Ok obviously, you would want 0 counts of knock, but the fact is thats pretty much impossible, so what i want to know is, how much knock is really ok? The reason why im asking is because some days ill be knock free others im hitting 5 counts all the time.

plus i had a friend that had a flash, i log his car, he is getting 10 counts on almost every pull. He has been driving his car for almost a year, im like damn hommie, i tried to kind of fix it for him, his timing was just way too aggressive for 91, but when i checked compression it was PERFECT across the board. his car still runs smoothly, so a year of crazy high knock and his motor dosent seem like its been phased. I had to lower some timing across the entire board,

10+ counts for a year? ( this guy beats his car every day) and his motor is still holding up perfectly.

Honestly that makes me wonder if i should even worry about knock that happens every so often. especially if its only 5 counts vs his 10 counts , i have seen his pulls have 2 digit knock across the entire board.

What do you guys think?

 

btw his motor has 38 k on it, he got the car flashed at 20k, so 18k miles of spirited driving. (with 10+ counts , sometimes across the entire rpm range).

 

Remember, the reason his motor is probably "fine" (Notice quotations) is because the ECU is pulling timing to get the motoro where it should be timing wise. The real way to tell is by the data logs, and look at what his Octane number is doing. If it is not 100, then the motor is using more than the high octane maps, as in, interpolating betweek the two based on the octane number.

The best way to go about that, if the knock is consistent, which it sounds like it is, would be to data log the car, and look at what I mentioned before. Check to see what the timing valued should be during the pull, and see if they match up to what is on his high octane timing map. If not, reduce the timing numbers to closer to the maps. Of course, all of this is providing his AFR values are OK, and not to lean/rich.

I know if I see logs like that, I am likely to bring the timing numbers down to match waht the ECU is trying to run the car at. If his car is running 91 and knocking on every pull, think about what the knock numbers will look like if he happens to get a tank of bad gas..

 

It seems to me that you should keep the knock count low because if you are adding alot of timing and the ecu subtracts timing anyway. For this reason knock counts consistently more than 1-3 is silly IMHO.

 

For what it's worth... a high knock count will also affect the higher timing advance a LOT.

So if your friend tuned his car better or reduced timing, then his top end would stand to do better as well.

Sustained high knock is just reducing the timing overall, and pushing it into the lower octane maps. High knock means bad detonation = higher engine temps = problems in the end.

Ie, I can certainly tune more aggressively for higher timing and more power for drag runs. I certainly would not want to keep the same map for a road race where sustained rpm and speeds were held longer.

 

I wouldn't keep a tune that has the car knocking higher than 3. Personally I don't like to see anything but zero knock. Keep in mind that midrange partial throttle load areas DEFINATELY need to be dialed in. When I compare my midrange timing and fuel maps to the stockers they are MUCH MORE CONSERVATIVE. My high RPM numbers are more aggressive but midrange is much more tame.

 

they key is to keep knock to random 1-3 at the most...you're far better off setting the fuel/timing for that then letting the ecu get involved because when it pulls timing it's going to do too much and too late. If you can keep significant knock from happening in the first place you're going to be much more consistent.

 

if you want MAX power you are going to have to be on the edge of knock.

 

i drove my car for 11,000miles with a bad tune and KS of 15-18 for more then a year,nothing happen to the engine i did a compression test and it came out fine,i did have sparkplug problems,but it doesnt mean high knock sums are fine even stock evos with 91oct have up to 10KS and it isnt fine cause this cars are meant to be driven with 93oct and now that my car is properly tune with 0ks the car feels much smoother and faster then before.

 

yep, plenty of customers have come to me with 15 to 25 counts of knock and apparently it didn't cause any physical damage, it just made them extremely slow. We fixed the tune, relaxed the knock to 0-3 counts so the car feels so much better.

However, it is my belief that you can get away with it on a relatively low horsepower car but at high horsepower it's likely to hammer a bearing flat in no time with some detonation.

 

Knock at high load is where you should really try to avoid creating at all.

Also, 3 counts per sample at 3000rpm is like 6 counts per sample at 6000rpm, but theres tons of other factors too like sensor filtering, background noise, engine harmonics and so on.