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PV. Need help understanding VE tables

Started by rich1, January 29, 2022, 04:25:59 AM

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rich1

January 29, 2022, 04:25:59 AM
Bike was a Stage1 114ci Softail. Got PV map from Fuel Moto. Bike ran great. Added Woods 22X cam and got a map made for the cam from Fuel Moto. Bike runs fine. Today just out of curiosity I compared the Stage1 and Stage2 maps with WinPV. I was surprised to see the VE tables numbers for the Stage2 map were lower in the lower rpm range than the Stage1 map. I expected the cam would require more fuel in the lower rpm range and thus the VE tables numbers would be higher. Need help understanding this. Thanks
 

 
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rigidthumper

January 29, 2022, 04:38:14 AM #1 Last Edit: January 29, 2022, 04:44:33 AM by rigidthumper
Maybe a displacement increase in the stage 2 map? Maybe just the difference in airflow because of cam timing. Post the maps so we can see.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

rich1

January 29, 2022, 05:02:25 AM #2
Quote from: rigidthumper on January 29, 2022, 04:38:14 AMMaybe a displacement increase in the stage 2 map? Maybe just the difference in airflow because of cam timing. Post the maps so we can see.

Wasn't a displacement increase in the map. Will post if I can figure out how. Thanks

hrdtail78

January 29, 2022, 05:08:16 AM #3
While comparing the two calibrations.  Look at displacement as mentioned above.  But also, injector size and CDE tables.

If CDE tables are higher in the latest cal.  This will explain how the VE can be lower and will affect VE tales in the mentioned area.  This can be correlated by rpm.  Upping displacement will lower VE's across the board.  Lowering injector size will lower VE's across board.
Semper Fi

rigidthumper

January 29, 2022, 05:34:06 AM #4
I looked at a tune from a 107/468, and compared it to when the bike was a stage 1. On that specific bike, 10% smaller VEs in the lower RPM/lower TPS than the stage 1 map, and up to 20% increase elsewhere, so maybe it's simply a function of changed components requiring different airflow.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

rich1

January 29, 2022, 06:08:30 AM #5
Quote from: rigidthumper on January 29, 2022, 05:34:06 AMI looked at a tune from a 107/468, and compared it to when the bike was a stage 1. On that specific bike, 10% smaller VEs in the lower RPM/lower TPS than the stage 1 map, and up to 20% increase elsewhere, so maybe it's simply a function of changed components requiring different airflow.


Thanks. That's good info. I didn't think anything was wrong. I was just wondering if it was typical. The more I try to learn about the PV the less I know

Jamie Long

January 31, 2022, 07:52:41 PM #6
Quote from: rich1 on January 29, 2022, 04:25:59 AMBike was a Stage1 114ci Softail. Got PV map from Fuel Moto. Bike ran great. Added Woods 22X cam and got a map made for the cam from Fuel Moto. Bike runs fine. Today just out of curiosity I compared the Stage1 and Stage2 maps with WinPV. I was surprised to see the VE tables numbers for the Stage2 map were lower in the lower rpm range than the Stage1 map. I expected the cam would require more fuel in the lower rpm range and thus the VE tables numbers would be higher. Need help understanding this. Thanks
 

 
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The primary reason VE values are generally smaller in the lower RPM's with an aftermarket cam is the engine vacuum is lower in this area relative to the stock camshaft.  IVO/IVC, CDE, MAP normalization and other tables affect this as well.
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