Brettus

iTrader: (2)

possibly a little .


some background :
this happened a few days after a track day at which the engine was overheating .

Brettus

iTrader: (2)

Seen it before a few times ?

I'm guessing you wont have anything by next week ?

Charles R. Hill

iTrader: (7)

Haven't seen this particular matter but a brainstorming session resulted in an idea that would deal with this problem, too.

PhillipM

Drop the boost a touch, sort some better inlet charge cooling and advance the timing a bit.
Sorted.

nycgps

iTrader: (1)

Thats the divider ? Damn.

it doesnt really look like it ...

what did u do to ur engine? I thought that part is deadly stuck by Mazda from factory ? (its still removable tho)

olddragger

iTrader: (3)

DAN YOU DA MAN!!

Ouch! i can only think about the side seals. Damn Bro--stay out of those high rpms on track--learned my lesson. Track redline for me is 7.5K
How much boost were you running?
How high of temps did you get?
You have to tear her down and get a new center plate?---can that be fixed?
OD

Nubo

This thing

Brettus

iTrader: (2)

Did not go over 7500 all day shift point was more like 7000 once I realised I was overheating . Saw the guage move to about 3/4 at one point .
Tried to do some logs but I could not retrieve them for some reason .
Boost was set at 10psi and tapering down to 8.5 at 7500 .

I was going to tear the engine down anyway to repair an oil leak i've had for over a year now . I already had bought a full set of used irons and housings so that was a bit of luck .

Brettus

iTrader: (2)

yeah good call - need to monitor egts more closely and ease the timing up a few notches at a time.

jessedrifter

iTrader: (4)

is it vtech???? lol

olddragger

iTrader: (3)

thanks for the info--if temp gauge was at 3/4--thats about 230-240F?
Dang--- thats not "high" boost at all.
? is --why the overheating--your timing is not that advanced is it?
were you logging your a/f's also?
Maybe big old gauges with flashing red lights next time(like me). I am also considering adding a warning cow bell to get me out of that track "red mist".

This brings up a good point about egt's too hot and a/f sensors going beserko--i have had that happen in bumper to bumper traffic when it was over 100 outside and my w/m was out of fluid.
olddragger

Brettus

iTrader: (2)

Overheating was because of the new intercooler I had just fitted which blocked off the radiator . Not sure if the overheating caused this issue or not . It looks like had been working loose for some time .....
A/F was fine - in the low to mid 11s

Brettus

iTrader: (2)

Come to think of it - I had a strange rattling noise a while back which dissappeared a few months ago . That could have been it - gradually getting weaker then breaking free . In which case - I'm wondering if removing the divider altogether might be an option for FI ?
Will be interesting to see what the inside of the engine looks like .

dannobre

iTrader: (3)

The problem is that as you advance the timing...the chance of detonation increases greatly

Any ideas what your EGT's were running? And how much advance?

Some tuners have been retarding the timing a lot to help with the pinging...but this shows we need to be careful about that as well.....that chunk would not do your turbo much good

So we are kinda in between a rock and a hard place....melting exhaust ports on one end...and detonation and broken Apex seals on the other....

Hotter than usual temps and warmer intake charge temps likely didn't help much

I doubt the rotors/seals would hold up to that kind of abuse...so taking them out wouldn;t be an option

olddragger

iTrader: (3)

i dont think this engine likes running without that separator--i have heard of some tongue type extenders being placed on it but never getting rid of it.
There is also work that can be done to lower the exhaust port temps.
OD

PhillipM

^ What he said, the problem without the seperator is the pressure pulses affect the other rotor even more than usual, I'd get something back in there.

BDC

Where and how are you "monitoring" EGT's? The only real and right way to do it is in the exhaust manifold. You'll need a single probe per chamber. May be a bit difficult with the goofy exhaust port setup the Renesis engine has.

By the way, easing timing (all else remaining the same) raises EGT's.

B

BDC

Absolutely correct. In my view, without a separator, there's a big risk of being able to push high exhaust pressure into the adjacent, low pressure exhaust chamber, pushing hot exhaust gas into that adjacent chamber's next intake stroke. Nasty.

B

Brettus

iTrader: (2)

I have a feeling mine melted off some time ago (unrelated to the recent track day) - it has been running sweet

Wonder about reducing the length of the seperator significantly so there is just enough seperator there to turn the gas towards the outlet so none goes back into the adjacent port . It may be possible to significantly increase the x-sectional area of the port if you could find the right length seperator .

BDC

Perhaps I'm mistaken, then. I need to study this a bit more intently. I've got enough torn down Renesis motors here to be able to mock something up. It just to me, however, seems counter-intuitive to run without some sort of center exh port divider. But, then again, un-divided exhaust manifolds do the same damn thing only a few inches down stream from the exhaust ports on older motors. Hmmm...

B

dannobre

iTrader: (3)

No overlap...no foul..can't see any way to get exhaust reversion..

I wonder what the constant "annealing" is going to do to the side seal springs though?

Hopefully the outer ports can be cleaned up enough to get more flow than the center compromise ones...

PhillipM

That's where people were going wrong in the exhaust thread, just because there is no intake-exhaust overlap, doesn't mean you can't push exhaust gasses back into the chamber and compromise the fresh intake charge.

TeamRX8

iTrader: (25)

You will be blasting the opposite rotor side seals and side face without the divider, your engine won't live long without it

while there's no intake/exhaust overlap within a single rotor cycle you'd have to mock both rotors up to see where the intake/exhaust cycles between rotors lines up

IMO a wider housing with separate exhaust ports, a center e-shaft housing bearing, and 2-pc e-shaft would have made one hell of an engine, but the production costs would be a lot higher too

after 5 years they still can't even get their sh-t together on rotor variances for the current engine, so a higher tech engine would only be more of a production issue

.
.

Brettus

iTrader: (2)

I'm thinking leave the divider in place but only in the 'line of sight ' of the rotors . You should only need enough of a divider to turn the gases towards the exit . The stock divider goes quite a way past this point .

dannobre

iTrader: (3)

Poorer scavenging......but not as bad as it would be with overlap ...It's more of a "stuff doesn't come out as well" problem

I think that this is the biggest problem we have to deal with..there seems to be more "in" potential than "out"