Forza Horizon 4 tuning guide: Ultimate OP edition

The wait is finally over, my in-depth Forza Horizon 4 tuning guide has arrived. Read on for how to improve your car’s gearing, aero, camber, suspension and more.

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Anyway, the point of this Forza Horizon 4 tuning guide is to give you a basic overview because it’s something I get questions about all the time. Fortunately it’s really not that complicated once you’ve tuned up a lot of cars. In fact, the more I play the more I realise there’s this illusion of complexity. A weird combination of real-world physics, weird exceptions and the placebo effect.

Basically, try to avoid stressing about tuning as your driving technique and knowledge of the roads is almost always going to make up more time than fine-tuning your rear camber. Though it seems stupid to say that the pre-chosen settings usually work okay, it’s true.

But maximum performance and preferable handling to your driving style are rarely the same thing so stick around to help you get the best out of your cars and make them more drivable. Feel free to check out my Forza Horizon 4: 10 tuning tips article for some other useful stuff.

Forza Horizon 4 tuning: The best car upgrades?

Let’s start with how to pick your upgrades and their importance. I say importance because the lower Points Index or PI number (the thing that governs if your car is B, A, S1, S2 or X class), the more limited your options are.

Although it’s boring, the all-wheel drive or AWD conversion is best for racing as it gives you the best off-the-line acceleration and it’s easier to control. Rear-wheel drive and traction control (TCS) off can be a nightmare in this game, regardless of skill level to the point that I would recommend keeping it on.

Yes, it’s boring and, yes, usually it costs you points and weight, But it’s overpowered for a reason. Especially online where the skill level can be higher, a RWD car will take much greater effort to compete.

Next up I would say is a combination of reducing weight and increasing power. Because in the motoring world power to weight ratios really matter. I would suggest doing at least one stage of the weight reduction upgrade. The less weight an engine has to move, the more effective it becomes and the less strain there is on the tyres.

Grip is hugely important in Forza Horizon 4 so next I usually go into Tyres and Rims. Race compound is great if building an X-class car, but you can get away with stock sometimes if you need to save points.

Front width is okay to leave as is. In the real world it would help with cornering as there would be more tyre surface on the road, plus other benefits, but it doesn’t seem to make much difference as I found out while making my Forza Horizon 4 tuning guide.

Rear width, however, does make a difference so go as wide as possible. Usually doing this reduces your points because of a slight increase in weight, which can help free up other potential upgrade opportunities.

Front and rear rim size should help with grip, but in reality I’ve never really seen much of an effect when it comes to racing at the Goliath. Usually it adds a few kilograms and no points so it’s not a huge problem if you prefer it.

Rim style is useful because here you can usually save 6kg or thereabouts, depending on the car. Pro tip, just scroll left on the Sport and Specialised alloy options and wait until you see green. Rinse and repeat until you find a style that reduces the weight. Bear in mind that some reduce weight more than others so check thoroughly.

Now it’s time to add some muscle. In Engine I usually prioritise the biggest horsepower gain versus the biggest weight reduction and points cost. Cam Shaft is my go-to.

Then try pistons and compression, twin turbo or whatever you can have, the supercharger can be great too. Fuel system and ignition also increase power for relatively few points, while flywheel reduces weight at no real cost so worth doing that, too.

Avoid intercooler and anything else that really adds weight, as it’s usually better to keep weight down than try to compensate with power. But if you simply want a high top speed, then this is a route worth considering.

Brakes are another essential. In real life, braking later can make up serious amounts of time in a lap and superior braking systems help prevent fade. In Forza Horizon 4 it seems to be there’s not a lot of difference, I usually upgrade to a race system if I can but it’s okay not to.

Drivetrain is mostly about adding customisation to your car. Race parts allow you to customise your gears and differential settings, which do affect how your car handles, so if you have the points go for it. If you have to ditch one option, I’d say the gear upgrade as the final drive ratio usually does the trick. More on that later!

Another grey area is Aero. In theory, it should help you go round corners at the expense of your top speed. Most Forza Horizon 4 cars seem to favour it, but you should try it out to see if you can feel a difference as particularly the front upgrade costs numerous points.

If you think it does help, remember that too much downforce at the rear can reduce your ability to turn. Too much overall can slow you down and also reduce cornering ability. Too little at the front and you will reduce your potential cornering grip. More on this later.

