• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

TR6 TR6 Questions

Share this page

Webb Sledge

Webb Sledge

Jedi Warrior
Offline
I have read a couple interesting things about the 6 and I want to verify if they're true or not. I read that the chopped off tail of the TR6 was considered to be an aerodynamic aid. Is this true? And I also read that certain Triumphs (certain models years or something) have a lot of extra metal on the head, which can be shaved to give extra compression, which in turn gives more HP. I this true?
 
"Kamm back --
Named for the German aerodynamicist W. Kamm, who discovered that drag begins to increase after the rear of a car's cross-sectional area is reduced to 50 percent of the car's maximum cross section."

"At the very back of the Insight, the teardrop shape is abruptly cut off in what is called a Kamm back (a distinctive design feature also shared by the Honda CRX). The Kamm back takes advantage of the fact that beyond a certain point there is little aerodynamic advantage to be gained by rounding off or tapering and extending the tail section of an automobile, so one might as well abruptly truncate it at that point. The Kamm back is a design feature that has been incorporated into many high-performance automobiles and racing cars over the years."
D
 
Hello Webb,
you are quite right that there are varying thickness of heads on the TR 6 engine series. However there is no point in getting a thick head to skim it back to the specification of a thin head as Triumph have already done that for you. Thin heads have smaller combustion volumes, and were used on the injection engines, running 9.5:1 compression as standard.
Incidentally, comparing the TR 5 to the TR 6, visually the 6 is more attractive, but theoretically adding length on the same wheel base is detrimental to handling by adding weight beyond the wheel centre lines. i.e. less overhang is better.

Alec /ubbthreads/images/graemlins/thirsty.gif
 
I wasn't talking about skimming a thicker head back down to normal spec. I meant taking a normal spec, stock engine head and then shaving some metal off to give higher compression and more horsepower. How much metal do you think could be taken off, and how much extra horsepower would that give?
 
Webb,
You always ask good and intereting questions! You'll be smarter than all of us combined before you know it.

As for the Kamm tail, now that you have its orgins, I'll add it was made very popular by both the Ferrari 250GTO and the Shelby Cobra Daytona coupe. It allowed for higher top speeds and increased high speed stability.

That being said, on the TR6, it was only a styling element. A Kamm tail doesn't pay any dividends until around 150MPH (the actual number depends on the aerodynamic properties of the rest of the car.) Most of the Kamm tail cars, like the TR6 and the Alfa Spyder just wanted to look racy -- since their top speeds were about 110MPH. Even with the Kamm, the TR6 still fights the aerodynamic properties of a barn,and the structural ridgidity of a bellydancer.
 
Webb,
Piman is correct in stating that the UK spec head has a higher compression ratio than the US spec head. That is their "normal" for the PI model. The thicker US head is what is available for over here. You wouldn't want to shave a normal UK head, only the thicker US style. If you are going to shave the head, beware that there are other factors to consider - valves, pistons, rods, cam, ports, etc. Plus, a higher comp head will, as a rule, tend to run hotter. All I am saying is look at the whole package before you send your head to a machine shop. Higher compression isn't always the end-all for higher performance in a TR6. There are many other factors to consider. Remember, this is just a low reving, high torque tractor engine.

Bill
 
Thanks for the answers all. I don't intend to go cutting up any Triumph heads any time soon, I was just curious as to if it could be done.

sammy, why'd you have to tell me that the kamm tail on the six doesn't do anything? i was feeling pretty good about it, thinking that it must help a lot, and then you had to go ruin my dreams. /ubbthreads/images/graemlins/jester.gif
 
Back
Top