Chris,
Assuming you fix the problem that's killing your engine over 5,000 rpm,
let's look at the best recipe for quick quarter mile times. Let's say your
motor, after it's fixed, gets a maximum of 350 HP @ 6,500 rpm. You will want
to be able to run as close to 6,500 all the way down the track as possible
to optimize the output of the engine. That means, you want the engine rpms
to more-or-less bracket the optimum 6,500 rpm. That means, first of all, you
will want to use all four (or five) gears. It also means, although not so
obviously, that you want to use the close ratio, not the wide ratio tranny;
assuming of course we pick the right rear end gears. So, what rpm should you
be turning at the quarter mile mark? The answer is about 7,700 rpm; in fact
you want to make your lower shifts at higher than this rpm so as to keep the
motor running, on average, at the sweet spot 6,800 rpm. (The jumps get
progressively closer as you go through the gears.) So, what rear end ratio
would give you that? It can be computed it pretty accurately, but you know
from experience that running in the 12's will put you somewhere in the
neighborhood of 115 mph. So, if we're turning 115 @ 7,700 rpm in fourth, the
gear ratio is - - - voila!! 4.56 gears.
This little example should make clear a couple of points. First, don't build
a motor to give its top horsepower at any more than about 80% of the top rpm
you are willing to run it at. In your case, to get the most out of an engine
that makes its best horsepower at 6,800 rpm, you need to be willing to shift
it as high as 8,500 or so to get the full benefit. If the motor isn't built
to run that rpm, use a cam and other parts that will maximize the horsepower
at lower rpm, you'll be ahead in the long run both figuratively and
literally.
Now, I would like to hear what 12-second Dave's recipe is. And, I hope I'm
not part of the "clic" he's referring to, so any one else's opinions are
welcome too.
TTFN,
Bob
-----Original Message-----
From: owner-tigers@autox.team.net [mailto:owner-tigers@autox.team.net]On
Behalf Of cvaught@hawaii.rr.com
Sent: Tuesday, February 20, 2001 2:48 PM
To: tigers@autox.team.net
Subject: Re: E-Mail me off the list
simple in a tiger. posi unit in the rear with 3.55. gears, wide ratio in the
tranny, and a some NOS if your engine is stock and some drag radials to aid
in traction. now i thought this list was full of adults with mostly more
money
then brains to spend as much as we do an our cars (me included) let the
kiddies
stay at home and off of our list. i think it is funny as hell. maybe they
sniffed
to much gas while in garage and forgot how to get along with others.
chris in mississippi
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