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By Engine Simulator Team22 min read

Supercharger vs Turbocharger: Which Makes More Power? We Fitted Both to One V8

Supercharger or turbocharger? We fitted a Roots, a centrifugal and a turbo to one 6.2 V8. The turbo wins peak power, the Roots leads below 2,080 rpm.

A cast-aluminium Roots supercharger and a turbocharger side by side on a scarred steel bench in front of a bare V8 block, under one workshop lamp

Supercharger or turbocharger: which makes more power? The usual answer is that a turbo makes more power because exhaust energy is free, and a blower makes more torque because it is there from idle. Both halves are half right, and nobody in the thread has bolted all three machines to the same engine, because on a real V8 that is three intake systems, two exhaust systems and a season of weekends.

In our simulator it is one dropdown and one button. Load the supercharged 6.2 V8 and run the dyno with the Roots blower it ships with: 534.01 hp. Swap the blower for a centrifugal: 558.95. Take the blower off and press FIT TURBOCHARGER: 612.51. Take everything off and the same 6.17 L, 9.5:1 engine makes 338.65 hp on its own. Then hold the engine wide open at 1,000 rpm and read torque instead. The Roots makes 585.2 N·m, the turbo 505.7 and the centrifugal 495.7, so the machine that wins the dyno peak comes third at the bottom of the tachometer.

Key Takeaways

  • On one 6.17 L, 9.5:1 V8 on 98 octane, each induction sized to its own knock ceiling with the same intercooler: naturally aspirated 338.65 hp, Roots 534.01, centrifugal 558.95, turbo 612.51. The turbo wins peak power (+80.9% over NA) and peak torque (871.59 N·m against the Roots' 768.88).
  • The Roots leads below 2,080 rpm: 585.2 N·m at 1,000 rpm against the turbo's 505.7 and the centrifugal's 495.7. The turbo passes it at 2,080; the centrifugal passes the Roots at 4,610 and never catches the turbo.
  • The crank pays for a blower through the belt: 31.7 kW (42.5 hp) for the Roots and 41.5 kW (55.7 hp) for the centrifugal at 6,000 rpm. The turbo pays in exhaust backpressure, 2.06 bar at 6,000, and that bill comes to 9.1 N·m, 5.7 kW.
  • Response at a held 2,000 rpm, throttle snapped open: the Roots reaches 90% of its boost in 0.26 s, the centrifugal in 0.35 s, the turbo in 1.54 s, six times the Roots.
  • "1.5 bar" is three different curves. Pinned to the same target, the Roots holds 1.39 to 1.50 from 2,000 rpm up, the centrifugal passes 1.5 above its 5,270 rpm anchor, and the turbo creeps to 1.749 at 6,000.

On this page: Quick answer · One V8, four inductions · Which makes more torque, and where · What each machine costs the crank · How fast the boost arrives · Why 1.5 bar is three different numbers · Charge temperature and knock · The folklore · What we do not model · Try it in the simulator · FAQ · How these numbers were made

Quick Answer: Which Makes More Power, a Supercharger or a Turbocharger

The turbocharger, from 2,080 rpm to redline, and the Roots supercharger below it. On our 6.17 L, 9.5:1 V8, with each machine fitted the way the simulator's FIT button fits it and sized to its own knock ceiling, the turbo makes 612.51 hp against the centrifugal's 558.95, the Roots' 534.01 and the naturally aspirated engine's 338.65. It also takes peak torque, 871.59 N·m at 4,461 rpm against 768.88 for the Roots. Below 2,080 rpm the Roots is ahead of both, because a positive-displacement pump makes its pressure from the first revolution and a turbine has to be spun up by exhaust the engine has not yet made.

The price differs as much as the power. At 6,000 rpm the Roots takes 31.7 kW off the crank through its belt and the centrifugal 41.5 kW, while the turbo's bill, paid as exhaust backpressure, comes to 5.7 kW. The turbo is the cheaper machine to run and the slower one to answer the throttle: at a held 2,000 rpm it reaches 90% of its boost in 1.54 s, six times the Roots' 0.26 s. Those figures are this model's calibration of one engine, with a turbine inlet temperature scheduled from the throttle rather than computed from combustion, and the section on what we do not model says what that costs.

