Few days before I have few races, so the day after that I go see spark plugs. Colour is ok, dark brown, but I noticed few bits on electrode. It is very small silver bits... I have fear that maybe means knocking...

Can that be from knocking (from piston) or can be something else, from fuel, oil... ?

I have standard engine, just chipped (superchips) and run 14 psi (about 1 bar peak, holding 0.7 bar). Fuel mixure under boost is very rich, about 11.5 to 12:1. I use 100 octane fuel.

I also grab with screwdiver on piston, and have black coat on it.

 

Could be det.. although at .7 bar I doubt it on that fuel!

 

I didnt uderstand.... so you think that isnt det because of good fuel?

 

Maybe the inlet temps are to high, what are the ignition set to?

 

yes maybe is that possible... IC is standard. ignition is factory 12 degree... or 13 maybe.

 

does anyone have same situation as me, 12 degrees of ignition timing, 1 bar (or more boost) at MFI, afr about 12:1 ? and runs on 98 or 100 octane...

 

Is that afr at idle or under load?
iirc you want it closer to 14 under load or it'll det.....

 

afr under load is about 12:1 or 11.5 :1. I didnt understand yours last sentence... 14:1 is to lean for under load mixure isnt it

 

I'm pretty sure 14.7:1 is the ideal afr ratio

 

yes for n/a engine, but not for turbocharged one with mfi

 

Ignore DaveySaff!!!!

Your AFR's are spot on mate, combination of those AFR and that fuel should be very safe, I cant see you having det at the sort of timing you are talking about.

Can you not get a set of det cans on it and listen for det?

Failing that, its "off with its head" IMHO, better to spend an afternoon pulling it apart and checking than to just carry on regardless.

 

We live and learn
Hope you get it sorted

 

As a ROUGH rule of thumb:

N/A
Idle / Cruise = 14.5-15
Moderate load = 13.5-14
Hard load = 12.5-13

Turbo
Idle / Cruise = 14.5-15
Moderate load = 12.5-14
Hard load = 11.5-12

 

good info

 

Thanks mate. I will try to get these det cans. I hope on piston isnt so high temp because it have dark black material on it...

 

Do you have an EGT probe?

Worth fitting one if you can

 

No I dont have. I think I have safe setup, but when I saw little some bits on spark I have fear. I suspect ignition timing is 12 or 13 degree... maybe to much. and stardard IC,....