Sep 27, 2013 No Comments by



A brushless power boost breathes new life into the Blitz


If there was ever a truck ripe for an upgrade to brushless power, the Blitz is it. HPI's 2WD short course machine is based on the Firestorm, a stadium platform that belies its fun-running mission with a fully adjustable suspension system and an overall design that cribs freely from the most successful racing trucks. The Blitz is stretched to suit short course proportions and inherits all of the Firestorm's racing features, from its vertical ball studs and turnbuckle camber links to its behind-the-tower shock positioning and adjustable rear toe-in. To give the Blitz its brushless power boost, HPI supplies the sensorless Flux Reload V2 power system, which includes a 4300Kv motor and is good for nearly 35mph on the included 7-cell NiMH battery. The LiPo-ready speed control can handle a 3S pack as well—let's see how fast this bad boy can go, and how well it puts that power down in the dirt.

Everything you need to run the Blitz Flux is in the box, including a 3000mAh battery with Deans connector. A “wall wart” slow charger is supplied to get you rolling—make a fast charger your first upgrade.


  • Item no.: 109325

  • Scale: 1/10

  • Price* $365

  • Weight, as tested: 5 lb., 3 oz. (2,271g)


  • Type: Molded plastic semi-tub


  • Type: Upper and lower H-arm with turnbuckle camber link

  • Inboard camber link positions (F/R) 2/2, adjustable link height

  • Outboard camber-link positions (F/R) 2/3

  • Shock positions, towers (F/R) 3/3

  • Shock positions, arms (F/R) 2/2

  • Shocks: Plastic-body with threaded preload collars


  • Type/ratio: Enclosed gearbox, 2.6:1

  • Spur gear/pinion: 18/88T

  • Differential: Bevel gear, sealed metal housing, silicone filled

  • Driveshafts: Steel dogbone

  • Bearings: Rubber sealed ball bearings


  • Wheels: One-piece plastic, standard short-course dimensions, 12mm hex

  • Tires: HB Racing Megabite

  • Inserts: Open cell foam


  • Transmitter: HPI TF-40 3-channel, 2.4GHz

  • Receiver: HPI RF-40 3-channel 2.4GHz

  • Speed control: HPI Flux Reload V2, waterproof, 3S max

  • Motor: HPI Flux Shot brushless, 4300Kv

  • Steering servo: HPI SF-20W, waterproof, claimed torque 92oz.-in.

  • Battery: HPI Plazma 7-cell NiMH, 3300mAh

*Varies with dealer


The transmission gears are all steel. Note the 4-bolt diff cover. A gasket between the case halves and O-rings on the drive cup shafts seal the diff, and it arrives filled with silicone oil.

The move to brushless power required no upgrade in the transmission department, as the Blitz has always had steel gears between the gearbox halves. The transmission is configured in a classic “3-gear” layout, so named for the three internal gears: an input gear spun by the top shaft, differential gear in the bottom of the ‘box, and an idler gear between them. The differential is fully sealed by O-rings on the outputs and a gasket between the case halves, and is silicone-filled at the factory. A dual-pad slipper clutch is standard, and robustly constructed with cast-aluminum hubs keyed to steel pressure plates putting the squeeze on the spur gear. Steel dogbones send the spin to the wheels, and rubber-sealed ball bearings keep everything turning smoothly. Universal-joint axles would have been nice (especially since the Blitz' camber links are not captured, which means they can pop o' in a crash and let a dogbone part ways with the truck and go missing), but the ‘bones work just fine and are expected at the Blitz Flux's price point.


The Flux reload speed control is rated for 3S LiPo power and fully tunable. It's a keeper.

The sensorless 4300Kv Flux Shot motor offers good throttle response and runs cool with it's deeply finned can.


The star of the Blitz Flux is, of course, its brushless power system. Waterproof, fan-cooled, and 3S-capable, the Flux Reload controller is a smooth performer and fully adjustable. Settings include throttle mode (reverse, forward only, and “rock crawler”), 5–100% drag brake, punch control, brake force, motor timing, and more. The speed control is also thermal overload protected and equipped with genuine Deans connectors, so revving the Blitz up to its full 3S capability won't cook anything.


That's a lot of black. Bonus points for the thumbscrew-secured battery strap. The fewer body clips, the better!

The Blitz chassis is a stretched version of HPI's Firestorm stadium truck platform, and ticks off all the features expected of “low CG” short-course racing designs. The chassis' sides angle upwards from the center battery channel, a ording extra cornering clearance. Tall sills and a few well-placed gussets sti en the chassis, and modular construction allows the front and rear suspension assemblies to be removed intact. The battery compartment has enough room for a 7-cell “flat” NiMH pack, which will allow shorter LiPo packs to be fitted with room for fore and aft position adjustment. Whichever pack you install will be well secured beneath the battery strap, which fastens with a pair of thumbscrews — there's two less body clips in your life.

