[sear]

Lots of discussion lately about timing advance.

What should we be looking for ideally in a timing curve?

-Flat slope under boost?
- Increasing slope?
- No dips of negative slope?
- average around 10deg BTDC?
-?



Lots of threads with comments on timing curves as "good" or "bad", but hard to find some with some pointed specifics about exactly what the curve should look like under boost.

Comments appreicated.

BTW, question (for me) is relevant to this thread http://www.e90post.com/forums/showthread.php?t=581083

[MilehighM3]

I'll be watching this...:-)

[enrita]

this one is pretty good

[Jeff@TopGearSolutions]

Depends if your using methanol or not.

With methanol 10+ across the board is ideal.

Without depending on the tune and other exterior factors it can gas low as 2 degrees in the mid-range ramping up to 10 or so by redline.

They key is minimal timing drop outs (ideally none). IE 7 degrees ignition dropping to 2. It needs to look smooth.

As tunes become more advance you will likely see different timing curves with more advance on the top end.

[sear]

Originally Posted by Jeff@topgearsolutions

Depends if your using methanol or not.

With methanol 10+ across the board is ideal.

Without depending on the tune and other exterior factors it can gas low as 2 degrees in the mid-range ramping up to 10 or so by redline.

They key is minimal timing drop outs (ideally none). IE 7 degrees ignition dropping to 2. It needs to look smooth.

As tunes become more advance you will likely see different timing curves with more advance on the top end.

Thanks!!

What do you think of this log running Meth? 4th gear appears to look really good (flat right at 10deg), but not sure why 2nd and 3rd are low to start out. I think its good that 2nd and 3rd only increase up to 10deg, but not 100% sure if I should be looking for something.

These runs are only 15psi (V5 50% boost setting), but I believe this boost to be roughly equivelent to between 17.5 and 18psi at sea level. IF these should look more smooth, then I'm just wondering if I should be backing off bosst just slightly to 14.5 psi or not

Other relevant factors: pull was done at ~60F ambient temps on 91oct + PWM METH (75/25) 50%UT 0%IC

Here is the log in question:

[enrita]

try to display the log as i do. is difficult to see well from yours. log only before you go wot.

[sear]

Originally Posted by enrita

try to display the log as i do. is difficult to see well from yours. log only before you go wot.

I'll try again, but whenever I tried to zoom in further than this the vishnu SW it cut off some of the end of this log. Unless you are saying take another log and don't start it until just before the pull??

[stratos_335]

Originally Posted by enrita

this one is pretty good

Oh, another rev 3 user. How do you manage to get 12+ degrees after 5000 rpm? mine got at 13.5 degrees for a fraction of time

[enrita]

[QUOTE=enrita;10393979]try to display the log as i do. is difficult to see well from yours. log only before you go wot.[/QUOTE]

[enrita]

Originally Posted by stratos_335

Oh, another rev 3 user. How do you manage to get 12+ degrees after 5000 rpm? mine got at 13.5 degrees for a fraction of time

this is on rev2 upped turbos and tons of meth

[stratos_335]

Originally Posted by enrita

this is on rev2 upped turbos and tons of meth

so, the rev. 3 that is able for more than 14 degrees will give it only with upgraded turbos?

[Ilma]

Originally Posted by enrita

this one is pretty good

Enrita.....perfect logs!

Is 12.7 AF ratio kind of lean?

I run procede and it sits around 11.8 to 12.1 on my logs......but feels a bit rich now that I am on meth.

I was thinking of leaning out the open loop fueling a bit, but wasn't sure how lean you could go.

12.5ish?

[onesuperboi]

Waiting for Clap...

[dzenno]

Originally Posted by Ilma

Enrita.....perfect logs!

Is 12.7 AF ratio kind of lean?

I run procede and it sits around 11.8 to 12.1 on my logs......but feels a bit rich now that I am on meth.

I was thinking of leaning out the open loop fueling a bit, but wasn't sure how lean you could go.

12.5ish?

depends on your boost but i'd just have my AFR at 12 in midrange and 11.8 up top...you won't loose power but gain in safety

[Clap135]

A perfect timing curve is when you hit your timing targets. If you don't know what those timing targets are, look for gradually increasing smooth timing graphs. Also dont be fooled by 1 gear wonders, make sure you can hit the same timing at the same rpm in multiple gear pulls. If you can't you are relying on the ecu to react to knock.

[Brey335i]

Originally Posted by Clap135

A perfect timing curve is when you hit your timing targets. If you don't know what those timing targets are, look for gradually increasing smooth timing graphs. Also dont be fooled by 1 gear wonders, make sure you can hit the same timing at the same rpm in multiple gear pulls. If you can't you are relying on the ecu to react to knock.

And without post shift issues too. It's not just about timing in each gear but the transition between them... am I right?

[Jeff@TopGearSolutions]

Originally Posted by Brey335i

And without post shift issues too. It's not just about timing in each gear but the transition between them... am I right?

Of course.