I'm so excited this morning, you should be glad I'm not typing in
all caps. The Garage Queen is back from getting its new exhaust system and
being dyno-tuned.
Yesterday afternoon, fellow Tiger owner Larry Paulick met me to
drive down to Jeff's Mufflers in Owings, MD, where the GQ was ready and he
had his Tiger subjected to the same work recently. Fortunately, it was 25
degrees warmer than when I had dropped off the car. When we got there, my
Tiger was sitting in front of the front door, almost 'showcased'.
From what I could see, the exhaust work appeared flawless. All of
that 2-1/4" stainless steel tubing custom-bent (and he kept "templates" in
case any other Tigers show up at his door) and tucked well up under the car;
I have as much ground clearance as before, if not more. That includes the
new "H-pipe" up front. Those big Flowmasters look just a bulky as they did
coming out of the box, but again, no clearance problems. From the rear of
the car the new set-up is not very noticeable, just somewhat larger tips.
Those are cut off at a slant, just like stock, and are now short enough that
I shouldn't cut my leg on them every time I walk behind the car in the
garage, like I did on the exhaust I just removed.
Once inside, Jeff had the results of the dyno testing for me. Hoo
boy. He had done a baseline test on the old exhaust, and it peaked at 216hp
and I do not remember how much torque (this test was not on the final
print-out graph). Then on went the new pipes, and the output jumped 35
horsepower. It seems that power fell off (or at least didn't climb as well)
above 3,500 RPM with the smaller exhaust "in the way". Then came the
dyno-tuning. Actually, I didn't quiz him too much on the nature of the
changes made. One item I recall was that the accelerator pump on the carb
was about dysfunctional, and its cam and spring was replaced to improved
throttle response (it _had_ been hesitating a moment went the throttle was
mashed). Now, the output is: 272.2hp at about 5,800 rpm, and torque peaks at
285.4 ft-lb; all measure, of course, at the rear wheels. I say 'peaks', but
the printout shows such a flat curve from 3,000 to 4,500 RPM I'm not 100%
certain where the torque 'peak' is; anyway, its above 250 ft-lb on the graph
from 2,000 to 5,600. Enough.
Now, if the "accepted" value for drivetrain loss is 20% that means
340hp and 357ft-lb of torque "at the flywheel"; the latter # is sufficient
to make be stop & think about the strength of the T-5 transmission for a
moment. If, instead, one wants to be ultra-conservative and state that only
5% is lost getting to the rear wheels, then the #'s change to 287hp and 300
ft-lb, but I haven't heard anyone try to substantiate such a low percentage.
Let's just say "a lot". Even Jeff, who has his own drag-racing team
"Insane Racing" and works on high-output cars all day long, says he finds
the GQ "scary". He used his "calculator" for estimating 1/4 mile ET from
horsepower and weight, and arrived at 11.15 to 11.20 seconds. Huh???? Mind
you, that calculator assumes a seasoned driver (not!), best "hook up"
(slicks, at least) and the correct gears. Probably doesn't account for my
3.07's, eh? OK, add a second or two to that figure. No matter, for now I can
concentrate on areas of the car other than building horsepower.
Eventually, it was time to leave. The old system (stainless as well,
so I didn't want to discard it; perhaps I can sell it) went into the back of
my Toyota pickup, which Larry P would drive back, and we left. I decided to
take it _very_ easy on the way home, not being used to the car. Also, I
_still_ haven't had the front-end aligned since the suspension rebuild, and
straight-line stability isn't optimized.
It was still a hoot. At 60 indicated, 65 per Jeff's correction noted
on the dyno, in fifth gear, it took the rolling hills of MD route 2 with
zero additional throttle and no loss of speed. I mean _none_. Every few
miles, it seems, Larry P would either pull up beside me and make mash-gas
motions with his hands, or hold a hand to his ear at traffic signals; he
wanted to hear the Tiger roar. I don't blame him, it does sounds pretty
nice; but I never took it above 1/2-throttle and perhaps 3,500 to 4,000
(dead tach). Acceleration is effortless.
Once home, Larry P had to leave (he has been a big help on this
project), but Susan and I took it the mile or so to the in-laws to show it
off. My mother-in-law loved it; I could have sat in her driveway all evening
blipping the throttle for all she cared.
There are a few things left to do before the big Tiger event in PA
in a couple of weeks, but "the big stuff" is behind me.
Larry Wright
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