blackmount

I promise this isn't Passive Aggressive Trolling

I absolutely adore the RX-8, and I really do love Rotary engines. Currently my RX-8 is very healthy, runs great, Starts quickly, and had healthy compression test results at Mazda when I bought it.

Though I constantly dread what seems to be the norm for the lifespan of Rotary Engines, especially the Renesis which doing everything right still seems to be limited to 100,000 miles. As someone who suffers from mild Anxiety, this thought in the back of my head stresses me out.

I know RX-7 Folk get more, but it seems to be a bit of a subjective matter with limited details. Like Sure it still runs, but does it still make the power it use to?

Can you get a Renesis engine to last 100K miles? Sure, but how long will it continue to make factory like power, and run as if it were new? It seems to be about 30,000-50,000 from what I have seen.

I know the S2 Renesis has shown to have quite the improved life span, but still seeing Long Term owners taking their S2 in for Compression tests, and coming out with Low numbers and Mazda suggesting a engine replacement with less than 100k miles.

I drive alot, I enjoy putting miles on my car - It's my number one way of spending my free time. On the weekends I usually put 150-400 miles on one of my cars, Most of it is spirited driving.

Are there any Naturally Aspirated Rotary options that with proper care and maintenance, can get me 150,000-200,000 miles of use while retaining 75-80% of its power, that will meet or exceed Stock RX-8 Drive-ability and Power.

I am not really after big power, or even moderate power - in stock form, my RX-8 is plenty enjoyable. I prefer to spend more time Driving then Wrenching

All I want is to just drive the **** out of my RX-8

I am struggling to find a logical solution outside of swapping in a Piston engine.

I've got a 3.0L V6 in my garage that was assembled in 1991, Never cracked open since, has had 300,000 miles put on it (180,000 by me) with alot of track time, and heavily spirited driving mixed in there...

It still put down a solid 400hp with no mods except slightly bigger turbos, and an exhaust on 12 psi last year while being driven almost daily like it was nothing. That is the kind of reliability I want. I've considered using that engine (In Naturally Aspirated form) though it is a tad on the heavy side due to having 4 Cams, and a Cast Iron block with Factory Forged Internals so it would definitely impact the handling of the car.

Biased Opinions of Rotary Love aside, what do you guys think? I won't do anything until my Current RX-8's engine is completely dead.

9krpmrx8

iTrader: (46)

The logical solution would be to buy another car if you want long term durability. But a properly rebuilt Renesis by a qualified pro should last you 75-100k if done right and treated right. But there is always a chance with these that they fail even earlier than that. And a lot of that has to do with numerous variables.

blackmount

I have other cars I can drive, Problem is I own a RX-8 for a reason, and it is not because it was cheap, or looked cool. I personally have always LOVED the RX-8, and wanted one before they even hit dealer floors....So the Key here is keeping the RX-8.

I considered trading it off for something, Another 3000GT/Stealth, or selling it and putting it towards a Down payment on a 911 or a Lotus... but I would really like to just keep it as a forever car, and park it along side those additional cars in the future...

9krpmrx8

iTrader: (46)

Well if you have so many cars to drive then just drive it and rebuild the engine when the time comes.

comebackqid

iTrader: (13)

seems like you either
a. need to sell the rx8 and get a C5 or something
b. just drive and enjoy the car and quit worrying about engine failure.
c. stop worrying about things beyond your control do what you can to mitigate the issues and hope for the best prepare for the worst.
d.one or all of the above

blackmount

Depending on how much longer this one lasts That might be what I do - Then it depends on how long the second one lasts after that. It was replaced in 2009 at 59,000. I currently am at 93,000... bought the car in late June with just a tick over 84,000.... I'd really like to get to about 120,000-140,000 before I have to pull it - but I don't see that being case.

Also

996/997 S > C5

NotAPreppie

You're looking for us to give you a reason to do something drastic. I can tell because you're wringing your hands over something that isn't a problem at the moment.

Your options:

$5k for a reman/rebuild every 3-ish years (probably less often and less money but that's a worst case).
https://www.gossettparts.com/oem-par...e-n3y402200rv0

$10k+ for a LS swap (best case scenario if you do all the work yourself and are very, very careful with your parts selection).

