Forza Horizon 6 Conversion Tuning Guide

Forza Horizon 6 tuning is as deep as it is rewarding. Before you ever touch a slider in the Tune menu, every car's potential is shaped by the conversions you install: the engine you choose, how you aspirate it, the drivetrain layout, and the body kit you bolt on. Get these wrong and no amount of fine-tuning will save the build. Get them right and the car practically tunes itself.

This guide covers every conversion decision you'll face in FH6: engine swaps, aspiration, drivetrain conversions, and body kits, with the FH6-specific updates that arrived with the new game - including the expanded engine swap pool (motorcycle engines are now available for some subcompact cars), the rebalanced PI class ladder where A caps at 700 and S1 starts at 701, and an updated AWD differential UI covered in the companion Drivetrain Tuning Guide.

Engine Swap

Engine swapping a car will usually result in better overall performance. What you should be looking for is the engine that gives the best power-to-weight (P/W) ratio for the PI cost. A bigger engine isn't always better - if it pushes you out of your target class or adds more weight than the extra power can compensate for, you've made a worse car for more money.

How to evaluate an engine swap in FH6:

• Compare P/W ratios - In the Buy and Install confirmation screen, FH6 shows you the PWR value before and after the swap. A swap that improves PWR is usually worth it; a swap that drops PWR or holds it flat for a PI cost is rarely worth it.
• Watch the weight change - Heavier engines (V12s, big-block V8s) shift weight distribution forward, which affects handling. A V12 in a small chassis can ruin the balance of a car that's better suited to its stock engine.
• Match engine to discipline - High-RPM screamers (V10, V12, Racing I6) are great for road race; torque-rich V8s work well for drag, drift, and cross country; small turbo engines (2.0L F4 Turbo Rally) are dirt rally specialists.
• Listen to the engine - This is subjective, but sound matters for content creation and personal enjoyment. A bad-sounding engine in a beloved car can ruin the build.

Historically PI-efficient engines:

• Racing V12
• 6.2L V8 (415hp)
• 7.2L Racing V8
• 5.2L V10
• V10
• 4.0L V8
• 3.2L I6
• 1.6L I4 - VVT
• 2.0L F4 - Turbo Rally

FH6 engine swap notes:

• FH6 expanded the engine swap pool compared to FH5, including motorcycle engines now being available for some subcompact cars.
• Aspiration availability varies by engine in FH6. Not every engine offers every aspiration option - some large displacement V8 swaps (e.g. the 6.2L V8) only offer Positive-Displacement Supercharger or Twin Turbo, while other engines retain access to Centrifugal Supercharger and additional options. Always check the Aspiration section of the upgrade menu after choosing an engine swap to see what's available for that specific engine.
• As FH6's meta develops over the months after launch, expect this list to evolve. Always check community resources and competitive Discord servers for the current meta picks.

Aspiration

FH6 offers up to four aspiration types, though not every engine offers every option - availability is engine-specific. Always check the upgrade menu after picking an engine swap to see which aspirations are actually offered for that engine.

• Naturally Aspirated (NA) - Stock for non-forced-induction engines. Lightest, simplest, but has the lowest power ceiling. Best for builds where weight reduction and throttle linearity matter more than peak power.
• Centrifugal Supercharger - Often the most PI-efficient forced induction option in FH6, carrying forward from FH5. Provides a smooth, RPM-scaling power delivery with relatively low PI cost. Not available on every engine (some large displacement V8 swaps skip this option).
• Positive-Displacement Supercharger (PD SC) - Provides instant low-end torque with no lag, making it ideal for cross country, drift, drag launches, and any discipline where throttle response matters more than peak top-end power. The PI cost is typically higher than Centrifugal but the response gain is significant.
• Twin Turbo - Highest peak power potential but with noticeable lag. Best for top-speed builds, sprints, and engines that already make good torque without needing instant response. Works particularly well on high-displacement engines (V8s, V10s, V12s) where the lag is masked by the engine's natural torque.
• Single Turbo - Available on some engines, often as a stock or factory option on turbocharged cars. Less peak power than Twin Turbo but with less lag. Sometimes the best balance for mid-range power builds when the engine ships with it stock.

