Shift points for chipped 225 are much different from stock, looking at the APR web site
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Shift points for chipped 225 are much different from stock, looking at the APR web site
I went to the APR website and downloaded the torque and hp curves for our chips. Interestingly it appears that we should shift much earlier when in chip mode. The stock torque curve is flat up to 6000 rpm and the stock hp curve peaks at 6000 giving me the impression that 6000 is generally the best shift point in stock mode. I know that the exact point has been discussed in detail before, but 6,000 is close enough for me (after 6000 torque drops off steeply)
But the chip mode is quite different. The torque curve is steep up to 2800 rpm, at which point it flattens out and then begins to decline significantly at 5000 rpm (it is still higher than stock). Interestingly hp is pretty flat after 5200 rpm and actually begins to decline at 6000 rpm. This means our optimum shift points are much earlier than stock. For max acceleration we should shift near 5000 rpm. Since torque is a larger determinant in acceleration than hp it looks like 4500 to 5000 is going to give max performance.
This confirms my experience at Roebling. The car just seemed to run out of torque in 4th gear when accelerating past 5000 rpm, confirming my suspicion that we should shift up earlier.
Just a couple of thoughts.
But the chip mode is quite different. The torque curve is steep up to 2800 rpm, at which point it flattens out and then begins to decline significantly at 5000 rpm (it is still higher than stock). Interestingly hp is pretty flat after 5200 rpm and actually begins to decline at 6000 rpm. This means our optimum shift points are much earlier than stock. For max acceleration we should shift near 5000 rpm. Since torque is a larger determinant in acceleration than hp it looks like 4500 to 5000 is going to give max performance.
This confirms my experience at Roebling. The car just seemed to run out of torque in 4th gear when accelerating past 5000 rpm, confirming my suspicion that we should shift up earlier.
Just a couple of thoughts.
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Re: Shift points (as I remember) . .
Ahem, Shift point theory.
{Theory 1} For max. performance the engine should be on the torque peak AFTER the shift. i.e. after you shift and let out the clutch your tach should read "whatever the rpm your torque peak occurs."
{Theory 2} (a drag racing mindset) shifts should occurs to give the best performance. Sometimes (as stated) one might be 1k from redline - yet (the turbo clause)(ask him for a DV that works!)a vehicle might accelerate better at lower rpm. (As might be the case w/ the chipped TT).
we now return you to OT joke friday - enjoy.
{Theory 1} For max. performance the engine should be on the torque peak AFTER the shift. i.e. after you shift and let out the clutch your tach should read "whatever the rpm your torque peak occurs."
{Theory 2} (a drag racing mindset) shifts should occurs to give the best performance. Sometimes (as stated) one might be 1k from redline - yet (the turbo clause)(ask him for a DV that works!)a vehicle might accelerate better at lower rpm. (As might be the case w/ the chipped TT).
we now return you to OT joke friday - enjoy.
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Chart says shift at 6500 rpm
Shows nearly flat power band from 5500 to 6500. Don't forget you only have 80% of the torque in 5th compared to 4th, so you can still get more power to the ground with some reduction in engine torque if it is less than what the gear change would do. What's odd with the curves is the higher engine speed for stock horsepower on APR chassis dyno than the factory got on their test stand.
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I agree with John S. Using "Performance Analyzer" from Performance Trends....
I got these results using a 3200 lb gross wt TT:
Stock 225:
0-60 6.06 sec Best launch rpm = 5500
1/4 mile = 14.64 @96.3
1-2 shift @ 6300
2-3 shift @ 6250
3-4 shift @ 6150
Using APR's dyno curves in the same car:
0-60 5.00 sec Best launch @ 3500 Surprise!
1/4 mile = 13.68 @ 102.1
1-2 shift @ 6500
2-3 shift @ 6500
3-4 shift @ 6250
4-5 shift @ 5900
5-6 shift @ 5700
Top speed 150 (estimated frontal area, etc)
With good weight and dyno data, this program predicts very well.
@3400 lbs the 0-60 goes to 5.23 and 13.90 @100 in 1/4 mile.
Running the same APR chipped 225 as a FWD (bogus, I know) @ 3100 lbs, wheel spin is a big problem, and 0-60 = 5.53 and 1/4 is 14.04 @ 103.7
PA uses torque curves as well as efficiencies, inertia, etc. to predict. Too bad it's not made anymore.
My $.02
Stock 225:
0-60 6.06 sec Best launch rpm = 5500
1/4 mile = 14.64 @96.3
1-2 shift @ 6300
2-3 shift @ 6250
3-4 shift @ 6150
Using APR's dyno curves in the same car:
0-60 5.00 sec Best launch @ 3500 Surprise!
1/4 mile = 13.68 @ 102.1
1-2 shift @ 6500
2-3 shift @ 6500
3-4 shift @ 6250
4-5 shift @ 5900
5-6 shift @ 5700
Top speed 150 (estimated frontal area, etc)
With good weight and dyno data, this program predicts very well.
@3400 lbs the 0-60 goes to 5.23 and 13.90 @100 in 1/4 mile.
Running the same APR chipped 225 as a FWD (bogus, I know) @ 3100 lbs, wheel spin is a big problem, and 0-60 = 5.53 and 1/4 is 14.04 @ 103.7
PA uses torque curves as well as efficiencies, inertia, etc. to predict. Too bad it's not made anymore.
My $.02
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