RX-8 Buyers Guide: How To Hit The Apex Without Getting Clubbed By A Seal

Words By DT Contributor RyanM:

Man, I miss my RX8.

you’re a gearhead / amateur grease monkey with an engine hoist, there’s
no better deal out there right now in the sports car world than a first generation (SE3P) 2004-2008 Mazda RX-8 . Just go
into it with the right mindset and expect to spend $2k on the thing
every 10 years. And throw what you know about engine maintenance out
the door. They’re still a Mazda, so the components of the car are solid
– expect above average reliability from everything except the engine.

bottom line here is to go into the RX8 experience with your eyes wide
open.  Don’t go into it expecting an economy car and economy car
reliability.  Go into it expecting the reliability of an exotic, with
the driving dynamics of an exotic, and engine
maintenance costs (and frequency) of a Land Rover. 

The problem with the RX-8 isn’t the cars
themselves, it’s owners who don’t understand that owning a rotary is
different than owning a piston engine’d car. Thus, you can find low
compression examples that are still in great shape and fully loaded but
need an engine for pennies now a’days.

It’s an awesome car, think
of it as a heavy Miata with a roof and a back seat. I loved mine, I
only sold it because I had performed a few modifications and
realized it would never pass smog when I moved back to CA a few years
ago. As far as I know my former car is still in its 3rd owner’s hands,
and he’s loving every minute of it. He premixes.

is where I got most of the info (and support) needed to buy a slushbox equipped RX-8, (and do an MT swap) and if you
buy one of these that already has a manual transmission, good news, all
you have to do is pull and replace the engine which takes even less
time.  There’s also an RX8club FAQ that is probably a ton better than the
disjointed drivel I’m about to spew forth (and this one too.)

First off, forget all you know about piston engines when dealing with a rotary.  Here are some examples of the differences.

By design, these use oil, around 1.5 – 2qt per 3000-5000 miles. Here’s a video by EverydayDriver on youtube that talks about how they used almost 1/2 qt
of oil in one day of hard driving.  Oil is cheap, don’t worry about it.

2. The Renesis 13B-MSP (2-rotor, multi-side-port) Wankel engine burns oil as a part of the combustion process and thus, go through catalytic
converters like a MoFo – 60k is a good estimate if you premix.

3. DO NOT USE Synthetic oil.  Good for pistons, not good for Wankels.

4. Premixing 2 stroke oil or specifically designed Idemitsu premix actually helps these engines last longer.

A redline a day keeps the carbon away – carbon in these cars is the
enemy of compression..

Hot starting.  If the seller professes the engine to be “new” or have
“good compression”, a true test of whether or not the engine you have is
going to last more than just a year or two is to get the car good and
hot and turn it off.  Wait about 30 seconds to one minute, then try to
start it (as if you were filling up your gas tank, or running into the
store to grab something real quick.  If it starts right up, you’re
usually OK in the compression department.  But to double check / ensure
that you’re good, get a legit compression test.  Using a normal, piston
engine’d compression tester will not give you an accurate result.  In
order to gauge compression accurately, these engines need to be at a
specific temperature, with the rotors spinning at a precise RPM (or at
least normalized to that RPM by a rotary compression tester).

A word about compression and hot starting.  These actually start easier
when *cold* believe it or not.  I won’t bore you with the details but
the TL;DR version is that the epitrochoid shape of the rotor housing
expands and contracts with heat, and when it expands it pushes the walls
of the rotor housings slightly further away from the apex seals.  When
the seals are on their way out they out, they can no longer make contact
for long enough to ensure sufficient combustion.  Same is true but to a
lesser extent for the side seals.

8. 1.3L of
displacement is a bit misleading.  A normal 1.3l engine would return
favorable fuel economy and have low emissions.  The displacement of 1.3
liters is one thing, but you get twice as many combustions per
revolution – so it’s technically, for emissions purposes, a 2.6l.

