How easy is it to extract NA hp out of the RX8?
 

I am in the market for a new car and have the following list:

350Z-Lots of problems, very heavy, but has great looks and good performance.
S2000-Hand built, top down fun with good performance out of the box.
EVO8-Wow...great numbers, but damn could they make it any uglier.

Now the RX8-seems like it may be a compromise of those above. Better looks than the EVO, more room than the Z and just as much fun to drive as the S. But...the performance numbers are not as good as I would like for the money. How easy is it to get more naturally aspirated power out of the RX8? and..what type of problems (major) are people having, ie. clutch, tranny etc.?

Thanks for the input!

The easiest way to gain power will be ...

1. ECU , the highly encrypted 32-bit ECU is proving hard to dechipher & will take a bit longer before a plug-n-play upgrade is available. Worth getting when they are available. Should be good for around 10-25kW

2. Intake, already quite good for a production car. Should be good for about 5kW

3. Exhaust, the secret to NA rotary performance. Extractors are a must, then a free flowing exhaust such as the (pending) Racing beat system should net you 15-25kW depending on the muffler choice.


Remember this though, the previous 13B design was good for about 225kW (330HP) as a peripheral port race engine. very angry, very noisy, very peaky (power band starts from 6000). What the max power of the 13B-MSP will turn out to be should (in theory) be less than the best from the previous types

Canzoomer is (almost) shipping an ecu mod that gives 20-25 bhp more.

Looks like exaust/CAi will give 10bhp each ish.

From your 238bhp , without opening up the engine or FI I think you could get 280bhp at crank with the renesis.

Turbo will get ya into low 300's I think - probably not a lot more without opening up the engine.

As for problems:

Theres been a few dead engines (60?), either water in engine (seals?) or failed oil injectors which seize the engine.

Also there have been a few dead transmissions, mainly lead by Judge Ito who's managed to kill 2 so far (with 1/4mile powershift thrashing).

Thats it for major problems - and all under warrenty too.

The 350Z looked awesome the first few weeks of seeing it.

After that, seeing it every day, it makes me want to throw up...

Especially the white one that looks like a friggin bar of soap.

And the gold one that looks like a friggin bar of bronze.

I've looked at the RX-8 just about every day for six months, and it never stops looking incredible.

Get an RX-8. You never know when you're going to desperately NEED two extra seats!

While these type of increases sound tempting. Don't most void the warranty?

Yes. sort of.

Mazda would have to prove that the mod caused any problem.

So Exauhst shouldnt void warrenty, ECU updates/air intakes may (probably will).

But they couldnt refuse work on say a fuel pump if you have CAI fitted.

you guys that upgrade are braver men then I then

How is this? From my understanding the Renesis has some fundemental differences making it a more efficient engine then the 13b was while maintaining the same displacement. So it should be capable of superior power then the previous NA 13b.

From what I have picked up it is programmed stock to be very emissions friendly and these restrictions are hiding its true potential.

I've already replaced my exhaust for a slightly smoother ride and better growl. I've got my canzoomer mod on order too. After that some lower springs and it's time to make the carputer :D

I understand the warranty issues, but the exhaust and springs shouldnt be a problem for 90% of the service I might requiere, and I am prepared for anything else.


Weeeee!

Just for reference, 225 kW is equal to 301.7 HP (not that I care, but someone might.)

What type of increase in torq is predicted?

I'd suggest a drop-in high flow air filter as the stock intake system is very optimized (5hp), a complete high flow exhaust (header, straight pipe and high flow muffler) (20hp), and agressive air/fuel and ignition tuning with something like Canzoomer's Stage 2 kit or a programmable kit like e-Manage (30hp). Also, lightweight pulleys and flywheel improve throttle response and give some power because of less rotational inertia.

I believe the Renesis is capable of 300 hp at the crank in NA form without pulling the engine. Now, when the porting gets figured out it will be another story. :D

Keep in mind that rotary engines are capable of insane power levels (think over 500 hp streetable) with a correct turbo setup and porting.

You guys almost have me convinced...anyone tell me if the diff/clutch can handle the extra power? What about long term reliability with Mazda, this would be the first M that I own. If it becomes my choice

The previous NA engines from 1986-1991 RX-7s lasted about 150-300+K miles depending on internal modifications, driving habits (slow=bad) , and maintenance. Even when the engines did get low on comrpession, most were DIY rebuildable which cost ~$900 for the rebuild kit and mabey $100-$250 for new motor mounts & tranny mounts.

The transmissions last practially forever, but they do need new syncros every 135K miles or so.

The clutches were built with 250BHP in mind, and since HP will increase dramatically while torque increases mildly, any external modfications shoudn't overpower the clutch.

Anyone want to confirm this with realworld experiences?

The RX-8 is built from the ground up as a street/track sports car whereas the rally type cars are still sedan based. If you want the best feel, form, & function out there with 92% of the handling/grip of the 3rd gen rx-7s, the RX-8 is the only car to get. A few springs & shock upgrades will restore the full handling of the 3rd gens as well.

Another car I've been following is the Pontiac GTO, but that's still in the Cobra class and mostly likely won't have the RX-8s "I'm on rails, ultra tight grip/handling/feel" we've all come to enjoy from Mazda as the GTO is sports sedan based. Plus is looks like a luxury car. But if you want to hall lots of stuff/kids & go fast, it's roomy :D Doubt any of the owners will race them, just take them to the dragstrip.

