actually there is evidence of damage, however the evidence/sample is so small as to be unusable as an effective statistic

 

??? I must have missed it, sorry. Could you point me to the specific post?

 

I'm not trying to start an argument here .......... your sarcasm is noted

that aside - it was on one of the 350z forums where someone took apart an engine and posted pictures of damage to the pistons allegedly from detonation or pre-ignition - so as stated such a small sample that it can't really be relied upon

 

No, no sarcasm intended whatsoever. It was a legitimate question looking for some actual evidence. This particular topic comes up almost as frequently as oil and air filter discussions and unfortunately sometimes degrades into nastiness. I choose to post in these topics as the subject is of great interest to me.

I have no doubt that pistons can become damaged (I've fried many myself)- but whether it's actually from detonation on a stock engine driven on the street continues to be an elusive thing to pin down. I've yet to see a genuine case.

 

I found a thread - What can happen if you run your Zed on 95 Ron..... - 350Z FAQ - 350Z & 370Z UK

 

Can you direct me to your source? TIA.

 

Me neither, Mikey, on a stock engine. Very elusive to pin down for sure. Conservative maps and sensitive knock sensors keep things in check. The cracked pistons and plugs-missing-electrodes cases I can confirm were running aggressive curves, high boost and/or compression, or to quote from Unhingd's earlier post, "silly tuning." <--(Good one.)

 

I liked 'silly tuning' as well. Having said that, the saga posted by ioneabee (thanks for the link )

seems to be a 'plausible' case although there is speculation by the owner that the incorrect heat range of the plugs might be the actual cause- meaning that pre-ignition was the villain and higher/correct octane fuel would not have made any difference.

Also of note, Nissan does place severe restriction on the usage of low octane fuel (<97 RON) by limiting it to essentially emergencies only and restricting the engine to lower revs and load only.

There is also discussion about the knock sensor being deactivated above 5200 RPM which would jibe with the limitations of the manual.

Such restrictions and limitations appear to be only for the Euro market cars- the N.Am versions are tuned for 91 AKI.

Hmmmmm.

 

Unfortunately not. The observation came from looking at the OEM maps we pulled off my car a couple months ago (as interpreted by my local tuner).