You’ve probably heard me spout off about “the horsepower of a V6, the
torque of an I4, and the thirst of a V8.”  Yes, yes, and yes.  But when
you’re elbow deep in a flat out 3rd gear corner edging closer to 9kRPM
in one of these things that you’ve done all of the work on yourself,
none of that really matters.  These cars are an absolute scorching deal
right now if you’re handy with a spanner and you go into it with
reasonable expectations.  I would also budget for a copy of Cobb’s
Access Tuner – Race, and a Cobb Access Port to modify MOP tables and
suppress CELs from when you inevitably have to gut the cat.

thought is that the reason these cars have such a bad rep is that
people buy a 6 year old example for $4000 with a knackered engine but
they expect it to act lil’ like a 6 year old piston engine’d car.  There’s a
lot of misinformation out there, too. But there is good news though,
everything else is pure Mazda – brakes, suspension, steering,
components, sensors, interior, etc, all of that is good to go and
requires little maintenance.  If you get a Grand Touring, there’s all of
the amenities you’d expect in a $40k car, for under $3000.  Leather,
satnav (optional), 6spd manual, limited slip diff, TCS, Stability
control, heated power seats, awesome audio system, large sunroof etc.

As far as market references if you’d like
to focus on two distinct categories of RX-8 that would be a start.  One
category is the 100% running and driving examples that are either
obscenely low mileage OR had their engines replaced by Mazda during
their 100k engine warranty extension program (though there are a few
notable – and vocal on the forums – exceptions, generally there’s no
such thing as a 120,000+ mile RX-8 on its original engine that I would
feel comfortable relying on as daily transportation).  The other
category is the cars that need engine replacements.  Sub categories to
the latter can be buy a used engine, buy rebuilt from a reputable shop,
or rebuild yourself.  Don’t buy an auto.  Ever.  Unless you’re planning on doing a manual swap like I did.  The 2006+ auto had a 6 port with 212bhp. ’04-’05
autos had a 4 port that supplied 189-ish bhp depending on who you ask
and believe it or not, slightly more torques.  Typically the
6 ports have more vac lines due to the APV/VDI (the 4 port only has the
SSV). One way to tell would be to look at the dash cluster in the car.
Redline at 9k = 6 port, redline at ~7k = 4 port.

A quick scan of my local
classified produced a dozen RX8’s in the 80k – 120k mile range, all
Grand Tourings (leather, heated seats, LSD, sunroof, etc) all below
$3000, all needing an engine but otherwise in good shape.  For reference
2 years ago I bought a 2005 base RX8 that needed an engine for $500 and
some entertainment system wiring work.  I bought a JDM engine and trans
for $1200 shipped.  I drove it for a while and sold it for $5500.

these cars are awesome.  They feel like they rotate around the
gearshift knob, they can rev literally forever (though they stop making
power above 10krpm I’ve been told), and they are suuuuper smooth.

You can search any craigslist and find piles of cheap blown-engine RX-8s, but just for illustrative purposes, here are a few.

Here is a  2005 Mazda RX-8 automatic covered in Japananime style graphics with a grenaded engine and offered for $3,000 in Long Beach, CA.

The next one is a 2005 6-Speed  offered for $5,000 in Lakewood, CA with a nasty throw out bearing sound and cabin that smells like gear oil.

Here is a  2004 6-speed with “strong running 120k mile original engine” that doesn’t smell like gear oil, offered for $4,500 in Elk Grove, CA.

Here is a 2004 automatic with a busted engine, offered for $2200 in Oxnard, CA…but this is just a quick snapshot of cars — just head to your local list and find something cheap, it isn’t like you are searching for a stock STi or non-salvage title E36 M3.

If you can find a 6 port 6-spd Touring or Grand Touring car with a
toasted engine for under $3k, and a low mileage used-but-tested-good
engine for $1500, I’d say you got yourself a sweet deal for under $4500
that you can flog the beans out of for 3 or 4 years before you have to
think about hot start issues.

