If on a stock car I would say it would be more likely at WOT, but if something is off with the tune it is hard to say for sure.

 

It's the same Evans tune that the car ran perfectly on.

I'll check this stuff out as you guys mentioned above, but when I look up S2000 rod knocking videos... mine sounds exactly like that.

Mine sounds like Dagle's video, except much, much louder and at 2,500-3,500 rpms.

Same fuel is in it during these horrible knocks/sounds that I used at the track day without issue.

 

Dagles video I believe was piston slap, not rod knock. He can confirm but that is what it sounds like on my PC anyways. And that will occur, then usually go away once warm, on many, many s2000's or other cars and go forever like that without issue. Now you say yours did not do this and suddenly did, so may not be piston slap but for reference that is what his video sounds like. I can see spark knock sounding like piston slap to some though. Again, once we hear sound clips it may help. Billman250 would say to take a video idling, a few feet in front of the car, with the hood closed. It is a good way to catch abnormal sounds at idle. If yours is not doing it at idle, do the same but have someone increase RPM so the noise is apparent on the video. If not doing it sitting still and only when driving (again indicative of it only doing it under some amount of load) then just do your best to get some sound clips in a safe way. That may help us point you in the right direction.

 

Wow, really sorry to hear. Hopefully it's a different issue, and obviously worth going over things like others have said, but doesn't sound good.

I didn't see any other info posted like logs. Do you have an oil pressure gauge, oil temp, etc? I'd be curious to hear how your oil pressure looked on track prior to, on the day of, and after the track day. If there's a noticeable drop in oil pressure.

Edit: Nevermind, I see you mentioned everything looked normal. Can you post your readings if you recall? Would be interesting to compare, not that it's apples to apples but interesting to have more data.

 

lol yeah as mentioned in my post, mine is piston slap. it's actually not super common on stock block s2000's, it's very common in OEM rebuilds unfortunately because the piston's alloy doesn't grow very much. mine was set to 4thou i believe (0.004"). 0.002" might have yielded better results but i'm not sure the hole was round in the first place.

also to note, i don't think i've ever heard of someone having piston slap in a specific RPM range. the piston can only slap at idle because more RPM will introduce more speed which will stabilize the piston in the hole. it might be possible, but i sincerely doubt that's what's going on here. if anything, i would be more inclined to believe it's a main bearing knock which sometimes doesn't knock at idle.

 

Whatever it is, the ignition knock sensor is detecting and logging it. Someone asserted that rod knock does not get picked up by the knock sensor, which is precisely what I've been wondering since the beginning of this thread.

Two questions:

Is that statement accurate, rod knock does not get detected by knock sensor?

Does this also hold true for main bearing knock? And piston slap?

I would expect it is true, none of these things detected by knock sensor. Ignition knock creates a powerful force that vibrates the block at its resonant frequency. It always emanates from the same place, top of cylinder.

Bearing knock and piston slap do not create the same sorts of forces. Don't whack the cylinder like a hammer causing it to ring. These forces also do not emanate from same place as ignition knock.

For all these reason's I would expect mechanical knock to create different patterns than ignition knock, that I would assume the ignition knock sensor could differentiate.

So if it is being picked up by ignition knock sensor, it seems we can rule out mechanical knock? Is that a correct conclusion?

 

Here’s the video. In this video the motor is completely warmed up 180 deg oil, with 85psi oil pressure at idle.

All sounds normal to me except at 1:11 and the rev right after you can hear it. I couldn’t replicate it otherwise. I even took the car for a drive after this video and couldn’t replicate it.. but a couple weeks ago I couldn’t make it stop.

Either way, 1:11 is a hint of the sound. When this happened originally it was that sound exactly, just 5 times louder. The flashpro registered over 90 knocks just driving a few miles when this happened.

I pulled the plugs and they all look perfect, no oil on them, no peppering, nothing.

 

I’m going to get an oil sample to Blackstone and see what they say.

 

that sounds like chain noise more than knock. what TCT do you have on, and if it's original, how old is it?

 

Inline pro TCT, ehh a year or so old. Maybe 2,500 miles on it.