One V8, Four Inductions

The engine is sc_v8_6L2, our supercharged 6.2: a 6.17 L 90° V8 at 103.9 × 90.9 mm, 9.5:1 on 98 octane, idling at 750 and red-lined at 6,200 rpm. It ships with a Roots blower. We ran it four ways: naturally aspirated with the blower removed; Roots as shipped; centrifugal with the blower type switched in the spec panel; and turbo, with the blower removed and the FIT TURBOCHARGER button pressed. The same 0.72-effectiveness intercooler sits on all three boosted variants, so cooling stays constant across the comparison.

The FIT button sizes each machine against its own knock ceiling, which it finds by inverting the end-gas knock chain for this compression ratio and octane; a compressor that heats the charge less earns a higher cap. The Roots, at an adiabatic efficiency of 0.60 on a 2.5:1 drive, earns 1.567 bar. The centrifugal, at 0.70 on a 7:1 drive, earns 1.679. The turbo, a 95.4 mm wheel behind a 1,224 mm² turbine throat, gets a spring wastegate target of 1.450 bar and creeps to 1.696 at redline, for a reason the section on boost targets measures. Roots vs centrifugal superchargers explains how the two blower ceilings fall out of one calculation, and this article does not repeat it.

VariantMachineBoost cap or targetPeak hp @ rpmPeak N·m @ rpmvs NA hp
NA——338.65 @ 6,200521.43 @ 3,765—
Rootsη 0.60, 2.5:1 drive1.567 bar534.01 @ 6,200768.88 @ 4,229+57.7%
Centrifugalη 0.70, 7:1 drive1.679 bar558.95 @ 6,200765.62 @ 4,693+65.1%
Turbo95.4 mm wheel, 1,224 mm² throat1.450 bar target, creeps to 1.696612.51 @ 6,200871.59 @ 4,461+80.9%

Read the last column first. The turbo's +80.9% is 14.7% more power than the Roots and 9.6% more than the centrifugal. The spec panel's lint warns of 10 K of detonation margin on 98 octane for all three, and the knock index read 0.0000 at every held point on every variant. Each machine is running as hard as the fuel allows, so the differences between them are differences in the machine.

Which Makes More Torque: Supercharger or Turbo, and Where

The Roots leads from idle to 2,080 rpm, the turbo from there to redline, and the centrifugal passes the Roots at 4,610 rpm without catching the turbo anywhere.

Line chart of brake torque against engine speed for the same 6.17 litre V8 in four forms. The naturally aspirated dashed line runs near 500 newton metres. The Roots line rises to 580 newton metres by 1,000 rpm and is the highest curve from 750 to about 2,080 rpm, peaking at 768.9 at 4,229. The turbo line starts near the naturally aspirated line, climbs hard through 2,000 rpm, passes the Roots at 2,080 and peaks at 871.6 newton metres at 4,461. The centrifugal line rises from the naturally aspirated line, crosses the Roots at 4,610 and peaks at 765.6 at 4,693, below the turbo everywhere

Torque along the 48-point sweep, at selected grid points:

rpmNARootsCentrifugalTurbo
750471.1514.1477.8474.0
982483.6580.2494.8498.5
1,446490.8645.1515.2544.0
1,678494.5666.6527.9579.4
2,141502.5699.7557.3723.6
3,069516.8745.9631.1810.7
3,997520.8768.0714.2862.2
4,461515.7767.6753.7871.6
4,924486.0732.5761.8834.9
5,852402.1628.7669.0717.3
6,084392.7617.7650.0707.0

Read the 982 rpm row. The Roots is at 580.2 N·m, a fifth above the naturally aspirated 483.6, while the turbo reads 498.5 and the centrifugal 494.8, both within a few per cent of the stock engine. A Roots blower is a positive-displacement pump, two rotors carrying a fixed volume from inlet to outlet on each turn (Eaton, TVS supercharger technology, retrieved 2026-09-11), so its delivery and the engine's appetite both scale with crank speed and the ratio between them holds. A turbine in the exhaust stream drives a turbocharger's compressor (Wikipedia, Turbocharger, retrieved 2026-09-11), and at 982 rpm wide open the engine is passing little exhaust, so the compressor adds little.

