Alpine listers,
For those of you following my alpine motor buildup, here's some
new info.
For those who are not, read no further.
I am in the process of final assembly of the engine now.
Photographs have been taken for posterity, and I decided
to gauge my efforts by weighing all the reciprocating parts
for comperative purposes.
Part Name Stock 92BHP 1725 150 BHP 1725
------------------------------------------------------------------------
---- ---------------
Con Rods 752 G 681 G
Wrist Pin 135 G 118 G
Piston 436.5 G 343 G
Intake Valve 80 G 78.5 G
Exhaust Valve 65 G 76.5 G
Flywheel+clutch 32lb 1oz(SV)/ 39lb 1oz(SII) 26lb 0oz
The engine was fully balanced, rods matched bearings mic'd for
race clearances. Engine crank, pistons, rods, pins, flywheel+clutch
harmonic balance ECT all went to the balance shop, and came
back matched.
The clutch is a custom McLeod piece having a replaceable
diaphragm spring, a floating driven plate, shimmed offset force,
and a iron/copper 4 puck sprung hub. A through out thrust plate
was installed to the diaphragm so the stock alpine TO bearing
could be used.
The head uses the largest possible valves that can be installed
into a rootes head "valve seats are interlocked".
Intake valve is 1.600 and exhaust valve is 1.400.
Stock is 1.490 in, 1.290 exh.
The valve guides have been modified to accept readily availably
guide seals.
the con rod is a carrillo 8740 forging with 6.0 inch length as opposed
to 5.625 as stock on the SV motor. The rod uses 7/16 inconel cap bolts,
and the rod was widened to the alpine rod spec.
The block had to be slightly modified to allow the larger rods
to clear the block nearby the oil pump.
Forged pistons were made to accept the longer rod. The pistons use
stock chevy wrist pins and 82.5 mm metric moly rings. The rings are
from some exotic toyota 1600 cc formula engine.
The pistons and rods must be installed from the crank side of the
block becuase the big ends of the con rods are larger than the
bores. This procedure is magic.
The head was modified to use the huge valves, ports opened up.
Intake and exhausts are port matched to the head, and the combustion
chamber was modified to deshroud both intake and exhaust valves
in the head. The head was NOT modified to holbay specs, as the
larger valves and the higher flow numbers do not need the same
level of modification as does a Holbay head. Emphasis was placed
on keeping as much of the squish zone "flat face on head" intact for
maximum compresion turbulence. Net compression ratio will be
10.7/1.
Camshaft is a 240int/250exh (at).050 on 111 deg centers.
Engine should produce 138 lb ft of torque at its 5200 RPM torque
peak. Peak BHP should be 153 BHP at 7500 RPM, where the
engine still makes 107 lb ft of torque.
This is all I have for now, BTW, the bore is still within Rootes specs,
so this is not one of the fames 2 liter alpine motors here, but wow
if it was.
Jarrid Gross
This archive was generated by hypermail 2b30 : Tue Sep 05 2000 - 10:00:06 CDT