What shipped, and when.

Automatic gearboxes

A hydrodynamic torque converter with a lockup clutch and a shift scheduler, on published ratio sets: a 4L80-E for the muscle class, a ZF 8HP for the exotics, an RX-8 Sport AT for the rotaries. Pick P, R, N or D and drive.

• A converter automatic never disconnects the engine, so an upshift is the oncoming clutch pulling engine speed down rather than a cut. Wide-open upshifts no longer flare into the rev limiter, and 0-100 km/h on the 5.0 V8 came down from 6.85 to 6.41 s.

• The same flare was landing in the event log as ignition-off entries that never happened.

• Rotaries can have one too: the RX-7 and the RX-8 both shipped automatics.

The LS7 joins the roster

Chevrolet's 7.0-litre LS7, built to its published bore, stroke and 11.0:1 compression. Seven litres on two valves and one cam, spinning to 7,000.

• The first engine here that takes a supercharger and refuses a turbo: a wastegate creeps past its knock ceiling where a blower lands on it. Real LS7 builds go the same way round.

• The piston-speed lint stopped condemning engines people have built: the F20C, the Ferrari F136F and this one run past the old flat threshold.

• V8 7.0L Pushrod

Turbo count capped at what the engine can feed

Shrinking a quad-turbo W16 in the spec editor kept all four turbos on a fraction of the displacement. At one cylinder the collective housing was 2.4 times too wide and peak power read 31 hp where a single turbo made 64.

• On a small engine the turbo assemblies no longer overlap: the spacing comes from the size of the housings themselves.

Two fixes from a player review

Free Roam lasted one edit, and the dyno showed numbers the car could not make. One player found both.

• Touching any slider on a Free Roam engine dropped it back to the stock bounds: the QSK60 went from 60.4 to 34.4 litres on one nudge, with no warning and no undo.

• The model sized injectors from displacement alone, so a boosted engine ran out of fuel under its own throttle while the dyno, which runs on unlimited fuel, showed the full curve. The YZ250 was down 65%, the Audi five 52%, the turbo six 24%. Each shaft engine now makes its dyno figure within 0.1%.

Two-stroke engines

A power stroke every revolution, port timing in place of valves, and three engines to hear it on: a YZ250-geometry motocross single, a Saab 93 triple, and the Detroit Diesel 6-71.

• Port timing is editable, and the spec panel shows the trapped compression ratio it produces. A two-stroke starts compressing when the exhaust port shuts, later than the bottom of the stroke.

• The roster gained a cycle filter, so you can list the two-strokes on their own.

• The 6-71 is the engine the Roots blower is named after, and the same blower model scavenges it.

• Two-Stroke 250 MX
• Two-Stroke I3 750
• Two-Stroke Diesel I6 7.0L

W12 and W16

Two narrow-angle W engines on a shared bank-geometry module: twelve cylinders in four banks, and sixteen in a quad-turbo 8.0.

• W12 6.0L
• W16 8.0L Quad-Turbo

Four requested engines, and Free Roam

The Viper's 8.4 V10, Audi's 2.5 TFSI five, Ford's 7.3 Power Stroke and the Cummins QSK60. All four are built to published geometry and land within 5% of their rated output.

• A 60-litre mining engine cannot share a spec editor with a road car, so those engines get a second bounds tier: 200 mm bores, 18 cylinders, 1,200 rpm floors. The panel says Free Roam when you are in it.

• V10 8.4L
• Inline-5 2.5L Turbo
• Diesel V8 7.3L Power Stroke
• Diesel V16 60L

The whole roster, filterable

The engine list is now a real index: filter by family, layout, cycle, induction and fuel, with the filter carried in the URL so a list is something you can send someone.

• Each engine gets a schematic drawn from its own bore, stroke, bank angle and cylinder count.

• Each card carries measured peak power and torque, re-measured on every build.

Engines say which real engine they match

Fourteen presets are built to a real engine's published bore, stroke and compression: the 2JZ-GTE, the Hellcat 6.2, a Bullet 500, the VR6, the K20, the Viper V10. Each one now says so, and says which figures agree.

• An engine that shares a layout and nothing else says that instead, so a claim means the same thing wherever you repeat it.

