Agree. That's exactly what will happen. But it also needs rather high loads as well to be fatal, especially at N/A engines. Also, without rather high loads, it really won't knock all the time.Originally Posted by RobZL1
Stock engines have knock (real or not) from time to time anyway and those same cars won't just explode because of that.
I'd like to think I'd notice something was up after one or two pistons had the sides burned out instead of continuing to drive the truck :lol:
Was stock tune on a Shelby truck (encrypted Whipple 2016). Was running and in less than 2 miles was not. 30 miles total pulling a boat.
2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
810rwhp and 820rwtq 91 Octane 6400 rpm
948rwhp and 951rwtq 105 Octane 6400 rpm
999rwhp and 997rwtq on 60% Ethanol 6400 rpm
wow! that sucks
How fast detonation can kill pistons. Was not me, my truck or my tune. I just got the work of putting back together. Funny though, after all this happened the people that built the Shelby truck changed the tune, put a no tow requirement in the purchase agreement and changed the boost.
Lesson to all, detonation kills a motor fast.
810rwhp and 820rwtq 91 Octane 6400 rpm
948rwhp and 951rwtq 105 Octane 6400 rpm
999rwhp and 997rwtq on 60% Ethanol 6400 rpm
Spark knock/ping and detonation are two very different animals.
I think I've never seen pre-ignition:
https://blog.edgeautosport.com/deton...s-pre-ignition
Interesting article from the Cadillac Northstar V8 designer:
"There is a situation called detonation induced pre-ignition. I don't want to sound like double speak here but it does happen. Imagine an engine under heavy load starting to detonate. Detonation continues for a long period of time. The plug heats up because the pressure spikes break down the protective boundary layer of gas surrounding the electrodes. The plug temperature suddenly starts to elevate unnaturally, to the point when it becomes a glow plug and induces pre-ignition. When the engine fails, I categorize that result as "detonation induced pre-ignition." There would not have been any danger of pre-ignition if the detonation had not occurred. Damage attributed to both detonation and pre-ignition would be evident.
Typically, that is what we see in passenger car engines. The engines will typically live for long periods of time under detonation. In fact, we actually run a lot of piston tests where we run the engine at the torque peak, induce moderate levels of detonation deliberately. Based on our resulting production design, the piston should pass those tests without any problem; the pistons should be robust enough to survive. If, however, under circumstances due to overheating or poor fuel, the spark plug tip overheats and induces pre-ignition, it's obviously not going to survive. If we see a failure, it probably is a detonation induced pre-ignition situation."
Also, never thought that cat overtemp functionality could have something to do with this:
"Consider the Northstar engine. If you do a full throttle 0-60 blast, the engine will likely run up to 6000 RPM at a 11.5:1 or 12:1 air fuel ratio. But under sustained load, at about 20 seconds, that air fuel ratio is richened up by the PCM to about 10:1. That is done to keep the spark plugs cool, as well as the piston crowns cool. That richness is necessary if you are running under continuous WOT load. A slight penalty in horsepower and fuel economy is the result. To get the maximum acceleration out of the engine, you can actually lean it out, but under full load, it has to go back to rich. Higher specific output engines are much more sensitive to pre-ignition damage because they are turning more RPM, they are generating a lot more heat and they are burning more fuel. Plugs have a tendency to get hot at that high specific output and reaction time to damage is minimal."
http://www.contactmagazine.com/Issue...ineBasics.html
Reply With Quote