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Next step : Scaling up to 40 litres displacement.
Design done, but not constructed yet.

Scaling up from 600 cc to 5 litres displacement unit has been demonstrated
and permit to conclude into a straight forward scaling to 40 litres displacement.

Below are some anticipated characteristics of this next machine!

Quasiturbine QT40LSC  Steam - 100 kW
(A 40 litres displacement per revolution)

Sales for ???? US$ (see purchase order at the bottom of the page)
Air freight available worldwide.
(Custom exempted within North America NAFTA zone).

Quasiturbine Uniflow Characteristic

In most reciprocating piston engines, the steam reverses its direction of flow at each stroke (counter-flow). By entering and exhausting the cylinder by the same port, the cylinder valve and walls are cooled by the passing exhaust steam, while the hotter incoming admission steam is wasting some of its energy in restoring the temperature. Some energy if further lost in reversing the motion momentum of the mass of steam within the piston. The aim of the piston uni(directional)flow is to remedy this defect by providing an exhaust port at the end of the stroke, making the steam flowing only in one direction, but has the inconvenience of recompressing some residual cylinder steam. Quasiturbine is a uniflow engine, with the further advantage of not recompressing any residual steam, resulting in superior energy efficiency. Recompressing residual steam means some reversibility losses, and the pressure increases makes a substantial restriction to the initial steam flow into the chamber, not to ignore the truncated cycle near bottom dead center - None of this with the Quasiturbine.

Quasiturbine has no vane

Unlike vane pumps, which vane extension is important and against which the pressure acts to generate the rotation, the Quasiturbine contour seals have an imperceptible extension and the rotation does not result from pressure against these seals. The vane geometry does not allow high compression ratio at TDC (top dead center), while Quasiturbine does, and this is why QT is efficient (less pressure charging losses), and this is why there is no vane combustion engine. Quasiturbine publishes « efficiency data ».

Product Description

The Steam Quasiturbine research application unit is very similar to the pneumatic one, except for thermal dilatation provision, lubrication and corrosion consideration. Each chamber has a 5 litre maximum volume, and the motor expands 8 chambers per revolution:

Displacement: Total = 8 x 5 litre = 40 litres intake per revolution.
Intake Volumetric Flow Rate = Engine displacement x RPM
Cylindrical outside about 32" (~81 cm) in diameter excluding peripherals.
Thickness 10" (~25 cm) excluding shaft and peripherals.
The casing and rotor are made of metal (no aluminum at this time).
Power shaft:  2 5/8-inch (~6.67 cm) diameter throughout.
2 intake ports 2" male NPT pipe threads.
2 exhaust ports 4" male NPT pipe threads.
Weight (all metal) about 1500 pounds (700 Kg).
Simple in-line lubrication.
A silencer may be suitable for some demonstrations.
Not to be used as compressor.

Present typical limitations under proper lubrication:
     - Intake pressure: 60 psi (4 bar) peak.
     - Revolution: 500 rpm.
     - Temperature: Under 150 °C (300 °F)
     - Torque (2009 version and later):
             Up to 2000 N-m (1600 pound-foot) peak (with no step down gearbox).
     - Power 100 kW (130 HP) peak
     - Pressure-flow energy conversion : +/- 80 % of theoretical single-stage
       (optimum across the range - no off-peak penalty)

Maximum Temperature Control: Provision for thermal expansion is for now limited to a rotor temperature of 150 C (300 F). This is generally not a concern with a water saturated steam source up to 60 psi.

Hydraulic and Condensate : It is best to remove the condensate in the steam line before starting and continuously if necessary (This could increase the overall system energy efficiency). This steam Quasiturbine can handle saturated steam, but it must not be use with incompressible fluid (liquid hydraulic mode) - When possible, avoid excessive internal liquid condensation and do not flowed with lubricant. This unit can however be used in pneumatic mode.

Not being mass produced, Quasiturbines are like precious « Ferrari »,
while the « energy cost » to run less efficient equipments may lead to no overall saving.
Among the new emerging technologies like
hybrids, hydrogen, fuel cell, PV solar, in-wheel motor, power windmill, nuclear thermal...
the Quasiturbine is by far the least expensive innovation to familiarize with!

