100mph HPI Nitro RS4
Today, it’s taken for granted that the fastest cars use LiPo batteries to spin brushless motors.
But back in the early 2000s, when brushed motors and NiMH cells were all we had, maximum
speed and power meant going nitro. With nitro racecars already reaching 70mph speeds,
burning fuel all the way to 100mph seemed doable. This HPI Super Nitro RS4–based rig was
built for Nitro magazine, and used a high-revving on-road engine, custom pulleys, and a speed-optimized suspension setup to achieve 101.7mph. Where do you go to drive that fast? We had a
connection at the airport.
Custom-made pulleys, clutch bell, and spur gear were needed to raise
the RS4’s overall gear ratio so that it could take advantage of the
engine’s high rpm range and horsepower.
A stiff suspension kept the car planted to the ground. The shocks were
filled with thick 100 wt oil, and they were wrapped with 40-pound
springs in the front and 35-pound springs in the rear. Universal driveshafts on all four corners applied smooth power to the rims.
A . 21 on-road engine was used to get the job done. It revs much higher
than a . 21 off-road engine, and it produced plenty of horsepower to get
the fairly light Super Nitro RS4 up to speed. The block of the engine
was machined down slightly to make room for the car’s larger pulleys.
Take a look at that
chassis! It’s almost too
pretty to drive, but we
did it. The chassis was
designed and made to do
a better job of accepting
the large . 21 engine.
The project started out with a