Rich, you may consider 40-45psi to be in a normal range for this tire on
such a light car but I am certain you will find that true tire experts who
are into rally and race events would dissagree.
As you likely already know, when we use treaded tires in dry track racing
or slalom events, we first shave off all tread down to about 1/8" depth and
this gives the NEW tire max grip on a dry surface. A deep tread rolls too
much and cannot maintain grip in high G's.
The T/A and GT tires 20 years ago were considered to be pretty good as far
as street use and general traction was concerned.
In your case there may have been several other factors present which might
have contributed to your slides. Shock action, wheel alignment, onboard
weight distribution, etc. all have some affect. I bet the one single thing
which gave you problems concerns the local road surface you ran on, since
you spoke of a certain stretch being a problem. Certain surfaces challenge
a tire to hang on to it!
My prior posting spoke of why and how a radial is supposed to work when
properly inflated and why it loses it's superiority if overinflated.
I have no further advice or comments and don't think I will encourage any
more exchange on this subject as we have all finished our comments..OK?
---------------------
Jarrid; I had several complete rear axle center sections built up for rapid
changeover. Also had several complete thrid member assemblies ready to go.
Naturally, I had 3.89 as well as 4.22:1 Rootes original gear sets but also
had other ratios both higher and lower which came from Spicer type axles I
believe(??) such as Studebaker or Volvo etc. if I recall correctly.
All diff. spider gears were fully welded solid and had no diff. action . I
also had a limited slip diff. unit which I tried on the track and found it
inferior to a welded unit and never again used it. I used to carry spare
axle shafts but never broke one..ever.
Because the SV race engine had tremendous torque from 3500 up to at least
6000, I frequently selected a rear axle ratio which would literally let me
run an entire lap in 3 and 4 gear with perhaps only one turn needing 2nd.
The track at Pueblo CO Motorsport Park is such a track , where the SV held
the lap record in class for some time. Another 3 & 4 gear track is Lajunta
CO,( on which I held the lap record for 4 years), which only has a short
stretch handled by 2nd gear. Not having to row the boat too many times
allowed max attention to brake points and clipping the corners properly.
I noted with interest, your opinion that 155hp at the rear wheels would be
needed these days to make a Alpine competitive in class.
I do not argue this opinion but would remind you that acceleration (torque)
is what gets you out of a corner quicker than the other guy and if your car
has an edge in mid-range accel. his high end HP advantage may not bring him
along side prior to the next brake point. Many a faster qualifying car
never was able to manage a pass during the actual race, yet when that car
qualified all alone on the track, he was quicker in lap times.
Lots of times, such a car would be right on my ass in a corner and I would
out pull him exiting and he would creep right up again near the end of the
next straight but could not move out and make a pass. Then I would of
course lead him through the next turn and we would play this game until the
checkered flag.
I don't think I could build a "legal" SCCA Alpine engine which would make
about 165 hp at the flywheel and deliver 155 at the rear wheels!!!
Do these 10,000rpm Srites or MGBs etc. really do this output on an accurate
chassis dyno? I cannot imagine an iron head 1500cc Sprite/Midget engine
doing this because that means that a 91.5 cu. inch outdated tractor engine
has produced 1.69 hp per cu. inch ! A maxed out 350 cu in. Vette which
could easily match that per cubic inch output, would then make 593 honest
hp !!
Using this output assumption on a 2.2 litre (E production class) Triumph we
would have it making 1.27 hp per cu. in. and this is also beyond
expectations for a legal race engine. The 350 Vette of same efficiency
would rate at 444hp!
I used the Vette V8 comparison because this design has "flow through"
porting (intake on one side and exhaust on the other side..very efficient).
The Alpine and others mentioned do NOT have this better design which
hampers output seriously. Anyone who manages to get 1.69 hp per cu in.
from one of these old fashioned power plants (without compressor) is going
to get my deep admiration and I in turn am going to get enlightened as to
how far the state of the art has passed me by over the years.
BTW...coming into turn 5 at Road America is a down hill stretch and speeds
do climb a bit.
----------------
Dick T.
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