Hi,
I just pulled these numbers from the Bentley manual:
inlet valve, head diameter: 1.441 - 1.445
exhaust valve, head dia.: 1.256 - 1.26
These numbers are obviously for the early cars. I found the reference that
Vance referred to in the Moss catalog - 1.18 for exhaust.
Interestingly, I pulled out my old SCCA rule book (2004) and for F
Prepared TR6, they list:
inlet: 1.438 or 1.45
exh. 1.26
I don't know any racers that are running the 1.18 exhaust valves. I have
no idea where SCCA came up with the 1.438 number, but I suspect that it's
related to the GT6 or something stupid like that. On the other hand, there
is a lot of "shrouding" around the inlet valve, perhaps better flow
numbers can be achieved with a smaller valve... that would be an
interesting experiment.
Regarding Desktop Dyno, I've asked a number of folks on this list and on
other lists about flow numbers and most of them are pretty tight-lipped
about what sort of flow they can get. That said, if you can get 130 CFM
into your TR6 (at the valve), you can make some pretty good numbers.
Getting 130 CFM appears to be the trick. I used to have a whole set of
numbers that I ran for all the cams that I had on hand and the numbers
that I got for the cam combo that I chose were surprisingly close to the
actual numbers (around 11:1, stock-ish head with a BP270 cam, webers and a
tubular exh manifold and single pipe exhaust - 140 HP at the flywheel.
This number was only off by less than 2% from the prediction that Desktop
Dyno gave me... not too shabby.
Now I just have to get working on that 12.5:1 motor with the flowed head.
Ya-boy, 200 HP??? And I can use non-factory fuel injection too!!!
rml
------------------------------------------------------------------------------
Bob Lang Room N42-140Q | This space for rent
Consultant MIT unix-linux-help |
Voice:617-253-7438 FAX: 617-258-9535 | Cell: 339-927-4489
------------------------------------------------------------------------------
|