Between 1,678 and 2,141 rpm the turbo's curve goes from 579.4 to 723.6 N·m, while the Roots moves from 666.6 to 699.7. The turbo passes the Roots at 2,080 rpm on the interpolated grid, a figure that leans on the model's scheduled exhaust temperature more than any other in this article, and leads at every point after it: 810.7 against 745.9 at 3,069, 871.6 against 767.6 at 4,461, 707.0 against 617.7 at 6,084. Its peak of 871.59 N·m lands at 4,461 rpm, 232 rpm above the Roots' 768.88 at 4,229.

The centrifugal's shape is the one the Roots post explained: pressure from impeller tip speed, rising with the square of rpm (ProCharger, supercharger technology, retrieved 2026-09-11). It trails the Roots until 4,610 rpm and leads it from there to redline, 650.0 against 617.7 at 6,084. It never passes the turbo, and the reason is in the next section: at 6,000 rpm the two are making manifold pressures within 0.02 bar of each other, 1.679 against 1.696, and the centrifugal is paying 41.5 kW for its share through the belt.

What Each Machine Costs the Crank

A supercharger is driven from the crankshaft, usually by a belt (Wikipedia, Supercharger, retrieved 2026-09-11); a turbocharger's compressor is driven by exhaust gas through a turbine. Neither is free. The blower takes shaft work through its belt for as long as it is turning. The turbine sits in the exhaust as a restriction, and the pistons push against it on every exhaust stroke.

Grouped bar chart of what each machine takes from the crankshaft at 2,000, 4,000 and 6,000 rpm at wide-open throttle, in kilowatts. Roots belt bars read 8.6, 23.2 and 31.7. Centrifugal belt bars read 1.5, 14.1 and 41.5, overtaking the Roots at 6,000. Turbo exhaust-tax bars, the pumping loss over the naturally aspirated engine, read minus 0.8, 0.7 and 5.7, the first one below the zero line

Held wide open at round engine speeds. MAP is absolute manifold pressure; belt kW is what the crank pays the blower; back is turbine inlet pressure; pump is pumping mean effective pressure in bar, positive when the piston pays and negative when the charge pushes it:

rpmNA pumpRoots MAP / belt kW / pumpCentrifugal MAP / belt kW / pumpTurbo MAP / back / pump
1,000+0.0571.237 / 2.2 / −0.1131.025 / 0.2 / +0.0391.044 / 1.08 / +0.049
2,000+0.0601.439 / 8.6 / −0.2521.100 / 1.5 / −0.0111.323 / 1.28 / −0.017
3,000+0.0671.505 / 15.7 / −0.2871.222 / 5.5 / −0.0901.545 / 1.53 / +0.002
4,000+0.0761.537 / 23.2 / −0.2911.393 / 14.1 / −0.1931.633 / 1.77 / +0.110
5,000+0.0841.555 / 28.6 / −0.2861.610 / 27.9 / −0.3211.678 / 1.95 / +0.214
6,000+0.0891.567 / 31.7 / −0.2841.679 / 41.5 / −0.3581.696 / 2.06 / +0.274

The belt

At 2,000 rpm the Roots is taking 8.6 kW and the centrifugal 1.5, because the Roots is at 1.439 bar and the centrifugal at 1.100. At 6,000 the ranking flips: the centrifugal takes 41.5 kW (55.7 hp) against the Roots' 31.7 (42.5 hp), because it is now making the higher pressure, 1.679 bar against 1.567, and compressing each kilogram of air to a higher pressure takes more work. The belt bill is not a new discovery: in 1930 NACA ran a Roots blower on a Liberty 12 at four drive ratios and reported what each ratio did to the aeroplane at sea level and at altitude (Schey and Gove, NACA-TR-327, retrieved 2026-09-11).

The turbine

The turbo's bill is the "back" column. Turbine inlet pressure climbs from 1.08 bar at 1,000 rpm to 2.06 at 6,000, and from 4,000 rpm up it sits above the manifold pressure, 1.77 against 1.633 at 4,000 and 2.06 against 1.696 at 6,000, so the engine is pumping uphill on the exhaust stroke through that band. At 6,000 the wastegate is 64% open and the rotor at 76,961 rpm of a 110,163 rpm limit.

