Question about knock and HG

[NHRA Super Gas]

I had been running 100 octane in the car for a while..never any knock even up around 19-21 lbs boost. Tried 93 and whoa, now I know what people are referring to. I was knocking like crazy south of 15lbs, up to 5 degrees KR for a split second.

My first question is can you always hear it if it's knocking? Is there a type of knock that is otherwise silent? For those who've lost a HG, I would think it that sound was unmistakable, and you'd have the chance to take your foot out of it?

Second question for those who run a knock gauge and scanmaster...Do they always correlate? I only have scanmaster at present.

 

[TurboDave]

I had been running 100 octane in the car for a while..never any knock even up around 19-21 lbs boost. Tried 93 and whoa, now I know what people are referring to. I was knocking like crazy south of 15lbs, up to 5 degrees KR for a split second.

My first question is can you always hear it if it's knocking? Is there a type of knock that is otherwise silent? For those who've lost a HG, I would think it that sound was unmistakable, and you'd have the chance to take your foot out of it?

Second question for those who run a knock gauge and scanmaster...Do they always correlate? I only have scanmaster at present.

First of all, NO, you can't always hear the detonation as it occurs. I could never hear mine until it hit 6+ degrees of retard (back in the days when my car was quiet enough to hear such things).

I was going to say you shouldn't even have any knock at 15# on good 93 gas. But then I saw what chip you're running.

A good modern low timing chip these days will easilly allow upwards of 19# of boost on good 93 octane fuel. At least it does around here.

 

[NHRA Super Gas]

I've already switched to a TT chip, and it was present here. Actually never tried the RA chip with 93. Have not ruled out the possibility of a bad batch of gas. I've heard Shell is the best, will try that after I run through this tank of 100.

I noticed the knock more when shifting gears at WOT or when the motor was lugging in third gear and you put your foot in it, rather than the top of 2nd or 3rd.

I disagree about 19lbs on pump gas, because of the cylinder heads higher airflow.

 

[BlackMetal]

A good modern low timing chip these days will easilly allow upwards of 19# of boost on good 93 octane fuel. At least it does around here.

Definitely not. 93 Octane in Chicago with a TurboTweak chip, and I can still make it knock around 15-16 if I go WOT.

 

[Marc87GN]

I have been running 20 psi on 93 Octane since November with the Extender chip. I think the front mount helps out quite a bit because I couldn't do it with the stock location even with the 3" neck. With the low timing(17 deg in 3rd), front mount and efficient turbo, I run 20 psi with no problem even with the converter locked and get a max of 1.1 KR. The knock is usually related to the full throttle lock up.