Quick answer: make a MetaSound with one looping engine recording and a PitchShift input. Each tick, read Get Engine Rotation Speed from the car and send 12 × log2(RPM ÷ recorded RPM) to it with Set Float Parameter.
You need one engine recording held at a steady RPM, ideally 3 to 8 seconds around 3000 RPM, that loops cleanly. Import it as a Sound Wave.
Step 1: Make the MetaSound
- Right-click in the Content Browser and choose Audio > MetaSound Source. Name it
MS_Engineand set Output Format to Mono. - In Members, add two float inputs:
PitchShift(default 0) andVolume(default 0.5). - Add a Wave Player (Mono) node. Set its Wave Asset to your recording and tick Loop.
- Connect On Play to Play, and
PitchShiftto Pitch Shift. - Add a Multiply node (audio by float): the Wave Player’s Out Mono times
Volume, into Out Mono.
Press Play in the MetaSound editor and drag PitchShift. You should hear the engine rev up and down.
Step 2: Play it on the car
- In your vehicle Blueprint, add an Audio component, set its Sound to
MS_Engineand attach it near the engine. - Give it an attenuation so it fades with distance.
Step 3: Drive it from RPM and throttle
On Event Tick:
- Get the car’s Vehicle Movement Component and Cast To ChaosWheeledVehicleMovementComponent.
- Read Get Engine Rotation Speed (RPM) and Get Throttle Input (0 to 1).
- Work out the pitch: Log of
RPM ÷ 3000with Base 2, times 12. Clamp it between −12 and 12. - Call Set Float Parameter on the audio component: name
PitchShift, value the result. - Call it again for
Volumewith0.4 + 0.6 × Throttle.
| Problem | Fix |
|---|---|
| Sounds like a chipmunk at high RPM | One loop can’t cover the whole rev range. Add more loops and crossfade them (see the next tutorial). |
| Pitch steps or jitters | Smooth RPM with FInterp To before converting it. |
| Silent | Check the cast succeeds; see the “Accessed None” fix below. |
Change Max RPM, and the sound changes too. The Chaos engine’s Max RPM sets the top of your pitch range, so keep it close to the real redline of the car you recorded.
We took the synthesis route instead of loops in our Any Car Engine plugin.
FAQ
Why log2 and not just RPM ÷ 3000? Pitch Shift is in semitones. Doubling the RPM is one octave, 12 semitones, which is what 12 × log2 gives you.
Can I use a Sound Cue instead? Yes, with a Continuous Modulator on pitch. MetaSounds is the newer route and makes the next steps (crossfades, layers) easier.
Where do I get engine recordings? Engine libraries, your own recordings or free sites. See our post on record, buy or synthesize.