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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 liter displacement unit has been demonstrated
and permit to conclude into a straight forward scaling to 40 liter displacement.

Below are some anticipated characteristics of this next machine!

Quasiturbine QT40LSC  Pneumatic - 100 kW
(A 40 liters 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 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 ».

Quasiturbine Uniflow Characteristic

In most reciprocating piston engines, the flow reverses its direction 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, while the hotter incoming admission is wasting some of its energy in restoring the temperature. Some energy is further lost in reversing the motion momentum of the mass of gas 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 gas flowing only in one direction, but has the inconvenience of recompressing some residual cylinder gas. Quasiturbine is a uniflow engine, with the further advantage of not recompressing any residual gas, resulting in superior energy efficiency. Recompressing residual gas means some reversibility losses, and the pressure increases makes a substantial restriction to the initial flow into the chamber, not to ignore the truncated cycle near bottom dead center - None of this with the Quasiturbine.

Product Description

The  QT40LSC Pneumatic research application unit is a scale up of the QT5LSC motor where all dimensions have been doubled. Each chamber has a 5 liter maximum volume, and the motor expands 8 chambers per revolution:

Displacement: Total = 8 x 5 liter = 40 liters 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 air motor rotor temperature of 60 C, and 150 C (300 F) upon special request. Exceeding limit temperature is noticeable by a sudden rpm reduction, in which case one should not insist and let the QT cooled down before trying again in proper condition.

Hydraulic : This Quasiturbine must not be use with incompressible fluid (liquid hydraulic mode) - When possible, avoid excessive internal liquid condensation and do not flowed with lubricant.

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

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 liter 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.

Air (gas) 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.
The « minimum theoretical air consumption » is exceeded by the same ratio as pressure-flow efficiency, which correspond to substantial saving when compared for example, to low torque high rpm vanes motors (see details below).

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.

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).

Most current compressors are not design for 20 - 60 psi output, which make them running at only a fraction of their nominal power when feeding a low pressure Quasiturbine. For this reason, compressor must generally be oversized to sustain experimentation, or the system must have an important air reservoir. In the case of very high pressure gas tank, not only one wants to harvest the energy actually in the pressurized air tank, but also take advantage of the energy amplification possible from using available external heat. On one side it is not efficient to make a too important pressure drop into one expander because the adiabatic cooling will strongly reduce the pushing pressure, and the exhaust gas will be thrown out at valuable high pressure. On the other side, using a pinhole regulator will dissipate pressure energy, but will allows the reduced pressure gas to be thermalized, such as to run the expander with much less adiabatic cooling and less gas pressure energy thrown at exhaust. Both methods are compromises. Multi-stages with heat input is hardware intensive, but the best way to get the most mechanical energy out of a high pressure gas tank with an external available heat source...

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
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.

Using Air Motor as Compressor

Turning in reverse a Quasiturbine air motor will make it act as a compressor (not efficiently if not properly design for that role). However, the direction of rotation can be keep the same, if both exhausts are plug by a small check valve line taking the exhaust pressure exit as the compressor output. Then, to prevent the air motor intake two lines to be vacuumed, a check valve on them allowing-in atmospheric air will suffice. This kind of switching motor-compressor mode without changing the direction of rotation is useful for application like windmill back up pneumatic air storage or vehicle breaking energy recovery device.

QT40LSC Pneumatic - 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 Pneumatic (100 kW peak)
(pre-commercial unit) with simplified central differential and shaft,
is intended for integration research, demonstration and projects.
To be use only under competent supervision.
Guaranty is limited to the 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 associated 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...)

