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Old 12-04-2012, 05:20 AM   #1
icmfamous2
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retarding timing I need someone to explain it.... how does it effect a tune??
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Old 12-04-2012, 09:05 AM   #2
Leafy
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Do you mean retarding ignition timing in the tune? If so it reduces torque and increases EGTs but it reduces the likely hood of knocking since it will lower the peak cylinder pressure. But you want to run the most timing you can without knocking, or hitting MBT. MBT is mean best timing, or mean best torque, or minim best timing, or a section of other words that fit the acronym and mean about the same thing. MBT is basically the lower amount of timing advance that results with the most torque possible under each condition. So if you were tuning on a mustang dyno, you would hold the car in one cell in the tune, and keep increasing the timing in that cell and watching the torque increase. Once it stopped increasing you'd pull it down a notch and move onto the next cell. Normally in boost you'll knock before MBT, but its still important to tune to MBT in your out of boost cells to maximize response and fuel mileage.

If you meant cam timing... Well ****, I wrote that for nothing.
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Old 12-04-2012, 10:01 AM   #3
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Quote:
Originally Posted by icmfamous2 View Post
retarding timing I need someone to explain it.... how does it effect a tune??


You need to explain better what you're asking. If you mean retarding timing due to knock that is the ecu reducing the degree at which the spark fires in accordance to top dead center of the piston. This is done in an effort to degree potential knock. If you are seeing large values of feed back knock or fine learn knock correction your ecu is seeing (actually hearing) detonation coming from a cylinder and is pulling timing in an effort to stop it, and save your engine for going boom.

This doesn't effect the tune at all, it's part of the tune that is a fail safe for a huge variety of external stimuli that could result in knock events. The tuner has the option of setting knock protection to specific ranges of load/rpm in order to provide safe guards. A google search on this topic will yeild countless articles writen about the nature of tuning, subaru knock protection, and timing; so start reading if you'd really like to learn.
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Old 12-04-2012, 03:03 PM   #4
icmfamous2
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Quote:
Originally Posted by NoGraffix

You need to explain better what you're asking. If you mean retarding timing due to knock that is the ecu reducing the degree at which the spark fires in accordance to top dead center of the piston. This is done in an effort to degree potential knock. If you are seeing large values of feed back knock or fine learn knock correction your ecu is seeing (actually hearing) detonation coming from a cylinder and is pulling timing in an effort to stop it, and save your engine for going boom.

This doesn't effect the tune at all, it's part of the tune that is a fail safe for a huge variety of external stimuli that could result in knock events. The tuner has the option of setting knock protection to specific ranges of load/rpm in order to provide safe guards. A google search on this topic will yeild countless articles writen about the nature of tuning, subaru knock protection, and timing; so start reading if you'd really like to learn.
thanks I will research more about it, but I thought I would ask someone with experience with subarus first, I'm not afraid to ask a question about something I don't know even if I look silly lol
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Old 12-04-2012, 03:05 PM   #5
icmfamous2
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Quote:
Originally Posted by Leafy
Do you mean retarding ignition timing in the tune? If so it reduces torque and increases EGTs but it reduces the likely hood of knocking since it will lower the peak cylinder pressure. But you want to run the most timing you can without knocking, or hitting MBT. MBT is mean best timing, or mean best torque, or minim best timing, or a section of other words that fit the acronym and mean about the same thing. MBT is basically the lower amount of timing advance that results with the most torque possible under each condition. So if you were tuning on a mustang dyno, you would hold the car in one cell in the tune, and keep increasing the timing in that cell and watching the torque increase. Once it stopped increasing you'd pull it down a notch and move onto the next cell. Normally in boost you'll knock before MBT, but its still important to tune to MBT in your out of boost cells to maximize response and fuel mileage.

If you meant cam timing... Well ****, I wrote that for nothing.
from what u wrote I am now understanding a bit more about it.....and actually cam timing and mbt and knock go hand and hand together or at least they should right??

Last edited by icmfamous2; 12-04-2012 at 03:13 PM.
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