Thread: Secondary Knock Sensor Setup

Hey,

Going to be doing some tuning on a new high compression setup for my NA 20VVL. However, I do not have any datalogging capabilities with my daughter board setup. I want to install another knock sensor to my engine and log the readings with my DMM. Could someone that has undertaken this before give me some help? Things that come to mind
where to place it?
what resistance level indicates a knock?

Also interested in looking at EGT's wheres the best place (ie. location in exhaust to place sensor) to take measurement?
and whats the "safe" ranges?

bump... does anyone atleast know what resistance level indicates a knock?

Knock sensor should be placed between cylinders 2 and 3 near the stock sensor. No clue what resistance indicates knock. I don't even think that's how it works. I think it is a voltage level? Not sure though. Really a stethoscope is probably going to be way more useful and easy to work with.

EGT prode should go in cylinder #4 exhaust port as close to the head as possible, or you can do cylinder #3 since it seems to have the most problems in my experience. Temps to look out for are going over 1,500*F because then you run the risk of melting valves. But that's never going to happen on a properly tuned N/A engine so you're really just going to be able to use the EGT data to tune to best torque for all rpm. There is no set temperature to aim for. You just need to find best torque and use that temp as a goal.

reading a thread.... 500-800*C thats that Im going for

Knock sensors are piezo electric tranducers that vibrate with the natural resonant frequency of the block. the stock ECU uses an elaborate passive filtering network to try and filter out the 'noise' and only detect knock, but even then, it doesn't get it right (information to the best of my knowledge).

I know there are aftermarket 'knock boxes' and other such devices available. I've heard of tuners using a long piece of silcon hose hooked up to an ear piece like a stethoscope to listen for knock as well.

I don't think its something you're going to be able to pickup on a DMM without doing smulations of idle, normal load, and inducing pinging to see what result you get.

oh ok cool, thought it was possible... I have access to the stethoscope but I just wanted to explore all my options...

regarding the EGT... Ben can I use a thermo couple and wrap it around the runner? how inaccurate you think thatll be?

That would not be good enough. The data you'd be getting wouldn't be timely, or accurate.
You need to install a probe.

sigh... I really wanted to try it out. guess good ol afr will have to do until I get a probe. what you recommend? give me a link