Let's see your fully tuned timing maps
Sometimes I wonder if those of us changing timing really understand some of the reasons we do, or need to change it. I think its valuable to understand that the rate of expansion, or the explosion of gas in the chamber can vary. Especially with forced induction, so that if you press more air in the chamber through some mods, or more boost, or IM, etc you are effectively changing the mixture in the chamber and may impact the rate of the burn. (the way molecules align for reaction and so on).
This is key because the precise moment you exert the maximum force on the piston to travel on the downstroke, or power stroke, will maximize the energy you get from that cycle. A little too early and you miss out on some of the force, and may walk into some knock as shock waves may bounce around against each other. A little too late and you are missing out on power as the force is essentially chasing the piston downward.
So just the right fraction in time gets you maximum force, and most note it as 15-20 degrees ATDC. Imagine if you were pushing down on the piston by hand (I did when I had my motor apart) the best time to use your force the most efficiently was not without its irony right around that point. If you imagine the rod and crank and all that rotating its easy to consider.
So my point was really that the reason you may need to reduce timing is that the rate of expansion has actually increased through better air flow or something, and the spark needs to be slightly later so the expansion maximizes at just the right instant on the piston. You basically have to lead the chemical reaction just so, and many things impact how fast that reaction is occurring. We are dabbling in perfecting that timing to maximize energy extraction. Torque.
This is key because the precise moment you exert the maximum force on the piston to travel on the downstroke, or power stroke, will maximize the energy you get from that cycle. A little too early and you miss out on some of the force, and may walk into some knock as shock waves may bounce around against each other. A little too late and you are missing out on power as the force is essentially chasing the piston downward.
So just the right fraction in time gets you maximum force, and most note it as 15-20 degrees ATDC. Imagine if you were pushing down on the piston by hand (I did when I had my motor apart) the best time to use your force the most efficiently was not without its irony right around that point. If you imagine the rod and crank and all that rotating its easy to consider.
So my point was really that the reason you may need to reduce timing is that the rate of expansion has actually increased through better air flow or something, and the spark needs to be slightly later so the expansion maximizes at just the right instant on the piston. You basically have to lead the chemical reaction just so, and many things impact how fast that reaction is occurring. We are dabbling in perfecting that timing to maximize energy extraction. Torque.
Sometimes I wonder if those of us changing timing really understand some of the reasons we do, or need to change it. I think its valuable to understand that the rate of expansion, or the explosion of gas in the chamber can vary. Especially with forced induction, so that if you press more air in the chamber through some mods, or more boost, or IM, etc you are effectively changing the mixture in the chamber and may impact the rate of the burn. (the way molecules align for reaction and so on).
This is key because the precise moment you exert the maximum force on the piston to travel on the downstroke, or power stroke, will maximize the energy you get from that cycle. A little too early and you miss out on some of the force, and may walk into some knock as shock waves may bounce around against each other. A little too late and you are missing out on power as the force is essentially chasing the piston downward.
So just the right fraction in time gets you maximum force, and most note it as 15-20 degrees ATDC. Imagine if you were pushing down on the piston by hand (I did when I had my motor apart) the best time to use your force the most efficiently was not without its irony right around that point. If you imagine the rod and crank and all that rotating its easy to consider.
So my point was really that the reason you may need to reduce timing is that the rate of expansion has actually increased through better air flow or something, and the spark needs to be slightly later so the expansion maximizes at just the right instant on the piston. You basically have to lead the chemical reaction just so, and many things impact how fast that reaction is occurring. We are dabbling in perfecting that timing to maximize energy extraction. Torque.
This is key because the precise moment you exert the maximum force on the piston to travel on the downstroke, or power stroke, will maximize the energy you get from that cycle. A little too early and you miss out on some of the force, and may walk into some knock as shock waves may bounce around against each other. A little too late and you are missing out on power as the force is essentially chasing the piston downward.
