Quote:
Originally Posted by jonnypym123
Intresting stuff, I might be downloading WinOLS and taking a look. I had my A8 4.2tdi D3 remapped on stock hardware and was down on power on the dyno 300hp 630nm took it to the Perfomance Centre in Sunderland, they upped it to 340hp 866nm, which if I honest looking back was disappointing however they thought it was to do with carbon build up but I wasn't sure. looking at a lot of dyno video for the A8 4.2tdi BVN the car seems like 340-360 peak is about right for stock hardware with everything intact. Since then I removed the dpfs and egrs and removed the silencers, changed the glow plugs and fitted a new clean top manifold and oil service and BMC air filters and it feels faster to when it was only remapped I think, I'm doing the swirl flaps next when I get some time off. The max peak hp I've seen dyno proven without modifying the turbos is around 385hp dyno proven, theres some claim 430+ on the D3 without uprgading turbos but I dont think thats possible, if you upgrade the turbos yeah, those figures probably only possible on the d4 as they have upgraded compressor wheels and upped rail pressure as standard along with different intercoolers and gearbox. Hope the tuning goes well and will be interesting watching your progress
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That's a lot of torque for not that much of power, not something you would expect. Stock engine has 650Nm 1800-2500 rpm and 326 HP at 3750 rpm which would be 620Nm at 3750 rpm. If your peak HP were at the same point as your max torque it would be max power at 2790 rpm. Or if your maxpower was at 3750rpm then it woulfd be 650Nm at 3750. So something was cutting torque a lot as rpm went up, could be restriction in intake or exhaust, exhaust gas temperatures getting too high or not enough fuel delivery - blocked fuel filter or weak fuel pump. Did you have picture/ printout from dyno? Or maybe they did what's called 'economy map' where you get a lot of torque only at low rpm to encourage upshifting ang keeping highest possible gear. For example 700nm at 4k rpm is 393HP. Maybe they went too high with torque, EGT got too high and ECU cut fuel to reduce EGT before it got to max power. Did they do any logs while on dyno - EGT's or DPF pressure differential, fuel pressure, lambda? You are a bit too far, otherwise I would have been interested to read the file from your car and see what they have done.
From what I heard it's the DPFs and exhaust limiting how much power you can get. Push too much and exhaust gas temperatures and back pressure goes too high and cuts the power. Without DPF and more freeflowing exhaust it should be good for 420-450HP and then you run into what turbo and fuel pump can do and then soon after also intercoolers and injectors. you do not need bigger turbos to get more air to reach 450, it's more about how much exhaust can you get through them without them getting too hot or spinning too fast and reducing life severely. I am in no rush getting it mapped, just having a look at different tuning approaches in the tuned files I have got and then will make a decisions what I will do and how far will I push it, .Will start a bit safe and gradually increase while monitoring EGT and DPF differential pressure, might raise EGT maps a bit if required but not completely flatten like some tuners do.