Hi Cliff,
I just celebrated passing inspection with 6 hrs of intense yard work. Yuck,
but I'll be in good shape for the rest of the summer!
I had considered switching to headers before I actually had my manifold off
and in my hand. I was going to clean up the ports in the casting but I was
amazed to find that it was a super quality piece with very smooth flowing
insides!
The manifold is a Tri-Y design, an exhaust design that was popular on some V8
muscle cars in the '60 (and Triumphs - and other brits?) and is coming back
into vogue. Essentially, the 1 & 4 cylinders empty into one pipe and 2 & 3
cylinders in to the other, then, about 18" down the line, those pipes merge.
This design is considered a torque maximizer, as opposed to a 4 in to 1
header, which seems to have an HP advantage at higher RPMs. The Spitfire MKII
used a similar "Tri-Y" exhaust. 4 in to 2 in to 1! I've seen TR6 headers with
this design, but every 4 cyl TR header I've seen is 4 in to 1.
For the street, I'll go for torque at useable RPM's every time. I've also had
trouble fitting and sealing every header I've ever used since my K10 Chevy
pick-up in high school.....that being said, if anyone out there knows of a
"tri-y" header in stainless for the 4 cyl TR please let me know!
Chris L.
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