Midrange vs Top End Spark Timing

[Sasuketr]

Hi guys, i have a quick question regarding the spark timing.

Sometimes between 4500 rpm to 5500 rpm the spark timing drops to values such as 23 on 93 octane, but crawls back up to even 30's around 6300 rpm. This is on one version of the tune. The other version, holds min 25 degree of timing during midrange but goes up to 28 degrees of timing at upper rpms. Since the weather is super cold, testing both versions on the track is out of question. As experience wise which one do you guys think is better? Thank you!

Sponsored

 

[melwff]

not an expert but just doing internet research the first one sounds too aggressive thus the drop in the 4.5k to 5.5k range triggered by knock sensors . I think you are safer with the second version topping out at 28 degrees.

 

[DarkestHour]

As RPM rises you have to increase spark advance. During periods of peak torque you typically scale back on timing advance.

These cars, and many nowadays, modify timing based on ECT, IAT, presence/lack of knock, commanded air fuel, load etc...

Follow up with your calibrator for their opinion.
Unless someone has disabled these adjustments you're often going to record varying values in your logging.

 

[Sasuketr]

Thanks guys!

I don't see any knock in midrange, the sensors show negative but timing does go down and it might be due to real torque exceeding the commended torque or something. Worse lamba i see is around 0.88 in the midrange and thats when the spark timing also starts going down.

 

[Terminator2]

Thanks guys!

I don't see any knock in midrange, the sensors show negative but timing does go down and it might be due to real torque exceeding the commended torque or something. Worse lamba i see is around 0.88 in the midrange and thats when the spark timing also starts going down.

It's likely pulling spark based on lambda. Stock it pulls about 1.5-2* at 0.88. It sometimes adds when richer like 0.82.

 

[Sasuketr]

It's likely pulling spark based on lambda. Stock it pulls about 1.5-2* at 0.88. It sometimes adds when richer like 0.82.

So i m running little lean? This started after putting the mishimoto silicone tube and swapping my dry filter with the higher flow oiled one. Weather might be another problem too i guess, its cold and dense air.

 

[Terminator2]

So i m running little lean? This started after putting the mishimoto silicone tube and swapping my dry filter with the higher flow oiled one. Weather might be another problem too i guess, its cold and dense air.

Just a tad. 0.88 isn't horrible by any means I just find 0.85-0.83 makes a bit more power.

Sponsored