To confirm the thoughs that the housing is growing due to heat. My external coolant hard line setup is showing signs of leakage, but doesn't leak under normal street driving conditions. I also haven't seen any noticeable loss of coolant. The highest recorded water temp was 230F and 245F oil during the time attack I did a while back. Need to upgrade my oil coolers.

Currently I see knock at 15 degree IGL and it's very light as well ~60 Hz. This is at 15/16 psi, from N16 through N19, ~200F (93C)water temperature, 97F (36C) air temperature and ~11 afr. This would be just before ignition timing is retarded 3 degrees due to water temp.

The rest of the time I see below 15 Hz as far as engine noise.

I feel the coolant mods I did has made a difference in openning up my timing window. Then again I may be wrong, I'm not totally done tuning though.

https://www.rx7club.com/attachment.p...1&d=1220921498

https://www.rx7club.com/attachment.p...1&d=1220921498

https://www.rx7club.com/attachment.p...1&d=1220921498

how does it come out as rust?

Spark plug temperature range thought!

Considering that the intake charge is the main cooling agent for the spark plug electrodes, and that E85 cools way more than gasoline and has a higher octane rating; a warmer plug should be used for E85 than you would for gasoline.

That is why 10-11 leading plugs may not work well with E85.

It's not rust, it's the color of what my coolant is. The residual material on my rotor housing is just evaporated coolant.

Chuck, comments on my IGL timing mag??? Pump gas, Bur9s all around.

The oil cooler ducts are completely sealed with aluminum heater ducting tape.

Actually the HP was going up consistently up until I stopped to this timing configuration. I definitely have gains to be had from N8 to N13 though. You maybe right as far as being too advanced for longevity purposes.

Afgmoto -

Not to be a downer, but when will we see this baby torn down for housing surface examination? Just curious as to how the extra coolant flow has impacted the problem.

Borescope - sometime later this year.

As far as teardown, you can front me the money for replacement seals and such and it can be as soon as this winter. :tonque:

lol I figured, but the boreoscope will do :)

Well Jeese sk8rpunk1983 popped the motor on our way back from SSXI. Once the fd gets transported back to Portland I be will tearing it apart. The motor as well as the intake temps wet too cold. It leaned out to 11.94afr at 0.85 Bar with an IGL of 17, 4 deg. more advaned than what I set it at. Knock of 81.

Awww damn Adam I'm really sorry to hear that...... From what you can see/tell so far how bad is it? New turbo? Is it clunking pretty bad or just loose compression?

-J

If you were closer I'd let you borrow mine.

It sounded like just a loss off compression. Won't know for a while it will be at least 12 days before it gets transported.

Datalog of blow up, the high knocks following the first I believe is an apex seal rattling about. Yeah...

https://www.rx7club.com/attachment.p...1&d=1222994421

What seals were you running? OEM 2piece?

Interesting log too. Doesn't seem to be any real weird stuff going on just - pop + noise. I know your pain :(

Iannetti 2mm one piece, just really cold air intake temps and advanced timing.

WOW!! a ceramic took a crap in those conditions? That blows my mind.

I realize the air temps were cool (I'm usually around 55C without AI during extended hard driving) but that blows my mind something (maybe its a side seal?)would let go in that situation.

Sorry for your loss, hopefully we all learn something on this one :)

Well, it has knocked a few time before this one during tuning and track events under extreme environments, but all at 65 knock levels and the motor was really hot i.e. +215F water and +230F oil.

I'm total sold on the Iannetti ceramic seals, won't go back even with the added cost. It would be cool if it was a side seal, but I doubt it.

Since when does that apply to piston engines?

Max advance doesn't lead to max HP there, either.

The difference is that for most piston engines, you have the option of turning up the compression ratio until you become detonation limited at best advance.

And in a lot of cases, the combustion chambers are crappy enough that advance is detonation limited, not power limited.

Complicating matters is that if you do it right, increasing CR *decreases* the amount of ignition advance is optimum! Best HP might be as silly high as 38-40 degrees on something with only 10:1 compression but if you get it on up there then you see that closer to 30 degrees is best. Or even less than that if you have good chambers...

I believe he was speaking in general about the common thought process when talking about 4 stroke engines and timing.... piston and rotary alike.

-J

Thanks Barry, though one good thing about this failure is it allows me to look at the internals sooner than later to see if what I have done has made any difference outside of tuning.

As far as my timing goes I had backed off considerably from the timing map I posted earlier and I was seeing max knock of 15 throughout the rpm range, except for when I was pushing the car hard for long period, i.e. the Palomar Mtn run. I saw ~60 at 6200-6400 rpms a couple times once the motor got good and hot.

A BMEP recording device would be ideal as far as understanding what really is happening. From that a true rotary tuning ethos would be established. Granted each motor is slightly different, but the general tuning window would always apply.

Adam, were you using any water/ alcohol injection at that time?

Do you have any other safeguards that might drop ign timing with added air/water temps?

What range plugs were you running in the leading/ trailing positions?

Barry

Unfortunately no, this would not have happened if I was running AI.

Beyond what is available through the PFC no.

BUR9s all around, since this occured during low load highway driving the plugs would have not been an issue.

Attached a pic of one of the housings I did for my recent (and first entirely solo) rebuild.

I just did the common jacket mod, nothing super special. Used a dremel engraver bit (#100) on the drill press and went one groove at a time :). The only other thing I did thats neat is welded up the EGR holes in the exhaust sleeves and groudn them smooth. Take a good look at a housing next time you get the chance and take note of all the cavities that would be filled with (at WOT +1600F) HOT exhaust gas and soaking into the coolant as a result.

Don't know how effective that mod will be, but I'm giving it a shot nonetheless.

On the rebuild I'll do on the keg I'm swapping this one for, I plan to do similar jacket grooves (done with a dremel engraver bit on the drill press, nothing too special...) but with my newly found thin and LONG end mill I will add a piece of 1/8" AL to either side of the leading plug bore on a diagonal. I'll be cutting out a piece from center of the "divider/support" between the dowel bores and then notching the inside and outside edges (inside on the upper tension bolt hole, outside on the lower) to provide support for the piece. Also, doing it on a diagonal will allow for support/guide notches at the ends of the additional piece without having to cut into the tension bolt land. It will be a minor interferance fit and the sandwiching of the engine will also prevent it from uprooting afterwards.

Keep the discussion/thoughts going

https://www.rx7club.com/attachment.p...1&d=1224684154