Thread: broken plug

p11
stock fresh sr20de, gtir manifold, gtir turbo, 370cc 4bar, 3inch exh., nistune
10psi of boost
bkr6e spark plugs
base timing 15degrees.
at wot 13-20degrees
egt at 800degrees celsius, 95% duty cycle, 4.8volt p11 maf
afr 12.5:1

Now during driving on highway spark plug at 2nd cyl has demaged.. melted or somewhat. Other plugs looks ok. And there is no compression on the 2nd cylinder.. the cyl is also full of oil...

My question is why. I know the afr should be lower but tell me please would it happend if i have been running bkr7e's?


:/

yep

Probably still would have happened, yes.

any idea what to do to not happen next time?

Stop running 12.5:1 AFR.

http://www.sr20-forum.com/tuning/16056-why-i-tune-12-0-1-f-ratio-0-82-lambda-why-you-should-too-all-welcome.html

yep, i tuned it to 12:0 but something has changed and it started to run at ~12.5 (maybe the manual boost controler has moved little bit. sometimes there were 11psi and the afr was about 12:0.. because of not so well adusted TP scale fuel table at nistune) .. i have many logs from various pulls also..

well you are running almost to the maximum on your injectors and your maf, you should take that into consideration

I usually run richer than that under wot. 12.0 is about the max you would want to go. I tune mine and my buddies cars to 11.5-11.8:1 just to be safe, Id rather be down a couple hp than to risk melting a piston. But even then if something happens and say you overboost there is not much that is going to stop detonation from happening.

is it possible with that setup to run the car at wot uphill for about 5 minutes?
Thats pretty bad that the EGT gauge hasnt helped to avoid that. I started to run this engine with retarded timing(by rotating distributor) and the EGT temps went to 900celsius very quickly. Then i raised timing forabout 2-3 degrees and the egt went to about 870celsius and sits there. After that i added another 2degrees and the egs started to sit at 800celsius. Unfourtunatly it made just a few pulls. I made only 900km at this engine ...

The previous engine(original stock engine) i was running at stock boost and it made 30 000km boosted, but it never can drive for a longer time at wot too. Pulling it uphill at 5th gear always did missfire after some time at wot. After that that engine started to mix water and oil. I changed headgasket, but it doesnt stop mixing That engine is already sitting at my garage.....


Now i am thinking about selling everything and having no fast car anymore.

great idea sir