Copier / coller d'un post qui date de 2008 sur Jean pierre car : arrow: http://www.japancar.fr/forum/viewtopic.php?t=117142
CITATION
MessagePosté le: 23-05-2008 15:25 Sujet du message: Répondre en citant
Ptis tuto en anglais pour reglage allumage (nissan mais applicable a toute les caisses), source:
http://filebox.vt.edu/users/bkline/docs/BikiROM.pdf
IGNITION MAP
This map is commonly referred to as the “timing” map. Unlike the fuel maps, all of
the Nissan ECU’s currently supported by BikiROM utilize the same style timing maps.
(This is excluding KA24E and CA18 maps, which are known to be set up slightly
different, and are not currently supported.) The axes of this map are the same as
the fuel maps: horizontal = RPM, vertical = TP (load.) The values in the map refer
to actual timing in degrees Before Top Dead Center (BTDC). Keep in mind this is
assuming that the distributor or CAS is set to stock, which is either 20 or 15 degrees
BTDC based on the engine. In cells of the timing map with values greater than 128,
the knock sensor is “listened to” to sense if detonation is occurring. For example,
for a cell to have 15 degrees timing with knock sensor enabled, the value would be
128+15= 143. When knock is detected while in the area of a cell with the knock
sensor enabled, the ECU switches to the Secondary Ignition Table.
While fuel tuning is very important, many people regard ignition timing to be the
most vital aspect of tuning these engines. Not only is there a lot of power/torque
to be made here, but it is also very important not to have “too much” timing (which
ultimately results in pre-ignition/detonation, and that’s not good for the life of engine
internals.) While the “acceptable” amount of timing varies between engines, the
same theory applies to all. Several knowledgeable tuners in the Nissan community
stress the importance of the following concept: the internal combustion engine is an
air pump -- all of your maps should be very smooth and linear. If you see big jumps
anywhere, you are doing something wrong or you aren’t approaching things correctly.
With that said, I’ve adapted (well, actually just re-worded them to sound better) some
ideas from Scott of RS-Enthalpy about the general forming of a base timing map.
Remember, this is an example, and it may be too aggressive for your engine, so
you’ll need to play with these values for your setup. Some people say not to touch
the values where the engine is in vacuum, as they’re already “tuned” from the factory,
but it’s important to realize that just because Nissan set the timing that way doesn’t
mean it was for maximum performance. Things such as emissions and safety were
involved when Nissan’s engineers wrote the OEM maps. The following pages will
show examples for timing in each engine situation: low load (idle/cruising), middle (0
psi), and high (full boost).
For Full Vacuum (Low TP):
500 RPM - 20 deg
1000 - 20
1500 - 24
2000 - 28
2500 - 32
3000 - 36
3500 - 40
4000 - 40
4500 - 40
(...)
6500 - 40
7000 - 36
7500 - 34
As a safety measure, it is advised to roll off the timing in the high RPM / high vacuum
areas. When you have timing increasing as vacuum increases you get the equivalent
of a vacuum advance distributor -- very good for part-throttle driving. Vacuum advance is
necessary because the air/fuel mix is at a much lower initial energy state when it is pulled in
at a high vacuum. All the molecules are pulled farther away from each other and thus your
burn time takes longer. For that reason, you need to start the burn sooner to reach peak
pressure at the correct time.
For 0 Boost
(Middle TP - You’ll need to experiment to see what TP value you’re at when you hit 0 psi):
500 RPM - 20 deg
1000 - 20
1500 - 22
2000 - 25
2500 - 27
3000 - 30
3500 - 32
4000 - 32
4500 - 32
(...)
7500 - 32
The reason for increasing timing as you approach peak torque (3500 RPM in this example)
is that the actual time that the combustion has to take place gets relatively long at lower
RPM. Therefore, the ignition advance should be less than that of higher engine speeds.
The burn time of the air/fuel mixture is a relatively fixed time for a given intake pressure.
So, if the time of the compression stroke is getting longer due to low RPM, then you
want the ignition advance to be less so that you can reach peak cylinder pressures at the
appropriate time (15-20 Deg AFTER TDC).
For Full Boost (14.7 psi / 1 Bar in this case) (Max TP)
As the car comes into boost, you will want to retard the timing. For an example of 1.0
kg/cm2 (14.7 psi), we will go with a solid .75 degrees timing retarded per psi. Therefore,
you will need to take away exactly 11 degrees of timing at full boost (14.7 * .75 = 11.)
Following this example, your timing map at 14.7 psi should look like below.
500 RPM - 9 deg
1000 - 9
1500 - 11
2000 - 14
2500 - 16
3000 - 19
3500 - 21
4000 - 21
4500 - 21
(...)
7500 - 21
The timing retards under boost for the exact opposite reason that it advances under
vacuum. With the A/F mix coming in at a much higher energy state due to pressure, you
get a much faster burn rate. Therefore, you need to fire the mix later (less advance) to get
peak pressure at the correct time. It is advised to pull the timing out from everywhere: even
in places that you might not ever see boost. It is more of a safeguard than anything, but
it also makes for very linear maps, and ones that are easy to view in the 3D view of map
editing software such as BikiSoft.
After reading the above example, it is clear to see that the areas in between low, middle,
and high TP values need to be interpolated (“blended”) to create a smooth looking map
overall.
FIN DE CITATION
J'espère que ça t'aideras
@+ Vince
Sujet: Re: monoplace Sport Proto Nissan Tame TA120 
je prefere une barquette fermé, mais pourquoi pas une barquette ouverte
4408,14 € de chez Malcolm Garrett Racing Engines ...
Je crois que c'est le préparateur officiel de ce moteur qui le vend, demandes lui pour ton allumeur... si il prépare ce moteur, il doit avoir de la pièce.... 
+ Vince 
t'as des photos de ton allumeur 