Dear all,
I've been bothered by this for quite some time, as far as I know,
ignition advance would mean moving the ignition timing further away
from BTDC and retard would be getting it closer to BTDC. After
referring to most of the maps uploaded here, I've noticed that most,
or rather all the maps that I've seen had their ignition timing
retarded. I've sent my car for dyno tune recently and the tuner
advance all the timings from 3-6deg. I gained only about 2hp with
this setting. I'm driving a 4g18 SOHC NA Engine.

My question is, where do most factory ecu set their ignition timing
at with reference to BTDC? I've came across one article which says
around 10 - 12 deg BTDC. Since most(or literally all) of the maps
here had their timing retarded, I would also like to remap the
piggyback with retarded timing. Any advice on this?

Thanks
Jeff

 

you generally want the most ignition advance possible without knock. a better way would be on a load bearing dyno and have it set to the minimum advance that makes the best power, which might be what your tuner did.

The maps here are for boosted cars too.. more boost a lot of times means less timing..

I wouldnt recommend touching your tune..

 

Jeff,

Below are some points on a turboed motor's timing, same general points apply, the one specific to you would be that timing is set to what the motor will take before it starts knocking. Or before it starts to loose power because Peak Pressure is attained before it is desired. Generally a tuner will advance timing until he sees no further gain in power then back off just a bit for a little safety.

Best timing gives peak pressure around 15* atdc. in order to achieve this timing is set anywhere from 40*btdc on down to whatever keeps the motor from knocking, I've seen some maps set with minus numbers at very high load.

when you set timing for wot you might see 1 to 6 degrees around 3500rpm on a evo motor

there are several factors in timing, 1, more boost means quicker burn, therefore less timing is needed. 2, the hotter the charge the quicker the burn, same as above. 3, injectants tend to lower the temps and allow more timing. 4, Quicker motor rotation means there is less time for the motor to get to the peak pressure point so more timing is need at high rpm.

But you have to remember you are shooting for the same Peak Pressure, around 15* ATDC. So you do what is needed to get as close to that as you can. Typically the evo is knock limited or at least tuned that way. In other words, a tuner sets timing just below the onset of knock. That is why you will see such low numbers in a timing map on an evo.

The fact that you only gained two horsepower from three degrees of timing sounds like you were about safe with your timing before your change.

hope there is something useful there.

 

Below are some points on a turboed motor's timing, same general points apply, the one specific to you would be that timing is set to what the motor will take before it starts knocking. Or before it starts to loose power because Peak Pressure is attained before it is desired. Generally a tuner will advance timing until he sees no further gain in power then back off just a bit for a little safety.
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I see, in that case advancing timing would mean igniting the fuel earlier BTDC? like for example current setting is at 10deg btdc, and advancement of 5deg would mean the spark will fire off at 15deg btdc, am I right to say that? I'm getting more and more confused. pardon me.


Best timing gives peak pressure around 15* atdc. in order to achieve this timing is set anywhere from 40*btdc on down to whatever keeps the motor from knocking, I've seen some maps set with minus numbers at very high load.
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Does "40deg btdc on down" mean playing with the numbers downwards? like from 40deg btdc untill say 10deg btdc?


when you set timing for wot you might see 1 to 6 degrees around 3500rpm on a evo motor
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Yup, I have small figures set at WOT.


there are several factors in timing, 1, more boost means quicker burn, therefore less timing is needed. 2, the hotter the charge the quicker the burn, same as above. 3, injectants tend to lower the temps and allow more timing. 4, Quicker motor rotation means there is less time for the motor to get to the peak pressure point so more timing is need at high rpm.
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I see, so that explains why most turbo cars got their timing retarded. I'll keep that in mind since I intend to BOT for e 4g18 in near future.


But you have to remember you are shooting for the same Peak Pressure, around 15* ATDC. So you do what is needed to get as close to that as you can. Typically the evo is knock limited or at least tuned that way. In other words, a tuner sets timing just below the onset of knock. That is why you will see such low numbers in a timing map on an evo.
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I'm driving a 4g18, SOHC 1.6L NA. does the same "low numbers" apply to my engine?


The fact that you only gained two horsepower from three degrees of timing sounds like you were about safe with your timing before your change.
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So should I push the numbers further up till an optimum point or should I lower them or even retard them?

hope there is something useful there.
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You've been very helpful my dear friend, appreciate the time you spent for your explanation.

 

40 degrees before top dead center is "more> timing than 20 degrees BTDC. to say one is retarded isn't really correct.
If the 20 is the right timing for your rpm/load then the 40 degrees needs to be retarded.
Yes, if you have 10* now and you advance 5 you would have 15* BTDC.
The confusing part to my mind is the differences in time it takes to get the Peak Pressure at 15*ATDC. Part of the issue there is the burn rate of different gasoline grades and the effects of heat and such in the cylinder.

A NA car will likely not see single digit numbers at wot. Remember that if you bypass your turbo on an evo and run wot your load will never get as high as it does with the added boost pressure. In fact since the evo has less compression ration than a designed NA car it will need a bit more timing, everything else equal, than a lancer. But in a nut, no, a NA car will likely be running 15* (generally speaking) or more at peak load while a evo would have to run around 3*

tuners set the car up on a dyno and add timing until power falls off or knock starts. they then back off on the timing (reduce the number) a few degrees for a safety margin.
A car that is really retarded and you add a few degrees will gain lots of HP. A car that is close to optimum timing will not gain much at all. In this case 2 or 3 HP does not sound like much. Think I'd leave it up to my mechanic to decide where the timing should be. IOW I don't know what you timing is supposed to be set at.

You sound like you are straining to get more power from your car. How are you determining how much HP you are getting or loosing?