Engine Base¶

Bore, stroke, and cylinder count set displacement. This is the foundation every other part builds on.

What it is¶

The engine base defines the fundamental geometry: bore (cylinder diameter), stroke (piston travel), and number of cylinders. From these the sim computes displacement:

\[\text{displacement} = \frac{\pi}{4} \times \text{bore}^2 \times \text{stroke} \times \text{cylinders}\]

The base also carries the engine's recommended octane, its fuel-system settings (target fuel pressure and pump size), a thermal profile, a set of default parts, and a default factory tune.

Engone ships three bases:

Base	Layout	Bore × stroke	Displacement	Rec. octane	Fuel pressure	Pump
STANDARD I4 1.8L DOHC	inline-4	83 × 85 mm	1.84 L	91	3.5 bar	1500 cc/min
V8 5.7L OHV	V8	99 × 92 mm	5.67 L	91	4.0 bar	3400 cc/min
4.7L V12 65-Degree DOHC	V12	85 × 69 mm	4.70 L	98	3.5 bar	4000 cc/min

The default idle target is 850 / 700 / 1050 RPM, and the default rev limiter 7500 / 6200 / 8500 RPM, for the I4 / V8 / V12.

Why it matters¶

Everything downstream scales from the base:

Displacement is the single biggest factor in how much air (and therefore power) the engine can move — it's the displacement/2 term in speed-density.
Bore/stroke ratio shapes character: a big bore / short stroke revs higher and breathes well up top; a long stroke favors low-end torque.
Bore also affects the tune: a bigger bore wants a little more spark advance and loses a little knock margin (see Spark Fundamentals and Knock & Detonation).

How to tune it¶

Choose the base for your target. Want big power? Displacement is the easiest route. Want a high-RPM screamer? Favor a larger bore and shorter stroke. The recommended octane is the default for that base; match your fuel to the compression you intend to build.

Switching base reloads the base's default parts and its factory tune.

Rule of thumb

"There's no replacement for displacement" — a bigger base makes every other gain easier. But it also raises the bar for fuel and breathing to keep up.

In the game¶

The base is the ENGINE BASE dropdown on the SETUP page. Displacement, compression ratio and the other figures in the specification summary update as you change it and the parts around it.