# How to determine value of Force to apply to custom car chassis?

Hi everyone, my friend and I are working on a racing chassis, and I have some questions.

Firstly, how much Force should be applied to accelerate the vehicle forward? Currently we’re just applying 1000 studs of force in the LookVector direction using a BodyForce, but I’m confused as to how we can relate this to horsepower and other adjustments.

For example, in the A-Chassis and other chassis’ you can simply change the horsepower value, and it will automatically change the car’s speed/acceleration and other adjustments. Is there a certain amount of force we need to apply? Or do we need to just accelerate the car and then get the other values like RPM, Torque, etc?

So I believe the problem is mostly with getting things “rolling” (pun intended haha). Any ideas where we could start in the beginning force formulas? Really just how much force to apply, and based on what. We’re planning on, in the latter stages, including friction, air resistance, and perhaps spring force calculations if necessary, etc.

Thanks,
MJT Free Time (Matthew)

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bump

Any thoughts? We’ve gotten the chassis vehicle to move forward and backwards by pushing the body with BodyForce… I believe it was `BodyForce.Force = chassis.CFrame.LookVector * 1000`. Thanks.

Hmm, why not try out this equation for force accounting drag for a character? Perhaps you can modify it for a car chassis in a way.

Plus this is quite a difficult topic and will require a lot of fine tuning here is another post with similar issues and solutions.

Like this website included in the post above for car physics in game.

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Ah thanks! I’ve actually already been reading through that website article (car physics for games) throughout the past couple weeks - it’s pretty awesome.

Thanks, and I’ll check out those posts while waiting for different input from people on this topic (if there will be more); they seem like they’d be a big help.