

It's a question I asked before and did not receive any replies on it.

What would happen if we open the VFAD by default? Wouldn't this increase volume of air and volume of engine noises?

I tried to get to that part but figured I would have to take the front off. Due to the lack of tools and time, I decided to see if someone else has experience with this. As for myself, the main purpose will be to make the car louder, the benefit of additional HP in the lower RPM's would be a bonus.

I thoughtI read on another thread that hp gains from exhaust mods on the 6 speed were veryminimal. It wouldnt be any different for the automatic wouldit?

Originally posted by TrAsHeR
It's a question I asked before and did not receive any replies on it.

What would happen if we open the VFAD by default? Wouldn't this increase volume of air and volume of engine noises?

I tried to get to that part but figured I would have to take the front off. Due to the lack of tools and time, I decided to see if someone else has experience with this. As for myself, the main purpose will be to make the car louder, the benefit of additional HP in the lower RPM's would be a bonus.

When it opens it effectively shortens the air intake path and this changes the resonance tuning. It will be louder but it will probably reduce your low end power somehow. (Key word: PROBABLY as in "I don't know for sure" hehe)

You hit it right on the spot with that one! The intake box utilizes a form of Helmholtz resonant tuning. At lower rpms, the engines demand for air is less (duh!). The size of the airbox and the length and size of the intake tube into it affect the airflow into the engine at a certain point. At a lower rpm, the tube needs to be smaller in area and longer. This effectively tunes the chamber at a low frequency. This all works the same as a ported speaker box. Longer port, lower tuning. Shorter port higher tuning. Larger port (area) higher tuning, smaller port lower tuning. Listen to your engine as your rev it up. The frequency of the exhaust note gets higher with rpm. Simple isn't it! At lower rpms, the box is tuned to give max power near the point that the smaller duct opens rather than lower in the rpm range. No point in power falling off before it opens. With this tuning, the total intake pipe area is smaller and the pipe is longer. This gives maximum benefit at a lower rpm. When the vavle opens the other pipe up, you now have a greater total intake pipe area and a shorter path for air to travel. This tunes it higher. Remember from above that more area and a shorter distance both raise the tuning point. During the design phase, Mazda had to determine how a short pipe and a long pipe together tune for a benefit since the airbox is not solely tuned to the short pipe but rather a combination of both when the port is open. FWIW: We all know that there is only the long intake pipe on the automatic cars but the auto has a longer pipe than the long one on the 6 speed which tunes that car slightly lower than the long pipe on the 6 speed. The short pipe opens at 7250 not 5500 rpm. With a 7500 rpm redline on the autos, there is no point in having a pipe asshort as the manual. The auto airbox is probably tuned around 6500 whereas the manuals in long form is closer to the 7250 changeover spot. If you run the port open, you may just serve to lose a little low end power but gain nothing anywhere else since there is no more airflow potential anywhere.

The aftermarket kits are seeing small gains because they have a greater amount of flow even though there is no actual tuning per se. The total open ontake port area to the intake box is smaller then the throttlebody so there is obviously a little more power to be had just be allowing more airflow in. I would rather concentrate more on leaving the actual stock airbox in place but redesign the intake tubes using a larger diameter and different lengths to keep the same tuning but increase the airflow. No one would even see it. I'm relatively confident that you would see bigger gains than any aftermarket companies cone systems. With a little measuring it would be very easy to figure out how to do this. Too bad I don't own an RX-8 or I would just go outside and try it.

In all honesty could you guys tell me if it even be possible to make a 38 horsepower gain w/our automatic engine w/o purchasing ridiculously expensive nonpractical mods like a turbocharger supercharger or nitrous system? The Canzoomer Stage 1 mod I have been reading about lately seemslike a great way to make gainsbut he said there is not enoughdemand from automatic owners so he has no plans to produce them for the automatic Rx8.

I have realizedthat the difference in price between a stickRx8 and automatic Rx8 is $1500. So Ive decided that if I ever do performance mods to my Rx8--this amount that I "saved" when I bought the automatic instead of manual is the minimum amount of money Id be willing tospend on modifications and upgrades. Id really love to boost the horsepower of my automatic Rx8 so that it would be very close --if not equal-- to the 235 hp levelof the manual Rx8. All I want to know fornow is if that goal would even be possible to achieve on a practical level.

