What's Your Timing at 18psi?

[AceInHole]

I'm looking for a point of reference since I had to screw up my timing maps after having coil problems. How much timing are you running (KA or SR) at 18psi (or less)?

On the dyno we had timing advanced to around 26deg @ 9psi in order to get the car to run right, but that was also with a 0.020 plug gap. I'm assuming the advance was needed due to the small gap choking burn at the start, but now that my coils seem to be working properly, I'd like to open the gap back up and start cranking some boost. I'm backing the timing tables down, but with only a week left before the next event, I'd like to at least be in the ballpark for timing before testing next Friday.

Someone tell me if I'm off base with this setup:

KA24DET
9.0CR
GT2871r
S13 cams

RPM: 4000 and up
0psi: 32 deg
9psi: 22.75 deg
14psi: 19.2 deg
18psi: 15.7 deg

[McCoy]

Mine's fairly conservative and I've yet to dyno the setup.

SR20DET
8.5CR
T3/T04E 50trim
S3 cams

At 16psi I'm at 12 deg

[WorkInProgressK]

depends if your base timing is 15deg or not.

Because if your base timing is 0 and McCoy is 15, you would both have to one deg near the same timing.

[McCoy]

Enthalpy posted this (http://forums.freshalloy.com/showpost.php?p=646866&postcount=16) up on FA a long time back and seems to be a good starter for making sure you have a safe tune. Basically from 0 boost, you subtract .75 degrees for every pound of boost past zero. I'm even more conservative than this setup and the car still feels pretty strong at 16psi.


I had the WG vaccum line off and ran 2 laps on track at 20-22psi and didn't blow anything up. Was a fair bit faster than a modded Z06 down the straight, which didn't seem right at the time...

[Colorado S14]

I did not read the link (on phone) but I think Scott (Enthalpy) suggested .75/lb on the SR and .85/lb on the KA.

[Def]

Yea, you generally want more timing retard with rising MAP for a higher CR motor. Bigger bore motors need a little more timing as well with all things being equal.

[AceInHole]

I've seen the 0.85 per psi for the KA, but it'd depend on what you run at 0vac. I've seen some people say the KA is at 24-26deg at 0vac, but I've also seen maps where KA guys have had 32deg. Right now I'm at 32deg timing at 0, pulling timing from 1.2deg per psi initially until 18psi where it'd be 0.85 deg per psi. It keeps me above 0.5deg per psi assuming 26deg is actually the stock timing at 0vac.

[CodyAce]

20 psi, 21/22 degrees up top

[AceInHole]

20 psi, 21/22 degrees up top

Guessing your timing is climbing and not constant like some of the other maps, but is that with race fuel or E85?

[WorkInProgressK]

20 psi, 21/22 degrees up top

wait what? with the cam angle at 15 degrees?

[greenman100]

Guessing your timing is climbing and not constant like some of the other maps, but is that with race fuel or E85?

bumping this because I'm curious. I think its on 93 octane, though

[WorkInProgressK]

I just looked at all my tunes I had and most of them are around that. 20 at WOT at 6800 RPM.

Forgot to mention, its on a sr20det.

[Wheelman]

Wow, I'm glad I ran across this thread as I'm in the process of tuning my KA-T right now.

Anyone care to share some AFR numbers they run under boost?
I've seen a lot of discussions online where guys talk about running in the 11 range, I personally think that is richer than it needs to be and would like to run in the 12 to 12.5 range assuming I can put together a timing map that is compatible.

What do you guys think?

[Colorado S14]

11.5:1-12:1 under load and full throttle. 12:1+ is not that bad but you have pretty much the same power at 11.5 that you do at 12.5 and 11.5 is safer.

[AceInHole]

I'm running at around 12.5 from 0 to 6psi, and 11.5 beyond that.

[Equinox]

I run 13s until 7psi and then down to 11.8 for 18psi.

My motor doesn't like anything 12+ under full boost. It can take a fair whack more timing in the high 11s.

[CodyAce]

wait what? with the cam angle at 15 degrees?

15* base, with that up top. JWT ECU.

[CodyAce]

Wow, I'm glad I ran across this thread as I'm in the process of tuning my KA-T right now.

Anyone care to share some AFR numbers they run under boost?
I've seen a lot of discussions online where guys talk about running in the 11 range, I personally think that is richer than it needs to be and would like to run in the 12 to 12.5 range assuming I can put together a timing map that is compatible.

What do you guys think?

It's all dependent on timing. You can have it soft, and run leaner and be ok, or you can run with more timing, and more fuel.

I personally would not remove to much timing, as it makes these things feel sluggish as hell, and the turbo doesn't spool as fast either.


11.6/11.8 at WOT for me.