The Junior Dragster Inertia Dyno & Dynamometer has a 40 horsepower flywheel with a 125 hp one-way sprag clutch designed in case the engine locks up or pulls down, so you can let up on the throttle and let engine die or lock up and the flywheel will coast until you use the brakes to stop the flywheel. On outlaw engines, you won’t want the dyno pulls any longer than 15 seconds due to them running 330 feet in about 4.1 seconds. A fresh motor is supposed to be about 55 hp. I would recommend a slightly larger flywheel. We put in the “New” Ultra Torque start system which cranks much faster and will crank these much larger flywheels fairly easily. We also installed a large torsion shock system to make all the major parts on the axle last much longer due to its ability to absorb large shock loads of the electric start system. We used 1 ¾” stress-proof axles with 125 hp one-way sprag clutch. The starting system has a relay so the starter gets maximum voltage & amperage and cranks much faster than previous systems. We also installed 2 gauge battery cables, again to get maximum speeds out of the starting system. This helps keep belt breakage to a minimum by cranking the engine rpm higher before engaging throttle or fuel. This dyno was powder- coated medium silver as shown in the pictures. Since the weight on this dyno is quite high, we are getting more requests to install locking casters so that the dyno can be moved around in your shop when you need to. We use a 62mm wide belt drive system so the chance of belt breakage is very small. We had a custom made belt driver that was lightened to keep weight down. I would highly recommend crank supports on both ends of engine. These engines turn over 9000 rpm and the cranks flex quite a bit. We use a large belt drive on the dyno axle so that belt breakage is almost non-existent. We installed a “Pro” data system with 4 channels of temp or you can add air/fuel ratio. This system also has internal S.A.E. weather correction. We built an adjustable motor mount so that the carburetor is level and the belt tension can be tightened easily. We did several test pulls and this dyno works great! The sensor to measure horsepower is placed on the main drive axle so it measures true hp before any slippage or chatter of the one-way sprag clutch. Make sure to check out “What you can do with a Hewitt Inertia Dyno” to see what the data system and software can show you. If you have any questions, call me on my cell 1-641-512-3395?
THANKS for considering the Hewitt Inertia Dyno, the BEST Dyno out there! Sincerely Yours, STAN HEWITT
Stan Hewitt – Dyno Guru - c 641-512-3395 - can customize to your needs, call me - let's talk! 