Re: Knock. A question for Graham or Marc

[XfireZ51]

Originally Posted by jss06c6

Gents,

I have a pristine 1993 that I'm about through with. 100% stock, including the MEMCAL provided to the owner by Marc. I will datalog this car and provide the file to you Dominic. Having to replace the Brake Master Cylinder, which should be complete tomorrow. Will have 93 octane fuel in it.

As always, the insights from Marc and Graham and yourself Dominic, are extremely valuable.

Steve

Sent from my SM-G950U using ZR-1 Net Registry mobile app

Awesome Steve. That would very cool. I would envision a drive of about 1hr which would be inclusive of city stop and go, incline/decline(as much as possible in TX), decel, and steady cruise through about 80-85mph(without breaking the law of course ). Moderate acceleration.

[XfireZ51]

Steve's offer brings up another point of clarification.
Does the fact that the 93-95 block have 4 bolt mains alter the knock characteristics in any way?

[grahambehan]

Wow, now your testing my memory, let's see, the original sensor was around 6khz, we tested 6.3 khz for 93, but the pre-ignition test showed no real difference so my recollection is the sensor is the same, but I will check when I get home.

Graham

[XfireZ51]

Originally Posted by grahambehan

Wow, now your testing my memory, let's see, the original sensor was around 6khz, we tested 6.3 khz for 93, but the pre-ignition test showed no real difference so my recollection is the sensor is the same, but I will check when I get home.

Graham

Graham,

Maybe this may assist you. These are the param values from stock bins for the 92 v 93 when it comes to Knock controls. Not much difference except for the values for Max Retard in PE mode. Interesting.

[grahambehan]

Thanks, that would suggest my memory of events that took place in 1991 is acurate.

[jss06c6]

Stand by. Hopefully I will get the '93 on the road tomorrow night or Thursday morning..

Sent from my SM-G950U using ZR-1 Net Registry mobile app

[XfireZ51]

All,

Well thanks to Steve at Crossed Flags, he was able to provide a datalog of a totally stock 93. The log showed no sign of knock present during a driving session combining city and highway driving, both w and w/o AC on. Perhaps Steve may want to comment further, but at least based on this one sample, it appears that there isn’t any characteristic knock signature that would appear across the spectrum of LT-5s, regardless of state of modification.
If ur recording knock, whether false or not, it needs to be eliminated or minimized because it does affect the performance of ur motor. Even if its false, it would be a mistake to ignore it.

[Ccmano]

Now that’s interesting. No knock? A number of years ago Mark Haibeck documented (in a presentation still on his website today) what he called “typical” knock for both “tip in” and “shift” related knock. I copied the attached charts from that presentation below. I still think we’re missing something here. I find a car with zero knock highly unlikely. Mine was like that when I first started tuning. When I changed out the knock sensor and we suddenly had knock back in the picture.
H

[Ccmano]

Come to think of it, if we assume for the moment that shift knock is a real thing on a stock car, which means gear clash is being picked up by the knock sensor, it begs the question, are Fidanza single mass Flywheel equipped cars more likely to experience false knock? The transmission noise of a single mass equipped car is well documented up to about ~2k rpm. Is that noise, under various load and speed parameters, generating false knock throughout the rpm range as we shift and move on and off throttle without the dampening affects of Dual Mass Flywheel? Food for thought.
H

[XfireZ51]

Hans,

Did u "ohm out" the original KS? How about the new one? And when u installed the new one, use teflon tape? How tight did u make it?
I, like u, was suspicious of Steve's results and asked Steve if he had validated the sensor. He was able to show that it would record knock so his result should be valid.