sleeper7

Side seals burned and lost compression. Anyone see this before?

arghx

iTrader: (3)

Makes me wonder about the condition of the parts and the clearances

cewrx7r1

iTrader: (2)

Looks like blowby across the side seals.

sleeper7

I dont think anything was wrong with the motor before this happened. no blowby at all. Started and idles good. Pulled good vacuum for the port.

sleeper7

But what caused it? is what I am asking.

smg944

iTrader: (34)

from what i see it looks to be a rotor from an engine that had a previous bearing failure. you can see some long scraches on the faces of the rotor around the same area where the side seals stuck. it aprears that a bad rotor was used and the side seals just became stuck in.

trainwreck517

iTrader: (1)

I agree, I have seen similar failures from a bearing failure.

sleeper7

All four pics are of the same rotor, same side. The other side of the rotor is perfect. No scratches or burn marks.
The ends of the side seals still had movement up and down. Just the middle part of the seal was stuck in.

Oil pressure was good. Bearing looks good, no signs of excessive wear. The rotors came out of a good running motor.

Don't most bearing failure cause the corner part of the rotor to go bad. (from rubbing the side plates) Stuck corner seals, or the ends of the side seals to stick. Also there was no marks on the rotor face from hitting the housing. Apex seals and grooves were good.

trainwreck517

iTrader: (1)

This is my assumption on what happened based on what you provided.

This rotor at some point in it's life had a bearing failure. The clearance on the side seal were not properly checked when the motor was rebuilt (actual grove clearance), the grove clearance was not enough. This caused the side to not spring back against the iron very well allowing blow by. Overtime this blow by allowed carbon buildup to get stuck into the side seal grove. This resulted in stuck side seal.

Now I'll admit, the motor I took apart hard a much worse failure which caused the corner seal to sick, and the rotor itself was un-usable.

I don't think you have a had a bearing failure, I think the rotor at one point did causing the side seal grove to become damaged. That or the spring was some how damaged during assembly.

Now if this is not a rebuilt motor, than you can pretty much ignore what I said as I am only assuming this is rebuilt with an out of spec rotor.

I am no expert, however have rebuilt a few engines for road racing applications and have seen some pretty interesting failures from miss shifts / over revs which resulted in bearing failures.

j9fd3s

iTrader: (3)

hows the side iron?

13B-RX3

iTrader: (2)

Did you build the motor Chuck? What was the side seal clearance and what fuel are you running?

It is kinda weird that it only damaged the side seals of one rotor. I think j9fd3s may be on to something, is there something on the iron that could have damaged the same area of all three seals? Step wear at TDC?

sleeper7

Rotor measured 79.71/79.73 thick were the burn marks are.

sleeper7

Side plate was good. Low mileage JDM motor. It looked like a mazda reman motor. The apex seals had very little wear on them. New housing that had the red and blueish marker marks on them. Good running motor.
Motor was taken apart and ported and new apex seals installed. It ran perfect with no blow by after it was put back together.

Made a few light 25psi passes, no issues. Max rpm-9100, 11.5afr, 14deg timing at 25psi. E65 (pump and E85 mix) Water intercooler with air temps 50 to 80f. Water temp never above 175f

Then made a wide open pass and this happened. AFR jump to 12.5 in first gear but everything else was the same. side seal failure happened in second gear. 12.5 is lean but ran this afr in the past with out issues. I do try to keep the afr in the low 11s.

It could be motor parts problem but since the motor ran great before the wide open pass leads me to believe it was a tuning issue that the side seals burned like they did.

Dont think the map was adjusted for the larger ports and 90mm throttle body with a JW lower intake. Kinda used the same MS but added only 10% more fuel over the last motor. Very small ports and stock manifold/t-body. And at wide open throttle, thinking this thing was moving some air.

Pump gas?
Air temp to low for ethanol?
AFR?
Just plain incorrect MS of fuel at Wide open throttle?
Parts problem?

Liborek

On previous motor, E65 worked without problem at such AFRs and boost levels? If so, then increase in VE% of new combination would call for less timing.

I think that alcohol and gasoline blends are somewhat problematic to tune around. They donīt have sheer cooling abilities of alcohol nor octane number of superior fluid in given mix

smg944

iTrader: (34)

what kind of apex seals were in there? to me it still seams like a parts problem. 12.5 afr will raise your cyl pressure considering power will be higher and hotter egt temps. given that it did not detonate.

Turblown

iTrader: (12)

I usually find side-seal groove clearances are tightest around those areas. The seals stuck first then the blow-bye( black marks) came next.

flaco

iTrader: (7)

over rev???

sleeper7

Makes the most sense. One thing that bothers me is the motor had 50k kms on it before the new seals and porting was done. Motor ran great in the FD I removed it from.

It ran great until the WOT run. I was mistaken, it was the top of second gear not first when this happened. The guys in the pits said they heard what sounded like a rev limiter at the top of second and when I shifted into third gear it was running on one rotor. Front rotor showed 110psi with good even bounces. Rechecked my REV limiter and it is on soft/ignition at 9400 and starts at 9100rpms. and I did hit this area according to the datalog.

Going to try and take it back to the track tonight. Added more fuel, minus 2deg of timing and moved the rev limiter to 9800 and start at 9700 and try to keep the rpms at 9000. No more pump gas. C16/E85

thewird

iTrader: (8)

Define soft rev limiter? You should only be using hard ignition cuts for rev limiters on rotaries.

thewird

sleeper7

Haltech PS1000 REV limiter. Not sure how it works but there are options for soft or hard, and fuel or ignition. It says soft cut, cuts ignition dwell 300rpms before the acuall rev limit then full ignition cut at rev limit. 9400rpms

sleeper7

One of the local guys is thinking it was the pump gas that caused my problem right before I shifted out of second gear. This setup must be moving allot more air then my last setup. More then I calculated for in the fuel map.

Gohan3rdrift

iTrader: (11)

Where does it pinch the side seals when you start flexing the engine?
Is it in the middle like this or the ends, near the corner seals?

This happened to me earlier this summer.
I just assumed it was because I didn't get it race clearanced.

Nick_d_TII

iTrader: (6)

Kind of strange how all three seals on that side of that one rotor stuck in the same spot...

Agree with turblown.

j9fd3s

iTrader: (3)

very possible! we did that to an apex seal once....

if its just near the tips, that seems to be a symptom of overrevving. however when mazda was designing the FD engine, they did have problems with wiping out all the side seals (and iron) on one side of one rotor. their fix was to use a more exact bearing clearance, raise the oil pressure, and side cut the rotors a little, and that was just to go from 215hp to 255!

also since there was alcohol involved, maybe the premix was getting washed away? or it wasn't getting enough?

i am speculating, but it seems like the tune was good enough

Howard Coleman

iTrader: (6)

the speckled rotor bearings show clear evidence of alot of knock.

knock puts huge loads on the crank and generally the SSs on the opposite side of the stationary gear suffer most. the heat got to the supporting sideseal rail opposite the combustion chamber and locked them up. pretty common.