What about engine swaps, you ask? I favour the V10 if it’s available as it’s a good balance of power output and weight, but you can go for the Racing V12 as that’s also fast and the linear power delivery from low revs makes it versatile in racing.

It’s usually best to try out each engine and see what power output and weight you get, then go from there. Given that you can apply all upgrades and then write down the numbers without having to pay for them, there’s no reason not to compare. Or, better still, pay and test them all on a circuit.

Alternatively, look at other people’s tunes (the likes of DJS) and see what end horsepower result they have. Drive them. You can then work out what engine they used and go from there. Sometimes the sound alone will be enough, as the Racing V12, for instance, sounds distinctive.

Really go over your setup to ensure you have used as much of your point limit, if there is one, as possible. If you’ve gone over, consider ditching some of the less important upgrades above. Go for another engine, ditch race brakes etc.

In certain situations where you are just out of reach of a serious power hike, you can try adding heavier alloys to decrease your points rating. Worth bearing in mind if, say, you are very close to fitting a supercharger.

The best car tune settings?

So now you have a car and it’s kitted up with upgrades. Now for the way I tune my cars. Just a quick reminder before that, go check out my 10 tips for how to tune in Forza Horizon 4, I talk about some useful stuff such as what tuning tools exist and some of the theories.

Also bear in mind that real life and the descriptions in Forza Horizon 4 for each section of the tuning menu aren’t the same as what works best. In fact, a lot of the negative ramifications seem to be ignored, which makes sense as it’s meant to be more arcadey than Forza Motorsport.

Tyres

Tyre pressure is one of the less realistic options. Set the pressure too low and you would expect to see tyres overheating and affecting top speed among other bad things.

But the optimal setting is usually somewhere between 14 and 26PSI (1.0 to 1.8 bar). What I will say is that the lower you go, the more likely your tyre is to overheat and grip will be lost so keep your driving inputs gentle and smooth.

This can be done by adjusting the sensitivity of your steering in the control settings menu. For higher speed circuits such as Goliath, gentler inputs at the extremes of steering can be helpful to avoid losing control at very high speeds. For lower speed circuits, you may want to make it more sensitive.

Gearing

If there’s one thing that can really grind your gears in Forza Horizon 4, it’s tuning the gears. Get the wrong and you’ll end up being slower, which means losing races and making less money.

In Forza Horizon 4, the default gear setting for each car is usually acceptable, but not always. Even if it is, the moment you boost the horsepower you’ll need to take adjust it.

The optimal way to do this is to remember that combustion engine cars (and actually some electric motors but that’s not important today) have a peak horsepower and torque output. This is the point where the engine is at its most powerful.

What you want to do is to change the gears at peak revs because as the new gear kicks in, your revs are then closest to the peak engine output again, minimising the time between each change. Up-shift too early and you have to spend longer with less horsepower and that makes your acceleration slower.

In Forza Horizon 4 tuning, it’s possible to see where peak torque and horsepower kicks in by pressing up on a car within the My Cars area. Once you have this figure, you can then go into the gear tuning menu.

Here you only get a crude estimate of the revs thanks to the hard to see graph, but it will give you a rough idea of where your changes should be. Ideally acceleration is your priority, but not so much that it kills your top speed and you bounce into the limiter. If your car barely ever reaches 230mph during your typical races, why bother giving up so much acceleration?

In all honesty, I usually keep the default gearing and slide the top final ratio slider at the top left or right until you can see all of last gear change line. That’s step one.

For step two, you can then look at your top speed and acceleration figures and jot them down. Now bring the slider back towards acceleration (left). You can usually retain the same or better acceleration without sacrificing top speed at all or only a little.

Now you may see some gears crossing over on the gearing graph. This is because you have your unit of measurement set to kW instead of hp so change that and then you can change back after.

Some cars with huge amounts of horsepower and torque can actually get away with ignoring first gear when you launch, which reduces the issue of wheelspin (particularly if you have traction control disabled).

You can also choose to have fewer gears, reducing the need to shift gears as much. I did this on the Mosler MT900S for my Goliath runs and it worked nicely as you still go very fast but spend less time changing and worrying about gears, but it really depends on the car and situation. A lot of horsepower is usually necessary.

Speaking of which, gear tuning is largely situational. The instructions before will give you a versatile solution that should work for every type of normal racing, but what about on the drag strip?

Well, here you are only doing a short distance so sheer acceleration outweighs your top speed. In this instance, you want to focus on maximising acceleration to ensure you cover ground fast, but avoid topping out before you cross the chequered flag and too much wheelspin.

