GT2871 USERS. SR motor

[Mesarina]

Originally Posted by Conrad 2NR

Sure the timing on the PFC is properly synced?

synced as in putting 15 degrees from 500-1500rpms on the table and making sure the cas ignition timing with a timing gun is the same? I did that.

Originally Posted by di-devol

Shouldn't it be something like 19 up top? I'm no tuner, but I thought that was close to what it should be around. I could be completely wrong though.

I read in this thread that 10-12 timing with 18psi is about right

Originally Posted by LuckyX2

Yeah when I tuned my old setup with the S15 turbo I followed Enthalpy's guidelines on Freshalloy and that put me around 18 degrees or so at full boost (17-18psi). That was with 93 octane gas. The rule of thumb I used was 3/4 of a degree decrease for every pound of boost just btw.

It should not be knocking at only 8 degrees. Are you absolutely sure it was knock?

Also, it could be your AFR's. They look lean on that graph. You should be around 13 from 0-5psi and 11.5-12 for anything higher than that. Aside from the one run that dipped down to 11.5, your AFR's are all around 12.5-13 under boost which is not good.

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!

Thanks for that usefull post, My afr is different on my innovate wideband, stays between 11.5:1-12.2:1 at wot, I do trust more my wideband than the one on the dyno, the wideband used in this dyno may be wrong, it sucks, but it's the only dyno we have here in Guatemala, but im going to put all the table richer at the track to see if this helps, I hope so, best thing I like now is that it's safe, been using it as a daily without any problems, next mod are BC 264's, already have the spring kit and cams, i'm just waiting to get some studs and headgasket to do the job..