11-08-2014, 09:37 AM
To be fair, that's a cracking curve... However probably slightly unrealistic as to how it really is on the road, remember dynos will falsely load the car - you can change the curve by simply altering the dyno load!
Remember guys, the torque figure on variable geometry turbos is wildly adjustable - the peak figure generally isn't, that 220lb.ft just indicates that the vane stop screw isn't very far in, currently it won't spool up that fast, but won't produce high exhaust manifold pressures. Again, the dyno load will affect how the turbo spools... I wouldn't be surprised if you turned down the dyno load, it'd make another 20lb.ft less!
If you screwed in the vane stop it'd spool up much faster, I reckon would give you around a 250lb.ft torque figure. To me that graph looks pretty bob on, though from the looks of the curve, your actuator line might be a bit long, you get a spike as the vanes open up - try making the hoses from the take off point to the actuator as short as possible, this is also affected by boost pipework since it takes a fraction of a second for everything to fill before the actuator actually sees the pressure and adjusts the vanes accordingly, it'll overshoot and undershoot as you can see in the graph.
Don't get hung up on torque figures, it's the 175hp figure that's good in my eyes, also the fact it's a great curve that finishes at 5200rpm with you still making 175hp! It's not often you see one of those! The torque figure can be adjusted with simple turns of screws, but be aware that you may end up feeling like you prefer the lower torque figure so it doesn't feel pointless in revving the engine to 5k, if you massively screwed in the stop, you'd find it comes on harder and faster, but will feel worse at the top end - that's a personal preference thing.
Remember guys, the torque figure on variable geometry turbos is wildly adjustable - the peak figure generally isn't, that 220lb.ft just indicates that the vane stop screw isn't very far in, currently it won't spool up that fast, but won't produce high exhaust manifold pressures. Again, the dyno load will affect how the turbo spools... I wouldn't be surprised if you turned down the dyno load, it'd make another 20lb.ft less!
If you screwed in the vane stop it'd spool up much faster, I reckon would give you around a 250lb.ft torque figure. To me that graph looks pretty bob on, though from the looks of the curve, your actuator line might be a bit long, you get a spike as the vanes open up - try making the hoses from the take off point to the actuator as short as possible, this is also affected by boost pipework since it takes a fraction of a second for everything to fill before the actuator actually sees the pressure and adjusts the vanes accordingly, it'll overshoot and undershoot as you can see in the graph.
Don't get hung up on torque figures, it's the 175hp figure that's good in my eyes, also the fact it's a great curve that finishes at 5200rpm with you still making 175hp! It's not often you see one of those! The torque figure can be adjusted with simple turns of screws, but be aware that you may end up feeling like you prefer the lower torque figure so it doesn't feel pointless in revving the engine to 5k, if you massively screwed in the stop, you'd find it comes on harder and faster, but will feel worse at the top end - that's a personal preference thing.
