Crossplane and flat-plane V8: same firings, different growl
The Muscle V8 5.0 and the Euro V8 4.4 both fire four times a revolution, the same as every V8 built. Where they diverge is firing unevenness, 38 against 24, and the exhaust pipe length behind them, 150 against 125 decimillimetres. Two synthesis numbers turn one identical firing pattern into a burble and a bark.
Four firings, two different growls
Both classic V8s in the library fire four times a revolution, the figure for every four-stroke V8 ever built, since firings per revolution comes from cylinders divided by two. That number is identical for the Muscle V8 5.0 and the Euro V8 4.4. What varies is how evenly those four firings arrive: the Muscle V8's preset sets firing unevenness to 38, the Euro V8's to 24.
A crossplane crank, the layout the Muscle V8 5.0's spec names directly, staggers its throws at 90 degrees, so the exhaust pulses reaching each bank land unevenly spaced even though there are still four of them every revolution. That unevenness produces the familiar V8 lope at idle and low revs, and it is why firing unevenness exists as an adjustable value in this synthesiser rather than a fixed constant: raise it and the half-order content between the main firing frequency and its neighbour grows, giving the ear something to catch on to between beats.
Tighter by design
The Euro V8 4.4 carries a lower firing unevenness than the Muscle V8 5.0, and everything else about its preset points the same direction. Idle sits at 780 rpm against 800, the redline reaches 7,000 against 6,200, and the upshift point when pressing on comes at 3,400 rpm rather than 2,900. Eight gear ratios cover the road speed range, against the Muscle V8's four, so the Euro V8 spends more time near the top of its rev range rather than lugging through a long, low gear.
The exhaust model reflects the same split. Pipe length is set to 150 decimillimetres for the Muscle V8 and 125 for the Euro V8, which after dividing by ten gives a first comb delay of 15 milliseconds against 12.5. The comb filter is standing in for the resonances of the exhaust itself, and a longer pipe pushes those resonant peaks lower in frequency, adding weight to the low end that a shorter pipe does not have room for.
Comb feedback is set marginally higher for the Muscle V8 too, at 55 against 50, sharpening those low resonant peaks rather than leaving them as a soft colouration. None of these numbers is dramatic in isolation. Set alongside a firing unevenness of 38 against 24, they add up to two engines that share a cylinder count and little else in the sound.
What to listen for
At idle the difference is immediate. The Muscle V8's higher firing unevenness puts a clear chuff between the main beats, close to what a crossplane V8 sounds like sitting in a driveway. The Euro V8 idles smoother at a similar 780 rpm; the beats are still there, but the gap between them carries less energy, so it reads as a hum rather than a lope.
Through a gear the two pull apart further. The Muscle V8's first ratio, 9.5 km/h per 1,000 rpm, is long enough that pressing on holds the note for a while before the shift point at 2,900 rpm arrives, and the redline of 6,200 is reached only in the last of its four gears. The Euro V8's first ratio is shorter, 9 km/h per 1,000 rpm, but with eight ratios on the way to a 7,000 rpm redline, it climbs and shifts more often, so the pitch moves in smaller, quicker steps rather than long, slow builds.
On lift-off the overrun tells the same story again. Overrun pop probability is set to 35 for the Muscle V8 and 25 for the Euro V8, so the crack on a trailing throttle is the more frequent visitor in the crossplane car, arriving on top of a firing pattern that was already less regular to begin with.
Where a real flat-plane V8 sits
Neither preset in this pair is built from a recording; both are synthesised, which is why they need a firing unevenness value at all. The library's one flat-plane V8, the Ferrari 458, is recorded rather than synthesised, revving to 8,900 rpm and covering seven gears with a shift point at 4,800. A flat-plane crank fires at even 180-degree intervals rather than the crossplane's staggered 90, so the pulses arrive regularly and there is no lope to reproduce: the recording is exact between 5,300 and 7,700 rpm, the band it was captured in, and pitch-shifted outside it.
The earlier piece on the site's V10 and V8 covered how firings per revolution set an engine's fundamental note. This pair sits on the other side of that argument: the firing count never changes between them, so every difference in character has to come from parameters most listeners would never think to ask about, firing unevenness and pipe length among them, rather than from the firing count itself.
Two V8s sharing a cylinder count and a firings-per-revolution figure of four is where the resemblance ends. A firing unevenness of 38 against 24 and a pipe length of 150 against 125 decimillimetres are two lines in a preset file, but they are the lines doing the work that a crank layout does in the real thing.
Hear it
Ten seconds each: an acceleration run through the gears, then the overrun. The same presets the numbers above come from.
- MUSCLE V8 5.02.0 · crossplane burble
- EURO V8 4.42.0 · tight modern V8
- FERRARI 458recorded · 4.5 V8 · flat-plane