Choosing aspiration in FH6:

• Road race / circuit - Centrifugal Supercharger is often the most PI-efficient pick if available; Twin Turbo for peak power on big engines; PD Supercharger for smaller engines where throttle response through corners matters more.
• Drift - PD Supercharger preferred. Instant throttle response is critical for maintaining slide angles. Centrifugal works too if PI is tight.
• Drag - PD Supercharger for launches, Twin Turbo for top-end pulls. Many drag builds favor PD SC for the entire run; Centrifugal is a budget-PI alternative.
• Dirt racing - Single Turbo (where available) on small turbo rally engines preserves WRC-style character; PD Supercharger or Twin Turbo on larger engines depending on stage character.
• Cross country - PD Supercharger almost universally on big V8 swaps where Centrifugal isn't offered. Where Centrifugal is available on smaller engines, it can also work well for CC.

It is worth experimenting with each aspiration option when building, especially since PI cost and P/W impact varies by engine. The Buy and Install confirmation screen makes this easy - swap between aspirations and watch the PI counter and PWR value before committing.

Drivetrain

When it comes to drivetrains, each layout - AWD, RWD, FWD - has its pros and cons. It is car-, class-, and track-dependent which drivetrain you should be using. This section covers each in detail.

All-Wheel Drive (AWD)

AWD (all wheel drive) is the most commonly used drivetrain in FH6, but it is not always the best choice. When it comes to a car that comes stock as AWD, you should almost always keep it as AWD - factory AWD systems on cars like the Audi quattro, Nissan GT-R, Mitsubishi Evo, Subaru WRX/STI, and BMW xDrive models are well-tuned in FH6 and need very little adjustment. However, as a swap, converting to AWD is not always the most efficient choice.

The Pros of AWD are:

• Cars that are AWD swapped will have the same shift time on Manual as they do on Manual w/ Clutch;
• Has better corner exit acceleration than RWD and FWD;
• Has better launch than RWD and FWD;
• More overall traction;
• Used on almost every dirt and cross country car as a result of having more traction;
• Doesn't require throttle control to drive cleanly;
• Overall easier to drive, making it easier to get pace out of;
• Works in B, A, S1, and S2;

The Cons of AWD are:

• Heavier than RWD and FWD;
• Can add a lot of PI depending on the car (some swaps cost 30 PI, others cost 80+);
• Less top end than 2WD (RWD and FWD);
• Less turn-in than FWD;
• More understeer than RWD (FH6 AWD has an inherent understeer bias that must be compensated for with diff and ARB tuning);
• Isn't able to be powerbuilt (a build using weaker tires in order to get high amounts of power for sprints/acceleration tracks);
• Less competitive in D and C class where the PI cost of the AWD swap eats most of the upgrade budget;

Rear-Wheel Drive (RWD)

RWD (rear wheel drive) is the drivetrain that is most dominant overall in FH6 for skill-rewarding builds. RWD cars are able to be powerbuilt, due to the PI system allowing for RWD (and FWD) cars on weaker tires to receive high amounts of power, resulting in very high top end and acceleration relative to their class. These powerbuilds often claim many of the fastest times in rivals, due to most tracks favoring cars with high acceleration and top end over outright grip.

The Pros of RWD are:

• Lighter than AWD;
• Usually more PI efficient than AWD;
• Faster on launch than FWD;
• More top end than AWD;
• Less understeer than AWD;
• Less on-throttle understeer than FWD;
• Able to be powerbuilt;
• Works in every class;
• Required for drift builds;

The Cons of RWD are:

• Requires Manual w/ Clutch to get maximum pace out of - lots of time is lost on shifting without it;
• Requires throttle control to drive cleanly;
• Slower on launch and corner exit than AWD;
• Powerbuilds can be difficult to drive at the limit;
• RWD swap from a stock AWD car is rarely useful - it removes the AWD traction advantage without compensating PI benefit;

Front-Wheel Drive (FWD)

FWD (front wheel drive) is the least common drivetrain used as it serves more as a situational niche compared to RWD and AWD. FWD cars, like RWD, can be powerbuilt, but aren't as competitive as RWD powerbuilds.

The Pros of FWD are:

• Lighter than AWD;
• More turn-in than RWD and AWD;
• Able to be powerbuilt;
• Works in D, C, B, and A classes;

The Cons of FWD are:

• Either needs to be a full handling build or a full powerbuild, no in between;
• Requires Manual w/ Clutch to get maximum pace out of;
• Requires throttle control;
• Slower on launch than RWD, much slower on launch than AWD;
• Slower on corner exit than AWD;
• FWD cars often don't get good engine swaps (typically only 2.0L I4 - Turbo Rally and/or 2.0L I4 - VVT available);
• On-throttle understeer;
• Limited competitiveness above A class;

Body Kits

Widebody kits in FH6 increase the maximum tire width and the track width of the car, which increases mechanical grip and stability at the cost of additional drag. They are particularly valuable on cars that struggle with traction in their stock body, such as front-engine RWD sports cars at higher classes.

