WRECKSHOP
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posted August 29, 2009 09:17 AM
Advancing ignition timing ?
Whats the benefit of advancing ignition timing and what are the negative's of advancing the ignition timing ? Or better yet, when should one advance ignition timing ?? ZX-10, ZX-12, ZX-14....Doug Meyer, tcchin and Y2KZX12 please chime in on this subject, please !!!
  
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tcchin
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posted August 29, 2009 09:45 AM
 Edited By: tcchin on 29 Aug 2009 17:45
In a nutshell, ignition timing's goal is to make peak combustion chamber pressures coincide with a particular crankshaft angular position. Ignition timing also directly affects combustion chamber temps. If you have too much advance, your peak pressure will occur too early, you will generate too much heat, lose power and detonate. If you have too little advance, your peak pressure will occur too late, causing it to be relatively low and you will lose power.
The other two gentlemen you mentioned have a lot more hands-on experience with this topic than I do, and can certainly provide more detailed information.
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KZScott
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posted August 29, 2009 12:09 PM
i run 5.5 degrees on my 12 in the higher rpm range. not a stock motor though. (on pump gas)
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01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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aliveagain
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posted August 30, 2009 04:35 AM
quote:
i run 5.5 degrees on my 12 in the higher rpm range. not a stock motor though. (on pump gas)
Is that in addition to the stock 2.5* or total?
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KZScott
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posted August 30, 2009 05:24 AM
Im not sure what you mean by the stock 2.5? Im advancing 5.5 with the power commander
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01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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Y2KZX12R
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posted August 30, 2009 07:29 AM
quote:
In a nutshell, ignition timing's goal is to make peak combustion chamber pressures coincide with a particular crankshaft angular position. Ignition timing also directly affects combustion chamber temps. If you have too much advance, your peak pressure will occur too early, you will generate too much heat, lose power and detonate. If you have too little advance, your peak pressure will occur too late, causing it to be relatively low and you will lose power.
The other two gentlemen you mentioned have a lot more hands-on experience with this topic than I do, and can certainly provide more detailed information.
Yea, What he said.
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Y2KZX12R
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posted August 30, 2009 07:33 AM
Advance it to what ever the engine likes best. You have to dyno it because every engine is different.
Now, I can say, a stock zx12r or or one with a pipe, typically did like a few degrees of timing advance.
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KZScott
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posted August 30, 2009 08:55 AM
i was running 5.5 degrees on 91 octane with a 13:1 CR motor when i went 154 mph NA in the 1/4. thinking about trying more...maybe a degree or 2 and see how mph is affected if at all
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01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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Texas12R
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posted August 30, 2009 01:26 PM
Karl has a map with some " high" ignition advance numbers but he's doing
this as he monitors conditions on andys dyno
your results may differ
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entropy
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posted August 30, 2009 04:43 PM
quote:
Karl has a map with some " high" ignition advance numbers but he's doing
this as he monitors conditions on andys dyno
your results may differ
yep, i have 8's above 10K, but gonna try higher next weekend (Y2K tip!) on dyno. Monitor AF closely if you experiment like this bc adding adv tends to lean it out.
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KZScott
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posted August 30, 2009 06:33 PM
Karl, did you ever run that much advance way back when you were using normal CRs and pump gas?
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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NOX
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posted August 30, 2009 06:51 PM
Stock 12s like timing
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krexken
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posted August 30, 2009 08:14 PM
Weird how they like timing. It always seemed to me that a lower tech motor motor needed more timing and newer, more advanced combustion chambered motor (ls1s)needed much less timing to make max hp. I'm sure chamber shape and porting heavily influences timing needs and that's probably why timing numbers here vary so much.
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tcchin
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posted August 30, 2009 08:25 PM
Does anyone know what the total advance numbers, not just the added advance, for the 12 are?
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entropy
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posted August 30, 2009 10:07 PM
quote:
Karl, did you ever run that much advance way back when you were using normal CRs and pump gas?
nope, i ran max 5.
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entropy
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posted August 31, 2009 01:11 AM
quote:
Does anyone know what the total advance numbers, not just the added advance, for the 12 are?
at one point I was told:
OEM Spec stock ignition timing is 10 degrees BTDC at 1,000 RPM
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tcchin
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posted August 31, 2009 05:48 AM
You're gonna make me go look this up, aren't you. OEM is:
10 @ idle
35 @ 4800/100% (Max advance)
33.6 @ 6000-11.5k/100%
32.5 @ 12k/100%
80% and 100% curves are identical, except for a slight difference at 1800.
That being said, it seems like Karl's advance numbers are in the 41-42 range at the big end. That seems like a lot, and it may need even more!
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entropy
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posted August 31, 2009 06:17 AM
quote:
You're gonna make me go look this up, aren't you. OEM is:
10 @ idle
35 @ 4800/100% (Max advance)
33.6 @ 6000-11.5k/100%
32.5 @ 12k/100%
80% and 100% curves are identical, except for a slight difference at 1800.