Youtube Video Channel Quasiturbine
Technical Paper: Large-Scale Steam-powered Quasiturbine Engine Options

Typical Characteristics

QT40LSC theoretical main characteristics can be approximated from 3 parameters:

  • Instantaneous maximum torque for 2 opposed working chambers is 500 + 500 = 1000 N-m / bar (25 + 25   = 50 pound-foot / psi). The average torque is 65 % of the instantaneous maximum, which is 670 N-m / bar (32 pound-foot / psi) differential effective pressure through the motor, assuming no truncated intake);

  • The RPM revolution within reasonable range and the intake geometric flow (5 litre x 8 chambers per revolution x rpm, assuming no truncated intake);

  • The power output which is proportional to the product: Torque X rpm.

Typical value given as indication only. May vary from one QT to another.

Steam consumption: For most positive displacement engine, the Intake Volumetric Flow Rate is the displacement time the rpm, which gives for the QT40LSC:
     = 40 litres x 500 rpm = 20 cubic meter per minute.
QT reacts to gas or steam volume (not mass) given as the « Intake Volumetric Flow Rate - IVFR » which depend only of displacement and rpm, not of pressure, nor of power. At higher power, pressure is higher and mass flow is higher, but the Volumetric Flow stay unchanged.

Mass flow conversion involve assumptions and rules of practice that each customer may decide for himself in relation to his design. Calculation uses Mollier diagram www.chemicalogic.com/download/mollier.html,
or online « Steam Table Calculator » like:
If the design does not capture the condensate at engine intake, the mass flow will in practice be higher with no additional power output, while IVFR stay unchanged. Liquid other than water could provide better efficiency at low steam temperature.

Efficiency reminder: Specific steam flow in kg/kW-h is not a comparison efficiency criteria between different turbines, because there is much less energy invested in 1 kg of steam at 4 bar and 150 C, that there is in 1 kg of steam at 30 bar and 300 C. For efficiency comparison, one must look at the turbine energy output versus the energy content within the kg of steam?

Theoretical Output Power Extrapolation: Pressure increases both the rpm and the torque. Since the power is proportional to the product of rpm   X   torque, the power output is roughly proportional to the square of the pressure.Increasing the pressure by 3 fold would then increase the power by 9 times!  (100 kW at 4 bar would theoretically become 900 kW at 12 bar   - or   -  130 HP at 60 psi would theoretically become 1200 HP at 200 psi). This is of course outside the operational range of the present machines...

Expander Efficiency

Expanders expand the gas of a reservoir, but not necessarily the gas within the expander. The efficiency is a ratio expressed in %. It is used to evaluate an equipment result in relation to either the incoming energy (Semi absolute efficiency - when for example for gasoline engine: energy extraction, transportation and refining are discarded), either in relation to a partial form of energy (relative efficiency), or in relation to the result of an other equipment or reference theory (comparative efficiency). To further complicate the situation, different engines with same efficiency on bench test will lead to different efficiency applications (in mobility for example, due to weight and gearbox requirement). No correct efficiency interpretation is possible without knowing detail calculation. Consequently, it is not possible to optimized simultaneously an expander for maximum power and maximum efficiency, a choice must be done.

The efficiency is generally in relation to the task an equipment is attempting to accomplish, and in the present context all « single-stage expanders » can conveniently be compared to the « single-stage expander theoretical model (without intake cut-off) », which is simply a piston making work under pressure, while moving in an infinitely long cylinder (which is a useful reference):

Theoretical Single Stage (TSS) Calculation:

British units: (See theoretical line on the British units graph)
Power (HP) = Pressure (psi) X Volumetric Flow Rate (VFRcfm) / 229
(As an example: 1 HP = 7.63 VFRcfm at 30 psi)
Metric units: (See theoretical line on the SI units graph)
Power (kW) = Pressure (bar) X Volumetric Flow Rate (VFRm3/min.) X 1.70
(As an example: 1 kW = 0.29 VFRm3/min at 2 bar)

Devices are not all equally efficient when attempting to match this theoretical piston-cylinder model, but Quasiturbine does it (with no intake cut-off) at +/- 80 % of the perfect theoretical single-stage (with potential improvements up to 95 %). To reach such a level of comparative efficiency, other concepts need to run at nominal power only, or to use intake cut-off techniques. Such techniques are adaptable to the Quasiturbine as well, for an overall top performance.

Condensate Steam trap at engine intake could increase the overall system energy efficiency (not the engine efficiency): Either steam condensate are trap at the high pressure intake side of the engine and return to the boiler (without much heat energy lost), or the high pressure condensate (liquid drops) are let go through the engine low pressure exhaust side in total heat energy lost).

