Ignition Timing Question
#1
02-20-2008, 06:18 AM
Ignition Timing Question
In the SERT software there are three tunes that come with the CD for a Sportster. I noticed that the timing maps are very different in the high RPM and low MAP section of the map. Like 30 degrees timing different. What could they ever be doing that requires that much differance for one motor to the next? The three motors are stage one 883 and 1200 that have the same heads and the stage 2 1200.
Note that this is in a huge downshift.
AW
Note that this is in a huge downshift.
AW
#2
02-20-2008, 08:34 AM
Road Master
RE: Ignition Timing Question
Looks like two different tuners with two different strategies. The guy on the right did not have enough time, such asto go back and smooth things out, like a Friday tune. Keep in mind that some areas that look bad on the map are never used or don't matter, such as the mid-high RPM range in the 20-30 kpa range. I'll bet the map on the left works the best.
#3
02-20-2008, 08:54 AM
RE: Ignition Timing Question
The funny thing is that if "that is a friday tune" is the reason then how do we explain that the file came right from the v477 CD. I would think that having timing that lat would give huge flames thu the exhaust. I prefer to have most flames going on with the valves closed.
The other thing that is strange is that at near idle and high MAP (100 kpa) the timing is real close to 0degrees. 100 KPA can happen at about 15 degrees throttle opening so is not that hard to get to this point on the map. Is it even remotely possible that the motor needs 0 degrees timing? Added: Now that I think about it, it is fairly easy for someone to get to this section of the map as pulling away from a stop in second... that sort of thing.
AW
The other thing that is strange is that at near idle and high MAP (100 kpa) the timing is real close to 0degrees. 100 KPA can happen at about 15 degrees throttle opening so is not that hard to get to this point on the map. Is it even remotely possible that the motor needs 0 degrees timing? Added: Now that I think about it, it is fairly easy for someone to get to this section of the map as pulling away from a stop in second... that sort of thing.
AW
#4
02-20-2008, 09:27 AM
Road Master
RE: Ignition Timing Question
ORIGINAL: whittlebeast
The funny thing is that if "that is a friday tune" is the reason then how do we explain that the file came right from the v477 CD. I would think that having timing that lat would give huge flames thu the exhaust. I prefer to have most flames going on with the valves closed.
I have seen this technique used for head cooling, decel with a rich mixture, late timing carries heat from heads out exhaust.
The other thing that is strange is that at near idle and high MAP (100 kpa) the timing is real close to 0degrees. 100 KPA can happen at about 15 degrees throttle opening so is not that hard to get to this point on the map. Is it even remotely possible that the motor needs 0 degrees timing? Added: Now that I think about it, it is fairly easy for someone to get to this section of the map as pulling away from a stop in second... that sort of thing.
I agree, strange, at least will never get a complaint about ping. I'm not familiar with the SERT but when changing timing with it, is the tuning map for ign timing TPS or MAP referenced?
AW
The funny thing is that if "that is a friday tune" is the reason then how do we explain that the file came right from the v477 CD. I would think that having timing that lat would give huge flames thu the exhaust. I prefer to have most flames going on with the valves closed.
I have seen this technique used for head cooling, decel with a rich mixture, late timing carries heat from heads out exhaust.
The other thing that is strange is that at near idle and high MAP (100 kpa) the timing is real close to 0degrees. 100 KPA can happen at about 15 degrees throttle opening so is not that hard to get to this point on the map. Is it even remotely possible that the motor needs 0 degrees timing? Added: Now that I think about it, it is fairly easy for someone to get to this section of the map as pulling away from a stop in second... that sort of thing.
I agree, strange, at least will never get a complaint about ping. I'm not familiar with the SERT but when changing timing with it, is the tuning map for ign timing TPS or MAP referenced?
AW
#5
02-20-2008, 09:58 AM
RE: Ignition Timing Question
Timing (and AFR) is MAP based at least in every map I have opened.
As far as head cooling I like to totally kill all fuel on extended decel but this is not an option in the SERTsoftware or any of the other tuning commonly available in the Harley world.
Granted the parade logic gets a lot of this done in the Harley world but we are locked out of all that logic with the v477 software.
AW
As far as head cooling I like to totally kill all fuel on extended decel but this is not an option in the SERTsoftware or any of the other tuning commonly available in the Harley world.
Granted the parade logic gets a lot of this done in the Harley world but we are locked out of all that logic with the v477 software.
AW
#6
02-20-2008, 10:31 AM
Road Master
RE: Ignition Timing Question
OK, timing and fuel is MAP based, which I understood to be the case for the original Delphi ECM based maps but I thought for SERT tuning that someone previously posted that it is TPS based for custom changes. Didn't we recently have a thread discussing part MAP and part Alpha Nstratagies in the HD ECM? I apparantly misunderstood.
Some years back it was not unusual to see a map in the mid to high RPM/low kpa range to add somefuel for decel, that was until the EPA got ahold of this. This fuel quickly cools the combustion chambers with retarded timing, still often used in road race applications, ever notice the exhaust flames on decels before a turn on some cars.
Some years back it was not unusual to see a map in the mid to high RPM/low kpa range to add somefuel for decel, that was until the EPA got ahold of this. This fuel quickly cools the combustion chambers with retarded timing, still often used in road race applications, ever notice the exhaust flames on decels before a turn on some cars.
