RX-8 Preventative rebuild

I have been researching RX-8s of late. Based on their perceived higher reliability, my initial thought was to get a S2. I see them from $11k to $15k. Running S1 cars sell in the $4k to $7k range. From what I gather, most of the expensive damage to the engine occurs when the apex seals let go. Banzai Racing charges $1700 Renesis Level 1 rebuild. Would it be worth it to buy a high mileage S1 car for $4k-$5k and rebuild the engine preemptively? Of course you would be under-water on the value of the car but not by much. And you would have a fresh properly built engine in the car.

Yup.

or LS3

Or buy this:

https://sfbay.craigslist.org/eby/cto/d/immaculate-mazda-rx-rebuilt/6149618573.html

I thought Renesis Rebuild was pronounced "LS Swap."

In reply to alleykat:

Honestly, with the price point of rebuilt renesis engines plus the price point of RX8's, a fresh engine RX8 is an excellent choice.

The LS has plenty of power, if anyone could ever finish one.

I've only actually seen a couple of finished LS swap Rexes. Even those didn't crack the Canbus (didn't have working gauges, etc).

LS is fun, but not a simple match with the RX8.

I'm looking for another nice RX8. I'll be doing a fresh renesis, not an LS.

I'm putting my LS into my Miata.

As cool as the LS even LFX swap would be, I don't have the time and don't want to spend the money it would take to accomplish.

I want the RX8 to haul the kids around in and have fun on my 15 mile round trip commute. It will replace my E36 325i.

I also have a Miata (or 2). I have decided I'd like to do a K24a2 swap on one of those. I'd rather spend my money on that.

Keep in mind that while some rotaries expire due to broken apex seals (every five miles according to the internet at least), higher mileage ones suffer from similar wear as piston engines do. For those you'll need new housings as the cheaper refurb housings are often just reground and have too much clearance. You can't get oversized Doritos so you can't run an oversized housing.

A $1700 rebuild will not include new housings, in fact I suspect it's more like a reseal with maybe new apex seals. A full gasket set for a 13B or Renesis is at least a grand...

In reply to SVreX:

Psst, wanna buy one? Mine's still for sale, especially now that I bought the FST and the Mini.

If you are looking for the best reliability of a RENESIS an S2 is where you would want to be as you also get the upgraded transmission and slightly better rear end gearing, if you are lucky enough to find an R3 thats not beat to hell you also get a lightened rear sub frame, recaro seats, and bilstiens.

An S1 has a much better aftermarket if you are looking for something to tinker with, but you can interchange a good amount of stuff between the S1 & S2, if you happen to get one with a bum engine that can't be rebuilt a mazda reman from Mazda motorsports for an S1 last I saw was around $3k with a $1k core.

Biggest thing I can say is get a compression check before buying (need a special compression tester or someone who has done it on a rotary before) pay attention to hard starts on both cold starts and once fully warmed up hot starts.

Good luck, and if you find one in Central VA would glad to put eyes on it for you (or anyone for that fact!)

Edit: just saw you are in richmond, if you want to put some time in an S2 I'm in your neck of the woods.

JtspellS wrote: ... if you want to put some time in an S2 I'm in your neck of the woods.

That would be great. I will take you up on that for sure. I'm going to go look at a 2010 in CVille Sunday.

As others have noted, that rebuild price is contingent on basically nothing else being wrong with the motor other than seals and not even all the seals. Granted, if the car is running okay then that's probably what you would do for a preventative rebuild.

If you get into any of the rotor housings being damaged those run around $500 a piece at least and then you start adding in labor for that you are well past $2000, probably into $3000 as you probably end up into more parts that need swapping. Some friends of mine got a running RX-8 with low compression for $2k off some nervous sellers and ended up putting $2k worth of parts into it and they did all the work to rebuild it. If you have someone do it for you then that's probably $4k of rebuild, parts and labor. They spent a lot of time in the garage on the rebuild making sure it was correct and they have all the tools to pull the motor, disassemble, assemble etc.

I'm honestly not sure why you would do a preventative rebuild of an RX-8 at all though. If it has good compression you just run it, if it has low compression then you rebuild it, but there is no reason for a preventative rebuild. With the 8 you get some notice of issues before it blows an apex seal, usually a loss of compression causes hard starts and a gradual loss of power. Before you completely blow the motor you will undoubtedly notice something in that regard. The question then becomes how far did you let it go? Did you do damage to the rotor housings or not?

You can also just measure compression every so often to see where you are at, but if it is down on compression, no matter how far down, then that is where you do a rebuild.

The S2 fixes a lot of issues with the car to make it more reliable. This is why most of them go for twice what an S1 goes for.

If you're gonna get an S1 and rebuild then find the cheapest running one you can find that has the best low compression values. That way you can still say, compression is low give me a deal, but it won't kill you on rebuild costs. I wouldn't pay more than $2-3k for a low compression RX-8.

Common wisdom is that the S2s are better. Improvements aside, how do we know the S2s are that much better? I think we're mostly basing it off of internet hearsay. S2 also sold in much lower quantities, so less issues are reported and they're newer, so fewer problem have happened so far.

RX-8s aren't the most reliable car, but it's difficult to predict if the engine will become bad unless it's close to bad. I don't think it's a bad idea to pick up a S1 with a fresh engine. RX-8s are awesome in many ways (I have one), but recognize the engine could go. If you bought one with a low milage engine, I'd recommend going in with the anticipation of getting 3 years out of it, that way anything beyond is extra. :) In that circumstance, anticipate the car being down for a month for a new engine and renting/buying something to get around.

