MAF value need


analogdesigner

GT Owner
Mark IV Lifetime
Nov 15, 2005
949
San Clemente, CA USA
I'm trying to troubleshoot a low boost problem. What is the expected MAF value for a stock engine setup at 6,000 RPM, WOT? My car has the Roush pulley (worth about an extra 2 PSI of boost) and I am getting about 32-33 lbs./min. of airflow, WOT at 6,000 RPM. A mechanical vacuum/boost gauge shows about 10-10.5 PSI which is obviously too low. Any help is appreciated. Thanks, Jay
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
Point a GoPro (or similar) at the SC bypass actuator and take the car for a drive. Practically no other way to lose boost in an otherwise normal running motor.
 

SMOKDU

GT Owner
Dec 17, 2011
412
I'm trying to troubleshoot a low boost problem. What is the expected MAF value for a stock engine setup at 6,000 RPM, WOT? My car has the Roush pulley (worth about an extra 2 PSI of boost) and I am getting about 32-33 lbs./min. of airflow, WOT at 6,000 RPM. A mechanical vacuum/boost gauge shows about 10-10.5 PSI which is obviously too low. Any help is appreciated. Thanks, Jay


Did you figure this out ? If not PM me when have some information that might help.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
The MAF value is should be pretty close the the theoretical one. Find the grams per liter if air at STP, scale by the expected boost and multiply by the engine's intake displacement at the RPM in question halving it because of a 4 stoke engine. One same caveat I don't recall if the numbers are scaled in the stock OEM tune. I know I scaled my custom tune so that the boost would be correct even with the added Mafia. I now use a real boost sensor connected to Speedhut gauges.

But since your real boost guage is reading low I would suspect that something isn't right. As Kendall said it might be your bypass valve, dirty air filters, collapsing bellows. Something is limited the expected airflow.