Speaking of hot starts, if you end up buying one of these ticking time bombs, you need to read up on the starter business here. TL;DR version — Look for the newest p/n, these starters spin at a faster RPM and can
stave off the dreaded rebuild (i.e. hot start failure) for a year or

One thing I forgot to
mention earlier is that these things will flood if you shut them off
after a cold start before the engine has a chance to fully warm up.  Or
they will flood on a hot start if you have really low compression.  To cook off the cat
they dump fuel in on a cold start.  If you shut it off before the engine
is fully warmed up, the excess fuel in the chambers will wash the oil
film away from the rotor housing surface (where the infamous “apex seal”
does its thing) and cause a low compression condition.

you’re going the used engine route, I implore you to have the
compression checked with a rotary compression tester.  I’m not going to
get into the intricacies of how they work because there are a dozen
youtube videos out there showing exactly what happens and why.  

you’re going the rebuilt route, 2 words: Rotary Resurrection.  Or even
if you go used, you can sell Rotary Resurrection your old “keg” (what
the rotary “block” looks like) which is what I did.  He paid for
shipping, and gave me ~$200 – 250 for my knackered old engine.

selling spares from the swap (duplicate pulleys, injectors, throttle
body, sensors, alternator, MOP, MOP lines & injectors, harness, ECU
etc) I ended up only paying $700 for the used engine.

note: sometimes you can get lucky with a car that the owner says “won’t
hot start” “just stalled on me on the highway” or floods… check the
model number on the starter and check the health/age of the battery. 
Even if both look new, check them.  While I was acquiring parts for my
swap I was actually able to daily drive the car after I replaced the
battery with an older (but still 100%) Optima red top I had laying
around and upgraded the starter to the latest and greatest.  I also
de-carbed the car a few times.  

Every now and
then you can get lucky and decarb these engines (much more involved than
just sticking a vac line into a can of Seafoam and bouncing it off the
rev limiter for a few minutes) and regain some lost compression. 
Carbon (due to unburned fuel + the oil required by these engines to lube
the apex seals) can over time decrease compression enough so that it
won’t hot start.

cars have timing belts you change out every 100k and if done at the
dealer will cost $1000 – 2000 (like my Audi…).  If you play your cards
right, you can get a good used replacement engine for that much dough — wring another 4 – 5
years out of it, love every last second of it, and sell it along for
about what you paid when you’re done.  But don’t go in expecting to make
any money.  And don’t go in expecting it to be easy (though it isn’t
hard).  I put myself through college (before I joined the military to
pay off my loans) wrenching on cars, so I’m fairly handy and I do have a
garage and full set of tools.  HOWEVER All I really needed to pull the
entire engine AND transmission from this car in under 4 hours was a
$29.99 100 piece made-in-China tool kit and a used $100 engine hoist.  I
think I had to buy one 22mm socket for the PPF bolts.  That’s PPF for
PowerPlantFrame… yep the same thing as in a Miata.  I didn’t even have
to discharge the A/C I just moved the compressor out of the way.  It
takes me longer to pull the engine in my Volvo and I’ve done that a
dozen times.

Lastly, if you’re ever down on
your luck and pissed at the car, check this video where they took an
RX-8 and put it up against a BR-Z/FRS back when the BR-Z/FRS came out. 
Even though it was a few years older, it actually held up admirably to
the Toyobaru twins… and providing you can get one in good shape just
needing an engine, it should cost you much less than a Toyobaru as well.

about it.  If you want to look at 1st gen RX8 vs 2nd gen RX8 that’s
fine but if you’re going to stick around  the $2500 – 5000 “all in”
budget, I think the 2nd gen RX8 will be out of that pricerange.

DT: Big thanks to RyanM for taking time away from his newborn baby to write this article and help save a few RX-8s from the junkyard. All images from mazdausamedia.com, except craigslist where noted.