May 05 update:
Here's the dyno sheet from my last run in January 05 (more dyno sheets and
comparisons can be found in the "Engine" section). Since January I put the
stock block motor through 3 track events. That's about two hours of driving in 20
minute segments. Check out the video clip "Button Willow, One Lap" in the
Video section to get a feel for the abuse (or lack of) I give the motor. So far the
motor's holding up just fine.
Changes since the Jan 05 run. Goal - 500 RWHP/400 ft/lbs
To make more power I needed more air flow. In my
case, that meant increasing the blower speed by
about 12%. This process begins at the blower pulley.
Shown are three pulleys (left to right), 8lbs, 10lbs and
12lbs (I calculated).
Unfortunately, nobody made a smaller
pulley that fit my blower shaft so I had to
make one pulley from two. The rim shown
is from a Ford Lightening and the hub was
cut from one of my many larger pulleys.
Calculating the correct offset so
everything would line was the toughest
part. Cutting the parts so that they would
"nest" together and maintain concentricity
and axial run-out was the next challange.
The housing on the M90 would not
accept anything smaller so I had to
turn it down a bit on the lathe.
Here's a picture of the final two piece pulley compared to
my 8 lb pulley. I also added some fittings so that I could
cool the S/C oil. The only failure I had to this point was
that the blower housing got so hot the seals softened and
allowed oil to pass. The result was lots of smoke but no
The next step in my upgrade was to install a new
ported blower housing. As you can see by the
comparison, the lower housing has considerably
more intake cross section. The increased VE
alone from this housing was suppose to be good
for about 1.5 lbs of boost (flow).
Since the intake size and shape had changed
considerably from my previous housing I needed to
modify my fabricated throttle body manifold to
match. The top picture was my original design and
the lower the new design.
Modifying my original manifold was
a real pain as the complex shape of
the new housing didn't lend itself to
standard sheet metal design. It
worked, but it was ugly. The lower
bolt hoes were so close to the
housing walls that I had no edge
distance for the attach hardware. I
needed to weld blocks to the side
of the manifold and use long bolts
to solve this problem.
It doesn't look pretty but it worked.