Collected few maps but can't understand why the timing differ so much..

Some people say no reason go beyond 26 BTDC for NA:
Then see mad 40-50 in other maps/posts.

Some people say use 0 split for NA.
Then see 5-15 splits and WARNINGS of big boom for <=0 split.

Where is the truth? (Talking about near stock engine).

 

i remember back in the day when the Rx8 came out, you could hook up the laptop and go for a drive and watch timing, it was really instructive.

the stock ECU's can run up to 48 degrees of timing, but it would have to be low load, and high rpm. at WOT they start around 0 and will climb up to the 20's. if you look around people try running different timings and usually only make 1-2 more hp at 26 degrees than they did at 20

the stock ECU's also tend to run a timing split at WOT, however the race setup used no split at all. i believe the race cars ran zero split partially because when you fire the plugs at the same time, they cannot crossfire.

 

good point! i never really thought about it from that point of view before. did/does that apply to cars that ran 3 plugs per rotor as well? just curious.

 

As mentioned above, when people say "don't go over ##" they are making the following assumptions about your engine as it relates to theirs...
1) they are talking about wide open throttle
2) they are talking about their powerband/redline
3) they are assuming you have the same ports
4) they are talking about their fuel type
5) they may be referring to a boosted application

At lower loads, much higher advance can be run and that is how mileage and emissions are optimized from the factory. All of those charts have very similar WOT values +/- 2 degrees. Other sections of the map vary because some tuners aren't focused on low load. They are only tuning the powerband and maybe idle and just copy and paste values into the other cells to save time.

I haven't messed with spark split myself but I have heard people running no split. They probably don't run as much advance as the people who do run a split...or perhaps they are running race gas. I don't know. Messing with timing is usually something you play it safe with until you can get your car on a dyno to see what works best for your motor. If you're chasing 1-2hp it probably doesn't matter that much.

 

i don't know. i have a feeling it runs splits, just because its got an ECU and they can, plus they were looking for every bit of HP and mileage they could get.

if you've ever seen it run, it basically runs like a stock car