Setting up an initial ignition timing table

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wildman
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Re: Setting up an initial ignition timing table

Post by wildman »

search at turbo124.com for a completed spreadsheet. i believe limits were put in place to stop negative numbers and ridiculous maximums at the borders of the logic.. the algorithims needed limits.
milesinfront
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Re: Setting up an initial ignition timing table

Post by milesinfront »

No joy locating at turbo124... Why not post the link?
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wildman
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Re: Setting up an initial ignition timing table

Post by wildman »

wrenchdad
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Re: Setting up an initial ignition timing table

Post by wrenchdad »

milesinfront wrote:No joy locating at turbo124... Why not post the link?
Here is a link that I found.

http://www.turbo124.com/forum/viewtopic ... 91&p=49960

wd
Mark_Marine
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Re: Setting up an initial ignition timing table

Post by Mark_Marine »

What does everyone think about this as an initial spark map?

Image

This is a 1600cc 4AGZE big port with 8.5:1 compression, forged (stock) internals, t25 making around 15PSI boost on the best pump gas I can find.
My boost threshold is fairly high (small displacement, medium turbo, large-ish intercooler) I don't see full boost until about 3600-3700 rpm, so any of the higher boost/lower rpm values are irrelevant
I just want to find a good base map that I can start tuning on the road from, and when I've got it at the 75% mark I plan to bring it to the dyno so I can safely dial in all the high load/high boost areas. I built this from some interpolation and extrapolation of the suggested map in the megamanual.
PSIG
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Re: Setting up an initial ignition timing table

Post by PSIG »

I'd say that looks very conservative and a good place to get your first tuning runs in. I understand that you don't have cruise timing in yet as it's not tuned, though I would find your best idle timing before leaving the driveway. Once that's set, start tuning NA. Since you are basing all your advance and retard against timing at atmo (~101kPa), that is your primary tuning goal - finding MTBT (minimum timing for best torque) through the entire rpm range at 101kPa (or whatever yours runs at WOT off-boost). It would suck to get to the dyno only to find the engine really wants 23° or 29°and you have to re-do your table. Do you have a plan on how to do that on the street? If you don't, I have developed a method that works well for me that I can pass along if you haven't already read it.

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R100RT
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Re: Setting up an initial ignition timing table

Post by R100RT »

CAn you provide a link or copy of that "street" method, I'd love to read it.
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HidRo
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Re: Setting up an initial ignition timing table

Post by HidRo »

I would be interested as well.
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Mark_Marine
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Re: Setting up an initial ignition timing table

Post by Mark_Marine »

Yes, I'd be very interested as well. I just want something safe enough that I'm not going to hurt anything, but close enough that I'm not p*@#ing my money down the drain at the dyno, paying for runs that just tell me I'm really really far off.
Mhm
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Re: Setting up an initial ignition timing table

Post by Mhm »

I would also be interested in reading that method of setting timming on the road, just for a start to get going.
sedd
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Re: Setting up an initial ignition timing table

Post by sedd »

Attached is a spreadsheet that is based on research from the net. I have attached this before in other posts. I see very recent activity in this one. I am not saying this is fully correct, I want to create some feedback from others who are a lot smarter and more experienced. I feel that the dyno effort and testing may be the only way to get this correct. So this is a first step toward that.

The theory of this spreadsheet it that it uses torque values and the curves from similar engine and cam combinations, and then also adjusts the values higher as the MAP values are decreased, when the throttle is not as far open. The torque is supposed to be an indication of where power is being created and those areas of highest torque need less advance. The entire effort allows the tuner to create much more detail and fine tuning than the old mechanical and vacuum advance set ups.

I had been concerned about the high values at low rpm and was reluctant to set them per the table. Still a bit leary about that. I feel the only reason the old mechanical vaccum distributors had the low values at low rpms was to allow the engine to start. Those old distributors didn't have the seperate starting advance settings like the MS systems. The MS uses a low value at start and then switches to the table which can and should be much higher. I am thinking there isn't much to use from the old distributor settings except the data from full throttle efforts and then only at higher rpm. Those old distributors had to be set for full throttle and had no way to adjust properly for lower MAP = not full throttle.

I am sorry this spreadsheet is not very well designed as it takes quite a while to figure out what is happening, even for me. I feel one nice thing is that is does create a smooth 3D plot.
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thomas1510
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Re: Setting up an initial ignition timing table

Post by thomas1510 »

What happened to Lance Gardiner's original reply (I guess it would have been would have been the second post in this thread)? I remember reading it years ago and it was quite useful. Anyone got a copy?

