On my mates P1.

He was holding it flat in 5th and hit the limiter.

He did see a flash of det on the power FC (seen many times before when running Ultimate)but managed to slow down as normal with no noises or any signs of failure.

Stopped for a chat and left the car running then drove off ten mins later to hear a noise like he had ran a big end.

But upon stripping the engine we found all the bores looked like this.





clear det but how are the bores scored? we found no metail particles in the oil??

 

I don't know what would have caused the scoring but I know that Subarus don't like top speed runs and big end failure afterwards is quite common

 

Either letting in sh1t fom the intake side or sworf in the oil ?

 

To me it looks like the oil got to hot and lost some of the bearing in it?

 

are you talking about the cross hatch in the bore if so thats normal but if you are on about the fine lines that are strate its obstruction bettwen the pisston and the bore and its a strip and rebuild

 

are the pistons out yet? I bet you will find the top ring land worn away by melting ?

 

totally agree detting it nuts off and snuck downs the side ot the piston

 

thats nonsense mate...this one has done top speed runs for 3 years with no worries.

 

That is heat related piston expansion. It's got a little to hot on that last run. Maybe down to the det.

 

Hitting the rev limiter at high speed is never a good idea. That itself can cause an apparent lean condition sometimes, depending on the type of limiter, which could cause the piston to melt slightly, and pick up on the bores like that.

If holding flat out for any length of time, always ensure AFR's are on the safe side, and timing isnt too aggressive....

 

That is exactly what happened to a friends YB, it was never mapped for top speed and after hitting the limiter in 5th it had a meltdown.

Euan, why has this thread been started again ?

 

Also...if it sounds like it had run a big end....strip it all down, because it probably has !!!!

Although you should easily be able to feel this with the engine down as far as it is.

 

just throwing it in there, although doubtful due to the fact it detted slightly, could bore wash possibly be a cause to scoring like that?

 

No, the piston has melted slightly. Its been running too lean.

 

yeah thought as much, just chucking it out for discussion!

what sort of symptoms would borewash cause? just accelerated wear or falure/marks like this?

 

i recall stu giving the reason about cossies diying at top speed runs because of fuel starvation due to poor pumps and stuff due to the pump not being able to supply enough fuel to the rail for a sustained high revving time

and he posted it about 3 times and everyone's answered in different threads