Note: There is more intrinsic energy in the compressible incoming flow (energy accumulating in the infinitely long cylinder as the piston moves) that single-stage expanders are not attempting to recover (it is not within their tasks), and which end up in the exhaust. Additional recovery would require cut-off intake valve and multi-stages (QT?) expanders, but at a much reduced machine specific power density (larger expander and higher cost).

Selecting a high efficiency engine is a good start, but other system components and thermodynamic cycles also impact the global system efficiency, which should not be confused with the engine component efficiency.

Comparing Quasiturbine to Vane Motor

Several manufacturers are offering quality products based on Vane Motor concept.
As a matter of preliminary comparison (assuming intake pressure near the effective internal pressure), here are some typical data of Quasiturbine versus a GAST air product (calculated under same running pressure):

Quasiturbine QT.6LSC under 4 bar (59 psi) and 500 rpm: 1.7 kW // 2.3 HP
Detail: quasiturbine.promci.qc.ca/EProductQT75SCPneumatic.htm
Intake Volumetric Flow Rate (IVFR) = 0.3 IVFRm3/min // 10.6 IVFRcfm
Effective Displacement: 0.3 IVFRm3/min / 500 rpm = 600 cc // 36.6 po3 per revolution
Consumption: Free air* = 1.5 m3/min of free air // 53 cfm of free air
(* Estimated at 4 bar (59 psi) as 5 times the IVFR of 0.3 m3/min).
Consumption Specific = 0.88 m3/min-kW of free air // 23 cf/min-HP of free air
Theoretical Single Stage Power (TSS) = 4 bar X 0.3 m3/min X 1.70 = 2.04 kW
Theoretical Single Stage Power (TSS) = 59 psi X 10.6 IVFRcfm / 229 = 2.74 HP
QT Performance: 1.7 kW / 2.04 kW = 2.3 HP / 2.74 HP = 83 % of TSS

GAST 4AM Vane motor under 7 bar (103 psi) and 3000 rpm: 1.3 kW // 1.7 HP
Detail: www.gastmfg.com/pdf/airmotor/specsht/4AM.pdf
(Notice that this motor accepts air only - no steam)
Intake Volumetric Flow Rate (IVFR)* = 0.25 IVFRm3/min // 9.2 IVFRcfm
(* Estimated at 7 bar (103 psi) as 8 times less the flow of 2.0 m3 free air /min).
Effective displacement: 0.25 IVFRm3/min / 3000 rpm = 83 cc // 5.1 po3 per revolution
Consumption: Free air = 2 m3 free air /min // 70 cfm of free air
Consumption Specific = 1.53 m3 free air /min-kW // 41 cf/min-HP of free air
Theoretical Single Stage Power (TSS) = 7 bar X 0.25 X 1.70 = 3.0 kW
Theoretical Single Stage Power (TSS) = 103 psi X 9.2 / 229 = 4.0 HP
GAST Performance: 1.3 kW / 3.0 kW = 1.7 HP / 4.0 HP = 43 % of TSS

From the energy reversibility (heat lost) point of view, the difference is even greater, as one consumes its air volume at 7 bar (100 psi), while the QT consumes it at only 4 bar (60 psi). In conclusion, the Quasiturbine concept (without intake cut-off) operates at 80 % of the Theoretical Single Stage (TSS) Power, compared to 40 % for Vane Motor concept (even when using some intake cut-off saving), with QT potential to reaches 95 % under high mechanical tolerances. Furthermore, QT operates in the most demanding conditions of high displacement, low pressure and high torque. Consequently, the Quasiturbine air/steam concept exceeds substantially the relative efficiency of Vane Motor concepts, which is consistent with the vane loading chamber volume lost. For many applications, there is little or no benefit to use vane air motor when the pressured fluid consumption is the dominant cost factor.

Feed Line Capacity

Flow velocity near a piston valve is always impressive, and it is not different with the Quasiturbine intake ports. To sustain 500 rpm in a 40 litres displacement QT40LSC, the intake flow rate must be (40 litres X 500 rpm) = 20 m3 / min.. Knowing that a 2 inch diam. tubing contains 2 litres / meter long, this correspond to a flow velocity in the tube of :

(20 m3 / min.) / (2 litre / m)  =  170 m / s or 600 km / h

Could be half, considering that the Quasiturbine has 2 intakes which could be feed individually. Velocity near the intake ports will be even higher. Consequently, such a relatively small tubing must be quite short (or act as a limiting safety factor to protect the unit?). This shows that a proper feed line design capacity must not be under minded to achieve a good system integration, with special attention in matching the end of the feed line with a damper tank for optimum load under fluctuating flow. Notice that once the pressurized fluid gets into the engine, the flow velocity reduces to match the tangential rotor speed, which is:

(engine perimeter = 2 m) X 500 rpm = 17 m / s = 60 km / h

and flow speed increases again into the exhaust, which must show minimum restriction.

