Rally-proven: an LS3, a ZF 8HP75X and IOcan in Ashley García's Peruvian rally truck

The ZF 8HP expects a constant conversation with the car it was born in — engine torque, wheel speed, gear-lever position and dozens of body signals arriving over CAN every few milliseconds. In this build there is no donor car at all: an LS3 V8 sits in a JAC T8 Pro, and none of the electronics the 8HP75X is listening for exist anywhere in the truck.

Rally competition raises the stakes. The gearbox had to deliver clean, repeatable shifts across a full stage, at 4,500 metres, under real competition load — an environment with no room for a transmission that refuses to shift when the network goes quiet.

IOcan sits between the LS3's engine management and the 8HP75X, recreating the CAN messages the transmission expects and passing real engine and driver data through in real time. The factory mechatronic stays sealed and stock — nothing is reflashed, and the conversion is fully reversible. A built-in semiconductor relay handles transmission power, wake-up and shutdown internally, which is why the complete transmission install came down to five wires.

Real torque, not a placeholder

The 8HP's shift quality is a function of how well it knows the load it's shifting under. IOcan calculates engine torque independently rather than depending on the ECU to publish a value it may not have. That torque model is what lets the transmission fill, hold and release clutches correctly across the whole operating range — not just at the one load point a static value happens to match.

This is the part most swap solutions skip, and it is exactly the part that decides whether the gearbox survives a season.

Torque coordination during the shift

In the factory car, the gearbox asks the engine to back off for a few tens of milliseconds during a shift, and the engine obeys. IOcan restores that conversation. Torque requests from the transmission are routed out to the ECU, and on García's truck the reduction is configured as proportional ignition retard, scaled from 0 to 30 degrees.

Proportional matters. A binary cut is a hammer; the gearbox gets either full torque or a hole. Scaling the retard in proportion to the request means the shift is met with exactly as much torque reduction as it asked for — which is what a smooth, repeatable, unshocked shift actually requires.

The side effect, on a rally truck, is not unwelcome: it pops on every upshift.

Shipped, not roadmap

Torque coordination on IOcan is not a planned feature or a beta. It is running in this truck, in competition, on a rally stage.

The truck competed at over 4,000 metres and came away with a P1 at Rally La Cordillera, plus a P2 finish, with the 8HP75X taking every instruction from IOcan. Shifts stayed clean and repeatable across full stages under competition load — a transmission the crew could trust completely, in one of the hardest environments there is.