madcows

After reading MazdaManiac mention that his EGT runs a bit high since he purposely runs short dwell times on his coils, it got me wondering:

When the stock coils are going bad, causing the spark to be weak and leading to higher EGT, is it possible that at least in some instances this had been a big factor in destroying the seals (the side seals in particular)? And since we know the stock coils are pretty much crap, it leaves one wonder if this had accounted for a number of dead renesis rotaries.

Brettus

iTrader: (2)

carbon is the main cause of dead renesi

MazdaManiac

iTrader: (3)

Could you point me in the direction of that quote?

Coil failures cause engine failures through detonation induced by a leading misfire.

madcows

https://www.rx8club.com/showthread.p...Ts#post2993351

MazdaManiac

iTrader: (3)

I think you didn't understand what I was saying there.
I experimented with the dwell set very low to see what it would do. I wouldn't actually drive the car that way.

Easy_E1

iTrader: (2)

No.

olddragger

iTrader: (3)

is the failure rate of the oem coils because of the high rpm's this engine makes? If the redline was lowered to 7.5 for example would the oem coils be ok?
OD

dannobre

iTrader: (3)

^ That wouldn't be much fun

9krpmrx8

iTrader: (46)

And the leading cause of carbon is gas right? With this engine I am trying to stay with a good gas (Shell 93) only. Well, I'm gonna try anyway.

MazdaManiac

iTrader: (3)

Not really. They aren't firing any faster than any other OE arrangement that uses wasted spark (like the Miata did forever).

Exactly. Don't put gas in your car and you'll be fine.

Brettus

iTrader: (2)

E85 all the way - could be mothers milk for the rotary

9krpmrx8

iTrader: (46)

rotarygod

Oh damn that's funny! I've always said that gasoline is the dirtiest thing you can put in your car. Keep it clean. Keep gas out of it!

madcows

Maybe I'm mistaking, but it I think I've read at least several stories that at the same time significant compression was lost, and the motor replaced, it was determined that some of the coils were bad as well.

MM, whether or not your tune is set up for low dwell was not the point of my comment. It just struck me as a curiosity, which I then did a bit of research on to determine why weak spark would increase EGTs. From the little that I know the renesis, it sounds as if exhaust temps REALLY need to be kept in check, or damage can quickly occur. Which brings up another point, aren't a lot of the cat failures attributed to being soaked in fuel due to no/poor spark, leading to excessive backpressure - in turn destroying one seal or another?

I'm by no means a rotary expert, nor do I pretend to be - I'm just genuinely curious, and that's why I'm asking it among professionals.

madcows

Since high RPMs require lower dwell times, which in turn prevents the coils from saturating, and thus overheating; it would seem that the high rate of ignition cycles wouldn't have much to do with it.

However, is it possible that it's related to high amounts of heat under the hood?