QT Steam Lubrication

As for piston steam engine, periodic oil needs to be injected into the motor intakes steam flow. One possibility is oil injection within one of the intake port using a small pulsed pump (electrical or pneumatic). An other more simple way is to keep an oil reservoir pressurized (with air?) slightly over the QT intake pressure, and to simply control the oil flow through a needle valve.

The grade of recommended steam cylinder oil for these conditions is ISO 460 which contains 4% tallow oil. This is the grade of oil that the “ride-on” locomotive community uses. It is generally available in 5 gallons, but Sulphur Springs Steam Models sales@sssmodels.com provides it in quart cans. Chevron USA has a relatively new steam cylinder oil on the market that is lighter in viscosity than ISO 460 by about half (1103 SUS vs. 2335 SUS @ 100 F). Other steam oil may do as well, search " steam cylinder oil" on the web for local suppliers. It does not require much oil, and it can be re-circulated.

Never use motor oil or inappropriate lubricant. Never use oil with additive like antifriction, because large air flow or steam oxidized the oil and precipitate the additives in « glue like product », as it will oxidize and degrade into solid or viscous material under steam contact. If this happen, attempt cleaning the engine with a glass of kerosene in the intake, while turning the engine slowly by hand. Re-oil properly.

QT40LSC Steam - Purchase Order (PO) Form

(Notice: Product not yet available)

To : Quasiturbine Tronçonneuses
Casier/Code/Porte 2804 - 3535 Papineau
Montréal Québec H2K4J9
514-527-8484  Fax: 514-527-9530
Associated website : www.quasiturbine.com

Quasiturbine model QT40LSC Steam (100 kW peak)
(pre-commercial unit) with simplified central differential and shaft,
is intended for integration research, demonstration and projects.
To be used only under competent supervision.
Guaranty is limited to replacement (pick-up) of defective parts.

Sale done FOB Montréal, Québec Canada
No Canadian local sale taxes on export.
Not including the shipping (pick-up) and custom fees
(NAFTA Exempted?) H.S. # 8413.81:        ???? US$
Money rate conversion at http://fr.finance.yahoo.com/m3

The web page
is an integral part of the present purchase order
and constitute the terms and conditions accepted by the buyer.

          Authorized Officer                              Date: ______________

Company Name: __________________________

Shipping address: _________________________


Phone: ____________________     Fax: _______________________



Weight: 1000 kg / 2200 pounds.
Size: 1.2 m X 1.2 m X 1 m high / 48 X 48 X 40 inches height.

Email the form to info@quasiturbine.com or fax to 514-527-8484.
An invoice will follows with payment instructions.
(Terms: 50 % on invoice, the balance 10 days before shipping).


Electric Generator

A 12 poles AC generator would be a good RPM match with Quasiturbine.
For information (not necessarily recommendation), see also the following:


The PTO Generator considered by APUQ on their website at

A fraction of the engine output is lost in the electric conversion process.
Example: 8 kW for 900 $ at
Also available up to 150 kW in European standard (ex. Winco)

(The following are non-tested possibilities...)

Rotary Pressure Regulator

What about an "energy recovery rotary pressure regulator" ? An interesting application of the steam Quasiturbine is to recover the high pressure energy at pressure reduction stations. Instead of using a conventional cooling station, a steam Quasiturbine will rotate under the pressure differential and the flow will be controlled by the rpm, i.e. the torque applied on the Quasiturbine shaft. This way, the Quasiturbine can transform the pressure differential into useful mechanical work to run pump, compressor, ventilator, electricity generator or locally convert the energy in high grade heat. Because conventional turbines can not be widely modulated in rpm and load, they are not suitable for gas flow and pressure control, while the Quasiturbine is essentially a closed valve at zero rpm (subject to appropriate construction), and has high efficiency at all torque and all flow rpm. All experimental demonstration has to be done only by steam experts and under all current rules and regulations.

ORC (Organic Rankine Cycle)

Engine suitable for ORC (Organic Rankine Cycle) in Solar, Geothermal and Waste Heat Recovery.

Condition of Operation

It is the buyer and/or operator responsibility to comply with all applicable national
and local laws and rules, including those on security and pressurized products.
In several countries 1 bar (15 psi) is considered as high pressure!

