Do I need to retune if changing pulleys on procharger
12-23-2018, 08:07 AM
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Do I need to retune if changing pulleys on procharger My car has a speed density tune and is currently making 830 to the wheels. I am planning on making a trip in it and would like to change to a bigger pulley to slow the blower down. Do you guys think I need to retune it? I may leave the bigger pulley on it for a little while. Thanks
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12-24-2018, 08:36 AM
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12-24-2018, 09:08 AM
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12-24-2018, 09:44 AM
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12-24-2018, 02:16 PM
#12
Example.
Well tuned car has a BOV or coupling.intercooler start leaking pressure losing a couple of lbs after the tune...Still runs perfectly fine as far as AFR and driving is concerned it is just down on original power. Bigger pulley will do the same thing as far as what the SD Tune reacts to.
The inverse may not be (probably isn't) true if the original tune doesn't have enough fuel (injector duty cycle or pump) or exceeds the MAP sensor range or anything else Danger Zone.
Well tuned car has a BOV or coupling.intercooler start leaking pressure losing a couple of lbs after the tune...Still runs perfectly fine as far as AFR and driving is concerned it is just down on original power. Bigger pulley will do the same thing as far as what the SD Tune reacts to.
The inverse may not be (probably isn't) true if the original tune doesn't have enough fuel (injector duty cycle or pump) or exceeds the MAP sensor range or anything else Danger Zone.
12-25-2018, 06:26 AM
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If the car is tuned well and you change the pulley to reduce boost it is likely your fueling will be near perfect. What will happen is you will not get into certain areas of the VE table as you would have before. Lets say you are well tuned and get to 170 kpa so you know all areas at all rpm and kpa values below that are good. Now you've reduced boost and only get to 150 kpa no problem those areas are all well tuned. Now going the other way and adding boost may be different, but even then you should be fine as far as fueling if you continue the trend on the VE table. I've added a pound of boost at a time with a procharger and my AFR has been pretty darn good right off each time. I just have the VE table continuing the rate of increase all the way up in the areas I never reach. When I add boost I enter higher areas that I haven't been, but it's accounted for and takes very little if any adjustment. Now adding boost or reducing boost may change what amount of timing it likes for max power without KR, but as far as fueling if it's tuned well it shouldn't be an issue.
12-25-2018, 06:30 AM
#14
It all depends on how much time was spent during the tune. Speed density is calculating fuel need based on amount of air density at a given rpm. With a centrifugal supercharger, it's pretty linear, so doing a tune is straightforward. Now that you changed the pulley, you change the boost rate/rpm. It should be 'close' but if you are just going on a long trip, just stay out of the boost and you'll be fine. I don't see the need to change the pulley just for a trip.
