GVK 1 Posted January 4, 2007 Report Share Posted January 4, 2007 What reading should you usually see on an OBD II VR6 MAF when viewing 'mass air flow g/s' on VAG-COM?Mine reaches 150 g/s at about 6k rpm on the road. Link to post Share on other sites
IbiVR 0 Posted January 4, 2007 Report Share Posted January 4, 2007 Bear with meFor a general idea of what the maf should read, peruse these maths.You have 2.8 litres. It takes 2 revs to fill all cylinders to suck in the whole 2.8 litres of air.Got to take volumetric efficiency into it, to simplify it we'll only work with wide open throttle so we can forget the restriction of the throttle plate. Lets go for a VE of 85% at 6k. Its a reasonable estimate given you have filter/6 branch/cams to help it breathe.2.8litres x 85% = our new capacity - 2.38lso do 2.38 x revs / 2 (remember 2 revs to fill all 6 cyl) and you get your litres per minute.divide by 60 and you get litres per second.so 2.38 /2 /60 x rpmin this case 6000rpm119 Litres of air per second.ok now at 0 degrees C air weighs 1.293 grames per litre119lps x 1.293g153.8g/sAgain that only works at wide open throttle cos it doesnt take into account the restriction of the throttle plate. Also very rough maths, and only taken air at 0 degrees C and guessed volumetric efficiency. so there a fair margin for error.saying that i work out 153, you get 150. I'd say thats close enough to say that 150g/s at 6k is about right 8-| You could use the maths backwards to work out your volumetric efficiency. be interesting to see who flows best, or work out VE of std VR.Better VE = more air in = more torque = more power. therotical max tourque of an NA engine is 100%VE (Although 100% is impossible to achieve).*VE is rpm dependant so would need to be at a set rpm. Max VE of the engine will be where you see max torque.Tom. Link to post Share on other sites
GVK 1 Posted January 4, 2007 Author Report Share Posted January 4, 2007 Genius !Hats off to ya Tom! Link to post Share on other sites
SiGainey 1 Posted January 4, 2007 Report Share Posted January 4, 2007 I'll do a reading tomorrow for you. Good to compare between cars Link to post Share on other sites
GVK 1 Posted January 4, 2007 Author Report Share Posted January 4, 2007 Cheers ! Link to post Share on other sites
VR6_Absy 0 Posted January 4, 2007 Report Share Posted January 4, 2007 That's impressive Tom ;-) Link to post Share on other sites
IbiVR 0 Posted January 5, 2007 Report Share Posted January 5, 2007 That's impressive Tom ;-)Hehe ta. 8-| Tom. Link to post Share on other sites
Russ_vr6 12 Posted January 6, 2007 Report Share Posted January 6, 2007 ur a bloody god i swear it lol Link to post Share on other sites
SiGainey 1 Posted January 15, 2007 Report Share Posted January 15, 2007 Cheers ! Sorry - forgot all about this - got a reading of 151 on a full throttle 2nd gear run so looks the same as yours At least these cars dont go through MAF's like the 1.8T's do! Link to post Share on other sites
lee060 3 Posted January 15, 2007 Report Share Posted January 15, 2007 Wow . thats useful . **bows down to tom . amazing , something ive always wanted to know what about turbo cars? thanks Liam Link to post Share on other sites
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