I've noticed that on my car that I'm not reaching MBT before I see knock on my knock sensor. Is there anyway I can filter my knock sensor?

 

what fuel you using?

unless it's E85 you will probably not hit MBT before hitting knock...

 

Are you suggesting the knock your seeing is false knock? If so, have you tested that by finding that pulling timing doesn't clear it up, using det cans you don't hear it, etc?

 

This helped me in the low rpm and low loads areas.

https://www.evolutionm.net/forums/ec...ble-found.html

 

I run c16 117octane Leaded Race fuel.

I know I'm not at MBT because with a degree of advance I picked up 7-10whp.... yet my knock sensor is starting to give me 2-3 counts with another degree. It's quite evident on the dyno chart as well.

 

You may be very near MBT and you are getting occasional knock events with it?

FWIW, on a friends car I was tuning using VP Import, being 2 degrees from MBT cost it 80HP at the 700HP level. Being 1 degree shy only cost like 10HP. Being 1 degree over caused serious detonation.

Some setups can have a very fine line between MBT and detonation. On that setup, I felt it was better to leave it 10HP down.

 

maybe that ur timing in that area is not as smooth, onsetting knock. try that.

 

It's definitely smooth. 03whitegsr might be onto it. I'll try and retard a degree at a time next time I'm at the dyno and plot a curve.

 

I am pretty sure Knock != MBT

Since your running such a high octane fuel, maybe you can fiddle with the knock maps.

But ensure its not real knock by using detcans or such...

 

Really depends on who you ask.

MBT is the point where the car makes the best power for a certain amount of timing in it's current configuration. You'll know when you hit MBT when more timing doesn't make any more power or if the car actually drops power.

Seeing knock before MBT just means the fuel you are using is knock limited. A good example is you will never ever ever ever ever see MBT on 91 oct.

- Bryan

 

Yup that's what I thought...

 

Thank you for understanding MBT.

I don't think c16 should be on it's knees at 538whp. I'll have to log my air temps to see what I'm doing to it.

Notice the choppy dyno graph on my last pull Bryan? It screams that it needs more timing. I went from 505 to 517 adding one degree of timing at 32psi... knock light lit up by adding one more degree. (knock light is set at 3 counts or more)

It could be due to running the Red WAY outside of it's efficiency range and heating the crap out of the intake temps...and then not having a big enough intercooler :/

 

Was that choppiness from the ECU pulling a degree or two from the 3+ counts?

What kinda AFR and timing are you running right there?

 

The strange thing is that you can induce knock sums with more timing and its not totally random. That means the ecu is picking up something when you add that timing in. Maybe it is false, but my experience says listen to that damm knock sensor. I would highly suggest pulling plugs and reading them. You need fresh plugs. Make sure the insulator is clean looking (you will need a doctors ear scope) and make sure that the ground strap isn't showing too much heat.

I've never had good luck with det cans. Apparently my hearing is bad and my cars are too loud.

 

dont forget the knock sensor just listens to "noise".

You can quiet easily hear that timing will make a difference - especially @ cruise, ie 40* sounds/feels much smoother than 44* (on my GSR X)

so yes its quite possible you will need to "relax" the knock maps so the ECU doesn't ****-its-daks when it "hears" new/different noises!