Now that I have my LC-1 installed, I'm working on optimizing the tune. I started off by leaning out the 4000-6000 rpm range to 11.0:1, and that worked well. I picked up about 5-10 WHP. Now working on 6000-7000 rpm range which has traditionally been knock prone. At 10.5:1, 11-12 deg, and 20 psi, its pretty well knock free. However when I leaned it out to 11.0:1, I instantly started getting 5-7 knock counts.

Trying to decide on the best course now. Should I just go back to 10.5:1? Pull back a degree of timing? Should I try lowering the boost to 19 psi and reoptimizing there? Any value to messing with the MIVEC? Mods are listed in my sig below.

10.5:1 at 6000-7000 rpm


10.5:1 at 6000-7000 rpm, HP and TQ



11:1 at 6000-7000 rpm


11:1 at 6000-7000 rpm, HP and TQ

 

Pull back some timing and see if you get rid of the knock.

 

If you plan on tracking the car with this tune, I'd probably just richen it back up a little; I think it'll keep the EGTs a little cooler. Better for the motor and the cat. Retarding the timing will increase the EGTs.

 

Not always true, advancing timing also helps lower egts. I think you are running too much timing for that much boost on 92. I would bring it down a degree and see what happens. I personally prefer more boost, less timing.

 

I would keep the 11:1 afr and take a degree of timing out right before the knock starts. I have seen 1 degree removed take away 5 counts of knock on my car before so that could be all it needs.

I prefer building my timing map around my afr rather than vise versa.

 

yea, bring down teh timing if youre having a problem. Ive noticed that it averages teh timing across the 5 cells, so if you ahve any steep slopes you might not get consistant timing across the board.

I ended up with a map that looked very similar to the timing map Naji posted in his thread. I ended up just using his timing map (cause it was more well tuned in the 100-140 load areas), and you'll find its pretty knock proof. I then went back and tuned out the lift off knock parts (i.e. the load areas of 80-120 from 3250-7500)

I posted logs of my 93ish mixed octane logs in here. It was built off a mix between Naji's timing and the stock timing map.

p.s. i run 11.8:1 on 91oct all day long. No difference in EGT's between that and 10:1. But, I did notice that taking out the cat lowers EGT's by 100°F

 

Which thread has the timing map?

Yeah, I don't think the leaner mixtures affects EGT as much as it affects burn rate.

 

i ran in the same situation, I decreased my MIVEC a little. I would keep your timing and a/f ratios the same and just decrease MIVEC. If that dont work, keep a/f ratios at 11.1-11.5 and decrease timing a little.

 

I run 11.8 - 12.0 as well....loves it (but im on 93)

 

Reduce your mivec advance after 6.5K to 0 for the top end knock if it's not already like that. I think some smoothing of your fuel map could get rid of that 1 count of knock in the midrange. In your logs it looks like it goes just a tad lean right before the onset of that 1 knock.. see if you can flatten that out. But overall I agree 1 less degree of timing will make it much more knock resistant.

 

Its Naji's tuner thread.

this is the base map i tuned off of. ITs tuned for 91oct. Its a great starting place, especially if you are runing his Mivec map.

I never had to tune out my Mivec to rid myself of the knock. It was all in the timing/fuel.

here is my log thread:
https://www.evolutionm.net/forums/sh...d.php?t=329699

Ive actually ran 12.2:1 (max peak Tq AFR) on my 93/94 mixed octane and the car loved it even more

 

take out a degree of timing @ 6500 and 7k that should clean it up with a 11:1 afr

what is your datalogged load right when the knock picks up?

 

Some aggressive mivec maps will cause knock in the higher rpm ranges like what is seen in his graphs.

 

Mrfred,

Here is a little secret I use to help man-handle that tricky area.

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Try it out, it might help.