Forza 7 Build Guide

Part 3 - Grip and Speed Building

This part explains how to build cars in a way that they will work better on grip or speed oriented tracks.

Understanding Grip and Speed Builds

Understanding the different grip and speed build types is crucial when it comes to optimizing the build for best handling.

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Generally there are Grip, Speed, Full Grip and Full Speed builds possible depending on used engine, chassis reinforcement and tire width upgrades.

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Build types impact chassis and tire upgrades when you want to build for best handling.

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Grip and Speed Builds

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Grip and Speed builds are builds that use only grip or speed engine upgrades but don't facilitate minimum or maximum tire widths.

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For cars that don't offer any Grip or Speed engine upgrades there are no Grip or Speed builds possible by definition which is the case for many race cars that don't offer engines upgrades besides installation of restrictor plates.

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Full Grip and Full Speed Builds

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Full Grip builds are considered builds that use maximum tire width front and rear. Full Speed builds are considered builds that use stock (minimum) tire width front and rear.

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For cars that don't offer any tire width upgrades there are no Full Grip or Full Speed builds possible by definition which is the case for some race cars.

                                 Engine Upgrades           Tire Width (F/R)

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Full Grip                             Any                              Max / Max

Grip                                Only Grip                               Any

Speed                           Only Speed                             Any

Full Speed                         Any                                Min / Min

Step 1 - Setting Your Target Handling

Start the car building by deciding for which handling you want to shoot for. When building cars for speed or grip most of the time you will want to build the car for a certain class or division.

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The following list provides the upper and lower bounds for speed and grip handling as an orientation for each car class:

  • E300: Speed <3.7  Grip >4.3

  • D400: Speed <4.2  Grip >4.8

  • C500: Speed <4.7  Grip >5.3

  • B600: Speed <5.2  Grip >5.8

  • A700: Speed <5.7  Grip >6.3

  • S800: Speed <6.2  Grip >6.8

  • R900: Speed <6.7  Grip >7.3

  • P998: Speed <7.2  Grip >7.8

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For divisions it's mainly the same since each division also has a class assigned albeit sometimes with a lower maximum allowed PI as the car class would allow. If the divisions maximum PI differs significantly from the car class maximum PI you may simply reduce the provided lower and upper handling bounds accordingly.

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Step 2 - Base Handling Upgrades

Platform and Handling

First install base platform handling upgrades to hit your target handling depending if you going for a speed or grip build.

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For grip builds you will always want to upgrade to full race platform and handling:

  • Race brakes

  • Race suspension

  • Race anti-roll bars

  • Race weight reduction

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For speed builds at very least you will always want to install race anti-roll bars as these offer some kind of adjustment and don't cost most of the time minimal or no PI:

  • Race anti-roll bars

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Now depending how much handling of the speed build you want to achieve you also may want to install race brakes and race suspension. These usually don't cost too much PI and should only dropped when you want to extract the most power out of the PI budget: 

  • Race brakes (opt.)

  • Race suspension (opt.)

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Lastly weight reduction is your biggest factor when it comes to spending your PI budget on power vs. handling. So depending on PI budget, car weight and target handling either street, sport, race or no weigh reduction might be feasible:

  • Street / Sport / Race weight reduction (opt.)

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Drivetrain

No matter if you're building for grip or speed always install the adjustable race differential as it costs no PI and is always beneficial:

  • Race differential

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Aero and Appearance

Now install aero kits depending if you're going grip or speed builds.

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For grip builds you will always want to install adjustable front and rear race aero kits:

  • Race front bumper

  • Race rear wing

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For speed builds depending on how much top speed you want to achieve street, sport or race aero kits might be feasible. Race aero kits severely impact the top speed while street and sport aero kits only marginally impact top speed.

  • Street / Sport / Race front bumper (opt.)

  • Street / Sport / Race rear wing (opt.)

Tires and Rims

Now have a look at your handling stat, if it is still below your target handling install tire upgrades. Upgrade tire compound and tire width to barely hit your target handling.

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Tire Compound

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First upgrade tire compound if your handling is significantly lower than your target handling then proceed with upgrading tire width to fine tune handling to the required target handling.

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Tire Width

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Upgrade tire width starting with upgrading tire width of the driven wheels (rear wheels for RWD/AWD, front wheels for FWD)  before non-driven wheels to barely hit your target handling..

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On FWD cars upgrading tire width of rear wheels can also be used to lower PI while increasing handling at the same time.

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Note that upgrading tire width to widest tires front and rear switches the build to a Full Grip build. For Full Grip builds there are different rules regarding rims which may affect your available PI budget for power upgrades.

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Likewise leaving tire width to stock tire width front and rear switches the build to a Full Speed build. For Full Speed builds there are different rules regarding rims which may affect your available PI budget for power upgrades.

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Note that since tire width upgrades should match the cars power for best handling as described in Part 1, upgrading tire width that doesn't follow these rules will create balance issues that need to be addresses when tuning the car.

