Amici,
For what it's worth, the following is synopsis of just another TR-4 motor
rebuild. For those of you much smarter than I, it may serve as source of
amusement. For those even less experienced in this game, it may be a
questionable source of primary education.
First off, my MO for racing is to drive to the track, take off my
windshield, put on my race tires and try to stay out of everybody's way.
This has worked fine for five HSR races (including one third place ribbon
at Road Atlanta). The car has been, as they say, box stock except for a
set of exhaust headers, TR-6 power brakes and a fatter anti-sway bar. The
motor has 125,000 miles on it and I have no reason to believe that it has
been apart. I estimate its output at somewhere around 85 to 90 hp. Rugged,
yes. Fast, no.
In keeping with my intention to race a street legal (and streetable) car, I
set out to build an engine which would produce higher hp and better torque
but limit my rpms to about 5500 rpms. Higher revs quickly gets into a
whole new elevated currency exchange rate with which I do not want to
become familiar With help and advice from Ken Gillanders and my friends
Lamar Keene and Bob Wagner at Atlanta Import Auto Parts, we came up with
the following package. Neil Estes of Neil's Restoration fame was my main
wrench.
1. Mill the head .0090 in.
2. Install the 89mm piston/sleeve set.
3. Install a 282 degree cam
4. Install a set of HD 8 SU carburetors
5. Install new bronze guides and three angle ground valves.
6. Lighten flywheel about 8 lbs.
7. Balance crank, rods, pistons, clutch and flywheel.
Last week we got the motor all painted and put together and mounted on a
dyno. After about a two hour run-in, we ran a series of tests using 110
octane race fuel. First with the 1.75" Stromburg carburetors, then with
the SU's. Then with the timing @ 30 degrees then @ 33 degrees. We then
ran a test with the entire exhaust system (mit big pickle type muffler) on
and another test with a two foot straight pipe out of the collector pipe at
the end of the headers. The second test was not only very interesting but
excruciatingly loud.
Ok, now here's the test.
1. What was the peak horse power and at what rpm?
2. Which was the better spark advance?
3. What was the effect of the 2" carbs?
4. Other than loud, what is the difference in the full exhaust system and
the short pipe?
Come on now, group. Opinions are like...what is it? Maybe it was belly
buttons. Everybody's got one. We're always guessing about how much
horsepower this or that change makes on an engine. If you provide me with
your best guesses, I'll be glad to share my numbers with you all. Hell,
I'll do it anyway but let's have a little fun with it first.
Ok? Let me hear from you
Richard Taylor, Atlanta
|