Hi there
An update!
Went Powerstation Friday, had gearbox oil changed, idler and tensioner pulleys changed, result gears no longer notchy when cold and cold start squeak has gone, result.
Now to the dyno:-
Run 1 = with x51 air box and 82mm tb and plenum = 375BHP, 5 up, but less torque/power under 3000rpm, car very lean at WOT.
Run 2 = with x51 air box and stock tb and plenum, same as last time 370BHP and still lean.
Investigating it the stock air box aperture where maf sits is 86mm whereas x51 aperture is 91mm. So for the same air speed over maf the x51 air box flows 12% more air which is not fuelled for.
Remember maf works on air speed based on the pre-loaded map, so as the X51 air box has a larger aperture it means their is more air volume for same maf speed and hence mixture is leaned out.
Short story stock air box would have made more power with larger tb as it would have being Fuelling correctly.
Spoke with Porsche who confirmed the X51 map does have a different pre-determined setting for air box aperture to account for extra volume. Also potential a local OPC could be willing to upload to my car for me.
Being in touch with the map supplier in US kudos where due he has taken a map from an official X51 equipped car and re-written the file for my mods and UK fuel. Now that low-down response is back and it feels a lot more eager and seems more powerful up top, just better everywhere, but more fuel would do that when running too lean. So back to the dyno next weekend to check Fuelling and see if it is making more power and where.
An update!
Went Powerstation Friday, had gearbox oil changed, idler and tensioner pulleys changed, result gears no longer notchy when cold and cold start squeak has gone, result.
Now to the dyno:-
Run 1 = with x51 air box and 82mm tb and plenum = 375BHP, 5 up, but less torque/power under 3000rpm, car very lean at WOT.
Run 2 = with x51 air box and stock tb and plenum, same as last time 370BHP and still lean.
Investigating it the stock air box aperture where maf sits is 86mm whereas x51 aperture is 91mm. So for the same air speed over maf the x51 air box flows 12% more air which is not fuelled for.
Remember maf works on air speed based on the pre-loaded map, so as the X51 air box has a larger aperture it means their is more air volume for same maf speed and hence mixture is leaned out.
Short story stock air box would have made more power with larger tb as it would have being Fuelling correctly.
Spoke with Porsche who confirmed the X51 map does have a different pre-determined setting for air box aperture to account for extra volume. Also potential a local OPC could be willing to upload to my car for me.
Being in touch with the map supplier in US kudos where due he has taken a map from an official X51 equipped car and re-written the file for my mods and UK fuel. Now that low-down response is back and it feels a lot more eager and seems more powerful up top, just better everywhere, but more fuel would do that when running too lean. So back to the dyno next weekend to check Fuelling and see if it is making more power and where.