Originally posted by JeRKy 8 Owner
In all honesty could you guys tell me if it even be possible to make a 38 horsepower gain w/our automatic engine w/o purchasing ridiculously expensive nonpractical mods like a turbocharger supercharger or nitrous system? The Canzoomer Stage 1 mod I have been reading about lately seemslike a great way to make gainsbut he said there is not enoughdemand from automatic owners so he has no plans to produce them for the automatic Rx8.

well, not that one chip is as good as another, wait a little while and someone, somewhere will come up with an electronic solution.

because of the heavily baised tune in this car's computer, huge gains can be found with just a modification of the brains, so once this comes along you'll see most of those gains you want, it's only a matter of time.

There are so many limiting factors working against making 38 hp more on an automatic car. It is always easier to make more power higher in the rpm range but the 4 port engine doesn't rev near as high as the 6 port engine. That is a big holdback. Making 38 more power at 7500 rpm is much harder than making 38 hp more at 9000 rpm. A retuned computer, intake, exhaust will probably get you close but you are really going to be pushing the limits. You would probably like the car alot more if it had more midrange power. You alo need to be careful on an auto that you don't change the way the transmission shifts. The Camaros would mess up if anything was done different to the mass air flow sensor of the throttlebody. A retuned computer needs to take into account the added power and where it is in relation to when to shift. Even if you get some more power out of that engine, it won't feel anything like the 6 speed engine.

Just for knowledge sake here is some info as to just how different both engines really are. Just thought some people would find this interesting. The 4 port engine has everything that makes it a more efficient midrange engine which is right where you need it for an automatic. Here's the difference in intake runner length:

6 speed
primary runners 19.8" (long)
primary runners 13.5" (short)
secondaries 20.4" (long)
secondaries 14.2" (short)
Auxillary 17.3" fixed


Automatic
primary runners 27.4" (long)
primary runners 14.5" (short)
secondaries 29.1" (long)
secondaries 16.5" (short)
Auxillary none


The long and short runners are the effective lengths before and after the VDI valve opens on the intake manifold. That is how it affects the powerband. The engine only "sees" the length up to that point. Note that the primary and secondary runners are siamesed before the VDI valve so there is a useful interaction over a much wider powerband when the valve is open. The above numbers only apply if you disregard the siamesed section and just measured from intake port to the first intake split in the manifold. The auxillary numbers are only the length to where both sides join each other. Before this number is irrelevant.

As you can see the runners are much longer on the auto which gives better low end power. An easy way to get more total power would be to shorten the runners on the intake manifold but now you will lose low to mid range power. The auto needs this range. The auto also has less total intake runner area than the 6 speed which will max out its potential much faster. After the air intake velocity reaches .6 mach in speed in the manifold, power will start to fall back off. The total area of the runners is a limiting feature. The port timing is also much less. Even the individual ports between the engines are different. Here"s another comparison.

Port timing: 6 speed
IN: OPEN: Primary port ATDC 3
Secondary port ATDC 12
Auxillary port ATDC 38

CLOSE: Primary port ABDC 65
Secondary port ABDC 36
Auxillary port ABDC 80

EX: OPEN: BBDC 50
CLOSE: BTDC 3


Port timing:auto
IN: OPEN: Primary port ATDC 3
Secondary port ATDC 12
Auxillary port ATDC -

CLOSE: Primary port ABDC 60
Secondary port ABDC 45
Auxillary port ABDC -

EX: OPEN: BBDC 40
CLOSE: BTDC 3



The port timing isn't even close. The primary and secondary intake ports aren't even similar. They aren't even close to the old 13B 6 ports. The exhaust ports are smaller on the auto. There are alot of things going against it in the power department. There is one more thing that is holding the auto back and that is the intake tube to the airbox. The auto only has 1 while the 6 speed has 2 of different lengths for tuning sake. The only one that the auto has is longer than the long tube on the 6 speed. This will again tune lower down.

Mazda worked pretty hard to get more average power out of the 4 port engine but the big sacrifice is top end power. All of these factors add up to make improving this engine in terms of ultimate power much more challenging.

Originally posted by rotarygod
There are so many limiting factors working against making 38 hp more on an automatic car. It is always easier to make more power higher in the rpm range but the 4 port engine doesn't rev near as high as the 6 port engine. That is a big holdback. Making 38 more power at 7500 rpm is much harder than making 38 hp more at 9000 rpm. A retuned computer, intake, exhaust will probably get you close but you are really going to be pushing the limits. You would probably like the car alot more if it had more midrange power.
As you can see the runners are much longer on the auto which gives better low end power. An easy way to get more total power would be to shorten the runners on the intake manifold but now you will lose low to mid range power. The auto needs this range. The auto also has less total intake runner area than the 6 speed which will max out its potential much faster.