Honestly, it’s trial and error because each car will have different engine outputs and characteristics. The simple way to perfect your gears here is to run the drag strip over and over until you reach your fastest time. Or perhaps Google to see if anyone has created the fastest ratio already.

I’m not sure if this would necessarily work, but in theory you could test your gears with traction control off and set to automatic so that you have one consistent factor, which will make it easier to compare any adjustments to the ratio.

As I said before, you can also cheat a bit when it comes to copying gearing ratios. Simply download and install a setup from someone you know who makes a good tuning setup, then drive the car and write down at what speed each gear reaches its top speed.

With this information, you can move each individual gear until your car has the same shift pattern. It’s a bit cheeky, but it works.

Alignment

This is one of the more complicated tuning options to get your head round so I’d suggest reading the description to the right for the real world principles. For camber, this is about making sure as much of the tyre surface touches while cornering. Negative camber and conjunction with suspension compression will affect this.

To see this stuff in action, use the live telemetry overlay and go round a corner with full steering and at pace. If your tyres are around zero degrees at this point, you are okay. You can access the overlay by assigning it to a button in controller settings, in my case I use ‘down’ on the D-pad, and then press your selection while driving along.

If your car has good levels of turn-in and downforce, you can set the front to around minus 1 of negative camber, give or take a bit. Go more negative if your car is struggling to turn into a corner, AKA understeer. Also check your downforce settings, if applicable, as that could be part of the problem.

For the rear, I usually make this an even lower value as it’s less necessary although you still want as much of the tyre to touch the ground in a corner. Around 0.7 to 1 usually does the trick.

Front toe is usually left alone until you have done all other stuff, as it’s a good way to make little handling characteristic adjustments without affecting other stuff. Basically, increasing toe in at the front helps improve turn-in. Leaving both at zero can be perfectly acceptable.

Caster is usually best served as a higher number when it comes to Forza Horizon 4 tuning. This will help with turn-in and not really at the expense of straight-line stability. Somewhere between 5.5 and 7 works best, in my opinion. Higher can be better but lower can help reduce twitchiness.

Anti roll bars

This is the setting for mid-corner stuff, the bit after turn-in. Basically, the theory is you can control oversteer and understeer by increasing or decreasing front and rear anti roll bar stiffness.

In Forza Horizon 4 tuning physics seem to be irrelevant. For an AWD car, you can just whack the front stiffness value to 1 and the rear value to 65. If oversteer is happening, as in that moment when the rear tyres start to want to overtake the front, decrease the rear number and increase the front.

For rear-wheel or front-wheel drive, you may have to make the values more balanced. As much as I hate to say it, AWD is so much faster that unless I’m drifting or messing around I rarely use anything else and so my advice is limited. Blame the developers, not me.

Springs

Here you can control how soft or hard your springs are. Soft helps soak up bumps but can also reduce cornering grip. Firmness, meanwhile, helps with grip but can also make it easier to lose grip suddenly. Softer seems best, which makes some sense as Forza Horizon 4‘s races take place on actual roads and not typically smooth circuits.

Alternatively, if you have a car that’s oversteering out of a corner or is always trying to gain traction, it’s best to stiffen the front springs while softening the rear. I sometimes use Hoki Hoshi’s tuning formula here as that factors in front and rear weight balance.

Ride height, in theory, is best served as low as possible on a circuit because of the lower centre of gravity and improved downforce. If you ever see or hear your car bottom out, something that can happen during the Goliath road race because of such extreme G-force changes, up the value until it’s sorted. Up to four slots from the bottom is usually sufficient.

Damping

Another one that’s somewhat complicated so have a read of the description first. Lowering the bump stiffness at the front usually helps turn-in grip, but too can reduce mid-corner oversteer. The rear setting can do a similar job so I would suggest using a similar or slightly stiffer number and see how you like the feel of the car.

Rebound stiffness is similar in principle, but set it to a much higher stiffness value compared to bump stiffness. Go softer and you will see more oversteer at turn-in but then less so for the rest of the turn. If your car turns in like a champion, then you can go stiffer to help mid and exit speed.

The opposite applies for the rear rebound stiffness. As before, give this a drive and then see if adjusting the balance between the two settings gives you a car more attune to how you drive. Sadly, there’s no one size fits all solution.

