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I am not a professional obviously but i so far I have had no real issues with my build (that i know of). any way after my pitiful performance at the track I decided to up my boost but it seems at 19lbs i have to use negative timing at one point.. Im sure I can use 1 or 2 degrees in that area but what i want to know is - is it ok to run negative timing or is it normal that I would need negative timing on a stock engine??
To really get a good tune you will play with the timing throughout the RPM range...but on a boosted engine it isn't uncommon to retard timing "x" degrees per pound of boost to obtain the most performance throughout your RPM range.
You cn do some minor tuning yourself, and if you have a datalogger system you can get some real-world results for your specific driving instead of going to a dyno.
You shouldnt have negative timing under 100% load. What are you using to tune? Post up some logs with AFR, RPM, knock, and timing.
i dont drive my car during the week so i would have to post logs on the weekend.. I have an evo 8 ecu with ecuflash -- - my last tune on 16psi i was running 5 degrees advance but when i bumped the psi up i had to run a few load cells in the negatives or i would get 2 counts of knock... **load is way over 100 its at 245 with 19psi... I have never seen a log hit a negative number which if i am correct there is no advance and we are now retarding btdc??
Well first off, what is your injector duty cycle? If you are running 450cc injectors, I bet they are way over 100%. On a 2L 4g63 and a 14b, the 450cc max out at 17-18psi. Running a 2.4L and a 16g, I bet the 450s are past 100% @ 14-15psi. What octane gas are you running? Have any e85 stations around?
Post up some screenshots from your ECU flash.
they are now at 89% at 16psi they were at 80ish..... i have some 680ss i may throw in as im at the limit