In a message dated 98-01-01 22:33:52 EST, William Eastman writes:
> About long strokes limiting power, this in not always the case. Acura
> Integra's are long stroke motors in fact the bore and stroke is very
> similar to the MGB. The type R puts out 195 hp on 1.8 liters and an 8200
> rpm redline. Smaller bores mean smaller valves and poorer cylinder filling
> and this is what limits rpm as much as inertia from the long stroke
> although an MGA connecting rod is one substantial chunk of iron.
>
You failed to mention that the Acura( powered by HONDA) is also a variable
valve timing engine with Overhead camshaft. virtually no extra linkage between
the camshaft and the valves, direct acting mechanisms help minimize valve
float and will allow a higher rev limit too. Multiple valves per cylinder
instead, of just two, ensure a quicker filling and emptying cylinder too.
The heavy, longer connecting rods do play a part in the rev limiting aspects
of MG engines, but if Morris Garages had hit the perfect setup with a 3 main
block....why did the ever develop the 5 main? Because a stronger bottom end
is inherently able to live with a higher RPM limit with added longevity... How
many mains in the Honda power plant?
Answers?...I don't have any magic advice to the 3 versus 5 main argument but
will add this to each side....BALANCE everything that rotates when you've got
it apart....weigh the rods both big and little ends....match the pistons gram
for gram...ensure that the clutch mechanism is also balanced to the crankshaft
AND indexed to the balancing position....also have the machine shop Square up
the transmission mounting faces....you can lose valuable horsepower and revs,
thru a misaligned gearbox....and as we've already determined...anything that
you can do to aide the engine in overcoming friction and inertia will help
it's revving ability and it's longevity...
As Smokey Yunick said....Horsepower costs money...how fast do you want to go?
Cheers,,, and happy new year fellow MGA'ers
Tom
|