Davs

My friend just rolled over 150k miles on his 05 rx8 6spd. Got a compression test to celebrate. Passed with ease. He has never redlined the car according to him. No premix or anything. Drives it "hard" occasionally to a maximum of 7k. I've never really believed the whole redline once a day to keep her happy thing so I didn't do it. Mine lasted to nearly 150k b4 she overheated in traffic and blew a coolant seal. Got her compression tested for giggles and passed beautifully. Lots of 8s in junkyards here I've found with over 200k. Even in automatic form! The 8s really do get a bad rep. Just some food for thought tho. I do know the theory behind the 9k carbon cleaning tho. Have done due diligence

mazdaverx7

iTrader: (6)

A lot of how long an engine will last is in how its maintained. With proper maintenance and care, the engine should last a long time. Sometimes you get an engine that was assembled poorly, and sometimes you get one that was assembled perfectly and will last. Many owners neglect their 8. They don't check the oil or change the fluids and ignition system components regularly. They just drive it like they stole it an once the engine gives up the ghost, they sell it or junk it. I buy those 8's and rebuild them. Glad to hear your friend has made it to 150k!

New Yorker

Good points, all. I've long believed the 8's checkered reputation is the result of legions of owners maintaining their cars the same way they've always maintained every car they've ever owned. Which is a recipe for trouble with a rotary engine.

Do note, however, that every new RX-8 came with a Mazda Drivers Guide that plainly states:

Buzz it.
"The RENESIS rotary engine generates linear power and torque that truly engages you at higher rpm ranges. Models with the 6-speed manual transmission redline at 9,000 rpm, while Sport AT models redline at 7,500 rpm. While the RENESIS rotary engine performs best in upper rpm ranges, an engine overrev warning buzzer will sound when the tachometer needle enters the striped zone."

I suspect this was Mazda's gentle, positive way of saying "this engine is not like other engines you're used to. Don't baby it! Rev it high frequently, not only for best performance, but also to avoid premature engine wear."

Alas, few owners probably read it. And many who did failed to get the hint.

Loki

iTrader: (1)

Those 8s in the junk yard, are they on original engines?

The rpm is not what's important, the engine load is. Rpm is just a side effect of engine load over a period

Davs

They were actually, atleast MOST of the ones we checked out. Some werent so easy to tell/was missing paperwork so disregarding those ones. We were looking 4 miata parts for lil brothers miata and found some 8s. I agree, and have seen that message before as well. I think it's more in moderation though I guess is what I was trying to get at. My friend as I had or meant to say frequently drove it hard but never really going over 7k. Maybe we've just got some lucky engines:P I'll take a trip to the 100k mile club and see if there's any similar results.

Davs

Good point Loki. I was actually thinking more or less maybe the heat was a slow killer of the springs and made it lose compression faster, or increased wear spinning faster. All just spit ball theory off the top of my head of course. Also saw something on jay lenos garage I think it was about a cosmo, he said something like "I've heard if u can keep these engines under 6k (or 5k) their seals will last forever" thought that was interesting to.

Davs

Just saw your post mazdaverx7 that's very true, and we can see PLENTY of examples of poorly put together remans in the 8 club alone. I've finally gotten my more piston headed friends to believe that rotaries will last with proper care and their failure is usually contributed to owner negligence

skc

A good long journey, track day or mountain run will do wonders in cleaning out carbon. Each time I did one the exhaust was nice and clean. I am sure the engine would be the same.

9krpmrx8

iTrader: (46)

The redline a day stuff is a truckload of bullshit. Carbon build up is from gasoline. Plenty of Renesis engines that were meticulously maintained have died from low compression, starting with my first one that was bone stock and died at 22,000 miles (130,000 miles ago) after roughly four oil changes. And everyone who has a well maintained RX-8 thinks their engine will last well past 100k, until it doesn't.

The faults of the Series 1 Renesis (and every wankel honestly) are from an engineering stand point and there is nothing an owner can do to overcome them and there is no hard data that proves premixing, etc. does anything to extend the life. Yes I am sure a lot of poorly maintained Renesis have died early than they should have but they would have failed sooner or later anyway. This is why there are only a couple of original engine cars over the 100k mark and only in the Rotary world is one or two cars reaching 150k something to brag about. The S2 Renesis is way better but we are still seeing low compression numbers in the 100k range of well maintained examples.

And a long mountain run isn't doing **** to remove carbon. Tear one apart yourself and you will see.

Davs

Lollll so true tho. Anything past 100k is icing on the cake. The carbon build up thing really does seem like a relatively moot point. Kevin at rotary resurrection even says that he's only seen like 1 or 2 engines in all the ones he's rebuilt that have TRULY died of carbon build up. If someone's really worried about that I'd say try water Injection from the start. My point about all this was tho to say that by babying ish the engine, my friend and i were able to get over 100k without issue of compression loss. I did look at the 100k mile thread and someone posted a similar finding. Of course that's only 3 people. Far to small of a sample group for any conclusive answers. Just putting it out there that I PERSONALLY don't think it's necessary to live and die by the 9k carbon cleaning theory that I see everywhere from here to you tube to reddit lol