STE
At 12:28 PM 10/5/00 -0700, you wrote:
> <snip>
>I not sure about the response time. I didn't notice any difference in
>quarter times between auto and manual modes of shifting. You can get a
>little more rpm out of shifting manually, but this did not translate into a
>noticable difference in ET's. In an autocross, an extra 500 rpm is crucial
>in allowing you to stay in the first gear through low speed corners. So I
>shift here. But at the drags, I have let the auto do it (with O/D off of
>course).
>I'd be interested in what your observations are as to whats the best
>technique. I frankly haven't experimented that much in straight line
>performance. My old drag racing friends would never believe that
>statement! Sorry dad, I'm hooked on twisties.
I know that you have a 4.7L and its unique auto. tranny while I have a 5.2L
and 44RE auto. tranny, but I thought that you might find something of value
with my experiences.
I consistently run 2/10s slower if I let the tranny do the shifting. With the
way my TV cable is now set, auto. shifting at WOT is about 1-2 at 5200
and 2-3 at 4800. I find that a WOT 1-2 manual shift at about 4800
and a 2-3 at about 5200 results in better 60' and 1/8 times and thus better
1/4 times.
My dyno figures show that my manual shift pattern is not at the ideal rpms
(ideally I should be shifting at around 5500 rpm) but, because of erratic
upshifts
with the Transgo kit, the shift points that I use give me the upshifts most
of the time. These dyno figures also show that, if my WOT 2-3 shift is done
below 5200, the rpm when 3rd starts upon completing the shift is just below
where my powerband starts (3300 rpm) and this is the main culprit in causing
the longer ETs. Why starting off with the gear shift in 1st as opposed to
Drive gives me better a tick better 60' times (I am certain that the tranny
is still in 1st with the auto. shifts at the 60' mark) is something that I
haven't been able to figure out as yet.
BTW, timing is drastically retarded between shifts on the '97 MP PCM (CA
version;
Fed version did not get EPA approval). E.G. on one 1/4 run, there was a 22
degree
advance at 2944 rpm while in 1st and during the 1-2 shift at 5280 rpm, the
timing
had been retarded to 7 degrees. There was also a retarded timing at the 2-3
shift but not as drastic (26 to 15). I suspect that future MP PCMs will be
doing
the same as emission standards become higher and higher.
Bob. Ont, Canada.
'97 Dakota CC, 5.2L, 4x2, 3.92 SG, auto., 4265 lb.
PB: 14.737 @ 91.75 9.364 @ 72.95
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