-stig-

hello guys!



had a car on the dyno a few days ago, they had a lean run ( 13:1) with meth/water injection, a gt4094r at 25psi. that run made 565rwhp, but when calming down to idle they heard some noises from the engine, and then it blew out the seal around the oilpan.



then i opened the engine i found 2 part of 2 sideseals on the aft rotor to be missing! they have knocked a piece of the oilseal off, went trough the engine and landed in the turbo, with is pretty much scrap.... no other danmage inside the engine than thoose on the pictures.. is the plate useable? housing and rotor is just fine!



I'll post some pictures for you. do you think it had a detonation? apex seals are NRS 2mm, and looks just fine, all other seals looks good to!

Lynn E. Hanover

It looks to me like a single detonation event took off the end of the side seal. The side seal scrap got run over by the outer oil scraper and it got broken. Pieces of both escaped out the exhaust port to damage the turbo.



In order to blow out the pan gasket this had to happen at high cylinder pressure. Probably near to or at full throttle. The failure of the seal allowed combustion gasses to enter the pan through the oil drain back in the rear iron, and the loss of combustion pressure stopped the detonation. Check to see if the rear seal has been unseated, or the lip turned inside out with the spring loose. In any case, replace the rear seal.



This probably happened just before the throttle was closed at the end of the run. Although it seems like a long time for the events to unfold, I suggest that it happened in a few revolutions, and the realization of the data at a lower rate, makes the time seem longer.



It looks like the open side of the port is just along the path (track)of the leading end of the side seal. If this is the case, I would radius the bottom of the port a bit more so that the unsupported trailing end of the seal will not be damaged should the engine be turned over backwards.



The iron only needs to be smooth on the intake side. Scratches have far less affect there. Nearly perfect sealing on the combustion side is needed. So if there is damage there it needs to be lapped or ground and lapped. Of course a little lapping won't hurt anything.



Alcohol washes off lubricant, and is very "Hygroscopic" which means that it bonds readily to water. So the container of Ethanol or Methanol must be kept sealed until ready for use. Lest it collect huge amounts of water from the air.



So in using it for enhanced detonation resistance, you must replace the sump oil often. Sulphur products from combustion combine with the water to form sulphuric acid, which desolves bearing material. You might think about using the highest recomended volume of premix oil when the alcohol is flowing.



I have no experience at all with turbo engines, so I could be completely wrong.



Lynn E. Hanover