would timing map be the same?
09-19-2004, 07:45 AM
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would timing map be the same?
would timing map be the same if u switched out to a bigger turbo?
is timing pulled according to horsepower or is is pulled according to boost pressure?
is timing pulled according to horsepower or is is pulled according to boost pressure?
09-19-2004, 08:20 AM
#2
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Re: would timing map be the same? (b_ron007)
i would make it a little more conservative even at lower boost because you will be making more power per psi.
09-21-2004, 05:13 AM
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Re: (b_ron007)
Timing is determined by charge density and the optimum length of burn before you blow it all out the exhaust valve.
When you say "switch to a bigger turbo" there are two aspects to address - one of which, the turbine, you may be ASSuming stays the same and just thinking of compressor.
A bigger compressor - not always but usually with most T3/4 and GT stuff - is more efficient at any boost level. You get denser fuel:air charge, at a cooler temp and have to fire the mixture sooner until thermal mass of burning charge overcomes cooler temps and you start pulling timing again.
A bigger turbine effectively lowers exhaust manifold pressure, allows the spent (spending?
) charge to evacuate the chamber sooner, which can (not will always!) like more ignition timing to start things off a touch sooner. Less hot side pressures also translate to less reversion, and less chamber temps because less hot exhaust is hanging around the head/exhaust port/exhaust valve to keep things hot. Refer back to combustion temps, thermal mass, comments in re denser, cooler charge in the above paragraph.
There's a lot of give + take, not really any one general trend for ignition. You'd be surprised how particular it can be if you want to be wholly **** about it - most timing maps I see are generic, operating off the retard + advance whole columns until she doesn't knock theory aka expediency.
When you say "switch to a bigger turbo" there are two aspects to address - one of which, the turbine, you may be ASSuming stays the same and just thinking of compressor.
A bigger compressor - not always but usually with most T3/4 and GT stuff - is more efficient at any boost level. You get denser fuel:air charge, at a cooler temp and have to fire the mixture sooner until thermal mass of burning charge overcomes cooler temps and you start pulling timing again.
A bigger turbine effectively lowers exhaust manifold pressure, allows the spent (spending?
) charge to evacuate the chamber sooner, which can (not will always!) like more ignition timing to start things off a touch sooner. Less hot side pressures also translate to less reversion, and less chamber temps because less hot exhaust is hanging around the head/exhaust port/exhaust valve to keep things hot. Refer back to combustion temps, thermal mass, comments in re denser, cooler charge in the above paragraph.There's a lot of give + take, not really any one general trend for ignition. You'd be surprised how particular it can be if you want to be wholly **** about it - most timing maps I see are generic, operating off the retard + advance whole columns until she doesn't knock theory aka expediency.
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