#7
02-20-2008, 12:00 PM
RE: Ignition Timing Question
Most EFI stratagies I have seen for true racecars run stoch or no fuel at all in overrun. The problem comes up on reopening the throttle takes a ton of AE if you turn off the fuel entirely on relighting the fire. Turbo motors are a little different as they run tons of fuel an really late timing to expel a bunch of exhaust flame to keep the turbo spooled. Way good stuff. Google Evo turbo spooling
AW
AW
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#8
02-20-2008, 06:22 PM
Outstanding HDF Member
RE: Ignition Timing Question
ORIGINAL: whittlebeast
In the SERT software there are three tunes that come with the CD for a Sportster. I noticed that the timing maps are very different in the high RPM and low MAP section of the map. Like 30 degrees timing different. What could they ever be doing that requires that much differance for one motor to the next? The three motors are stage one 883 and 1200 that have the same heads (Huh????? The heads are NOT the same... 883 heads are completely different, and the Stage II build is with SE Performance heads.... Compression is the mitigating factor for the difference in the tunes...) and the stage 2 1200.
Note that this is in a huge downshift.
AW
In the SERT software there are three tunes that come with the CD for a Sportster. I noticed that the timing maps are very different in the high RPM and low MAP section of the map. Like 30 degrees timing different. What could they ever be doing that requires that much differance for one motor to the next? The three motors are stage one 883 and 1200 that have the same heads (Huh????? The heads are NOT the same... 883 heads are completely different, and the Stage II build is with SE Performance heads.... Compression is the mitigating factor for the difference in the tunes...) and the stage 2 1200.
Note that this is in a huge downshift.
AW
FWIW, the XB, Thunderstorm or 1200S heads are the ones that make the best power and are more easily dialed in for performance applications....
The 883 heads are really lousy for flow, and need really big valves to get anything in the combustion chamber, but the downfall is the piston match... Dished domes is all you can use with 883 heads... 10:1 CR
The stock 1200 heads have a slightly dfferent chamber, and can operate with Flats or mini-domed pistons... 10.3-5:1 CR.... XLH or XL /S heads
The XB and Thunderstorm heads are the best bang for the buck.... Domed pistons and a 10.5:1 CR.....
And please, get your facts correct prior to eliciting erroneous info.....
#9
02-20-2008, 08:13 PM
RE: Ignition Timing Question
But the only thing is that this differance in timing is when neither head has any real flow. This is all in the 20 - 40 KPA range.All the things you are pointing out really come into play up on top, and there the two maps are almost identical.
FWIW, I thought in 2007 and later both bikes had the same heads.
This is going to be my first try. I fixed what I think is just not correct and then ran it thru a smoothing program I wrote.
Still asking questions...
AW
FWIW, I thought in 2007 and later both bikes had the same heads.
This is going to be my first try. I fixed what I think is just not correct and then ran it thru a smoothing program I wrote.
Still asking questions...
AW
#10
02-20-2008, 10:39 PM
Outstanding HDF Member
RE: Ignition Timing Question
ORIGINAL: whittlebeast
But the only thing is that this differance in timing is when neither head has any real flow. This is all in the 20 - 40 KPA range.All the things you are pointing out really come into play up on top, (Says you.... Are you really believing that the differences in cylinder head construction only affect the top end???) and there the two maps are almost identical.(Now you say that they are almost identical... so what is it?????? In your initial post you state that they are, and I quote "..Very Different in the highRPM and low MAP sections..")
FWIW, I thought in 2007 and later both bikes had the same heads. Not true...
This is going to be my first try. I fixed what I think is just not correct and then ran it thru a smoothing program I wrote. (The ONLY way that timing should be modified is with a load applied to the motor and knock control disabled.... For all of the maps that I have designed, not 1 has ever been that uniform or smooth, whether it be VE or Timing... There is a blending of the cells with their adjoining cells, but it will still be "Choppy" to correct for all of the variables.... I wish you luck in your endeavours to attempt to educate us Tuning Neanderthals... We only work on V-Twins, and not a hi-po Megasquirt powered whatever you are involved in...)
Still asking questions...
AW
But the only thing is that this differance in timing is when neither head has any real flow. This is all in the 20 - 40 KPA range.All the things you are pointing out really come into play up on top, (Says you.... Are you really believing that the differences in cylinder head construction only affect the top end???) and there the two maps are almost identical.(Now you say that they are almost identical... so what is it?????? In your initial post you state that they are, and I quote "..Very Different in the highRPM and low MAP sections..")
FWIW, I thought in 2007 and later both bikes had the same heads. Not true...
This is going to be my first try. I fixed what I think is just not correct and then ran it thru a smoothing program I wrote. (The ONLY way that timing should be modified is with a load applied to the motor and knock control disabled.... For all of the maps that I have designed, not 1 has ever been that uniform or smooth, whether it be VE or Timing... There is a blending of the cells with their adjoining cells, but it will still be "Choppy" to correct for all of the variables.... I wish you luck in your endeavours to attempt to educate us Tuning Neanderthals... We only work on V-Twins, and not a hi-po Megasquirt powered whatever you are involved in...)
Still asking questions...
AW