Tune builder
Pick your way through every upgrade category and learn what each choice changes, when to reach for it, and the Forza Horizon 6 quirks that catch people out. Build a sheet you can read straight into the in-game upgrade menu.
Once your parts are on, get slider baselines from the tuning calculator, or learn what every setting does in the full tuning guide.
This advisor explains what each upgrade does and which way it moves your car. It does not simulate PI or stats, because those change with patches and would be guesswork. Arrows show direction only. Confirm the real numbers in the in-game upgrade menu.
Aspiration
How the engine breathes. Forced induction is the biggest single power lever and the cheapest way up the PI ladder.
Engine swap
Changing the engine itself. Swaps unlock power a stock block cannot reach, but they move weight around.
Drivetrain swap
Which wheels get the power. This reshapes how the car puts power down and rotates more than almost any other part.
Tyres and compound
The single biggest grip lever. Compound sets how much mechanical grip you have before any tuning.
Brakes
Often skipped, and newly important in FH6.
Transmission
Gearing and shift behaviour.
Differential
How locked the driven wheels are, which controls rotation on and off throttle.
Weight and chassis
Less mass and a stiffer shell help every part of the lap.
Aerodynamics
Downforce trades top speed for cornering grip, and shifts balance front to rear.
Build sheet
Pick parts on the left to assemble your build sheet, then copy it to read in the in-game upgrade menu.
Frequently asked
Does the tune builder calculate PI?
No, and that is on purpose. It does not simulate Performance Index or stat numbers, because those shift with game patches and anything we showed would be guesswork. Instead it explains what each upgrade does and which direction it moves power, weight, grip and PI, then you confirm the exact numbers in game.
How is this different from the tuning calculator?
The tune builder helps you decide which parts to fit. The tuning calculator gives you slider starting points for springs, dampers, anti-roll bars and the rest once those parts are on the car. Use the builder to plan the build, then the calculator to set it up.
What does it get right about Forza Horizon 6 specifically?
Brakes now matter and weak stock brakes can lock a wheel on downshift, a race transmission removes clutch behaviour even if you drive manual with clutch, the 6.2L V8 swap is roughly 100 lb heavier than in FH5, and the rally differential often feels better than the race diff on road. Each of these is flagged on the relevant upgrade.
Sources
Upgrade guidance is general Forza tuning knowledge cross-checked against these references. Last reviewed 2026-05-29.