So just the right fraction in time gets you maximum force, and most note it as 15-20 degrees ATDC. Imagine if you were pushing down on the piston by hand (I did when I had my motor apart) the best time to use your force the most efficiently was not without its irony right around that point. If you imagine the rod and crank and all that rotating its easy to consider.
So my point was really that the reason you may need to reduce timing is that the rate of expansion has actually increased through better air flow or something, and the spark needs to be slightly later so the expansion maximizes at just the right instant on the piston. You basically have to lead the chemical reaction just so, and many things impact how fast that reaction is occurring. We are dabbling in perfecting that timing to maximize energy extraction. Torque.
Thought I would post my timing map. Sorry about the 2 screen shots, my tuning computer is a 5x10" Sony Vaio. The timing map doesnt fit on one screen lol.
Im currently hitting 275 @ 3570 rpm, tapering down to 220 @ 7500 rpm. 91 oct.
Any advice or comments would be appreciated.
Im currently hitting 275 @ 3570 rpm, tapering down to 220 @ 7500 rpm. 91 oct.
Any advice or comments would be appreciated.
Newbie
Joined: Mar 2013
Posts: 4
Likes: 0
From: Sacramento
30 psi on a 9 turbo, Hallman MBC, bolt ons, OBX intercooler, Megan manifold, AEM intake and fuel mods. 91 octane.
Runs high 11's and daily driven, no knock. And a little how to for the guys that are almost there.
Runs high 11's and daily driven, no knock. And a little how to for the guys that are almost there.
Evolved Member
Joined: Oct 2009
Posts: 926
Likes: 15
From: UAE
Thought I would post my timing map. Sorry about the 2 screen shots, my tuning computer is a 5x10" Sony Vaio. The timing map doesnt fit on one screen lol.
Im currently hitting 275 @ 3570 rpm, tapering down to 220 @ 7500 rpm. 91 oct.
Any advice or comments would be appreciated.
Im currently hitting 275 @ 3570 rpm, tapering down to 220 @ 7500 rpm. 91 oct.
Any advice or comments would be appreciated.
No knock? You must have some good 91oct! It looks more like a 93 map.
Boost drop is significant!
Newbie
Joined: Mar 2013
Posts: 4
Likes: 0
From: Sacramento
I get around 25 mpg highway. 20 something around town under normal driving. The timing strategy I'm using gives me the best acceleration from cruise through spool to peak load.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
Former Sponsor
Joined: Mar 2013
Posts: 452
Likes: 1
From: Colorado
I get around 25 mpg highway. 20 something around town under normal driving. The timing strategy I'm using gives me the best acceleration from cruise through spool to peak load.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
I was looking for your article on another forum, but it got deleted. You should do a write up like you did there.
Last edited by PureDrivePerformance; May 12, 2013 at 05:29 PM. Reason: Wrong identity.
I get around 25 mpg highway. 20 something around town under normal driving. The timing strategy I'm using gives me the best acceleration from cruise through spool to peak load.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
If you log a true 1st, 2nd, 3rd gear acceleration and spend time on the timing in the transition area, you can achieve acceleration that will almost break your neck when it takes off.
Evolved Member
Joined: Oct 2009
Posts: 926
Likes: 15
From: UAE
I'm really impressed, but I wonder if you could run it with more timing advance @ lower boost/load, around 25psi?
Something like 9-10 degrees @ 270 load vs 6-7 @ 300 load
Great article!
Evolved Member
Joined: May 2011
Posts: 964
Likes: 0
From: New Zealand
I'm after a bit of feedback on my 98RON (93 equiv) map. Intake, exhaust, fmic, stock turbo @ 23psi. How does this look? (Not tuned by me).
I also have a random question that I can't find any info on, why do I have 3 high octane and 3 low octane maps in my rom and definition?
I also have a random question that I can't find any info on, why do I have 3 high octane and 3 low octane maps in my rom and definition?