Quote:
Originally Posted by Dimman
Playing around with a gearing spreadsheet and eye-balling a couple of the dyno screens I noticed a couple things about the dip/flat-spot. First thing, is in performance all-out redline shifting, it has basically no effect. The rpm drop from the upshifts at 7400+ rpm always (well almost, 2nd starts just a wee bit from the flat area) put the next gear's rpm in the upper super-flat torque area. I calculated the following;
1-2 @ ~4500
2-3 @ ~5200
3-4 @ ~5800
4-5 @ ~6100
5-6 @ ~5700
@ 4500 rpm the dip is starting its rise and is probably ~90%+ of peak. So shifting at redline we will probably (based on the dyno graph accuracy) ALWAYS have at LEAST 90% (95%?) of max torque AVAILABLE ALL THE TIME.
The second thing is what the dip may be like while putting around town. Given the curve, based on feeling the torque taper down for the dip it may encourage short shifting at ~ 3600 rpm which puts the next gear just on the other side of the low rpm peak (which looks very close to the 151 total peak). So it will probably feel pretty strong even taking it easy. Maybe a minimum of 80% of peak available in this operating range.
Only places I could see the dip being noticed are on the highway and trying to accelerate from cruising to passing without downshifting, and light aggressive (no wheelspin) launch in first gear only (like taking off gently then punching it).
Lastly with the power, torque and rev limit shifted up ~ 800 rpm, plus a ~5% torque increase in the upper range (5k+), and a 4.3:1 rear end (Mk3 NA Supra, if the guts are interchangeable), this car would run with an out-going model GenCoupe V6. This may be just headers, intake, exhaust and a re-flash. But would probably kill the nice putting around town effect.
Other thoughts? Corrections?
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When I head from the review about this dip, and then it got confirmed by the dyno graph, I made excactly the same interpretation as you. And in fact the dip does not hurt unless you drive the car as if it was turbocharged. When I drive normally in my car which has a similar torque curve, with the dip but still less flat, I shift between 2.5-3.5K, I the car pulls quite well. When I do a spirited driving, the I use the range between 4.5-6.5K. The GT86 will be far better.