Finally. This motor has taken years of FI abuse and det. So surprised it lasted this long.

I will say that this confirms my suspicion that RX8 motors don't just blow. You have to do something stupid or on purpose. They don't just pop. And they last a good while even FI if you take care of your tune.

As for what it took to pop, it was a boost spike to 15-16 psi. Interestingly, I had recently heard a bit of det and have let off each time. I didn't fix the issue as I was a little curious as to how much it would take (as I have a new motor to put in.) Well, I was in a tunnel and punched it. I couldn't hear the motor the same. The car accelerated like crazy, but as I decelerated I could tell something was wrong. I looked at my boost gauge which shows a graph of the last ten seconds and saw the boost ran just off the graph, which ranged up to 15psi.

The symptoms were high idle vacuum, running rough, and a swish, swish sound coming from the motor.

I drove it a good 40 miles after the event and have it home. Gotta drop my new motor in now. I will have to really pay attention to my tune. Perhaps spring for some methanol injection.

An odd result of this is that the car now sucks gas, even more than before..

This event does precipitate two questions:

1) Why does boost creep over time? I had my boost set at 12psi with both my waste gate actuator arm length and a ebc. How did it get to 14, 15, 16?

2) Why does max boost increase at higher gears? In first I get no boost (this is common and explainable), in second I can maybe hit max boost but it is unlikely. In third, if I set max boost to 10, in fourth, fifth and sixth boost incrementally increases over this setting.

 

How long did this engine last? How is the new build different?

 

Wow, didnt make the connection with your screen name today i was the guy with the miata.

Just subscribing to see if the questions get answered. Good luck with the replacement swap! That 8 is too gorgeous to stay off the street.

 

1/ leaking or kinked or blocked hose ? Leaking actuator ? Frozen WG pivot ?
2/ Does not happen on mine so maybe refer back to 1

 

This was the original engine (2004, 36kmiles, 15kmiles FI) New build has lightened rotating bits and cryo treated internals and seals. Studded, polished and "street ported (which basically means polished)" Black apex and MS side seals. KDR build.
Very nice talking with you, I forgot to mention forum names. Sorry. It was great to meet you finally and I look forward to seeing you at other meets soon. Good luck on your own build!
It is possible that something in the boost control system failed. the ebc is several years old and was used when I got it. It is possible that something in it or the wg failed. Not sure at this point.

 

Hey man, its been a long time since I've posted on these forums lol. Sorry about the motor. I'm glad you were able to come out, and the car looked beautiful. The open house had a really nice turnout, I hope you had a good time despite the engine failure. At least you were able to drive it after the failure and didn't need a tow. Let me know when you get the new motor broken in, I definitely want to see it.

 

Sucks it blew up, but Dave at KDR is great and know what he's doing.
Good luck with the rebuild. Is your car at KDR now? I'll be up there sometime this week or next