Smoothness on slow machines

The sim now hands the renderer a fresh pose every frame instead of one sampled at panel rate, and extrapolates crank and propeller angles across the remainder of the fixed physics step. Idle crank jitter dropped from 6.6% to 1.1%.

• Meshes share their materials instead of rebuilding them per engine, and the data panels update at 15 Hz: the numbers stay readable and the frames go to the engine.

Single-cylinder engines

A 500 cc Bullet thumper and a Honda GX160 utility single, with the vehicle classes they needed to have something to pull.

• Thumper 500
• Utility Single 163cc

Pages paint styled on the first frame

Pages below the landing shipped their markup without the stylesheet that styles them. On a slow connection an article sat unstyled for over ten seconds; each page now carries its own stylesheet in the head.

Superchargers, centrifugal and Roots

Fit a blower to any piston engine with the knock margin to take one. Two machines with different curves: a centrifugal builds head with tip speed squared, a Roots runs flat from off idle.

• Drive power comes off brake torque, and the mesh brightens the belt with it: the one parasitic loss the simulator draws.

• You can hear the difference: four lobes at 2.5:1 is a 1 kHz moan, ten vanes at 7:1 is a 7 kHz shriek. Both fall away when you lift.

• The Hellcat 6.2 is the first factory-blown preset.

• Supercharged V8 6.2L

Your build survives a refresh

Your browser keeps your spec edits and restores them when you come back to the same engine. A shared link wins over a stored build, and picking a different engine starts clean.

A dyno you can trust at redline

The sweep now scales its step to hold 12 degrees of crank per substep, and waits for boost to settle before it samples. Turbo engines had been reading up to 41% under their real output through the spool.

Partnerships page

Guest posts, articles written for your site, mentions and embeds. No commissions and no affiliate tiers: a trade of work and audience.

Turbochargers

Fit one to any piston engine with the compression to take it. The refusal is half the feature, and it is why the turbo engines here run 8.5 to 9.5:1.

• A wastegate that creeps, a blow-off valve you can hear, a surge line that rises with tip speed, and a turbine housing that glows with inlet temperature.

• The whistle sweeps up through the audible window as the rotor spools, the way blade-pass frequency does.

• Fitting one re-plumbs the engine: the air filter moves to the compressor mouth and a boosted V8 gets one exhaust exit instead of two.

The data drawer came back for radials

A check listed engine types instead of asking what an engine can do, and that hid the gauges, the dyno and the P-V trace from a whole engine family.

Radial engines and propellers

An M-14P nine and an R-2800 eighteen, on a master-rod and link-rod linkage: each link cylinder solves its own stroke and its own compression ratio, and the spec panel shows the spread.

• A reduction gear and a fixed-pitch propeller give the throttle something to work against on an engine with no gearbox.

• Both run 130-octane avgas, which is why they make their rated power.

• Vedeneyev M-14P (9-cyl radial)
• P&W R-2800 Double Wasp (18-cyl twin-row)

Three rotary fixes

Silence on overrun, a rotor drawn to the wrong shape, and a dyno that lagged behind the engine.

Wankel rotaries

One to four rotors off a 654 cc chamber, in the 13B, 20B and 26B shapes, on a 1,080-degree eccentric-shaft cycle with three chambers per rotor and no pistons.

• Naturally Aspirated 2-Rotor 1.3L
• Naturally Aspirated 3-Rotor 2.0L (20B)
• Naturally Aspirated 4-Rotor 2.6L (26B)

Six more presets, and more room to build

Six more engines, and wider piston spec bounds, so the editor stops fencing you in halfway through a build.

Engine picker and mobile controls

A proper engine selection flow in place of a dropdown, and controls you can drive with a thumb.

Five things at once

A realism pass that shipped as one release: a live P-V trace, engineering lint in the spec editor, shareable build URLs, audio driven per fire rather than by a volume knob, and a clutch, gearbox and vehicle to load the engine.

Turbojets

A J85, a FADEC J85 and a JetCat P300, with wet starts, torching, a fuel cock separate from ignition, and a compressor map you can watch the engine walk across.

• GE J85 (hydromech)
• GE J85 (FADEC retrofit)
• JetCat P300 (micro)

Where this started

Piston engines solved cycle by cycle from their own geometry, three fuel types, and an event-driven audio worklet that gets its pitch from the firing rate rather than a tone generator.