Possible Applications

Gas Pipeline Pressure Energy Recovery - Rotary Pressure Expander
What about an "energy recovery rotary pressure regulator" ? An interesting application of the pneumatic Quasiturbine is to recover the pipeline high pressure energy at local distribution stations. Instead of using a conventional pressure regulator (an energy dissipative device), a pneumatic 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. It does act as a dynamic active rotary valve. 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 (better than pre-heating the gas before that same "rotary expander", to avoid any residual condensation as done with conventional regulators). Substantial heat is now given to conventional expansion valve in pure lost, while heat given to the gas at the intake of a rotary expander is essentially all recovered in mechanical energy or electricity. 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, and has high efficiency at all torque and all flow rpm. With such a system, any heat added before the Quasiturbine expands the gas and increases the available volumetric flow with the result that this heat is converted in mechanical energy with a very high efficiency. All experimental demonstration has to be done only by gas experts and under all current rules and regulations. Ignoring gas expansion and considering only the gas pressure flow, a 36 inches diam. gas pipeline at 700 psi carry typically a pressure power in excess of 30 MW - 25 millions of pound-ft/sec - of zero pollution pure mechanical energy almost totally recoverable through Quasiturbines in the heart of cities and industrial parks. This is tens of giant windmills on kW-h basis!. A survey (M. Dehli, GWF Gas-Erdgas 137/4, p.196, 1996) showed that in Germany alone, the potential for utilizing this pressure in 1996 was 200-700 MW, and the gas consumption has increased since then... See the pipeline technical paper and the Quasiturbine Rotary Expander.

Enhance efficiency of LNG liquefaction cycle. Adsorption Refrigeration Engineering Thermal Physics. Conventional pressure regulators make all the gas to expand from the constant high pressure side, and the gas pressure-kinetic energy at the needle is converted into undesirable heat, reducing accordingly the amount of cold produced. The Quasiturbine rotary expander allow for individual chamber to expand at a variable reduced pressure during expansion, and such reduces the gas kinetic energy transformation into destructive heat. Furthermore, the Quasiturbine recuperates mechanically the gas differential pressure energy, which can be used to run more compressors and make more cold... A double energy efficiency gains! A single Quasiturbine in tubo-pump (tubo-compressor) mode could have one circuit used as rotary expander while the other is used to compress back some of the expanded gas. This offers great enhancement of thermodynamic cooling machine, and specially in high power LNG - Liquid Natural Gas liquefaction stations. Of course, this efficiency enhancement is also available for more modest cooling system and air conditioning equipments. With Quasiturbine rotary expander, the efficiency of a gaseous only (like dry air) system reaches almost the efficiency of a phase change liquid-gaseous system, and sophisticated phase change chemical products often environmentally unwelcome are not anymore needed. See Quasiturbine Rotary Expander.

Low Pressure Modulated Power Station
Solar radiation varies greatly during the day while most engine keep their optimum efficiency at design power only. Because the Quasiturbine (steam or pneumatic) keeps it high efficiency on a large power range, it is well suitable for modulated (from source or demand) power production like solar, windmill, ocean wave station... where the pressure is generally low, and efficiency critical!

A 10 second vehicle Power Booster. Originally, hybrid was intended for efficiency increase, not for performance increase. More and more vehicles use 2 engines not for fuel savings, but to increase acceleration performance: As a 10 seconds Power Booster, benefiting a government grant! In this regards, the Quasiturbine QT5LSC pneumatic with an onboard air tank and compressor could eventually provide hundreds of additional HP for 10 seconds, and make an unbeatable acceleration Quasiturbine Hybrid vehicle... the market seem to ask for? Many others applications require high power bursts, like in smooth landing parachuting (with fast line-winding in less than 10 seconds).

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.

  • 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.

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

  • Intended for near ambient temperature intake air (be careful not to run a supply air compressor for a too long period, which could overheat the intake air).

  • 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 (pneumatic tool oil only).(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 flat 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 under load, half without load. 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 air must be reasonably clean and near ambient temperature.

  • Not be used 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.

  • Must be operated under the constant supervision of qualified adults.

  • 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/nitrogen 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.

  • Pneumatic air-nitrogen only (less than 4 bar - 60 psi),
    no steam conversion attempt must be made (could be dangerous).

  • 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.

  • Guarantee 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 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-Rotors 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