For those thinking of working with det cans, I suggest try it. The human ear has amazing response, fidelity, and bandwidth compared to man made alternatives. Having a knock suppression system stock, even if it isn't perfect (which the mitsu one is very very good) is a needed safety feature.

 

Knock really isn't a problem moderately above peak VE or torque, but once you mod the car with basic stuff (cams, boost) you throw the knock sensing frequency out of tune where it does work and it becomes much less accurate. Your left with relying on your ears anyway.

In rally races the knock sensors are removed from the block

 

Since the search feature isnt working well, how much knock do you guys normally see? Even with no timing and low boost I still get what seems like alot of knock when doing random pulls and going through the gears. It is not shift knock, my timing map is adjusted for that. I can usually get a single clean WOT pull in though... I know theres a thread out there called How much knock is normal? I cant do 3 pulls back to back without getting at least a little knock.

Thanks for the help guys

 

how much is a little knock? three count over the pull or one or two for the first second? more?

 

Normally less then 3 to 5 but it will spike up to 9 or 10 every once in a while, it usually doesnt hold throughout the pull though, pretty random. Usually right when you first punch it, or sometimes just anywhere throughout the pull.

 

I like to keep it under 3 at all times. Most of the time I can do full pulls with 0-1 counts through the gears to 100+mph. Over 5 counts and I lift. Sure on low power engines you can run 20+ counts for years with no damage. However the higher the torque the more each count hurts the engine. Evo 9's pull so much damm timing that it best to keep it 0-1 with the occasional 3 counts on a shift or something.

 

So you would keep pulling timing until you can beat on it a little and still not get more than 3 or so? I thought maybe my knock was normal since it is random and not consistant...

 

My stock tune gives 3 knocks usually..... I never kept anything more than 2, but it would randomly happen, regardless of what I changed.

 

So you guys never get any random 5 to 10 counts? Not even once in a great while?

 

Just as a clarification, I had a turbo failure due to negative timing which was a result of using low timing that got pulled lower by the inevitable knock counts that come with road racing. My point is this: If you're going to be in boost 20 minutes straight it is a different story than the street. You have to realize your car WILL pull timing over that 20 minute period. If you start low, you're eventually going to go lower. If you start at 0-2 degrees at peak torque you will have periods of time (in 4th and 5th gears) that will be -1 or -2 degrees. That means that you will have at least 1-2 more degrees of "ignition" (flames) that are going from the power stroke into the exhaust stroke. And if you have modified cam timing/cams you compound that problem.

I'm not trying to spook anyone, but realize the answer needs to be defined by the circumstances surrounding it. My rule of thumb is no less than 5 because it WILL go lower even if you run 11:1 on the track. On the street I got away with it all the time. I could make more power and pull much stronger with less timing an more boost all day long.... but 2-5 second pulls are entirely different than 19-20 minutes of 23psi.

On a side note -- I thought you wanted peak cylinder pressures to be 11 deg atdc.

 

When I was running pump gas, I never that much random knock except when I had my POS Vishnu mail-in flash. After I tuned it myself, knock was always 5 counts or less, usually no more than 3 counts in a pull.

 

Found the thread, its starts getting interesting around this page:

https://www.evolutionm.net/forums/ev...ml#post5329616

 

That has less to do with different parts making different resonance and more about rocks showering the engine bay and the like.

 

Sounds like it's time to bust out the O-scope pictures.

 

We have a 5v knock sensor in the 8/9 like we have since 1990 (and it has been alot better since the 2G in 95). What is this "wideband" knock sensor you speak of?