Pumping MEP

Mean effective pressure is work per cycle divided by displacement, and the pumping component of it is the work spent on the intake and exhaust strokes (Wikipedia, Mean effective pressure, retrieved 2026-09-11). Sign conventions differ between texts; here positive means the piston pays. The naturally aspirated engine reads +0.057 to +0.089 bar from its own intake losses, and that is the baseline.

Both blowers read negative: the Roots between −0.25 and −0.29 bar from 2,000 rpm up, the centrifugal down to −0.358 at 6,000. A pressurised intake pushes the piston down on the induction stroke, so the gas exchange does work on the crank, and part of the belt power comes back through the piston. The belt figure is gross; the torque curve is net.

The turbo gets the same push on the induction stroke and pays a turbine restriction on the exhaust stroke on top. At 2,000 rpm the manifold (1.323 bar) is above its own backpressure (1.28), so the loop reads −0.017, better than the naturally aspirated +0.060. At 6,000 it reads +0.274 against NA's +0.089, and the difference, 0.185 bar over 6.17 L, comes to 9.1 N·m at the crank, or 5.7 kW. That is the whole exhaust tax at redline, under a fifth of the Roots belt's 31.7 kW and under a seventh of the centrifugal's 41.5.

The tax in one number

Torque gained over the naturally aspirated engine per bar of boost, at 6,000 rpm: Roots 397.7 N·m/bar, centrifugal 382.1, turbo 451.6. Same engine, same fuel, same intercooler, and the machine that pays no belt keeps more of each bar it makes. The centrifugal, the more efficient of the two blowers, keeps the least, because at 6,000 rpm its belt is the biggest bill on the table.

How Fast the Boost Arrives

At a held 2,000 rpm the Roots is at 90% of its boost in 0.26 s, the centrifugal in 0.35 s and the turbo in 1.54 s. The naturally aspirated plenum, with no compressor at all, refills from 0.10 to 1.00 bar in 0.17 s, and that is the floor every machine is measured against.

Line chart of manifold pressure against time for two seconds after a throttle step from closed to wide open at a held 2,000 rpm, four lines. The naturally aspirated line climbs from 0.10 bar to atmospheric in 0.17 seconds and stops there. The Roots line crosses atmospheric at 0.08 seconds and reaches 90 percent of its final plus 0.44 bar at 0.26 seconds. The centrifugal line reaches 90 percent of its final plus 0.10 bar at 0.35 seconds. The turbo line crosses atmospheric at 0.32 seconds, half its final value at 0.75 and 90 percent of its final plus 0.32 bar at 1.54 seconds

Gauge-referenced, so "final boost" is above atmospheric; t atm is when MAP crosses 1.0 bar, t50 and t90 are when it reaches half and 90% of its final boost:

VariantrpmFinal boostt atmt50t90
NA2,0000.000plenum refill, MAP 0.10 → 1.00 in 0.17 s
Roots2,000+0.4390.080.140.26
Roots3,500+0.5240.070.130.25
Centrifugal2,000+0.1000.170.230.35
Centrifugal3,500+0.3020.100.150.28
Turbo2,000+0.3230.320.751.54
Turbo3,500+0.5930.230.380.48

The two blowers are geared to the crank, so their speed is fixed the instant the rpm is, and the delay you see is the manifold filling. The Roots crosses atmospheric at 0.08 s, before the naturally aspirated plenum has finished refilling, and reaches 90% of +0.439 bar at 0.26 s. The centrifugal at 2,000 rpm is fast to a small number, 90% of +0.100 bar at 0.35 s, with no delay and little boost at that speed.

The turbo's rotor has mass, and its turbine accelerates on exhaust the engine begins making after the throttle opens. At 2,000 rpm it crosses atmospheric at 0.32 s, reaches half its final boost at 0.75 and 90% at 1.54, six times the Roots, and it settles at +0.323 bar against the Roots' +0.439 at the same speed. At 3,500 rpm, with more exhaust to start from, the turbo is at 90% in 0.48 s, with the Roots at 0.25 and the centrifugal at 0.28. How compressor wheel size moves a turbo's spool time, measured on a different engine, a 3.0 L six, is in does a bigger turbo mean more lag, published alongside this article.

