How quick is it? Answer: 10.62 at 126 mph in the quarter.
Not bad. After posting those numbers on the web and in a YouTube video
("Crusher Camaro Hits the Dragstrip," HOT ROD Unlimited, episode 3),
folks wanted to know the skinny, so here it is.
The Power
The '67 Crusher has been with HOT ROD since 1993 and has
seen several makeovers. This time around, the focal point is the engine, which
is a 489ci big-block Chevy that's been around for many years, having seen
dyno-test time in HOT ROD, Car Craft, and Chevy High Performance magazines.
It's been so long since we last dyno'd it that we lost all the data after our
PC laptop crashed and burned, but we know from old stories that it made 650 to
660 hp at about 6,000 rpm and 650 lb-ft at 4,400. During a chassis-dyno test
the day before our road trip, it made 520 hp and 500 lb-ft to the Pro Trac
tires.
That's actually not too impressive for a blown Rat, but the
engine is very, very tame. The cubes come from a 4.280 bore and a 4.250 stroke
with a Scat cast crank, and the SRP pistons squeeze just 8.95:1 compression.
The cam is a weenie Comp Cams hydraulic roller that doesn't even lope with
224/230 degrees of duration at 0.050, 0.510/0.510 lift and a 110-degree LSA.
(Note: Incorrect cam specs were printed in the Dec. '09 story.) The heads are
little Holley oval-ports that have been discontinued but are comparable to
Edelbrock Performers. It's got Hooker's Darkside black-coated headers with
2.0-inch pipes and 31?2-inch collectors, and the exhaust is a 3-inch Flowmaster
kit with Series 44 mufflers.
Most important, induction comes from a Weiand 8-71 blower
that has been Teflon-stripped and blueprinted by The Blower Shop (actually, the
shop did that for us twice because we had an ignition problem that led to
multiple backfires that totally hashed the rotors). We run the blower
significantly underdriven to deliver only 5 psi of boost, and we've never run
it on higher than 91-octane gas, even at the track.
Drivetrain
The best part of the Crusher is the 4L85E auto-overdrive
transmission from Gearstar, which modernizes the dinosaur with
computer-controlled shift points and adjustable shift firmness. It's also beefy
enough to take as much as 400 hp more than we're making, so we have room to
grow. The transmission's 0.75:1 Fourth gear and lockup converter combine with
the 3.50:1 axle gears to deliver 2,100 engine rpm at a 70-mph cruise. The rear
axle is a Ford 9-inch with 35-spline axles and a Moser centersection with a
Wavetrac limited slip.
Chassis
Zero rocket science here. In fact, it's pretty wrong. Out
back, we've got sagged-out multileaf springs and old-school slapper bars. In
the front, it's all stock but with CPP (PN FCS6330D) big-block Chevelle springs
to hoist the nose for an old-school look. We've got QA1 double-adjustable
shocks all around. In race trim, the car weighed 3,475 pounds. Add 175 for the
driver and another 20 in video equipment, and you get 3,670 pounds rolling down
the track.
At the Drags
Our private test session at Auto Club Raceway in Fontana,
California, was the last one before that track closed due to whiners
complaining about the noise. We drove the Crusher 50 miles from home to the
track, bolted on some Hoosier 30x9.00-15 radial slicks, and let fly. The first
pass, leaving off idle, was 10.702 at 124.98 mph with a 1.574-second 60-foot
time. We hot-lapped it to see if heat soak in the blower was going to kill us
and hit 10.833 at 124.91. Much of the e.t. was lost up to the 330-foot mark, as
we foot-braked some rpm against the converter and spun the tires. But the mph
was a repeat, telling us the horsepower was still there.
Tuning ensued. Our FAST air/fuel reader was monitoring O2
sensors in both pipes and telling us we were seeing ratios of around 12.8:1 at
the leanest, which made the engine happy and the spark plugs flawless. However,
Finnegan noted that the timing mark on the ground straps was a little shallow.
We were using an MSD Digital 6 Programmable 6AL-2 ignition box, which allowed
us to lock out the centrifugal advance mechanism in the distributor and program
the timing curve on a laptop with MSD's Pro-Data software.
We had it tuned for 36 degrees of total timing at cruise and
26 degrees at max boost. Advancing the timing just 1 degree to 27 degrees BTDC
had a negative impact, slowing us to a pair of 10.90-second passes at 122–123
mph. But, in a display of remarkable sensitivity to timing, Finnegan finessed
it just half a degree, giving us 26.5 degrees total and picked up mph. We also
fiddled with shift points, having to click 'em at 6,000 rpm to avoid valve
float. In the end, our best run was the 10.621 at 126 with a 1.564 60-foot and
eighth-mile performance of 6.767 at 102.57. (Point of interest: To estimate
quarter-mile performance based on the eighth-mile numbers, many people use a
multiplier of 1.56 to 1.6; we use 1.57. Amazingly, the Crusher's 6.767-second
eighth-mile number times 1.57 equals 10.624, almost exactly our full-track
number.)
Conclusions
The Crusher's engine and rear gears are far more optimized
for the street and highway than for the track. At 126 mph in Third gear, the
big-block is lugging at just 5,200 rpm. Swapping the 3.50 gears for 4.10s would
almost certainly improve the e.t. if we could maintain traction at launch.
That's iffy, because the chassis is far from optimized. The rear springs are
sagged to the bumpers on the slapper bars and there's a little porpoising. The
front suspension offers almost no rebound droop to allow optimal body
separation at launch, and the car carries 57 percent of its weight on the nose.
The rear end could get better, but we're not going to be able to solve the
front end without losing our '70s stance. The front-end alignment could also be
a whole lot better, but thanks to that nosebleed posture, we're out of camber
adjustment.
Our other option would be to leave the rear gear as-is and
simply run more mph to get the finish-line rpm closer to the peak. How? Swap
the blower pulley, make 8 psi of boost, and gain almost 100 hp. We'd want to
use race gas at that point just to help protect that poor cast crank from
possible detonation, but we might even see a 9.99 pass. We have to try it some
time. We also have a slick dual-quad plate system from NOS. Hmm. And then
there's that leftover Bonneville short-block at 555ci that would look spiffy
under the 8-71. This could go nuts.
http://www.stevescamaroparts.com
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