$30k+ for a Porsche 996/997 S with unknown IMS status.

Realistically, even having to replace the engine every 3 years, it will still be cheaper to keep the 8.

blackmount

I am not so much concerned with cost as I am with Downtime, and the value of my Own time/labor

My Original Goal was a long term build of a very watered down 20B, that worked and ran as if Mazda put it in the RX-8 from the Factory AC and All, a very low power goal of 250-300whp would be all I'd really want out of it, but there would be a absolutely glorious sound behind it, and it would still be a Rotary.

Even if I do a Piston engine swap, the LS is last on my list of engines I want in this car, the only Reason I would even consider it is because of how easy the swap kits make it....

6B/6G Mitsubishi V6 is what I am leaning towards, or F22C if I use something with Pistons

NotAPreppie

Mitsu 6G engine? Mother of doG, why? LM4 engine, 799 or LS2 head, and a cam and you're close to 400 HP for under $2k in the engine. $2k for the swap kit and you still have $6k to get everything else done.
https://oppositelock.kinja.com/speed...und-1125469009

If you really want an oddball, high-reving, high-powered RX-8, step up to a big bore block (LS3, LS7, etc) with an LR4 crank and a better top end for a V8 that spins to 8000 RPM and can make over 600 HP.
4.8L Crank + LS3 Block: How to Build an 8,000 rpm LS Destroker - Hot Rod Network

I'd bet an aluminum (LS, LM4, etc) will weigh in the vicinity of a 20B and cost a hell of a lot less while making more power.

BigCajun

iTrader: (1)

If you want to be 'saved' from swapping it, then just accept the fact that an RX8 without a rotary isn't an RX8 anymore.
It's ripping the soul out of it, and then it's something less.

UnknownJinX

There are drop-key LS Swaps nowadays. They supposedly start from about 10k, but if you want AC it can cost more.

I don't see the point of a V6 swap. I used to have an Accord Coupe V6. The J35Z2 in that car is already pretty freakin' massive, and that was a SOHC V6. Most DOHC V6s are even wider. It will likely cost the same as a V8 swap while having less in return.

I don't really lose sleep over how much life my engine has left. Just roll with whatever happens next. If I need temporary transportation, there are always crapboxes I could buy for $1500 and sell for about the same amount of money when I am done.

UnknownJinX

Reminds me of this pic:



Just my opinion. If it's your thing then go for it.

blackmount

f It's not about power, and everytime I think of LS engines, I just get a bitter taste in my mouth - I really do not find them appealing in anything. That doesn't mean I wouldn't enjoy it in my RX-8, I just hate the idea of it, and it would be less meaningful to me to settle for an LS.

I like the 6G because I know them extremely well, I have a stock pile of parts new and used, They make excellent power with basic mods, even while Naturally aspirated. Also despite popular belief, they have always been EXTREMELY Reliable for me.

I'm not talking the bland and boring 200hp SOHC from like a 2003 eclipse though... It would be the DOHC 72 from the 3000GT/Stealth, or the 6G75 3.8 from the 05+ Eclipse (300whp with a flash tune and exhaust) or the 6B31 because it is a very very watered down 3.0L making decent power stock - It's also the first Aluminum block V6 Mitsubishi has made - It holds ALOT of power uncorked.... Like all of their Dakar Bred V6's

If I really just wanted horsepower, I would put a mildly built 4G63 in it.

It's kind of an acquired personal Taste.

It's a Solid Engine that I know and love, I would put one in just about anything.

LS Engines are just ew.

wankinit

Well I’ll tell you what I’m doing seeing I just popped my motor.
Buy another reny, when yours pops just swap it out and rebuild it.
I put 148,000km (not sure what that is in miles) in stock trim. Then I gave it a turbsky and it popped at 148,300.... but for those 300km she screamed like hitler, and was more fun than the other 148,000 I put on it. Just another option to consider!