Aero

Aero, short for aerodynamics, can be vitally important in racing. In fact, in Formula One it’s limited to stop drivers from blacking out, such is the level of cornering potential it can create.

In Forza Horizon 4 you really only need to know that increasing the front downforce increases oversteer, while increasing rear downforce increases understeer. Increasing either or both reduces acceleration and top speed as it’s effectively pushing your car downward at all times.

A usually good way to start aero tuning is to go the most you can at the front and the least at the rear. The sheer difference between the two helps maintain car rotation and cornering grip. If your car is already good in this area, you can reduce the front to reintroduce acceleration and top speed improvements.

Brake

Time for the penultimate tab of the tuning menu. This option is only available if you upgraded to Race brakes. If not, it will be unchangeable.

As far as I can tell, this isn’t another moment of Forza Horizon 4‘s physics playing loose with reality. If you move the slider towards the rear, you would think this makes the rear breaks do more work than the front. In actual fact the opposite is true for some weird reason. Favouring more rear bias actually increases front braking pressure. I typically favour a few points extra of front braking pressure, somewhere between 45 and 48.

Brake pressure is how much pressure is exerted when you push the brake. Some roll with 200 per cent so you get the most for the least movement of the controller button, which is faster, but you may struggle to avoid locking the wheels up. So consider a little under or above until you feel more confident, particularly if you have all driving aids, off.

Differential

Probably the most complicated to get your head round and also actually one of the most noticeable if you change, differential can make or break a setup. This is basically the system that governs the difference in speed between the left and right wheels and can be visualised using a duck. Yes, really.

The theory is that if you set front to 100 per cent you would experience understeer as the inside tyre will rotate at the same speed as the outside one. That’s the equivalent of the duck’s feet both paddling at the same speed. If you reduced the per cent to 0 at the front, this would be akin to the duck is only paddling with one leg. What would happen? The duck would swim in a circle. A faster spinning outside wheel helps the car make a circle.

But this is Forza Horizon 4 tuning we’re talking about so throw that stuff out of the window. Because increasing the per cent to 100 or just below actually seems to reduce understeer. Weird, I know.

For coasting through corners, front rear deceleration should be set low as it helps the car grip when you lift off the accelerator. It’s the one-legged duck thing all over again. For the rear, if the car is all-wheel drive you can get away with matching the exact same setting. 100 per cent at the front, 0 per cent at the rear. Or whatever adjustment you made.

This will be different for front and rear-wheel drive cars so you’ll have to play around with these settings on a road you are familar with and see how the car feels when you accelerate in a corner and when you take your foot off the gas. Obviously if there is no power going to the rear wheels, nothing would happen when you life off.

When it comes to balance, my Goliath setups tend to be somewhere between 65 and 70 towards the rear as this helps make an all-wheel drive car gain the positive characteristics of a rear-wheel drive car such as less understeer.

You can go higher if your current races favour less top speed and more handling, then 75 to 85 may work better for you. For even greater handling, you can go higher than 85 but it may start to make the car more of a handful. At 100 per cent you have turned an AWD car into a RWD one so the grip and acceleration benefits are hindered.

The best cars in Forza Horizon 4?

There are many good cars in Forza Horizon 4 but obviously there are winners. Here are a few to look into, as these rule or once ruled (new cars come along all the time) the roost and are still very effective. If you can master them.

X Class: Ferrari 599XX Evolution, Maserati MC12 FE, Maserati MC12 Corsa, McLaren F1 GT, McLaren 720S PO, Mosler MT900S, Porsche 911 GT3 RS PO, Radical RXC
S2 Class: BAC Mono, Dodge Viper ACR ’16, Ford Transit FE, McLaren P1, Ferrari F50 GT, Noble M600, Ultima Evolution Coupe 1020
S1 Class: Alfa Romeo 8C FE, Ford GT ’05, Mercedes AMG GTR, Nissan Skyline R33 ’97, Shelby Monaco
A Class: Alfa Romeo 33 Stradale, Ford GT40 MK II, Hot Wheels Bone Shaker, Shelby Cobra Daytona
B Class: Honda Civic RS ’74, Shelby Cobra Daytona, Subaru Legacy RS, Top Gear Track-Tor

Hope you have found my Forza Horizon 4 tuning guide useful! If so, share the love by sharing the article, subscribing or chucking a few pounds my way via Patreon. Also let me know if you have any other suggestions for Forza Horizon 4 guides or any questions about this article.