If you haven't already, I'd test drive the RX-8 and some of the other cars. Try to find a dealership that might be near some curvy backroads. Atlatna's Jim Ellis dealership let us abuse a test car, and I was thrilled to experience & show my passengers what the RX-8 could do with the ECU set to "limit HP due to breakin."

I personally ignore the #s and read what the Road & Track type magazines like / don't like about the feel & handling of the car. Fast numbers are just icing on the cake, but if the car doesn't have purist sports car "I love curvy roads more than quarter miles" soul, it's a sedan to me.

Also check some of the "I drove the others & bought an RX-8" post. That will give you some idea of what people do/don't like the RX-8.

Here's one, but it may be a bit biased as he's an FD owner:

https://www.rx8club.com/showthread.p...threadid=17401

That's why I'm waiting for Mazdaspeed to bring stuff stateside. Then I'm getting the kind boys at Mazda to install them. Will cost more yes...but the warranty will stay in tact, and my ass will remain unharmed because I will not have violated my agreement with my girlfriend and step-father ;)

Well, they would only have to prove it if asked so in a court of law. In reality, all they need to do is claim that you are abusing the car and simply deny the warranty coverage.

Boy you too... My wife won't let me do anything that might void the warranty so I am waiting for Mazdaspeed as well ;) .

(If I missed the answer to my question while reading, I apologize ahead of time.)
I'm researching engines to power the 818C that I will be purchasing soon. One that just keeps holding my attention is the Renesis (I know, it'll need an adapter plate for either the Subaru tranny or a fwd Mazda tranny). I prefer to keep things n/a (I count meth as still n/a, and I plan on including it in whatever build I decide to do). With meth, compression, port & polish, cai, tune, etc., can the Renesis reliably produce 300 whp? I love the rotary engine, but I'll stick with the subaru boxer if it can reach n/a 300 whp for less $$$ and reliably stay that way. I will check around the site for more information and maybe post this question elsewhere as well.

No that would mean producing 50% more power than stock and Mazda didn't leave much on the table with this one. Porting doesn't accomplish much, higher compression rotors would have to be custom made, nobody has been able to improve on the stock intake and exhaust gains are marginal. Meth might get you more of a bump, but not 50% more. You'll have to boost it to get that goal. You could add a rotor maybe ;)

But isn't that also true for a Suby motor? You need boost to get big power increases.

Also this thread is from 2003, I wouldn't take it too seriously. The car was only in customers' hands for a few months at that point.

You could consider an earlier 13b rotary. The peripheral exhaust port opens up more possibilities for a very high strung engine than the Renny side port.

OK. Looks like it is true for both; the n/a EJ tops out at around 165-200, even with meth injection. How easy is it to find a 3-journal crankshaft or a built 3-rotor engine? For a car weighing in at between 1800 and 2k lbs, 200 hp is a decent amount if the Renesis could be at least tuned to there. What internals are needed for the rotary to remain reliable for a long time? I could be convinced to s/c it, if there's a good screw- or scroll-type (probably universal) that doesn't completely break the bank. (I know the 818 is a sports car, but I would like for it to be reliable and stay in the $25k price class.) I did see that this one was from 2003, but it seemed like one of the best places to put this question. Thank you for replying.

There is currently no known way to make a Renesis last the 150k miles with no performance degradation you've mentioned in one of the many other posts you've duplicated on this topic.

It's just not possible without having the ability to bend the laws of physics to your will.

On a DD car 15k/year car, I'd say you should budget ~$4k for a rebuild/reman every four years. You may get more or less use out of an engine before its performance becomes unsatisfactory but 4 years/60k miles isn't unreasonably high or low.

I could handle 60k miles. Even with my annual trip back west added onto my daily work mileage, I figured my average to be a little less than your 15k example. 200-250 hp is a manageable number. That's still roughly 10lbs/hp in the FFR 818, which is more than plenty for a street application and a lot more than most factory cars in the $25k bracket, according to autoblog.com's power to weight ratio article (he had the top 10 for three different price brackets: 25k, 50k, and 100k).

200whp is what a healthy stock Renesis gets you. Define "reliable". If you want 200k miles from it, the odds are not great. If you want it to start and produce that power for some years, that's fine. There isn't actually a lot of maintenance, just a few things that cannot be ignored. If I was in your shoes I'd get a freshly rebuilt one, so you don't buy previous owner's mistakes. There are no internals that make a difference in reliability, OEM is fine. The recommended/common reliability mods are ignition coils and an adapter to inject 2-stroke oil instead of crankcase oil, as well as premixing a small amount of 2-stroke oil in your gas. There is a lot of info in the new member section sticky threads because these are almost daily questions.

Building a 3-rotor may cost as much as the car :/. Also its a bit long, not sure how it would fit in a mid-engine car.

After NotAPreppie's 15k/year example, I did some math and 60k should be plenty reliable. even 50k miles would be around 4-5 years between rebuilds. The big question now (which there is a response to on one of the other threads where I asked my original question, and I will read that as soon as I post this reply), is if it can be had and paired to the subaru 5 speed for 7~8k. Even at 2000 lbs, 250 hp puts the 818 close to the same lbs/hp as autoblog's $25-50k price bracket.

Oh wow... A thread dating back to era of George dubya and Palm Pilots.