Can you always hear detonation?
 

I just screwed around with my timing some more. I set the transfer slots so that they look like little squares and then I set my timing. The engine wanted 18 degrees base, so I put in an 18 degree bushing to get a total of 36, all in by 2600rpm.

The engine runs fine and I hear no pinging. So I'm sure it's ok, but just curious is it possible that it could be detonating slightly and that I'm not hearing it over my loud exhaust?

ask MsVetteMan :rofl:

Is that what the consensus was? That detonation caused the cracked piston and block? I lost track of that thread after awhile.

Everyone said "No way it was detonation. (Even 2 independent garages!) But Blueprint said it was... but they would honor the warranty anyway?!?!?.;)


I would say ask TwinTurbo.

Oh, man...that's cold...:flag:

I can take it.....and I know Jim was kidding........right Jim? :)

To be fair to blueprint......they said there were signs of detonation, but there were other gray areas as well.........therefore the warranty.

As far as answering the question....If your car isn't very loud, and you don't hear it, it probably ain't happening enough to hurt. The advanced state may kill your gas mileage, and would also make it run like crap.

Detonation is an interesting topic........do a search in google.

Audible knock levels generally vary with the magnitude of the pressure waves and cylinder ringing. Light knock can still occur under circumstances that are not heard outside the engine compartment. Loud exhausts are amusing at times, but make sure it's not masking serious knock and some long term damage to the pistons.

Yes, of course I was kidding.

after being wrapped up on that thread for so long and hearing the word "detonation" again... i couldn't pass it up. :lol:

:thumbs:

In theory, yes it's always audible. Detonation is also a charactersistic sound and in a specific wavelength range, that's why the knock sensor can accurately pick it up without the rest of the engine noise masking the detonation. However, for a human ear and the other noises in the engine, engine compartment and car it's not audible in many cases, not until it gets really bad. With a loud exhaust v8 it's much harder to hear than in a whisper quiet little 4 banger. The noise is from a supersonic pressure wave hitting and object (piston, chamber wall, cylinder wall....) so it's pretty characteristic.

A knock detection circuit is rediculously simple to build with some GM components (either and old ESC or you have to crack open a memcal from a weatherpack ECM), some soldering, resistors and a led. I posted how to do it not that long ago..nobody seemed to pick up on it. A flashing led is easier to notice than a sound coming from your engine with the exhaust blasting that wonderful tone :)

TT, how would you know if the knock sensor was working after you've made it?

And what does it sound like. I hear a slight high pitched tone that comes in around full advance, but I think that it's probably something else. Someone told me that detonation sounds like marbles in your engine.

yeah, detonation sounds like marbles in a can..a very characteristic ding ding sound.

You'd see the led flashing when there's detonation. To check it, lightly tap the block with a hammer to see if the system is working.

I built a similar LED driver (and pulsewidth stretcher) circuit several years ago to help dial in and correct the spark timing in my '84 single turbo. It's amazing how much WOT knock can occur that gets drowned out by a low restriction (read LOUD) exhaust. I use the '84 for road course use mainly, so I need the engine to survive 20-30 minute sessions under boost conditions.

I took it out tonight, gunned it at low rpm in second gear to see how the engine likes the new timing. It didn't. It hesitated once, picked up again, and hesitated once more. Then it was fine after 3K. Could this be a sign of detonation? Maybe just some bad fuel? There was no loud noise, just a quiet stumble and it didn't do this with less base timing.