HI22TT Series
Honda’s engine for the 2025 IndyCar Series. Honda and Chevrolet again will compete for the IndyCar Manufacturers’ Championship.
Honda’s HI22TT is a 2.2-liter, six-cylinder, twin-turbocharged engine. Cylinder bore is restricted to a maximum of 95mm, while stroke is free. Maximum engine revolutions per minute are a series-mandated 12,000 rpm.
Features of the engine include direct fuel injection, two Borg-Warner turbochargers, “Drive-by-Wire” throttle technology and a series-spec McLaren Electronics Engine Control Unit (ECU).
CHASSIS
Design | IndyCar/Dallara Automobili, Italy |
Configurations | Street/Road Course |
Components | Monocoque contains cockpit, fuel cell and front suspension; engine is stressed (integral) member of chassis; rear assembly contains bellhousing, gearbox and rear suspension members |
Materials | Carbon fiber, kevlar and other composites |
Chassis | Dallara IR-12 Chassis (2012-Present) |
Suspension | Double wishbone with adjustable geometry, camber, toe, and ride heights, pushrods, rockers, third springs, driver adjustable anti-roll bars and weight jacker, multi-adjustable dampers with quick change coil springs |
Brakes | PFC ZR90 monobloc aluminium calipers, with PFC carbon-carbon brake discs and pads |
Weight | Approximately 1620 lbs (Road/Street/Short Ovals) and 1590 lbs (Speedways) (Does not include fuel / driver / drink bottle & contents / driver equivalency weight) |
Length | Approximately 201.7 inches |
Height | Approximately 40 inches |
Width | 75.5 inches minimum (Road/Street), 75.75 inches minimum (Ovals), 76.5 inches maximum (measured outside rim to rim) |
Wheelbase | Adjustable 117.5" to 121.5" |
Fuel | Sunoco E85 ethanol; Single, rupture-proof cell, 18.5 U.S. gallons (standard) |
ENGINE
Engine Type | Twin turbocharged, fuel-injected, aluminum alloy V6 |
Displacement | 2.2L (134.25 cubic inches) |
Valvetrain | Dual overhead camshaft, four valves per cylinder |
Crankshaft | Alloy steel, four main bearing caps |
Pistons | Forged aluminum alloy |
Connecting Rods | Machined alloy steel |
Injection System | Electronic combined direct and indirect fuel injection |
Ignition System | Digital inductive |
Lubrication | Dry sump system, featuring multi-stage scavenge pumps |
Cooling | Single mechanical water pump feeding a single-sided cooling system |
Transmission | Six-speed sequential, paddle-operated, with a hand-operated clutch |
Fuel | IndyCar Series mandated E85 race fuel |
Weight | Approximately 250 lbs (112.5 kg), series-mandated minimum weight |