  • It is the buyer and/or operator responsibility to comply with all applicable national and local laws and rules, including those on security and pressurized products. Current research lab precaution and procedure must apply.
    Steam is dangerous, and steam qualification personnel is a must.

  • Familiarize yourself well beforehand with the Quasiturbine technology (see the associated site at: www.quasiturbine.com ).

  • For optimum performance, the feed line must be well balanced between the two intake ports, which must be done by ending the line passed the 2 T by an accumulator (buffer) tank (minimum 100 litres), on which the pressure gage can be located.

  • Always make it turns gradually (without abrupt acceleration).

  • In break-in phase, reposition the rotor away of a dead spot before each start, by turning the central shaft.

  • Always ensure that the rotor is adequately lubricated (steam oil only: search "steam engine oil" on the web for local suppliers). (Never use oil with additive like antifriction, because large air flow or steam oxidized the oil and precipitate the additives in glue like product fatal to the Quasiturbine operation). The best is oil injection within one of the intake port using a small pulsed pump (electrical or pneumatic). A convenient way is to keep the oil reservoir pressurized slightly over the QT intake pressure, and to simply control the oil flow through a needle valve.

  • Simplified differential periodically requires grease on the central shaft section.

  • Ensure that the hoses and fasteners (particularly the flexible ones) are of quality and well anchored.

  • Use a good pressure regulator to limit the maximum pressure and place a pressure gauge close to the engine intake.

  • It is recommended not to exceed 500 RPM and/or 4 bars (60 psi) at the pressure gauge when with load, half without load. 150 C max. No free running at more than 20 psi, and for short period only.

  • Avoid flow restriction at exit.

  • The use of a tachometer (with magnetic pick up, like the one used on bicycle ?) is cheap and also recommended.

  • Once in use, the engine will progressively break-in and rotate better and better,
    periodically dismantlement may require little break-in every time...

  • Never exceed the recommended limits.

  • Intake steam must be reasonably clean.

  • Not be used in reverse as compressor.

  • Silencer could be used (not supplied) with some effect on efficiency.

Safety Precautions

  • It is the buyer and/or operator responsibility to comply with all applicable national and local laws and rules, including those on security and pressurized products.

  • These unit must be operated under the constant supervision of qualified adults. Heat protection should be use at all time.

  • Anchor the unit well before each start-up.

  • Never exceed the limits and suggested conditions of operation.

  • Wearing safety glasses, mask and fastened hair is recommended.

  • The demonstration room must be well ventilated.

  • Check the tightening of the bolts and adapters. Be aware of the rupture
    or the decoupling of any of the flexible hoses.

  • Have a distant valve at hand to cut the air/steam flow as needed.

  • Particularly during breaking-in under compressed air, it can happen that the rotor stops at a dead point, and refuses to turn when the pressure is applied. This situation is unstable and call for urgent pressure release. In absence of pressure, slightly turn the rotor with the central shaft and pressurize it again...

  • During the demonstration, nothing should approach the central zone of the rotor; make observations at a distance of 50 cm (20 po.) or more.

  • Always remain vigilant and careful!

Sale Details


  • Sale and operation are restricted to adults only.

  • Use for integration research and demonstration.

  • Steam-air-nitrogen only (less than 60 psi).

  • Additional parts of replacement can be ordered by owners.


  • The Purchasers understand it is a prototype, and release the manufacturer from all responsibilities relative with the use.

  • Sold without detailed specification.

  • Guaranty of the manufacturer is limited to the replacement (pick-up) of the defective parts.

  • The purchasers must have read the present page as part of the purchase order agreement and invoice, and declare themselves satisfied with it.

  • Sales done FOB Montréal, Québec Canada.

  • The present document and conditions must be transferred to the chain of future owners of the unit.

  • If there is intellectual propriety risk, the manufacturer can simply refund and not deliver.


  • The price includes the applicable local sale taxes if required, but not the shipping and custom costs.

  • The insurances and customs fees are the responsibility of the purchaser.

  • As possible, shipping will be made in the ? weeks following the reception of the deposit, or according to the production capability of the moment (to be notified when ordering).

  • Failure of the buyer to make final payment or take delivery of the unit within 3 months of the notice of completion will be interpreted as an abandon of the product without compensation.


(Manufacturer under a privileged QT-BLADES supply license agreement)
Casier/Code/Porte 2804, 3535 Papineau, Montréal Québec H2K 4J9 CANADA
(514) 527-8484      Fax (514) 527-8484
Associated website www.quasiturbine.com   info@quasiturbine.com

Subject to changes without notice - January 7, 2019