Loki

iTrader: (1)

I think you're way over thinking it. The odds that it grenades one day out of the blue are no higher than the odds of any other engine grenading. The more likely scenario is it becomes harder to start until it doesn't start. That means you have time from first onset of symptoms to any actual downtime to make and execute a plan. The downtime of swapping anything else in there is significantly higher than just replacing the Renesis. As far as power, 80% of original is around 170hp, depending which original numbers you believe. It will drop that low around the time you start to show low comp symptoms. You will not feel it unless you're running timed laps. So relax and enjoy the car. You can always get a rebuilt replacement engine when the time comes.

And in the meantime, keep up preventitve maintenance to ensure longevity of what you have, even get a compression test to know exactly where you stand.

NotAPreppie

When the only tool you know how to use is a hammer, everything looks like a nail.

blackmount

I took it in for Recalls and a solid inspection when I bought it, also had a compression test done - I'll have to look at the results again but it was mid to high 8.X average on both rotors.

I don't expect it to grenade - I do expect it to die slowly. The problem is I would much rather it grenade after 70K miles randomly, then only run like new for 20-30K miles, and slowly drop power and starting ability for the next 50K miles

I don't disagree with this.


I am more than willing to give the Rotary a fighting chance.

I'd like to try Rebuilding a Rotary at somepoint, So that would probably be what I would try first, and so I can See how simple it really is (Or isn't). I can watch and read how-tos for hours on end, but it still won't do me any good, until I can physically touch it and attempt it for myself.

I understand there are stronger/better quality Apex Seals you can buy meant for Forced Induction - Any downsides to putting these in a NA Rotary? Will it extend life?

I see Non Renesis NA 13B's making RX-8 power, or more at the wheels - Is that a smarter/more Reliable route than a RE-building a Renesis?

Steve Dallas

Anxiety issue aside, we are all in similar boats. Most of us love the platform and the drivetrain and live in "fear" of eventual engine failure. We all have different levels of tolerance for the latter.

As has already been pointed out, an LS swap costs right at $10K, if you do most of the work yourself. Swapping in a Mitsubishi engine will cost more. If you can R&R your own engine, you can almost swap in 3 Mazda reman engines for that price.

Also keep in mind that changing the weight and location of the engine will drastically change the behavior of the platform. It will not behave like the same car. When it's all over, you may not like the chassis anymore, and you will be stuck selling a car that is worth nowhere near what you invested.

Having said that, K24 and Ecotec 2.4 swaps are becoming very common in the Miata world. Around 240WHP from lightweight NA engines. Might be worth considering.

9krpmrx8

iTrader: (46)

Yep even this K20 is putting down nice numbers.

blackmount

One of the better replies for sure, and a helpful one. Upsetting the weight balance is a big concern of mine as well. I don't want to be asking myself as I drive it, "Yes it's faster, but is it better?"

blackmount

Definitely do not want anything Turbo otherwise I would just REW swap it and walk away since they seem to be one of the more longer lasting Rotarys.

I love a good NA engine/build though, so I am pretty set on shying away from forced induction anything.

9krpmrx8

iTrader: (46)

A 13B-REW is long lasting? Take a look at a few of the REW swaps done and see how many have already replaced engines. Not to mention I have never known an FD owner who hasn't replaced an engine.

Loki

iTrader: (1)

This is not how it works. It will run and perform fine for the majority of its life and only toward the very end you will start to have symptoms. How long that life is entirely up to you. Your 8.x sounds good if its at 250rpm, so put your energy into maintaining what you have rather than throwing away a good engine.

9krpmrx8

iTrader: (46)

Or it could die from one day to another like my first engine and my first reman.

blackmount

As said above, I wouldn't be throwing away a good engine - I would be running it until the end of its days - Then decide from there.

What is "Fine" for the majority of its life is really a matter of opinion.

It may run and start well - but when its down in power significantly, that isn't exactly what I would call Fine or Reliable

This is from a 2009 R3 found here https://www.rx8club.com/rx-8-discuss...esults-266774/

I really wish We could have a power reference with these numbers to get an idea of exactly what was lost. If we were talking 10hp or so. No biggy, but I am betting it is significantly more than that.