Toronto Motorsports Park opened its season yesterday.
Weather was extremely good with a strong sun, 30.2" Hg
barometric pressure, light cross- and tail-wind, temps. in
mid to high 50s.
I made 6 T&T runs to evaluate the winter's mods: 4.56 gears
and cam swap. In 5 of the 6 runs, I hit the rev. limiter (around
6000 rpms) on either the 1-2 shift or the 2-3 shift. On the last
run, I short shifted both shifts 'drastically' and finally got clean
shifts but hit the limiter about 15 to 20 feet from the end as the
4.56 gears in combo with the 26" MT ET Streets. My pre-season
calculations indicated that the combo. would be close at the end.
It took 4 runs to get a good read of where the air pressures should
be with these MTs. For today's conditions, it turned out that 17 1/2 psi
in the left and 18 1/2 psi in the rights gave the best 60' time.
Run 5 was my best run even though I hit the limiter on the 2-3 shift.
I managed a 14.44 @ 97.08 crossing the trap around 6000 rpm.
Hitting the big L cost me a probable 14.2x run. Too top it off,
my reaction time was a .499 ... arghhh !!!
Run 6 gave me a pb trap speed of 97.36 mph with an ET of 14.56.
My previous best trap speed was 95.92 last season with the 3.92/26"
and MP RT cam combo. Last year, I was mainly doing the 1-2 shift
at 5400 and the 2-3 shift at 5600. On this run, I did the 1-2 shift at 5000
and the 2-3 at 5200. While the shifts were clean, the rear was wiggling
down the track all the the time I was in 2nd and about 15 to 20' from the
end I was approaching 6000 rpm because of the short shifting. Hello
rev limiter again :-)
I'm still in the process in trying to nail down why I now have to shift
at lower rpms so as not to hit the limiter as compared to last year.
Any opinions welcomed!
One possibility is that tranny fluid level. At the end of run 4, I found
that the fluid level was in the middle between the Min. and Max. lines.
I know that it was at the full line last year. The mechanic who did
my gear swap and replaced my speedo. pinion gear said that no
fluid was loss during the speedo. gear change. I figured that he was
more skillful than me since I always loss some fluid with a speedo.
gear swap. Anyway, I top it up as best I could with what I had at
the track.
Anyone have personal experiences with the effects of tranny
fluid level and WOT shifting? Thanks.
Bob Tom Ontario, Canada
97 Dakota CC Sport, 5.2L, 4x2, 44RE, 4.56 SG, 4,080 lb (truck, driver, 3/8
tank)
Track PB: ET 14.313 sec. Trap speed 97.36 mph
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:46:11 EST