Key considerations:

• Drag tradeoff - Some widebodies add too much drag to be worth using. The 2008 Mitsubishi Lancer Evolution X GSR was a frequently cited example in FH5; verify which widebodies have the same drawback in FH6 before committing.
• Downforce unlocks - Some widebody kits add adjustable downforce sliders or unlock the front bumper / rear wing aero tuning. This can be valuable for road race builds at S1/S2 where downforce matters.
• Weight change - Depending on the car, widebody kits will either add or remove weight. Always check the PI and PWR delta before installing.
• Tire width - The widebody's primary benefit is unlocking wider tire sizes. If you don't intend to upgrade tire width beyond stock, the widebody itself provides minimal benefit.
• Visual impact - For ForzaFire content, widebody kits often look great on builds. Worth considering for showcase cars even if the performance gain is marginal.

Conversion Decision Framework

Putting it all together - when building a car for FH6, here is a practical order to make conversion decisions:

1. Decide the discipline first - Road race, dirt rally, cross country, drift, or drag. This locks in tire compound and most chassis decisions.
2. Decide the target class - D, C, B, A, S1, S2, or X. This sets your PI budget for everything below.
3. Choose the drivetrain - Match to discipline and class. Dirt/CC almost always AWD. Drift requires RWD. Road race depends on chassis and class. FWD is rarely the best choice unless the chassis demands it.
4. Choose the engine swap (or keep stock) - Find the most PI-efficient option that fits your discipline. Keep stock if PWR is already strong and the swap doesn't deliver enough to justify the PI.
5. Choose the aspiration - PD Supercharger for response-critical builds; Twin Turbo for top-end builds; NA for light, simple builds where forced induction costs more PI than it's worth.
6. Install the body kit - Only if it unlocks needed aero or wider tires. Don't install for cosmetics if PI is tight.
7. Lock in chassis upgrades - Tires, suspension, brakes, diff, weight reduction. (See the Drivetrain Tuning Guide for differential decisions.)
8. Top up with engine internals - Race exhaust, intake, fuel system, etc. - to hit your target PI ceiling.

Common Conversion Mistakes

• Engine swap by default - Not every car benefits from an engine swap. Many factory engines have great FH6 character and PI efficiency. Check PWR before and after every swap.
• AWD swap on light cars at low classes - The AWD swap PI cost on a small B-class car can eat your entire upgrade budget. RWD usually wins below A class for non-dirt builds.
• Twin Turbo on small engines - The lag on a small-displacement Twin Turbo can hurt drivability without delivering enough peak power gain to be worth it. PD Supercharger is usually better for engines under 2.5L.
• Widebody for cosmetics - Widebody kits cost PI and add drag. If you don't need the tire width or aero unlock, skip them on competitive builds.
• Ignoring chassis character - A V12 swap in a small hatchback ruins the weight balance no matter how PI-efficient it looks. Match engine size and character to the chassis.

Glossary

• P/W (Power-to-Weight) - The ratio of horsepower (or kilowatts) to vehicle weight. Higher P/W = faster acceleration. The single most important number on the Buy and Install screen.
• PI (Performance Index) - The numerical performance rating used by FH6 to classify cars. D, C, B, A, S1, S2, X. In FH6, A caps at 700 and S1 starts at 701.
• Conversion - A major component change that alters the car's fundamental character: engine swap, drivetrain swap, aspiration change, or body kit installation.
• Aspiration - The method by which air is delivered to the engine. Options in FH6 include Naturally Aspirated, Centrifugal Supercharger, Positive-Displacement Supercharger, Twin Turbo, and Single Turbo. Availability varies by engine - check the upgrade menu after each engine swap.
• PD SC (Positive-Displacement Supercharger) - A type of forced induction that provides instant low-end torque with no lag. The premium response-focused option in FH6; sits alongside Centrifugal SC in the aspiration menu where both are available.
• Powerbuild - A build philosophy that intentionally uses weaker tires in order to free up PI for engine upgrades, resulting in maximum acceleration and top speed at the cost of grip. Most viable on RWD and FWD cars on speed-bias tracks.
• Widebody - A body kit conversion that widens the car's track and allows wider tires to be fitted. Trades drag for grip.

Thank you for taking the time to read our guide and we hope it provided you with helpful information! If you have any feedback or questions, or if you would like to contribute to our guides yourself, feel free to reach out to us on Discord!