Why 1.5 Bar Is Three Different Numbers

Pin every machine to "1.5 bar", the blowers by pressure ratio and the turbo by wastegate target, and you get three curves that share one label and little else.

rpmRoots MAP / N·mCentrifugal MAP / N·mTurbo MAP / N·m
1,0001.209 / 573.61.019 / 492.61.046 / 507.0
2,0001.387 / 670.01.073 / 535.61.356 / 683.5
3,0001.446 / 719.11.163 / 598.01.598 / 834.2
4,0001.474 / 741.31.289 / 666.71.687 / 890.7
5,0001.490 / 693.21.449 / 687.91.732 / 844.9
6,0001.501 / 596.51.643 / 664.11.749 / 731.7

The Roots holds 1.387 to 1.501 from 2,000 rpm up. It is a pump, and a pump's ratio holds with speed. The centrifugal's ratio rises with impeller speed squared and is anchored at 85% of redline, so it reads 1.073 at 2,000, reaches 1.5 at 5,270 rpm and passes it to 1.643 at 6,000. The turbo reads 1.356 at 2,000 and 1.749 at 6,000, a quarter of a bar past its target.

The turbo's creep is the wastegate. In its classic form a wastegate is a spring holding a flap shut and a diaphragm sensing boost pushing it open, a proportional device with no memory (Garrett Motion, wastegate vs blow-off valve, retrieved 2026-09-11). To hold itself open it needs a standing pressure error, so more flow means more opening means more overpressure, and boost drifts up with engine speed. How a turbocharger works measured that drift on a different engine, and on this one it runs 0.25 bar by redline.

Peak power on the pinned runs: Roots 513.65 hp, centrifugal 583.31, turbo 631.63. The same word on the spec sheet gives you 513.65 or 631.63 depending on the machine behind it, so a boost figure without the machine tells you little about the engine.

Charge Temperature and Knock

Cooling does not decide this comparison. With the same 0.72 cooler on all three, charge temperature after it at 6,000 rpm reads 312 K on the Roots, 316 K on the centrifugal and 312 K on the turbo. The centrifugal runs 4 K warmer despite a higher compressor efficiency than the Roots, because at 6,000 rpm it is making the higher pressure, 1.679 bar against 1.567, and the cooler removes a fixed fraction of whatever rise it is handed; the Roots post measured where that heat goes.

Knock read 0.0000 at every held point on every variant. Each machine sits inside its fitted ceiling: the Roots at 1.567 bar, the centrifugal at 1.679, the turbo aimed at 1.450 and creeping to 1.696. The FIT button sets the turbo's spring target below the ceiling, and the wastegate creep spends the gap; the knock index still reads 0.0000 at 1.696. The end-gas mechanism behind those ceilings is in what engine knock is, and how it caps boost against compression is in how much horsepower one point of compression adds.

What the Folklore Gets Right and Wrong

"A turbo makes more power because exhaust energy is free." The ranking holds here, 612.51 hp against 558.95 and 534.01, and the turbine's energy is cheap rather than free. The turbine is a restriction the pistons push against, and at 6,000 rpm it costs 2.06 bar of backpressure, which shows up as 9.1 N·m and 5.7 kW. That is under a fifth of the Roots belt's 31.7 kW, and around 2,000 rpm the turbo's pumping loop reads −0.017, better than the stock engine's +0.060.

"A supercharger has no lag." True of the Roots, at 90% of its boost in 0.26 s against the naturally aspirated plenum's 0.17 s. The centrifugal is at 90% in 0.35 s, and at 2,000 rpm that is 90% of +0.100 bar. A centrifugal blower has no spool delay, and at 2,000 rpm it has little boost to deliver without one.

"A supercharger robs power from the engine." True, and the belt figure is gross. The Roots takes 31.7 kW at 6,000 rpm and the centrifugal 41.5, and the pumping loop returns part of that through the piston on the induction stroke, −0.284 and −0.358 bar of pumping MEP. The net is the torque curve, after the belt: +57.7% over stock for the Roots at its power peak, +65.1% for the centrifugal.

"Turbos make more torque." At the peak, 871.59 N·m against the Roots' 768.88. Below 2,080 rpm the Roots makes more, and at 1,000 rpm the gap runs the other way by 79.5 N·m, 585.2 against 505.7. Which of those figures matters depends on where you spend your time on the tachometer.