In terms of getting stranded, often the car is drivable with a dead engine. I once drove a RX-7 Turbo II for 3 months on one rotor. The fuel economy was poor, but the car never failed to provide transportation.

alleykat wrote:

JtspellS wrote: ... if you want to put some time in an S2 I'm in your neck of the woods.

That would be great. I will take you up on that for sure. I'm going to go look at a 2010 in CVille Sunday.

Ah boo, I'm working the next 7 days (12's on the weekends ) Shoot me a PM and we can arrange something.

With looking at the one this weekend just be sure if nothing else pay attention to the cold start and the hot restart, it can give you a good idea of what you might need to budget for if anything yet.

Also forgot one big thing, the ignition coils and spark plugs on these cars can do horrible or magical things.

Long and short the stock coils do not have external heat sinks so with the excessive heat a rotary puts out and the fact OEM location is right over the top of engine they have a habit of getting cooked and going bad around 30k with OEM, with a bad spark it can show up as low compression symptoms and sometimes people can get away with more mileage, so before a rebuild try new coils and plugs (which are also about a 30k item no matter the situation), this is why most people (myself included) go with LS/LT coil kits.

It's crazy and I wouldn't believe it if a Mazda dealer guy I know didn't tell me. Take one (1) RX-8 that otherwise runs fine, measure the compression hot, record, replace plugs and coils with updated part, run for 20-30 minutes, measure the hot compression again, note that it is now 20psi or so better and now the car actually will start when hot instead of just flooding to uselessness.

What you still won't be able to explain to me is how an RX-8 engine has compression too low to start at 80psi, but my engine has compression in the 50-60psi range on a Mazda tester and starts hot just fine...

In reply to BoxheadTim:

Maybe buy. Talk offline

Knurled wrote: It's crazy and I wouldn't believe it if a Mazda dealer guy I know didn't tell me. Take one (1) RX-8 that otherwise runs fine, measure the compression hot, record, replace plugs and coils with updated part, run for 20-30 minutes, measure the hot compression again, note that it is now 20psi or so better and now the car actually will start when hot instead of just flooding to uselessness. What you still won't be able to explain to me is how an RX-8 engine has compression too low to start at 80psi, but my engine has compression in the 50-60psi range on a Mazda tester and starts hot just fine...

Sooo true.

Upgrade ignition parts. Compression goes up.

Ignition not used in any way during compression test...

EefFiing weird.

https://youtu.be/M-uwAt2SL1c

Gqm Quinn has been building his shinka with reliability in mind,

motomad1 wrote: In reply to BoxheadTim: Maybe buy. Talk offline

Sure - feel free to PM me.

I had an S1, and did preventative mods for miles 110k to 140k, before the compression got down to 80 in the rear rotor and I sold it. It was slow to start when hot, and that destroyed my confidence for a daily driver, though it never stranded me. I bet it would have lasted longer if it had been in my hands from day one.

"Mods" are:

-Open mid-pipe (or clean cat), to keep backpressure low and the rear rotor cool

-Regular ignition replacement, or the BHR upgrade kit

-Rotary premix, on top of the OMP injection, which addresses the known oiling deficiency (see S2, which gets extra oil injectors)

Other than that, I'm not sure what else you can do. Perhaps water/meth injection, which turbo rotaries love. I run water/meth on my TII. Not sure what it would do for a renesis. It does keep the internals squeaky clean.

In reply to colinshark:

I've also upgraded the cooling system on mine (Koyo radiator + Pettit AST), but that's more normal rotary engine precaution.

"High mileage" on a S1 is a bit tricky to define, since quite a few of the 04-07 year have received Mazda refurb engines under warranty. My '04, for example, has just shy of 70k chassis miles, but the engine has 55k.

S2 engines were tweaked with different oil injection ports, so the housings are different.

To address your "preventative rebuild" question, I'd look at how many miles the engine itself has, service history, previous owner's driving habits, and whether it's an automatic. There's a grain of truth to the RX-8 driver's maxim, "A redline a day keeps the mechanic away!", as it exercises the SSV and injector staging above 5500 rpm. Carbon buildup is a rotary's nightmare scenario; it can develop into stuck seals, can flake off and be caught in a port, breaking a apex or side seal, and a broken rotor seal in a Renesis is pretty much a guaranteed housing / irons purchase.

Freshening ("preventative rebuild") could probably catch something about to fail, not necessarily in the combustion chambers. Water jacket seals had a bit of notoriety for failure in the earlier engines / rebuilds, as an example. It has crossed my mind from time to time as I crank away at this supercharger installation, to stop everything and send the short block off to BHR or Rotary Resurrection for a refresh. I don't have cold or hot start issues, but it is something I'm salting away a bit of cash for.

buy an S2. literally everything that is wrong with the S1 is fine on the s2. Even the recalls (except takata one) but if you want to mod it go with an S1 and go wild. but it sounds like you just want something to drive.

The only issue I had with my S2 was the clutch pedal bracket snapped one day in February, which was out of warranty by a few months (from the extended coverage by mazda for the known issue but yet refused to call it a recall) but one call to mazda and they warrantied it free and clear.

time is money, just save your self the time and spend virtually the same amount of money and buy an s2.