Need definitive answer on spark plugs
#11
Maybe not, but the knock sensors on most cars are a completely separate and different system, and don't use the spark plugs or wires for sensing.
#12
Knock sensors are simply a crude device that measures a certain elevated physical "knock". You can still be experiencing detonation and the so called "knock sensors" will NOT even sense the detonation. The ONLY true and accurate method to read detonation is on a dyno. When detonation occurs under engine rpm load your hp dips, and your EGT's abruptly drop off. Like I stated above, I'm running NGK DCPR7E's and they work perfect, and wear much longer than the OEM HD Champions IMO .
#13
#14
Knock sensors are simply a crude device that measures a certain elevated physical "knock". You can still be experiencing detonation and the so called "knock sensors" will NOT even sense the detonation. The ONLY true and accurate method to read detonation is on a dyno. When detonation occurs under engine rpm load your hp dips, and your EGT's abruptly drop off.
Looking for power dips and EGT changes on the dyno as an indication of detonation can be pretty unreliable. First of all, a number of things can cause these conditions. Second, if an engine is being pushed to the limit, the damage can be done by the time these things register.
Acoustic detonation sensor systems can automatically retard timing very quickly (some doing a preliminary adjustment by the next time the cylinder fires), but sometimes even this isn't fast enough to prevent damage on forced induction motors.
Anyway, I wouldn't want to take the chance of defeating the detonation sensing system on my bike (until I know more about how the ion system works), any more than I would want to disable the rpm limiter. If either saves my azz even once, overpriced spark plugs would be the last thing on my mind.
To the OP:
Sorry, I know that doesn't really answer your question. I've been hoping to run into a Delphi engineer who KNOWS the ion sensing system, and KNOWS the answer, beyond "I put different plugs in my bike, and it seems to run fine".
For nerds (like me) who want to know more about detonation and acoustic-type detonation sensors, here's a link to an aftermarket supplier site which includes some really good semi-tech papers.
http://www.jandssafeguard.com/tech.html
By the way, I've been running one of this guy's systems for more than ten years on a blown dragboat, and while most around me have grenaded engines a few times, I haven't, and I'm finally planning on pulling my engine and getting it freshened up just because of many years of use and wear.
Detonation is nothing to trifle with.
Last edited by Warp Factor; 08-29-2012 at 05:30 PM.
#15
Why even worry about it? Just use the stock plugs. Don't fall for all that snake oil crap out there. I've never been convinced that a plug will make that much noticeable difference in performance, or anything else for that matter, on a street motor. Only my .02 of course, but just curious why that question even really needs an answer.
#16
By the way, a friend of mine lost his supercharged Harley engine on the rear wheel dyno the other day. It's not always easy to reconstruct engine destruction scenarios, but it looks like the first thing that happened was a piece of aluminum busting loose from the cylinder head, between the combustion chamber and the exhaust port. The dyno instrumentation wasn't set up with detonation sensors, which almost borders on negligence for a supercharged engine, in my book.
So far, it looks like the engine is a total loss, except the crank assembly maybe can be re-used after new rods are installed.
So far, it looks like the engine is a total loss, except the crank assembly maybe can be re-used after new rods are installed.
Last edited by Warp Factor; 08-29-2012 at 08:24 PM.
#17
The knock sensor statement was referring to a previous post about if a different plug would disable the knock sensor, by no means did it relate to tuning. Don't know how that got twisted?
So when you tune something on a dyno you rely on what it says without ever reading the plugs?
So when you tune something on a dyno you rely on what it says without ever reading the plugs?
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