Forza 7 Build Guide
Part 1 - Forza Build Basics
Understanding Car Types
As with tuning when it comes to building cars in Forza an important aspect you need to understand is the concept of car types.
Car types provide a general classification of all cars in Forza and group several body types. For each car type there is a distinctive set of build rules what upgrades and combination of upgrades work well and which don't.
Forza distinguishes between following car types:
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Trucks (off-road trucks & pickups, trophy trucks, race trucks)
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Utility Cars (vans, SUVs)
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Street Cars and Off-road Cars (sedans, wagons, muscle cars, compact cars, jeeps, buggies)
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Sports Cars (GT sports cars, rally cars, off-road sports cars)
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Race Cars and High Performance Cars (super cars, hyper cars, GT race cars, touring cars, NASACAR, V8 Supercars, LMP cars, F1, IndyCar, Formula-E, classic GP cars, Formula Mazda, Formula Ford)
To further diversify car types with regard to the period of time a car has been built Forza uses an era system:
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Modern: cars built 1995/96 or later
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Early Modern: cars built 1981-1994/95
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Vintage: cars built 1960-1980
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Early Vintage: cars built 1940-1959
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Pre-War: cars built before 1940
Car types mainly affect chassis and rims with older cars requiring heavier rims than modern cars and race cars requiring stiffer chassis and lighter rims than production cars.
Understanding Build Relevant Car Properties
Besides car type also power and weight influence car building.
The following table gives an overview which car property affects which build area. Please refer to the related section in the build guide for detailed explanations.
Engine Platform & Handling Drivetrain Tires & Rims Aero & Appearance
Car Type ✓ ✓
Power ✓ ✓
Weight ✓ ✓
Understanding Upgrades
Upgrading cars in Forza is all about balancing and aligning upgrades across the different upgrade areas so it is important to understand the dependencies between the upgrade areas:
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| v v
Engine Platform and Handling Drivetrain Tires and Rims
| ^
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As you can see from the above schematics engine upgrades affect drivetrain and tires and rims and platform and handling upgrades affect tires and rims.
This is because increasing power to a certain extent via engine upgrades requires also to upgrade drivetrain and tires to catch up with added power.
Likewise when reducing overall weight and or increasing chassis stiffness in platform and handling requires to upgrade tires for aligning overall grip level between chassis and tires.
Engine
Understanding engine upgrades is crucial when you want to maximize the cars power while maintaining a good handing. As you may have noticed already not all engine upgrades work well together, this is because Forza has a built-in set of rules which engine upgrades work well together and which not.
Each of the engine upgrades can be a street, sport or race upgrade and belongs to one of the categories: engine inputs, engine core, engine outputs, cooling and special upgrades.
Also engine upgrades can be either grip or speed upgrades. Grip upgrades are upgrades that offer power increases and come with a weight reduction, speed input upgrades are upgrades that offer power increases without weight reduction.
The following schematics shows how engine input, engine core, engine output and engine cooling components are interconnected:
Engine Input --> Engine Core (+ Forced Induction) --> Engine Output
^----------- Engine Cooling -----------^
The basic rule when doing engine upgrades is that input upgrades should not be higher than core upgrades and core upgrades should not be higher than output upgrades in terms of street, sport or race upgrades otherwise you will get inherent handling issues that cannot be tuned out.
That means when doing engine upgrades you will want to do it backwards, i.e. upgrade output before core before input components.
When balancing engine upgrades make sure to also consider stock engine components, e.g. the stock exhaust might be street exhaust (only sport or race exhaust upgrades are available) or the stock displacement might be sport displacement (only race displacement upgrade available).
Engine Input
Engine input upgrades deal with inputs of an engine which are air, fuel and electricity.
You'll find the engine input upgrades at the beginning of the engine upgrade list:
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Air Filter (Grip)
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Intake Manifold (Grip)
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Carburetor or Fuel System (Speed)
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Ignition (Speed)
Engine Output
Engine output upgrades are engine upgrades deal with the outputs the engine which are the exhaust.
There is only one output engine upgrades available which you will find after the input upgrades:
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Exhaust
Engine Core
Core engine upgrades deal with the core parts of the engine block that transforms the inputs (air, fuel, electricity) into power.
