GT2871 USERS. SR motor

[inopsey]

Originally Posted by LuckyX2

Found the link to that timing guide:

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And here's my basemap that I built from that:


As you can see, I have 18 degrees at 17psi.



Keeping everything linear and smooth is key as you can see in the 3D view.

Start with something similar to mine but retard the whole graph a few degrees. Then on a dyno, bump up the whole graph a degree at a time until you knock or stop making power then back it off a degree or two. At that point you're 90% there and just fine tuning is left. Ideally, you'd have a load bearing dyno to fine tune the cells in small groups from that point and extract the last bit of power/drive-ability.

This is the same map that did 293whp and 299ftlbs on an S15 turbo with poncams spiking to 17psi and falling off to 14psi by redline on a 95F day. Obviously, get your AFR's right first before you mess with the timing.

Hope that helps!

what did you use to make sure running all that timing wasnt causing knock wot? you use alot more timing everywhere than i do, and my map is basically the pfc base map minus a few degrees in a few places; pfc runs an aggressive base map iirc.

[LuckyX2]

Originally Posted by inopsey

what did you use to make sure running all that timing wasnt causing knock wot? you use alot more timing everywhere than i do, and my map is basically the pfc base map minus a few degrees in a few places; pfc runs an aggressive base map iirc.

Why would you take away timing from a base map? The idea behind a base map is that it's conservative and timing is supposed to be added to it.

And honestly, I just used my ears... Sounded nice and steady up top and the dyno curve was smooth, no jagged lines that would have shown up if it was knocking.

I rented a dyno for two hours (but spent an hour of that time fixing problems...) at Import Intelligence in West Chester and the owner there was nice enough to hang out for a bit with me and he didn't hear any knocking either. He also asked to see my maps when I was done and he seemed surprised what I did with it in only an hour of dyno time. He said my timing was close to how he would have done it, had I payed him to tune it.

EDIT:
Here's another post I found with an SR20 map. He's running 18 degrees at 18psi too:
http://www.toymods.org.au/forums/sho...=1#post1175381

Also, you'll notice that my timing only changes with load when under boost, not RPM too (except for a precautionary retardation in the low RPM boost area that it should never get to). This was the design of the basemap only but there is more power waiting to be had in the high RPM boosted areas with some more timing.
Timing can and should go up as RPM goes up because the piston is moving faster which means less time for combustion, which means you should start the combustion earlier with more advanced spark.