W.o.t Timing
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Joined: Dec 2003
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From: Houston
W.o.t Timing Ok I am running a 99 Formula heads and cam with a 100 shot . I checked the timing values with the engine running at 6700 rpm in park with a Snap On scanner and it was dead on 38 degrees. Does this mean that the wide open throttle timing is 38 degrees or does it have to have a load on it to read correctly. We have run this car for about 2 years at the track like this and this is the first time that I have checked this. I know the timing will flash to a higher setting during acceleration but it never moved from 38 no mater how long I held it at 6,700 rpm.
Alan
Alan
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Joined: Aug 2005
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From: Sunny London, UK
Take a look at the high octane table in the tune some time, you will see where it needs to be loaded to for the various timing points. It varies across the RPM range as well as g/cyl load points.
Without a load, the timing will read higher.
Here's the timing for a stock 98 A4 car. Typically, H/C cars will be tuned to ~27* of timing for WOT from about 2400rpm on up for .60grams/cyl and higher.
Here's the timing for a stock 98 A4 car. Typically, H/C cars will be tuned to ~27* of timing for WOT from about 2400rpm on up for .60grams/cyl and higher.
What exactly does the ".60grams/cyl" stand for? I know RPM...but what is the grams/cyl?
So as the grams/cyl goes up, you want to lower timing. I would assume the higher the grams/cyl the higher the intake charge(hotter air). What is the calculation to determine grams/cyl because I would like to know how air flow comes in to the equation.
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Essentially, it's load. You'll usually see the highest grams/cyl. numbers at peak torque.
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Verdad Gallardo So if I understand this correctly, if at 400rpm, I slam on the gas, the engine will get -4 degrees of timing? And if I slowly hit the gas it will get around 19 to 9 degrees of timing?
Like wise, at 6800rpm, if I hit the gas slowly, there is not much load on the engine until I start flooring it and then the grams/cyl start building up and then the timing is reduced to save the engine.
I would assume the lesser timing in the 4000-5200pm range is because that's where peak torque exists and you want to lessen timing to prevent detonation?
Like wise, at 6800rpm, if I hit the gas slowly, there is not much load on the engine until I start flooring it and then the grams/cyl start building up and then the timing is reduced to save the engine.
I would assume the lesser timing in the 4000-5200pm range is because that's where peak torque exists and you want to lessen timing to prevent detonation?
So if I understand this correctly, if at 400rpm, I slam on the gas, the engine will get -4 degrees of timing? And if I slowly hit the gas it will get around 19 to 9 degrees of timing?
Like wise, at 6800rpm, if I hit the gas slowly, there is not much load on the engine until I start flooring it and then the grams/cyl start building up and then the timing is reduced to save the engine.
Think of the 400rpm row in the instance where the motor is bogged down. Either too much traction or not enough gas or whatever. If you fall into that range, then yes, the high octane table can ask that the PCM commands -4* of timing. The final say, however, comes from the minimum timing table. According to the file I pulled that spark map from, the PCM isn't allowed to command anything less than 8* in the 400 and 800 rpm rows.
As for the 6800rpm area....99.9999% of the time spent in this area falls into two categories: WOT and 0% throttle. WOT is defined in this row just like any other. 0% throttle will revert back to the base spark table. There it commands 34* of timing at that rpm IIRC.
I would assume the lesser timing in the 4000-5200pm range is because that's where peak torque exists and you want to lessen timing to prevent detonation?
Like wise, at 6800rpm, if I hit the gas slowly, there is not much load on the engine until I start flooring it and then the grams/cyl start building up and then the timing is reduced to save the engine.
Think of the 400rpm row in the instance where the motor is bogged down. Either too much traction or not enough gas or whatever. If you fall into that range, then yes, the high octane table can ask that the PCM commands -4* of timing. The final say, however, comes from the minimum timing table. According to the file I pulled that spark map from, the PCM isn't allowed to command anything less than 8* in the 400 and 800 rpm rows.
As for the 6800rpm area....99.9999% of the time spent in this area falls into two categories: WOT and 0% throttle. WOT is defined in this row just like any other. 0% throttle will revert back to the base spark table. There it commands 34* of timing at that rpm IIRC.
I would assume the lesser timing in the 4000-5200pm range is because that's where peak torque exists and you want to lessen timing to prevent detonation?
Ok I am running a 99 Formula heads and cam with a 100 shot . I checked the timing values with the engine running at 6700 rpm in park with a Snap On scanner and it was dead on 38 degrees. Does this mean that the wide open throttle timing is 38 degrees or does it have to have a load on it to read correctly. We have run this car for about 2 years at the track like this and this is the first time that I have checked this. I know the timing will flash to a higher setting during acceleration but it never moved from 38 no mater how long I held it at 6,700 rpm. Alan