You'll find the related upgrades after the output upgrades:
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Camshaft (Speed)
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Valves (Grip)
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Displacement (Speed)
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Pistons (Grip)
Forced Induction
Forced induction upgrades deal with compressing parts of the engine exhaust and feeding them back into the engine for increased power output. They are available when a turbo or supercharger has been equipped via Conversion upgrades, some cars also have pre-installed turbo or superchargers.
You'll find the forced induction upgrades after the core upgrades, note that there can only be one of them installed at a time:
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Turbo (Speed)
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Twin Turbo (Speed)
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Positive Displacement Supercharger (Grip)
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Centrifugal Supercharger (Grip)
Cooling
Cooling upgrades deal with cooling engine core and forced induction components.
There are two types of cooling upgrades: core engine cooling and forced induction cooling upgrades and you'll find them after the core / forced induction upgrades:
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Oil and Cooling (core engine cooling)
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Intercooler (forced induction cooling)
For best handling cooling upgrades are required once you hit a certain engine power:
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Street cooling is required for cars with a power >= 400hp
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Sport cooling is required for cars with a power >= 500hp
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Race cooling is required for cars with a power >= 600hp
If you don't upgrade cooling to match engine power you will get inherent handling issues that cannot be tuned out.
Special Engine Upgrades
Special engine upgrades fulfill special tasks and can be found at the end of the upgrade list:
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Restrictor Plates
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Flywheel
Restrictor plates limit or open up the air flow into the engine and they are mainly available on race cars and high performance cars to meet homologated division restrictions. Installing restrictor plates has no implications on handling.
The Flywheel is responsible to smooth out the engine movement and also connects the engine with the drivetrain. For best handling the flywheel should match the installed engine upgrades so it should be as high but not higher than the highest engine upgrade.
If the Flywheel doesn't match engine upgrades balance issues are introduced. If the flywheel is higher than the highest engine upgrade except exhaust an oversteer issue is created on the front of the car, if the flywheel is lower than the highest engine upgrade except exhaust an understeer issue is created on the front of the car.
To learn more about balance issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
Platform and Handling
Platform and Handling upgrades deal with improving platform and chassis performance.
Platform Upgrades
Platform upgrades are brake, suspension and anti-roll bar upgrades. You'll find them at the beginning of the upgrade list.
Brake upgrades improve braking performance with the race brakes giving you full adjustable brake distribution and pressure which is beneficial in most situations. Also race brakes often come with a significant weight reduction which further improves overall handling.
Suspension upgrades improve the overall handling by lowering the ride height with the race suspension giving you full adjustable suspension tuning for alignment, springs and dampers which is beneficial in most situations.
Anti-roll bars reduce body roll while cornering by connecting left and right wheels which allows for faster cornering. Race ARBs will allow you to adjust front and rear anti-roll bar stiffness which is crucial in almost all situations and usually come at no additional PI costs.
Chassis Upgrades
Chassis upgrades include chassis reinforcement and weight reduction and are located at the end of the upgrade list. Generally chassis upgrades aim to improve chassis stiffness and overall chassis weight.
The chassis reinforcement upgrade strengthen the chassis by installing additional components with the race roll cage offering the most rigid chassis. As with ARBs chassis reinforcement reduces overall body roll. It also can translate into better transferring engine power to the tires leading to better acceleration performance but will often come with a significant weight increase.
For best handling you will want to install chassis reinforcement upgrade when the car hits a certain weight:
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Street chassis reinforcement for trucks with 3500lb or more weight
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Street chassis reinforcement for utility cars with 3000lb or more weight
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Street chassis reinforcement for street cars with 2500lb or more weight
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Sport chassis reinforcement for sports cars with 2000lb or more weight
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Race chassis reinforcement i for race cars and high performance cars with 1500lb or more weight
When chassis reinforcement doesn't match car type and weight stiffness issues are introduced. A too stiff chassis creates a stiffness on the front of the car, a too soft chassis creates a softness on the front of the car.
To learn more about stiffness issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
Weight reduction decreases overall chassis weight by removing unnecessary components. Weight reduction is the most effective handling upgrade since reduced overall weight contributes to improved braking, acceleration and cornering speed.
Race weight reduction is beneficial in most situations but its also usually one of the most expensive upgrade in terms of PI.