A belt-driven positive-displacement blower buys the left edge of the torque chart above and pays the belt; a turbo buys the peak and the smaller bill and accepts the spool time.

What This Simulator Does Not Model

The 2,080 rpm crossover and the 1.54 s describe this model, not a V8 on a dyno. Six gaps:

  • Turbine inlet temperature is scheduled from the throttle lever, not computed from combustion. The turbo's exhaust energy at low rpm is the model's own, so the crossover and the step times are the numbers with the weakest claim on a real engine, and this debt moves the turbo column more than either blower column.
  • Blower efficiencies are constants. 0.60 for the Roots and 0.70 for the centrifugal at every speed. A real centrifugal's efficiency falls as it is spun harder: the NACA J-33 compressor test the Roots post leans on measured 0.747 at 6,000 rpm and 0.617 by 13,400 (Beede, Kovach and Creagh, NACA-RM-SE8C15, 1948; retrieved 2026-09-11).
  • Belt losses are one fixed number. A 0.95 mechanical efficiency, priced on the pre-cooler discharge. No belt slip, no blower inlet restriction, no bypass valve on the blower.
  • The wastegate is a spring. A proportional actuator with no electronic boost control, so the creep from 1.450 to 1.696 bar is the classic mechanism, and electronic boost control is outside the model.
  • One lumped exhaust manifold feeds one wheel. No pulse separation, no twin-scroll housing, no variable-geometry turbine, no turbine outlet temperature. The turbo post lists the same limits.
  • Spark is one number per engine. The same gasoline default on all four variants, with no spark map, so nothing here trades timing against boost the way a real calibration would.

All three boosted variants run the same 0.72 intercooler. A blower without a cooler is a different measurement and this article does not make it. The full scope of the model, and the rest of what it gets wrong, is in how we build the simulator.

Try It in the Simulator

The preset ships with the Roots. Every run below starts from the shipped preset and one link, and the throttle-step timings are readable on the gauges.

  1. Open the supercharged 6.2 with the Roots and run the dyno. Read the left-hand edge of the curve first: torque is high from the first point and the curve is a shelf, peaking near 4,229 rpm. Note the peak power, 534.01 hp on our 48-point grid.
  2. Load the same engine with the centrifugal and run the dyno again. The left edge drops back to the naturally aspirated line, the peak slides up the rev range, and peak power rises to 558.95.
  3. Load it with the turbo. The left edge starts near the stock line, climbs hard around 2,000 rpm and peaks at 871.59 N·m, with 612.51 hp at the top.
  4. Load it naturally aspirated for the baseline, 338.65 hp.
  5. Hold 2,000 rpm and snap the throttle open on each of the three boosted engines. Watch the Boost readout: the Roots is there with the pedal, the centrifugal arrives fast to a small number, and the turbo takes over a second. On the two blowers the boost panel's Blower draw row reads the belt in horsepower, about 12 hp on the Roots and 2 hp on the centrifugal at 2,000 rpm, the 8.6 and 1.5 kW in the table above. On the turbo, read the Pump row: negative around 2,000 rpm, positive above 3,000.

Every horsepower, torque, boost, belt and timing figure above is this simulator's calibration of one engine; the mechanisms are the physics. The dyno correction calculator explains how to compare our reference-day figures against a real dyno sheet.

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Frequently Asked Questions

Which is better, a supercharger or a turbocharger?

For peak power and the smallest bill on the crank, the turbocharger: 612.51 hp against 558.95 for the centrifugal and 534.01 for the Roots on our V8, at an exhaust tax of 5.7 kW against belt loads of 41.5 and 31.7 kW at 6,000 rpm. For torque below 2,080 rpm and boost that arrives in 0.26 s rather than 1.54, the Roots. Both answers come from the same engine with the same fuel and intercooler; which one is better depends on the rpm you drive at.

Does a supercharger or a turbo make more power?

