firing order by degree.
03-06-2009, 08:06 PM
#1
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firing order by degree. I'm planning headers for my build and have a pretty good idea how to do that. I searched the net and can't seem to make sense of where each of the plugs fire in terms of crank degree. This is a problem that relates to pulse tuning the primaries so if anyone know when the buggers fire i'd appreciate learning about it.
03-07-2009, 08:58 AM
#2
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I'm planning headers for my build and have a pretty good idea how to do that. I searched the net and can't seem to make sense of where each of the plugs fire in terms of crank degree. This is a problem that relates to pulse tuning the primaries so if anyone know when the buggers fire i'd appreciate learning about it.
Are you planning 4 into 2 into 1 headers? Why? If you are planning 4 into 1s, why are you concerned about "primary pulse tuning" other than length and diameter of the primaries?
03-07-2009, 01:00 PM
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Ya but if the timing isn't correct you would be letting the gases into the exhaust to early or too late. If it's not in time with the crank then it'll all be off
03-07-2009, 03:08 PM
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I'm considering 180 headers and logic tells me firing should be 90 apart. I get confused with LR LL RL RR. The distance the pulse has to travel is quite long with crossovers at the back so I want to pair the left with rights and need to know time and distance. Merging pairs with short primaries @ 1.625 into 1.75 secondaries and merging those into 2.5 collectors. Why? For the hell of it. Its a project fitting an LS into a 968 Porsche and it has to have sound. But my understanding is the 180s also scavenge very well.
The LS firing order is 1-8-7-2-6-5-4-3, and they fire 90° apart. If you assume#1 fires at 0°, #8 at 90°, etc. you can figure out the rest. Remember it takes 2 complete revs (720°) to fire all eight cylinders.
Are you planning 4 into 2 into 1 headers? Why? If you are planning 4 into 1s, why are you concerned about "primary pulse tuning" other than length and diameter of the primaries?
Are you planning 4 into 2 into 1 headers? Why? If you are planning 4 into 1s, why are you concerned about "primary pulse tuning" other than length and diameter of the primaries?
03-07-2009, 05:33 PM
#6
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I'm considering 180 headers and logic tells me firing should be 90 apart. I get confused with LR LL RL RR. The distance the pulse has to travel is quite long with crossovers at the back so I want to pair the left with rights and need to know time and distance. Merging pairs with short primaries @ 1.625 into 1.75 secondaries and merging those into 2.5 collectors. Why? For the hell of it. Its a project fitting an LS into a 968 Porsche and it has to have sound. But my understanding is the 180s also scavenge very well.
You didn't ask for advice about making power, so i won't bore you with any other than what I just said above.
Have fun..
03-07-2009, 06:54 PM
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Thanks for the info. I appreciate it. I can't see how you could consider little knowledge regarding an exhaust is dangerous though. You are right i didn't ask advice regarding making power as thats not the point of the exercise and if it doesn't work so what.
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03-08-2009, 09:29 AM
#8
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Show car, huh? Oh well.
