100mph HPI Ni­tro RS4

RC Car Action - - BUILT FOR SPEED -

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 speedop­ti­mized sus­pen­sion setup to achieve 101.7mph. Where do you go to drive that fast? We had a con­nec­tion at the air­port.

The project started out with a Corvette body, but even­tu­ally a Toy­ota TSO20 body was used be­cause it was more suit­able for high-speed runs.

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.

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.

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 100wt 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.

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