Intake Talk
 

Every forum including the rx8club i see talk about on the rx8 the stock intake is the best for performance.. is this true? if so why? I also see in the forums that the aftermarket intakes actually make you loose hp ? so someone please school me up on this. I found so many intakes for the rx8 but nothing really good on them. Besides people talking about noise.. i dont care what kinda of noise it makes.. i want to know which aftermarket intakes you actually get some power from.. and whats the deal with the stock. thank you for your time.

The only ones that have been noted (dyno proven) has been the Racing Beat REVI intake and duct. All the others have either been for no change or a loss. Just like the exhaust. Mazda squeezed as much as they could out of the Reni. So after market stuff doesn't really get huge gains compared with earlier rotaries. Generally this means you are changing for looks or sound more than anything else. Yes there are a few exceptions to this but this has been what has been found out over the past ten years of the Reni.

The stock intake is pretty much a straight shot ram air intake from the factory, not like other cars where there are expansion chambers and built in silencers to keep the engine bay quiet. Those chambers and kinks slow the air down, so those cars benefit from an 'intake'.

I did the intake box 'mod' from the RX-8 club and didn't notice any difference...at all.

Hell, reddozen here has a bridge ported Renesis and still runs the stock intake.

I don´t understand why anyone could take this as tragedy, disadvantage etc.
Stock paper filter has superior filtration than any aftermarket intake and doesn´t posses pressure drop at NA flow. SpeedSource GrandAM guys are supposedly using stock RX-8 intake element - on 20B peripheral port engine with way more mass flow than renny is capable of. Reason - filtration. Also, IIRC RX-8 intake is ducted and exposed to ambient temp, not engine bay heat....

If you want gain power on Renesis, concentrate yourself on exhaust system, heat management and tune. Healthy engine is essential

I got the RB Revi for mine just because I wanted to buy the car a new toy, but there wasn't a big improvement. As above, the stock system is well designed. Not sure why this is a bad thing.

But, so far the best performance for the $ has been the Cobb AccessPort. It would have been the first thing I did if I had known. (Although it's probably best to be having it tuned with my intake and exhaust on.)

so the stock intake is just a good design.. so the best thing to do is just work on keeping this cooler under the hood.. i have been looking at a few hoods. thanks guys

You can install the RB intake duct with the stock airbox. This is probably the best "bang for the buck" on intake. You won't see huge advantages on the dyno, but at speeds on the track or highway it will keep your intake temps down. I run the stock box w/ a k&n drop in.

Using an access port is definitely worth it, but in my opinion, its not worth the cost if all your doing is a drop in filter and catback. The stock tune will work well with those mods. If you've changed coils, aren't running a cat, etc... this is where the AP shines.

I'm probably going to add some heat deflection material to the intake box and duct to avoid as much heat soak as possible in the grid (I auto-x the rx8).

With full exhaust (headers, high flow cat, and catback) with the RB intake and duct and better Bosch coils, I've seen the reni make 194whp. Best power I've seen so far. I know others have posted up 200whp or more which is PROBABLY possible, but it would take a very healthy engine and the right combination of parts. That same rx8 making 194whp has an AP but no tune yet... I'm sure there is still some power left to be had... but 200whp may be a stretch.

I will be redynoing my 8 in another month so I hope to try a few different tunes to see how it works out...


Long story short, if you want big power in the 8... you'll need FI.

what kinda tunes to you use... is there a plug and play so we can do things our self?
i dont plan on FI any time soon.. but im going to do some exhaust work high flow cat and stuff.. but thats going to be later.. right now its intake.. and work on keeping things cooler for now.

Personally, I think the AP is worth the money if only for the reliability benefits of being able to lower the turn-on point of the fans, and boost the output from the OMP.

As far as tuning the AP, you can download the AccessTuner Race application and have a go at it, but, all reports I've seen/heard say the RX8 is tricky to tune properly and you leave the door open to make a mess of things. (And that long-term use of the maps Cobb includes is bad as they aren't very good.)
Love him or hate him personality wise (hoping not to get moderated here) but the only source for new RX8 APs is MazdaManiac, and he includes a 6 month remote tuning subscription with the purchase. (You send him logs, he sends you back revised tunes.) I've been happy with the process.
The baseline maps he includes with a purchase (no tuning required) will do the above of boosting the OMP and lowering the fans turn on point.
The other benefit is, I've picked up 3-4MPG on the highway with the refined tunes.

Agreed with the above.. and I should clarify that I think the AP is a great product, but not for the faint of heart if just looking for a few HP.

I do all my own tunes. I've actually tested all the tunes from Cobb and they are horrible (on my '04 MT). I can pull up the dynos on those runs if people want to see them.

Not trying to start anything, but there were members of this forum with me when we tested some of the MM base tunes and they too were pretty bad. Not trying to trash his tunes - its just that I would definitely recommend getting the tuning service if you decide to use his units so he can get it fine tuned for your car. Do not run around on the base tune, lol.


Also, for the OMP... I run premix. Its a preference, and yes.. the AP is a good alternative.

I premix as well. I'm paranoid. :)
(and I'm on v7 of my MM tune. I haven't had the time to really delve into learning how to tune it my self properly.)

I'm nervous about using the Racing Beat intake duct because it blocks off a portion of the radiator. It's my understanding that the RX-8 radiator is already perhaps not up to the task of cooling the engine coolant in hot weather and spirited or track driving, so I'm nervous about reducing the air flow cross section to the radiator by installing that duct.

From everything I have read, not many aftermarket radiators, excluding BHR's, has been able to show any improvements over stock; in fact many have proven worse, with the end result being the owner going back to stock. Racing beat does alot of R&D with these cars, some of which is funded by Mazda, so I would trust their products. All cooling issues I had were solved by making sure the sides of the RAD were blocked off, and thats here in Florida were the heat is miserable and oppressive, at 100 regularly.

the stock radiator is HUGE, its WAY bigger than any other stock rotary car's radiator. the cooling "problem" might need a different solution, like a colder thermostat, or ducting or something.

i say "problem" because the rotary actually gets better mileage, and lower emissions when its hotter. so just because mazda has it running a little warmer doesn't really mean its bad.

there is less margin though if something goes wrong

Speaking of intakes though... There may be a new option on the market in a couple weeks...

Just sayin...
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