Drivetrain
Drivetrain upgrades deal with improving transferring the engine power to the wheels.
Transmission
The Transmission is the core component of the drivetrain and translates engine rotations into wheel rotations by using gear ratios. Having a sport transmission allows to adjust the overall ratio via final drive. A race transmission allows you to additionally adjust single gear ratios.
For best handling upgrading the transmission is required once you upgrade the engine beyond a certain amount of power:
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Street transmission is required for cars with >= 200hp
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Sport transmission is required for cars with a power that exceeds stock power by at least 100hp
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Race transmission is required for cars with a power that exceeds stock power by at least 200hp
Also for best handling the transmission should match the highest installed engine upgrade except exhaust.
If the transmission doesn't match power balance issues are introduced. If the transmission is too high for car power an understeer issue is created on the front and the back of the car, if the transmission is too low for car power an oversteer issue is created on the front and the back of the car.
To learn more about balance issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
Clutch and Driveline
The Clutch is the input connection for the transmission that connects the transmission with the engine while the Driveline is the output connection of the transmission that connects the transmission with the Differential.
For best handling clutch and driveline should match the transmission.
If driveline and clutch don't match the transmission balance issues are introduced. If the clutch is higher than the transmission an understeer issue is created on the front and the back of the car, if the clutch is lower than the transmission an understeer issue is created on the front and the back of the car. If the driveline is higher than the transmission an oversteer issue is created on the back of the car, if the driveline is lower than the transmission an understeer issue is created on the back of the car.
To learn more about balance issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
DIfferential
The Differential finally transfers wheel rotations from the transmission to the actual wheels. During cornering it allows to split rotations between the inside and outside wheel for better cornering since the inside wheel need to rotate slower than the outside wheel during cornering.
A race differential allows to adjust the ratios of inside and outside wheel rotation on corner entry (deceleration) and corner exit (acceleration) which is almost always beneficial. Also the differential is the only upgrade that costs no PI.
Tires and Rims
After weight reduction tires are the second most important handling upgrade because they connect the chassis with the road.
Tires
Tire upgrades allow to adjust the overall handling of the car by using a combination of tire compound and tire width upgrades.
Tire compound upgrades can be used to adjust the base handling of the car with race compound offering the highest grip level but is also the most expensive in terms of PI cost. Note that while drag compound offers even higher grip levels than race compound its really only suitable for drag racing, for normal racing drag tires are too soft.
For best handling tire compound should match the installed chassis reinforcement upgrade.
If the tire compound doesn't match chassis reinforcement upgrade balance issues are introduced. If the tire compound is higher than the chassis reinforcement upgrade an understeer issue is created, if the tire compound is lower than the chassis reinforcement upgrade an oversteer issue is created.
Tire width can be used to fine tune the car handling, usually you start upgrading tire width on the driven wheels (rear wheels for RWD & AWD, front wheels for FWD) before upgrading the non-driven wheels as this allows for finer handling adjustments.
For best handling tire width upgrades should match the cars power except when using Full Grip or Full Speed builds:
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each 100hp increase over stock power requires a tire width upgrade on the driven wheels (rear wheels for RWD, front wheels for FWD, front & rear wheels for AWD)
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each 200hp increase over stock power requires a tire width upgrade on the non-driven wheels (front wheels for RWD, rear wheels for FWD)
If tire width don't match car power balance issues are introduced. If the front tire width is higher than the power requires an understeer issue is created on the front of the car, If the front tire width is lower than the power requires an oversteer issue is created on the front of the car, same with rear width on the rear of the car.
To learn more about balance issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
Rims
While you may think that upgrading rims is only for pure esthetic reasons its not. Rims actually play an important role for adjusting the weight of the wheels depending on car type, build type and weight.
First rim style should match the car type. Generally race cars require lighter rims than production cars and older cars require heavier rims than modern cars.
Rims are available in 5 different weight classes. For best handling lightest rims are required for modern race and high performance cars. Second lightest rims are required for early modern race and high performance cars and modern street and sports cars. Third lightest rims are required for vintage race and high performance cars, early modern street and sports cars and modern utility cars and trucks etc.