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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,

Step 3 - Upgrading Power

With the target handling being set we can now focus on upgrading power.

Conversions

Engine

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First you need to check whether an engine swap is necessary to hit the PI limit. This mainly depends on how much PI is left after performing the target handling upgrades. If there is a lot room left especially if the car is still one more classes below your target PI an engine swap is probably required in order to hit your target PI.

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For grip builds you should try to spend not too much of the PI budget for engine swaps as engine swaps most of the time come with a weight increase so you will want to have enough PI budget left for engine upgrades that also reduce weight. Prefer engines that offer centrifugal supercharger or positive displacement supercharger conversions as these usually offer further power increases with a very good power to weight ratio.

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For speed builds try to swap biggest engines first as these usually provide the highest power gains and then proceed with smaller engines. Prefer engines that offer turbo or twin turbo conversions as these offer further big power increases.

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Forced Induction

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If you settled for the engine (either stock or swapped engine) you should check if forced induction upgrades make sense. This depends on your PI budget left and depending if your'e going for a grip or speed build.

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For grip builds if you have still a lot of PI budget Centrifugal Supercharger or Positive Displacement Supercharger can make sense. Generally Centrifugal Supercharger should be preferred over Positive Displacement Supercharger as it usually offers a better power / weight ratio. 

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For speed builds try to install Turbo or Twin Turbo upgrades if they fit into your PI budget as they generally provide the highest possible power increases.

Engine

After settling with engine and forced induction engine upgrades can be used to upgrade the cars power to roughly hit the target PI.

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For grip builds try to use solely engine grip upgrades as these provide the best power to weight ratio. For speed builds try to use solely engine speed upgrades as these provide the highest power increases.

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As in Part 1 explained you need to do engine upgrades backwards to avoid handling issues.

 

 

Engine Output

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First start by upgrading the Exhaust as this opens up the possibility for further engine upgrades without introducing handling issues.

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For grip builds upgrade to race exhaust if your PI budget allows because race exhaust offers the best power to weight ratio, then try sport then street exhaust.

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For speed builds upgrade exhaust as minimal as possible only to make other engine upgrades possible without introducing handling issues. Exhaust upgrades for speed builds should be carefully balanced against other engine upgrades since the exhaust upgrade is expensive because it also reduces weight which is not your primary concern on speed builds.

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Forced Induction

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After exhaust upgrade check if force induction upgrades are viable, these are only available if you opted for forced induction conversion or if the car is equipped with a stock turbo or supercharger.

 

For grip builds check if Centrifugal Supercharger or Positive Displacement Supercharger upgrades are viable. These upgrades will spend a lot of PI budget for power increases but without offering any weight reduction. You may want to jump between engine configurations with and without forces induction upgrades to see where you get the best power to weight ratio. In any case don't upgrade forced induction higher than exhaust to avoid handling issues.

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For speed builds try to upgrade Turbo or Twin Turbo if your PI budget allows as turbo upgrades usually will offer the highest power increases. You may want to jump between engine configurations with and without turbo upgrades to see where you get the highest power output. In any case don't upgrade turbos higher than exhaust to avoid handling issues.

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Engine Core

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After you've settled for forced induction upgrades you can now upgrade the engine core components.

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For grip builds try to upgrade engine core components only by using Pistons and Valves and proceed to engine input upgrades to spend the rest of the PI budget. Try first race then sport the street upgrades, make sure to upgrade pistons and valves not higher than exhaust. If you have still considerable PI budget left you may be forced to also use displacement and camshaft if no other upgrades are possible (engine swaps, forced induction upgrades).

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For speed builds try to upgrade engine core components only by using Displacement and Camshaft and proceed to engine input upgrades to spend the rest of the PI budget. Prefer camshaft over displacement upgrades as camshaft usually offers higher power increases. Try first race then sport the street upgrades, make sure to upgrade displacement and camshaft not higher than exhaust. If you have still considerable PI budget left you may be forced to also use pistons and valves if no other upgrades are possible (engine swaps, forced induction upgrades).

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Engine Input

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Use the remaining PI budget to upgrade engine input components.

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For grip builds try to upgrade  engine inputs only by using Air Filter and Intake Manifold upgrades. Out of the two especially the race intake manifold is noteworthy because it usually offers significant weight reduction and should be preferred if PI budget allows. Try first race then sport the street upgrades, make sure to upgrade air filter and intake manifold not higher than pistons, valves or forced induction upgrades. 

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For speed builds try to upgrade the engine inputs  by only using Fuel System, Carburetor and Ignition upgrades. Prefer fuel system and carburetor before ignition as these upgrades provide higher power increases. Try first race then sport the street upgrades, make sure to upgrade fuel system, carburetor and ignition not higher than displacement, camshaft or forced induction upgrades. 

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Engine Cooling

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No matter if you'r re building for grip or speed when the cars power hits 400hp or more either through conversions or engine upgrades engine cooling upgrades are required to match engine power and avoid handling issues.