HPI's TF-40 2.4GHz transmitter is one of the nicer units in the RTR realm, with such niceties as dual-rate steering, adjustable steering and throttle endpoints, and a third channel. Ergonomics are comfy thanks to the fat grip and drop-down steering wheel. No frills styling-wise other than the chrome wheel, but functionality trumps looks any day, and the TF-40 is a reliable long-range unit that needs no upgrading unless you're looking for an LCD screen.


Shocks on the back of the tower, camber links up front. The Blitz Flux features the current state-of-the-art in suspension design. Setscrew-secured aluminum wheel hexes are a nice touch.

Suspension technology for 2WD o -road trucks has been steadily honed since the mid-80s, and the Blitz Flux handily adopts all that's been learned in those many years and millions of laps. The front shocks are mounted behind the shock tower rather than in front of it, which places the shocks farther towards the back of the suspension arms, lowering them by a few millimeters to lower the truck's center of gravity. This displaces the camber links from their usual locations, and moves them to the front of the shock tower. As with the rear camber links, the inboard link mounts are vertical ball studs, which can be raised or lowered with spacers to adjust roll center. All the hingepins are captured, so there are no e-clips to lose (if you don't know what an e-clip is … good). Specs-wise, the Blitz's oil-filled shocks are standard RTR fare: plastic shock bodies, dual O-ring seals, and plated shafts. Volume compensation is handled by bladders, and the shock bodies are threaded for clipless preload setting. Tried and true stuff that works.



Let's get right to the burning question: how fast does it go? With its included 7-cell pack on board, the Blitz Flux topped out at 34.2mph. You can gear up a tooth or two if you want to go faster, but then you'll likely be over-geared for all-around fun running. I suggest sticking with the stock gearing, which feels spot-on. Acceleration from a standing start is brisk but initially soft, as the sensorless power system takes a split second to get rolling. But once rolling at any speed, the Flux Reload speed control responds with good “punch,” which can even be adjusted. The speed control offers nine punch settings from “soft” (setting 1) to “aggressive” (setting 9). Out of the box, punch is set for 7, and you can also set drag brake force, LiPo cutoff voltage, maximum brake force, reverse speed, initial brake power, throttle dead band, and motor timing. There's also a reverse-lockout for racing.

In addition to its brushless power system, the Blitz Flux also differs from the standard Blitz in the tire department. Instead of the brushed-Blitz's realistic Maxxis Trepador Comp tires, the Flux wears HB Racing Megabites. The tiny, closely spaced knobs and soft rubber generate track-worthy grip and make the Flux a more aggressive handler than the brushed truck. Steering feel is more precise, with less push at speed. Rolling into the throttle on corner exits results in a smooth surge of power with tractable oversteer if the track is loose. The stock servo isn't lightning fast, but it does have plenty of torque to keep the Blitz on course, especially when the servo saver is tightened up (better yet, get HPI's #104891 aluminum steering rack). The suspension does its job effectively on track-style obstacles and has enough travel and damping for plastic skateboard ramps and general fun-driving. If you're into mega-air G-outs, you can expect to slap the chassis on touchdown, but the Blitz is a tough truck and should roll away from any right-side-up landing. Flight is predictable, but as with all short course trucks, the large full-fendered body can “parachute” and make it hard to drop the nose down for a smooth landing. Drilling or slotting the front fender tops and hood to allow air to flow makes a big difference in jumping performance, especially when launching from steep jump faces or into a headwind on outdoor tracks or in your backyard.


Fully adjustable suspension and power system

Race-inspired LCG chassis

Waterproof electronics


Black on black on black styling drew mixed reviews


What the heck is a dogbone?

All RC cars and trucks with independent suspension require some type of articulated driveshaft to transfer power from the transmission to the wheels while allowing the suspension arms to move up and down. The simplest mechanism for this is a sliding-pin interface, better known as a dogbone (which it kind of resembles). It works fine, but has two disadvantages: one, the pin/slot interface is a source of friction and wear, and two, the dogbone can easily eject from the vehicle and go missing if the camber link comes off or the suspension arm breaks. A universal joint operates more efficiently, and connects the shaft to the stub axle so it can't separate from the vehicle in a wreck.

Final word

The Blitz Flux is a fast, solid, and all-around fun short course truck that also has features racers will appreciate, particularly its fully adjustable suspension and equally adjustable speed control. The tires are track ready, and at about $360 with a 3S-capable power system, 3000mAh battery, and 2.4GHz radio system with adjustable endpoints and dual-rate, it's a pretty good value. As my go-to 2WD short course truck, I'll be tuning and modifying my Blitz Flux for racing and fun. To keep up with the mods, read my blog at RCCarAction.com and follow @PeterRCCA on Twitter.


HPI Racing hpiracing.com

Performance Tests

About the author

I've been involved in RC for over 25 years, and first joined Air Age Media in 1997. I served as Executive Editor until 2008, when I went to work on the manufacturing side of the RC biz. Now back at RC Car Action, I'm thrilled to be doing what I love most--not just enjoying RC, but sharing it with all of you. In addition to RC, I enjoy spending time with my beautiful wife Kathleen and our wonderful daughter Audrey.
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