For many cars the stock rims have already the correct weight class so for these cars changing the rims is not required. However if you need to adjust also rim size (see below) you are required to change to 3rd party rims as changing rim size is not possible for stock rims.
If the rim weight class or rim doesn't match car type and weight stiffness issues are introduced. If the rims are too heavy for the car type and weight a stiffness issue is created, if the rims are too light for the car type and weight a softness issue is created.
Finally rim size should be upgraded to match the cars weight.
For best handling one rim size upgrade front and rear is required for each 100lb increase over 2400lb, i.e. cars with a weight 2500 - 2599lb require first rim size upgrade front and rear, cars with a weight 2600 - 2699lb require second rim size upgrade front and rear etc. However this only applies to production cars, race cars always require stock rim size for best handling.
Note that this includes the weight of the rims itself, so upgrading rim size might increase overall weight of the car to the next bucket which in turn requires to increase rim size even further.
If rim size doesn't match car weight stiffness issues are introduced. If front rim size is too high for the car weight a stiffness issue is created on the front of the car, if front rim size is too low for the car weight a softness issue is created on the front of the car. Same thing with rear rim size at the rear of the car.
To learn more about stiffness issues and how they can be remedied have a look at my Forza 7 Tuning Guide - Part 5 Balance and Stiffness Tuning,
Aero and Appearance
While aero and appearance upgrades also change the overall look of the car it’s the added downforce that makes them necessary in almost all situations.
Downforce Upgrades
The most important upgrades are the front bumper and the rear wing. In most scenarios you will want the race bumper and race wing because they offer significantly more downforce and also allow you to adjust front and rear downforce.
Street front bumper and street rear wing usually only offer cosmetic changes to the stock bumper and wing and don’t come with additional downforce.
Sport front bumper and sport rear wing offer slightly more downforce than stock bumper and rear wing but nowhere near the levels of the race upgrades.
On some cars also the rear bumper can be upgraded. However there is no adjustable race rear bumper available and generally rear bumper upgrades are not downforce relevant and are used to fine tune PI budgets.
Weight Upgrades
Some cars allow to remove aero parts to reduce weight further and thus improve handling and acceleration slightly.
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Remove Front Bumper (Speed)
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Remove Rear Wing (Speed)
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Remove Rear Bumper (Grip)
While removing front bumper and rear wing is really only an option for pure speed builds, removing rear bumper is also relevant in grip scenarios and can be used to fine to PI budget if no other upgrades fit into the PI budget.
Speed Upgrades
The remaining aero upgrades don’t offer downforce increases but providing more top speed by optimizing the air flow around the car:
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Side skirts (Speed)
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Hood (Grip)
Side skirts are usually only required when tuning for pure top speed on high speed tracks like Le Mans or Daytona.
Hood upgrades can be used to fine tune to PI budget if no other upgrades fit into the PI budget.
Conversions
The final part of the upgrades are conversion which deal with engine, drivetrain, forced induction and chassis upgrades.
By far the most important part here are engine and forced induction conversions.
Engine Conversions
Engine conversions allow you to change the cars stock engine with a 3rd party engine allowing for drastic power increases depending on the type of engine. Most cars offer engine conversion that allow to upgrade cars way beyond their stock class.
Engine swaps have no handling implications and just increases the base power level of the car.
Forced Induction Conversions
Forced induction upgrades allow to upgrade or change the cars stock aspiration to turbos or supercharger depending what forced induction is supported by the cars engine:
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Turbo (Speed)
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Twin Turbo (Speed)
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Positive Displacement Supercharger (Grip)
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Centrifugal Supercharger (Grip)
Choosing a turbo or twin turbo suggests a more speed oriented build while superchargers suggest a more grip oriented build.
Drivetrain Conversions
Most cars offer drivetrain conversions to swap the cars stock drivetrain with either an RWD drivetrain (for AWD and FWD cars) or a AWD drivetrain (for RWD and FWD cars).
Out of the two only RWD drivetrain swaps for AWD cars are sometimes beneficial since they can reduce overall weight significantly. RWD swaps for FWD cars are most of the time not beneficial since they add weight.
Bodykit Conversions
Only a handful of cars in Forza offer 3rd party bodykits which aside from the looks can be beneficial as they often allow for wider tires which allows for improved overall car handling.