Wow rotarygod thankyou very much for all that analysis! Anyway I think the auto alreadyhas terrible low to mid power. You really feelnothing until you pass 4000 RPM. Its very strong between 5000 and 7000 likeyou said though. I couldntimagine the low end power being any lower than where it is now. If onlythere were a feasible way to strengthen the low end!!

Butat any rate what you are telling me seems to be pointingto the idea that the automatic Rx8 has very limited mod potential unless something extreme and obvious is applied to the engine like a turbocharger. Unfortunately I seriously doubt Id be willing to make that typeof investment even though Ive read that turbo is supposed to work better w/4 port than 6 port rotaries.

It's funny how you aren't happy with the midrange power of the auto because the 4 port engine makes more power than the 6 port engine up to about 7000 rpm. If you had the 6 port engine in your car with the same redline it does now, you'd really hate it. An ecu update would probably be the best bang for the buck but finding one tuned around the 4 port engine will be tough unless it is programmable. Any ecu for this engine should be designed around more low to mid punch. You really need a positive displacement supercharger but obviously the price is out of the question.

Another thing to consider is that if any headers come out on the market that do show a gain, they will be designed for the 6 port engine and therefore have the most benefit at a range out of your engine's powerband. My header design that I have been planning uses 24" primaries for the outer 2 ports and a 32" runner for the center runner. This is assuming it will be for the 6 port engine and I can fit it in the car. I think I can get it to go. The 4 port engine is a little different with the outer runners being at a length of 32" and the center port runner at 42". That I can't fit in the car! At least not with the cat in its current location. See the design differences. The 6 port engine header is assuming not only a higher rpm peak but also a different exhaust port timing. These numbers should be close to actual but only dyno trial and error can confirm it. Anything you decide to purchase should be solely designed for the auto car and not the manual. Unfortunately it will be hard to find upgrades designed for yours since the amount sold is drastically less than the standards and a majority of the performance oriented people will have the standard.

The thing about the turbo on the 4 port engines is that they are far less complicated. I have seen some fantastic 6 port turbo RX-7's. When it comes to a turbo car, you can design the intake timing with a lot less port timing and install a longer intake manifold. This will help give the car good low end power and drivability. The top end is taken care of even though everything is tuned against it because the turbo can continue to force air in to the engine even after the intake manifold is out of its peak range. It is possible to have a turbo engine with a power peak far higher or lower in the powerband than the manifold and port timing were designed for. If someone were to use a properly tuned length manifold with a more aggressive port job, we'd have some really powerful engines that have less low end and aren't as driveable on the street in terms of fuel economy and emissions. A manufacturer wants max average horsepower but with reasonable expectations. You will never see a 1.3l rotary with 500 hp from the factory. It can be done but isn't reliable. While they could do a good 6 port engine with a turbo, the cost and expense of adding another component to an already complicated package is just too great. Also consider that while it may sound like a good idea to keep an intake runner/port on demand, the lower intake area will result in less total air going through the engine and greater turbo lag times. If you just had all the ports open at once, initial power may come on slower but once the turbo spooled, power would be greater everywhere up to the point that they would have all been open anyways. When it comes to forced induction, you are pretty much relying on the turbo/supercharger for your power production. They just like to keep it simple and who am I to argue.

I too thought the second slot for a cooler would be used for the AT fluid. As Mazda didn't do it, they apparently think that people who don't clutch/shift for themselves and settle for a lower power engine will not drive hard.
The AT is a modified version of an existing Mazda unit, so it probqbly was designed to operate without a separate cooler (I know, the previous engine would not rev to 7,500).

Very good thread this. Lots of good, honest information.

I think the CAI on the RX-8 is "best-of-breed" status.

And yes, ram air is a bit of a misnomer, especially on a MAF'ed engine. You need a gentle smooth flow of air over the MAF sensor to get a reliable reading. Most benefits of "ram-air" intakes on cars comes from the fact cooler air is getting to the engine. I have a performance/racing engine text book that a forward facing intake will give only 0.5 PSI "boost" at 100 MPH. That is not going to do much getting out of the hole, hey? What engines love is cool, calm, dry air.

Cheers,
Hymee.