Of course not!
First, let's banish this "net gain" business. 6 mph at the bottom end
is NOT equal to 6 mph at the top end, thanks to drag forces and the
probability of hitting a shift point. Which car would you rather own,
the one that runs 30-50 in 10 seconds of full throttle, or the one that
runs 35-55 in 10 seconds?
Looking at your RPM and speed tracks (and not knowing how such things
are geared, I'm going to refer to the five gears evident in the log)
There are 6 gears. Never use 1st gear except to start.
the performance of 4th and 5th gears off of T3 is much poorer than
off of T5. The one I'm calling 4th gear is the one you change to at
approx 67mph. Look at the time-in-gear from about 29 to 36 seconds,
then compare to the same gear at 54 to 57.6.
Comparing the runs on Lap 4 and Lap 8 it is possible that there was
traffic that he had to slow up for going into T3 on Lap 8. As you
can see from this overlap of those two laps
Lap 4 T4 entrance RPM 12,528 at 83 mph
Lap 8 T4 entrance RPM 12,033 at 79.7 mph
Coming out of T4-T5 looks almost the same and the even though he
stayed in 5th gear 1.7 seconds longer on the 4th lap then he did on
the 8th lap the end result is near identical.
Lap 4 T6 entrance RPM 13,154 at 87.1 mph
Lap 8 T6 entrance RPM 13,137 at 87 mph
Wonder if the aero drag is the ultimate limiting factor on this particular leg?
We were running a 17/23 (1.35) gear whereas the other 80cc that we
were pitted with was running a 18/24 (1.33) gear. Near identical
gearing. Our fastest lap was a 1:31.640 and Mike's fastest lap in
that same race was a 1:32.560. Same engine builder, same chassis and
near same weight although our weight is a bit lower. We were running
a 180 jet while Mike was a bit leaner at a 175. On the fastest lap
Mike only got to a 12,761 RPM at 85.2 mph while we hit 376 higher
revs at 13,137 for 87 mph
Turn 3 we were at 73.9 mph and Mike was at 72. T4 we were at 79.7
and Mike was at 78.7.
Maybe gearing to get into 6th sooner would have helped?
Mike's EGT trace is a lot smoother then ours. I may look at
shielding this wire away from the RPM wire. Regardless. Peak EGT
going into T6 was 1178 for Mike and 1165 for us. Our probe is about
2" inches from the exhaust port while his is about 4".
The comparison chart is interesting. Especially how much harder
Tyler tries to stay on the gas and keep the RPM up in the corners.
http://www.microworks.net/dave/kart/compare.pdf
The 5th gear track is even more severe; from about 37 to 42+ seconds
it only picks up about 300 revs, whereas over the same elapsed time from
58.5 onward, it gains about 1000, and continues climbing steeply for
another 3 to 4 seconds. The difference in slope is so dramatic, I
wonder if you actually got full throttle on the run down to T4?
Something was different in the runs down these two straights. How
strong were ground-level winds and in which direction? How certain
are you that T4/T5 are truly at a lower altitude than T3/T6? What's the
topo map say?
http://www.answers.com/topic/st-johns-arizona
Aerial Photo
http://terraserver-usa.com/image.aspx?T=1&S=12&Z=12&X=812&Y=4776&W=2
Topo map
http://terraserver-usa.com/image.aspx?T=2&S=12&Z=12&X=812&Y=4776&W=2
This picture of Tyler is taken at T6 (top of the hill) and you can
see a kart in the upper left hand corner that is on the downhill leg.
http://www.seeyourreflections.com/gallery/private/view.asp?img=St_Johns1335.jpg&count=5
These shots during the Open-wheel race might give a better indication:
http://www.seeyourreflections.com/gallery/private/view.asp?img=IMG_4275.jpg&count=1
http://www.seeyourreflections.com/gallery/private/view.asp?img=IMG_4512.jpg&count=4
On the faster leg, you also seem to have hit your shift points slightly
higher in the first three gears, but that doesn't seem to have hurt nearly
as much as the lack of performance in the higher gears.
I was wondering if the fact the kart was having to pull harder up the
hill was the reason? Maybe the harder pull got it into the top gear better?
________________________________
FormulaCar Magazine - A Proud Supporter of Formula 500
The Official Publication of Junior Formula Car Racing
Subscribe Today! www.formulacarmag.com or 519-624-2003
_________________________________
_______________________________________________
F500 mailing list - [email protected]
To unsubscribe or change options please visit:
http://f500.org/mailman/listinfo/f500
*** Please, DO NOT send unsubscribe requests to the mailing list! ***