What happened to Lance Gardiner's original reply (I guess it would have been would have been the second post in this thread)? I remember reading it years ago and it was quite useful. Anyone got a copy?

EDIT: Found it pasted in the spreadsheet (XLS file) for which there's a link on page 4
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khamzatS
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Re: Setting up an initial ignition timing table

Post by khamzatS »

It would be interesting for me to read too!
robinkyle11
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Re: Setting up an initial ignition timing table

Post by robinkyle11 »

I have an air cooled motor, Corvair), with good squish area, cut out the step from the heads, and the piston comes to within .040 or the squish, I have measured 10.5:1 CR on 5 holes with almost 10.75:1 on the sixth hole.

I use Sunoco 260 (94 octane), and have NO detonation problems running 40 degrees under max load, and 57 degrees max under low MAP. I have ALL my advance in by 2400 rpm, and could run MORE advance if I were racing.

I drive the car on the street so I have the motor under load at 2000 rpm and need to keep a little timing out to prevent knock. If I were racing, I would not have the engine under load below 3500 rpm, and could probably dial in 3 degrees more timing.Once I have my MS1 3.0 built, I will use that to control my timing and will therefore be able to dial in a little more timing for racing, and keep it as is for street.
robinkyle11
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Re: Setting up an initial ignition timing table

Post by robinkyle11 »

the values stored in the file are the values in MS units. to convert to
advance you need to divide by 2.84 and then subtract 10 from that total
so:
255 in the vex file = (255/2.84)-10 = 79.78 deg (actually this is deg BTDC)
0 in the vex file = (0/2.84)-10 = -10 deg (Since this is deg BTDC, a
negative number then makes it equal to deg ATDC (without the minus sign)
so a 0 in the vex table is equal to 10deg ATDC.
Mk4Vr6TurboMS3Pro
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Re: Setting up an initial ignition timing table

Post by Mk4Vr6TurboMS3Pro »

Cranking at -2degrees so you definately dont get start kick back.
500rpm at 6 degrees
1000rpm at 8 degrees and ramp up in straght line to 25 degrees at 8,000rpm even if you arent taking engine to 8,000. Timing should be in a straight line not all in at 3,000. If all in at 3,000rpm your definately right on border line of pinging at 3,000rpm. So basicaly make a graph on excell from 1000 rpm (at 8 degrees) to 8000rpm at (25 degrees) and make a straight line connecting 1,000rpm to 8,000rpm. This should be for all kpa 101 and lower. If boosting take 1 degree out per pound of boost. This timing strategy is a shure fire that you will never ping and break ring lands. So basicaly about every 1000 rpm will go up about 2 degrees from 1000rpm to 8000rpm. Ghis is for 9.5:1 compression and lower on 93 octane.

Tuners will argue and say all timing should be in at 3,000 but that dosnt make sense as the engine speed goes up timing should advance equaly w the speed of the engine to keep the maximum point of explosion on the same atdc point.
Mk4Vr6TurboMS3Pro
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Re: Setting up an initial ignition timing table

Post by Mk4Vr6TurboMS3Pro »

And if your going to rev past 8,000rpm (at 25degrees) add 2 degrees to every 1,000rpm after 8,000. So 9,000rpm would be 27 degrees of advance. 10,000 rpm 29 degrees of advance.
Mk4Vr6TurboMS3Pro
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Re: Setting up an initial ignition timing table

Post by Mk4Vr6TurboMS3Pro »

Heres my spark map. Vr6 12v 2.8liter 8.5:1 compression 276 cams 93octane. I can drive this thing knowing Im nowhere near detonation and still have good power.
Attachments
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DGA
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Re: Setting up an initial ignition timing table

Post by DGA »

I don't agree with your spark map at all, at 5000 rpm you only have 18.5 degrees btdc, and only 8.5:1 compression, and with 93 octane to boot! Everything under 100 kpa should be treated like an NA motor, you could easily have 15 degrees more there, I bet that motor feels flat before the boost kicks in.
Mk4Vr6TurboMS3Pro
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Re: Setting up an initial ignition timing table

Post by Mk4Vr6TurboMS3Pro »

Right some people wont. Its right and safe.
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