HPI Racing Vorza S Truggy Flux

The kind of vehicle the maker sells it as. It sets what the car is built to do and which cars it is fair to compare it with.

• A truggy is a 1/8 buggy with wider arms and truck tires: more stable and more forgiving on rough ground.

All four wheels are driven. That gives more grip under power, especially on loose ground.

• The cost is more parts to maintain.

A brushless motor has no brushes to wear, so it makes more power and runs more efficiently than a brushed one.

• It needs a brushless ESC.

Ready to run: built at the factory with the electronics installed.

• Some come without a battery or charger; the maker's box contents say which.

The maker's nominal size compared with a full-size vehicle. It works more as a class label than a measurement.

• A 1/10 monster truck is far bigger than a 1/10 touring car, so compare length and weight for real size.
• This one is 580 mm long.

The maker's product number for this exact version.

• A V2, a new color, or a kit instead of an RTR usually has a different number, and parts can differ between them.
• Check it against your box or receipt before ordering parts.

The small gear on the motor shaft. Fewer teeth gear the car shorter: quicker acceleration, lower top speed and a cooler motor. More teeth do the opposite.

• On this car one tooth changes the gearing by about 6.7%.
• A bigger pinion loads the motor and ESC harder, so check the maker's gearing chart and feel the motor temperature after a run.

The large gear the pinion drives. A bigger spur with the same pinion gears the car shorter.

• Pinion and spur must have the same pitch, or tooth size, to mesh.
• The Gearing parts table below shows this car's pitch and part numbers.

Every reduction after the spur, multiplied together: transmission, differentials and axle gears.

• It is fixed by the design; the gearing you change is the pinion and spur.
• This one is worked out from the tooth counts the maker publishes.

Spur teeth divided by pinion teeth: the part of the gearing that a pinion or spur swap changes.

• Here it is 3.333:1.

How many times the motor turns for one turn of the wheels. A higher number is shorter gearing: more acceleration and pulling power, less top speed.

• Among 1/8 truggies in the catalog, the middle half run between 13.7:1 and 15.7:1 on stock gearing; this one is 14.3:1.

The type of each differential, as the maker states it.

• A gear or ball diff lets the wheels on one axle turn at different speeds in a corner; a spool or locked diff turns them together for straight-line drive and climbing, at the cost of steering.

The nominal size of the hole that mates with the motor shaft.

• Match the pinion mounting method as well as its size. A press-fit hole cannot be inferred from motor shaft diameter.

The tooth spacing of the fitted gear, stated as metric module or diametral pitch.

• The meshing pinion and spur need matching pitch. A missing pitch can be inferred from the other fitted gear; module and diametral pitch are not silently converted.

The tooth spacing of the fitted gear, stated as metric module or diametral pitch.

• The meshing pinion and spur need matching pitch. A missing pitch can be inferred from the other fitted gear; module and diametral pitch are not silently converted.

The outside diameter of the mounted tire, tread to tread. A taller tire covers more ground each turn, which gears the car taller.

• This approximate diameter comes from a replacement advertised for the identified OEM tire. Calculated speed and rollout use this working size; measure your fitted tires for a closer comparison.
• At high speed tires can balloon and grow, so the real gearing gets taller as the car goes faster.

How far the car moves for one turn of the motor: tire circumference divided by final drive.

• It lets you compare gearing across different tire sizes; more rollout is taller gearing.
• Here it is 31.3 mm.

The hex on the axle that the wheel locks onto and is driven by. A wheel must match the hex size to fit.

• 17 mm is the standard size on 1/8 cars.
• The wheel nut is a separate size, so check its thread too before buying nuts.

What the main chassis is made of and how it is built, as stated for this car. Braces, stiffeners and skid plates are not counted.

• Aluminum is stiffer than composite, which keeps the handling consistent; it can bend in a hard crash, and a bent chassis is usually replaced rather than straightened.
• A plate chassis is a flat sheet the parts bolt to.

What the shocks are and how they are built, as the maker describes them.

• Oil-filled shocks damp with silicone oil; friction shocks, found on some entry-level cars, damp with a sprung plunger and cannot be tuned with oil.
• Threaded bodies set ride height with a collar you turn, rather than clips.
• The shaft size matters when buying seals, ends and rebuild kits.

The inside diameter of the shock body, where the piston moves through oil.

• It is a shock measurement, separate from the motor pinion bore. Match the actual shock part when ordering pistons, seals or a replacement body.

The stated length of the complete shock assembly. Sources may use mounting-eye centers or a nominal assembly length.

• Compare fully extended mounting-eye spacing, compressed length and mounting hardware before ordering. A longer shock changes ride height and travel, and can bind at full droop or bottom out.

RPM per volt with no load on the motor. Higher KV spins faster on the same pack; lower KV on more cells can reach the same RPM with less current.

• On 6S (22.2 V nominal) this motor spins about 48,840 rpm with no load.
• Under load the real RPM is lower.

The diameter of the motor's output shaft. A pinion's bore, the hole in its middle, must match it.

• 5 mm is usual on larger motors, including most 1/8 cars.

The highest LiPo cell count the maker rates the electronics for. Each cell is 3.7 V nominal and 4.2 V fully charged.

• 6S is 22.2 V nominal and 25.2 V off the charger.
• Running more cells than this risks the ESC and motor.
• Many cars also run on fewer cells, only slower.

The plug on the battery lead. Your battery needs the same plug.

• An adapter works, but it adds resistance and another joint that can work loose.
• Deans and other T-style plugs are older designs, still common on smaller cars and race packs.

The current the stock speed control is rated to carry, as the maker states it.

• It is the continuous figure: what it can carry all run.
• A motor or pack that pulls more than this risks the ESC.

The stock servo that steers the car.

• Metal gears take hard knocks to the front wheels better than plastic ones.
• A digital servo holds its position more firmly and reacts sooner.

How hard the servo can turn, at the voltage the maker rates it.

• More torque steers heavier cars and bigger tires more precisely and holds the wheels straight over rough ground.
• Kilogram-centimetres and ounce-inches measure the same thing; the other unit is converted for comparison.

How long the servo takes to turn 60 degrees, at the voltage the maker rates it.

• A smaller number is a quicker servo, which feels sharper when changing direction.

Stock servo dimensions: A documented servo or steering interface for this model. Matching torque alone does not establish mounting or horn fit.

Stock servo spline: A documented servo or steering interface for this model. Matching torque alone does not establish mounting or horn fit.

Servo mount pattern: A documented servo or steering interface for this model. Matching torque alone does not establish mounting or horn fit.

Motor RPM times rollout, worked out on 6S at nominal voltage with stock gearing.

• It assumes no load, no battery sag, no wheel slip and no drag, so read it as a ceiling for comparing setups.
• A GPS usually reads below it; the gap is load, battery sag, tire slip and drag.

The motor's RPM with no load: KV times pack voltage.

• Under load it drops, which is one reason real speed is lower than the theoretical figure.

Overall length as the maker states it, usually with the body fitted.

• Useful for comparing real size, since scale labels are loose.

Overall width as the maker states it, usually with the body fitted.

• A wider car is more stable in corners and harder to roll over.

Overall height as the maker states it, usually with the body fitted.

• Useful when checking it fits a shelf, a bag or a car trunk.

The distance between the front and rear axle centers. A longer wheelbase is steadier at speed and over bumps; a shorter one turns more tightly.