Safe Knock level

[Bmxr152]

What is a safe Knock level for a built motor, if it makes any diffrence. I had a wot run and for like one second my knock jumped up to 23 and then went imediatly down???

 

[crunchymilk]

you have a tuning issue at that rpm then, or perhaps it was a fluke.

Ideally, you want none obviously, but less than 4 or so won't kill ya. If you're running link, then you want less than 1 degree retarded

 

[chris4g63t]

As Long as you keep good gas in your car and have resonable timing and an a/f ratio then it will be safe. Knock counts can be picked up by a number of things.

 

[Bmxr152]

ill get little jumps every once and a while its weird??
Data log charts
http://www.cardomain.com/member_pages/show_image.pl?bg=FF0000&image=http://memimage.cardomain.net/member_images/2/web/2282000-2282999/2282369_17_full.jpg

http://www.cardomain.com/member_pages/show_image.pl?bg=FF0000&image=http://memimage.cardomain.net/member_images/2/web/2282000-2282999/2282369_18_full.jpg

 

[olmytsi]

That's definitely something you should look into. Is that at full throttle?

 

[nightspeed87]

could it be phantom knock, and if not what is phantom knock caused by and how much knock usually incorperates with that?

 

[Bmxr152]

no it was like 45% throttle LOOK???

 

[olmytsi]

no it was like 45% throttle LOOK???

Chart is too small

 

[Bmxr152]

so ### do you guys thinks going on??

 

[Bmxr152]

will bigger injetors get rid of knock or will i have to go with FMIC, or any suggestions??

 

[crunchymilk]

you need a 100% throttle 3-7k datalog. Then we'll see if it's really knocking. Since you were at less than 50%, I would think its phantom knock, but a real log would help.

 

[chris4g63t]

If its at 45% throttle its most likely phantom Knock. Phantom Knock can be picked up from a slight lifter tick all the way to a bearing starting to seize up. When i had the original motor in my car I tried so many different ways to cure my phantom knock and none of them worked. It turned out that my balance shaft bearing was making noise. It finally spun and thrashed my entire motor. Not trying to scare you though

 

[MrBoxx]

you need a 100% throttle 3-7k datalog. Then we'll see if it's really knocking. Since you were at less than 50%, I would think its phantom knock, but a real log would help.

I agree. This looks almost like a log I pulled on DSMLink. It showed that even at 18-21% throttle position between 2200 and 3200 rpms I was getting a full 12.7 degrees of knock retard. The pro's on the DSMLink forum agreed with my assumption that it was just phantom knock and I used Link to keep the knock sensor from coming online until 3500rpm.

I also agree that I'd like to see a log in 3rd gear at WOT from 2500 to 7000 to see if the problem is visible in your log again.

 

[Bmxr152]

i will try to post ASAP, But let me get this straight you have to be WOT to see any knock?

 

[chris4g63t]

i will try to post ASAP, But let me get this straight you have to be WOT to see any knock?

Because knock aka detonation only happens when there is a high amount of compression and load on the motor. I wouldn't worry about it too much unless its at wot

 

[MrBoxx]

No, but it's possible that at WOT you won't see any phantom knock. This was true in my case. I could barely touch the pedal and my CEL would flash and the stock boost gauge would peg (both functions of DSMLink to indicate knock), but if I went for a straight pedal-to-the-metal WOT run, there would only be a degree or so of knock retard and it wouldn't occur till late in the rpm band, indicating a normal knock condition. So the phantom knock only occurred at partial throttle.

If you do a WOT run and don't see any abnormally large knock reading like your log shows, it's safe to say that what happened was a phantom knock occurance.

Of course, I just started tuning, so maybe someone else can back me up on this.

 

[chris4g63t]

Phantom knock is over rated especially when its not happening at wot.

 

[keymaster]

Wtf? Over-rated? If it kills your off-boost performance, and getting 13* timing retard will do that, that's not over-rated.

 

[WillyC]

If its at part throttle it doesn't matter. MrBoxx you're correct. I have DSMlink and a forged motor. I used to get the same crazy knock while cruising. My pistons slap around pretty audibly from 3K-4K (think the cyliner bore may be a little too big, but no I'm not worried about it, if they fail I'll build another). I suppress the CEL with DSMlink. When I'm at WOT they make no noise and produce no phantom knock. Rarely ever will you find a tune with zero knock. Blips here and there are very common. 23 "counts" (on a logger I assume) is too high. You want to stay under 10 counts to be safe. The forged motor will hold up. Of course you always want to try and tune it out, but it isn't always possible to clear up every last little bit. I keep my CEL set to 2 degrees w/DSMlink.