300hp to 400hp upgrade
#273
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Those pistons are eroded, that doesnt just happen with a few spikes. You were consistently detonating. You need to make or get a set of detcans. There most deff was abnormal signs with the way your pistons look, you just didn't pick up on them.
#277
Severe detonation can melt a piston nearly instantly. I've had pistons on a two-stroke go from new to totally melted down in less than a 1/2 lap of a track. Mild detonation can also slowly erode the softer metals. But that to me looks pretty catastrophic (instant).
On second look, those are clearly marks from the engine builder. 6 marks on intake/exhaust valve, 7 marks on another set. That is a stupid way to mark them, just use a marker pen. Yes, those could initiate detonation due to a point source of heat forming, but they aren't the cause. The cause is you thinking you can run 20psi without proper tuning and fuel.
-removed my rude comment, unnecessary-
On second look, those are clearly marks from the engine builder. 6 marks on intake/exhaust valve, 7 marks on another set. That is a stupid way to mark them, just use a marker pen. Yes, those could initiate detonation due to a point source of heat forming, but they aren't the cause. The cause is you thinking you can run 20psi without proper tuning and fuel.
-removed my rude comment, unnecessary-
Last edited by Mudflap; 07-15-2018 at 04:31 PM.
#278
As I said, fuel was 11.5-12 all the time (could be the sensor is off, it is my ls4.2 spartan running for 7 years now).
The timing map is @ less then 10deg from 180kpa and up (could be base timing is off I got -13deg for ecu offset).
I understand the rising edge vs falling can advance timing too.
I'll double check everything on the new build with a new digital WB and 4.9 sensor.
Thanks for the input guys
The timing map is @ less then 10deg from 180kpa and up (could be base timing is off I got -13deg for ecu offset).
I understand the rising edge vs falling can advance timing too.
I'll double check everything on the new build with a new digital WB and 4.9 sensor.
Thanks for the input guys
Last edited by elior77; 07-18-2018 at 07:36 AM.