On our 6.17 L, 9.5:1 V8, the turbo, by 14.7% over the Roots and 9.6% over the centrifugal at each machine's own knock ceiling. Peak torque follows the same order, 871.59 N·m against 768.88 and 765.62, and pinned to the same 1.5 bar label the order holds, 631.63 hp against 583.31 and 513.65. Those are this model's figures with a turbine inlet temperature scheduled from the throttle, so the turbo's margin at low rpm is the least trustworthy part of the result.

Does a supercharger take power from the engine?

Yes, through the belt. At 6,000 rpm wide open the Roots takes 31.7 kW (42.5 hp) and the centrifugal 41.5 kW (55.7 hp); at 2,000 rpm the Roots takes 8.6 kW and the centrifugal 1.5. Part of that comes back, because a pressurised intake pushes the piston down on the induction stroke: the pumping loop reads −0.284 bar on the Roots and −0.358 on the centrifugal at 6,000 rpm, against +0.089 for the stock engine. The torque curve is the net, +57.7% and +65.1% over stock at the power peak.

Is a turbo more efficient than a supercharger?

In what it costs the crank to run, yes, on this engine. The turbo's exhaust tax at 6,000 rpm is 0.185 bar of pumping MEP over the naturally aspirated engine, 9.1 N·m or 5.7 kW, against 31.7 kW for the Roots belt and 41.5 for the centrifugal, and it keeps 451.6 N·m per bar of boost where the Roots keeps 397.7 and the centrifugal 382.1. The compressors themselves rank the other way: the centrifugal blower's 0.70 adiabatic efficiency beats the Roots' 0.60, and it loses on net because its belt bill is the largest.

Why do drag cars use superchargers?

The bottom of the torque chart and the step response answer that from our numbers alone. A Roots makes 585.2 N·m at 1,000 rpm on this engine against the turbo's 505.7, leads until 2,080 rpm, and reaches 90% of its boost in 0.26 s at a held 2,000 rpm where the turbo takes 1.54 s. Torque from the first revolution and boost that arrives with the pedal are what a standing start wants; the turbo's 612.51 hp against 534.01 sits at the top of the range. No real drag-racing figure appears here; the argument is the shape of the curves.

How These Numbers Were Made

It matters which kind of claim each figure is:

  • Physical principles that hold on real hardware: a supercharger is driven from the crankshaft and a turbocharger by exhaust gas; a Roots is a positive-displacement pump; a centrifugal's pressure rises with tip speed squared; a turbine is a restriction; a spring wastegate needs a standing error; pumping mean effective pressure is the work of the gas-exchange strokes. Corroborated by the cited sources, not derived from our code.
  • Simulator calibration: every horsepower, torque, boost, belt, backpressure, pumping-MEP and timing figure above. The 2,080 and 4,610 rpm crossovers, the 1.54 s, the 5.7 kW and the 451.6 N·m/bar describe one engine as this model calibrates it, with blower efficiencies of 0.60 and 0.70, a 0.95 belt, a spring wastegate and a turbine inlet temperature scheduled from the throttle. The NACA anchor for the centrifugal efficiency is in the Roots post.
  • Method: 48-point wide-open-throttle sweeps from 750 to 6,200 rpm, each point settled before sampling, in fixed reference air of 1.000 bar and 293 K with no correction, fuel unlimited and the rev limiter ignored. Held-rpm probes at round engine speeds supplied the boost, belt, backpressure and pumping figures; throttle steps ran from closed to wide open at a held 2,000 and 3,500 rpm, with t90 read at 90% of the final gauge boost. Belt drive power is priced on the pre-cooler compressor discharge at 0.95 mechanical efficiency. Each boosted variant was fitted the way the FIT button fits it, and the turbo's 95.4 mm wheel comes from displacement.
  • Consistency: the Roots and centrifugal figures reproduce the Roots post of 2026-08-23 within 2%, on a 48-point grid against 47 and after a friction re-anchor that moved every preset. This article quotes today's numbers.
  • No real-engine power, torque, boost or timing figure appears above. Where we describe what a real machine does, it carries a citation.

Every run reproduces from a shipped preset and one link: load it and you should land on the same curve, because the knock model's random component is seeded. If you do not, send it to us.

About this article

Written by the Engine Simulator Team, who build and calibrate the physics engine behind these numbers. We publish the model's limits beside its results, because a simulated figure is worth nothing without them. Found an error? Contact the team.

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