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As in Part 1 explained you need to install cooling upgrades in following cases:

  • Street Oil and Cooling and Intercooler if car power >= 400hp

  • Sport Oil and Cooling and Intercooler if car power >= 500hp

  • Race Oil and Cooling and Intercooler if car power >= 600hp

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Cooling upgrades usually don't come with high PI costs so most of the time you will not be forced to drastically change your engine upgrades but they will come with a weight increase which may cause to underrun your target handling.

Step 4 - Optimizing the Build

After you've settled with engine upgrades you now try to optimize the build in terms of handling and acceleration / speed. This may cause an PI budget overrun which may require to re-adjust engine upgrades. Sometimes even your target handling might be under- or overrun so you might even forced to go back to Step 2.

Platform and Handling

Chassis Reinforcement

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No matter if you're building for grip or speed there are several reasons why you want to install chassis reinforcement upgrades:

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1) Upgrade chassis stiffness to match car type and weight for best handling:

  • Street chassis reinforcement: for trucks with 3500lb or more, for utility cars with 3000lb or more or for street cars with 2500lb or more weight

  • Sport chassis reinforcement: for sports cars with 2000lb or more weight

  • Race chassis reinforcement: for race cars and high performance cars with 1500lb or more weight

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2) Upgrade to reach / maintain target handling

Sometimes only installation of street, sport or race chassis reinforcement allows you to reach or maintain your target handling without sacrificing too much power

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Note that if chassis reinforcement doesn't match car type and weight stiffness issues are introduced that need to be addressed when tuning the car.

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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

Drivetrain

Transmission

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No matter if you're building for grip or speed there are several reasons why you want to install transmission upgrades:

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1) Upgrade transmission to match car power for best handling:

  • Street transmission: if the power exceeds 200hp

  • Sport transmission: if the power exceeds the cars stock power by more 100hp or more

  • Race transmission: if the power exceeds the cars stock power by more 200hp or more

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2) Upgrade transmission to reach acceleration or speed rating:

Sometimes installation of street, sport or race transmission can significantly increase acceleration or speed rating which cannot be achieved otherwise

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3) Upgrade transmission to lower PI

In some cases installation of street transmission can actually lower PI

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Installing sport and race transmission has most of the time a serious impact on PI so you will probably need to reduce engine upgrades to hit the PI limit again.

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Note that if transmission doesn't match power upgrades balance issues are introduced that need to be addressed when tuning the car.

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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,

Tires and Rims

Rim Style

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Upgrading rims for grip or speed builds differs from the process for standard builds as grip and speed builds require lightest or heaviest rims depending on car weight for best handling:​

  • Grip and Full Grip builds: lightest rims

  • Speed and Full Speed builds: heaviest rims

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Generally you should try to use lightest rims respectively especially when building for grip as here handling is paramount. For speed builds you may deviate from the rule if your PI budget doesn't allow.

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Note that this despite the fact that above rules for upgrading rim style for speed and grip builds will get you the best handling it will introduce stiffness issues that need to be tuned out as it deviates from the standard rules that rim style should match car type and weight.

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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,

Rim Size

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Likewise upgrading rim size for grip or speed builds differs from Standard builds which always require to upgrade rim size to match weight.

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Grip and Speed builds: 

  • front rims: always biggest front rim size

  • rear rims: one rim size upgrade is required for each 100lb over 2400lb, i.e. 2500-2599 first rim size upgrade, 2600-2600 second rim size upgrade etc.

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Full Grip and Full Speed builds:

  • front rims: always biggest front rim size

  • rear rims: always biggest rear rim size except for older cars (build before 1980) stock (minimum) rim size

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Note that this despite the fact that above rules for upgrading rim size for speed and grip builds will get you the best handling it will introduce stiffness issues that need to be tuned out as it deviates from the standard rules that rim size should match weight.

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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,

Step 5 - Finalizing the Build

In the final phase you try to spend the last bit of PI budget.

Engine / Drivetrain

Driveline, Flywheel and Clutch

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Driveline, Flywheel and Clutch upgrades can be used to spend the last bits of PI budget.

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Start with Driveline, Flywheel then Clutch. Upgrading the Driveline usually cost less PI compared to Flywheel or Clutch. Upgrading Flywheel and Clutch becomes more important on high power cars.

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Note that if the flywheel doesn't match engine upgrades balance issues are introduced on the front of the car that need to be addressed when tuning the car.

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Likewise if clutch or driveline don't match transmission balance issues are introduced on the front and the rear of the car that need to be addressed when tuning the car.

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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,

Aero and Appearance

Rear Bumper, Hood and Sideskirts

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For grip builds removing the rear bumper or upgrading the hood can be used to extract the last bits of PI budget by slightly reducing weight or increasing top speed.

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For speed builds upgrading the sideskirts can be used to extract the last bits of PI budget by slightly increasing top speed.