Car Audio Pitch Without GEAR!

Hello guys i need make a engine audio for my car and i have no idea how i can make that can u help me?

my var

Thrust
currentSpeed
MaxSpeed

i'm testing this but i didnt like it.

Code (CSharp):

1.     public float lowPitchMin = .2f;
2.     public float lowPitchMax = .8f;
3. private AudioSource m_HighAccel;
4.  
5.     private void LateUpdate() {
6.         float pitchModifier = lowPitchMax - lowPitchMin;
7.         m_HighAccel.pitch = lowPitchMin + (kartControl.CurrentSpeed/kartControl.MaxSpeed)*pitchModifier;

 

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