That being said, it seems like Karl's advance numbers are in the 41-42 range at the big end. That seems like a lot, and it may need even more!
THANKS!!
cut n' paste 
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KZScott
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posted August 31, 2009 02:33 PM
quote:
quote:
You're gonna make me go look this up, aren't you. OEM is:
10 @ idle
35 @ 4800/100% (Max advance)
33.6 @ 6000-11.5k/100%
32.5 @ 12k/100%
80% and 100% curves are identical, except for a slight difference at 1800.
That being said, it seems like Karl's advance numbers are in the 41-42 range at the big end. That seems like a lot, and it may need even more!
THANKS!!
cut n' paste
how the hell do you find stuff that easy? Ive spent hrs trying to find that data.... THANK YOU!
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
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dougmeyer
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posted September 01, 2009 07:12 PM
There are lots of factors that go into optimum ignition timing for a given combination. Keeping in mind tchin's correct basic definition, consider how the following items can effect where the correct number is at each rpm and throttle opening......
Bore, stroke, rod length, compression, volumetric efficiency, fuel knock resistance (burn rate), fuel heat content, fuel induction system (atomization-droplet size), type of use, and of course Operator Budget.
Change any one of those and the optimum timing requirement will change. This is why you have to "map" the timiing. The optimum number changes with every change in rpm, load, and cylinder pressure.
Regarding the 12, we're working with very efficient, high turbulence, detonation resistant combustion chamber which gives a lot of latitude to mess with timing without danger.
Most high perf gas engines run a max advance at peak torque (max cyl. pressure) in the high thirties. The 32ish that the factory uses is primarily there to keep the engine out of detonation when using a wide range pump gasolines. This is why the +5's (NA) and higher don't tear things up, especially when using race gas. It only gets us up into the high 30's. It's VERY rare to see any gas engine above 42 deg BTDC. Add higher cyl pressures due to forced induction or a very high oxygen, lean mixture (N2O) and the more aggressive advance will bite you.
An old wedge chamber small block Chevy with 13:1 compression likes about 40 deg. Add 5 and you will hole a piston.
Alcohol burns much slower so you have to "start the fire" sooner. Ignition timing of 55 deg BTDC is not uncommon in an akly engine.. Run pump gas with 10% alcohol and you can add a little advance to recover the lost burn time.
Remember that I said peak torque was the highest pressure? You won't be able to add as much there; not as much room for error before knock set's in. At high rpm the you may need to add more because the efficiency of the cylinder fill suffers and there isn't as much time to accomplish the burn.
These are all generalities, of course. Individual results may differ...... 
Doug
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WRECKSHOP
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posted September 01, 2009 08:13 PM
Thanks Doug Meyer for the indepth response to this. Thanks to all who have given a response/and information to ingition advancement !!!
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tcchin
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posted September 01, 2009 08:23 PM
See? I knew Doug would have some good, detailed input for us to ponder.
So let me ask a related question: If peak torque coincides with highest pressure, why do the OEM ignitions maps tend to place max ignition advance there or thereabouts? Why does the timing always drop off three to five or more degrees with increasing RPM? Wouldn't the fact that flame speed is constant mean that you would need more advance as the engine speed increases, just to keep up?
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dougmeyer
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posted September 01, 2009 09:16 PM
Edited By: dougmeyer on 2 Sep 2009 05:17
That's part of CREATING the peak torque isn't it? Everything is optimized to create the peak, to completely burn all the fuel. I would expect that if you advanced or retarded the spark while holding the peak Tq rpm constant, the torque would decline, creating a new peak at another rpm.
As to your second question- I THINK it's because as the chamber volume diminishes as the crank angle approaches TDC, there is less distance available for flame travel, so the burn happens faster. The whole event takes less time. Or maybe I should say that as the RPM goes up there is less time available for the burn because the piston spends less time at the optimum crank angle. By starting the fire too soon we'd be wasting energy compressing the already burning mixture.
I know I'm contradicting myself from what I said above, but in that case I was speculating on why a particular combo might require more advance at high rpm, which is NOT, traditionally the norm, less it usually what you see.
I'm plenty open to other opinions on this as I haven't looked up any serious data on it.
Doug
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entropy
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posted September 01, 2009 11:51 PM
This is a great thread, thanks to WRECKSHOP for starting it and thanks to Doug & Tim & Jim for weighing in with expertise.
WRECKSHOP,
if you wanna watch experimentation on exactly this issue, come to Andy's 11am-ish this coming Sat.
Determining what max adv my motor responds to in the 10-12K range is the objective of the session.
BTW: bring double ear protection, we'll be running an open SW
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tcchin
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posted September 02, 2009 12:09 AM
I assumed that the timing was backed off at high rpm due to the extra kinetic energy (turbulence) in the mixture imparted by the piston, causing a more efficient burn. Of course, this was based purely on speculation, and I was hoping to get confirmation on it, but it sounds like I was off base.
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