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Power Flow System


  1. Increased Engine Horsepower
  2. Reduction in Takeoff Roll
  3. Increase in Climb Rate
  4. Reduction in Fuel Burn for Same RPM on Fixed-Pitch Prop Models
  5. Increased Air Speed at Full Trottle Position on Constant-Speed Prop Models
  6. Overall Cylinder Head Temperatures (CHT) reduced
  7. CHT Exremes Reduced Between Cylinders
  8. Exhaust Gas Temperature (EGT) Extremes Reduced Between Cylinders
  9. Smoother Running Engine
  1. System is Fully FAA STC'd Under FAA/PMA
  2. Complete 321 Stainless Steel Exhaust System Kit Includes All Installation Hardware
  3. New and Improved Design for Cabin Heat and Carb Heat Exchangers
  4. No Welds in Cabin Heat Area Practically Eliminating Possibility of Carbon Monoxide Poisoning
  5. Up to 1.5 Decibel Reduction in Cabin Noise
  6. Easy installation in Only 3-7 Hours with Little or No Modification to Aircraft
  7. 60 Day Money Back Guarantee From Day Of Installation
  8. One (1) year or 500 Tach Hour (Whichever Comes First) Warranty


Tuning an exhaust system is critical for an aircraft engine. It is easier to tune an aircraft engine than a car or motorbike, because the range of RPM's used is much narrower. The major obstacle is that space inside an aircraft cowl tends to be very scarce.

Although motorcycle and automobile racers have been tuning their exhausts for over forty years, until the late 90's, there were no tuned exhausts on certified aircraft. In order to work, a tuned exhaust must reduce the pressure at the exhaust port just before it closes, to below the pressure in the intake manifold at that time� called the overlap phase. At that moment, a fresh fuel/air mixture can be drawn into the cylinder and simultaneously spent gases can be removed from it. In an untuned exhaust, the pressure in the exhaust at that moment will be greater than that of the intake, and spent gases will remain in the cylinder or even flow backwards into the intake manifold.

Also in an untuned system, as the spent gases leave the cylinder, they are routed through a set of headers, into a common collector area, and pushed out the tail pipe by the remaining pressure in the system. Like a garden hose with a kink in it, pressure builds up throughout the exhaust system, making it more difficult for the spent gases from the next cycle to leave. So now, the exhaust is not flowing as freely as it should, leaving some exhaust gases in the cylinder, taking up space better used for a clean fuel/air charge.

A Tuned Exhaust System is totally different. When you break down our exhaust system, you have two "sets" of pipes; the primary (header/collector combination) and the secondary (pipe after the collector). The primary contains four independent tubes that all join at the "4-1 Collector." As each "exhaust puff" of spent fuel travels through the primaries, it leaves a vacuum behind. In our tuned exhaust system, we have adjusted the length of each tube so that the vacuum reaches the collector just in time to "suck out" the exhaust from the next cylinder. The exhaust gases are not only being pushed out by the cylinder, but "extracted" by the vacuum, so a bigger, fresher fuel/air charge will enter the cylinder during the next cycle. A tuned exhaust system really promotes a smoother, cooler, and finally more powerful running engine.


Your new Power Flow Tuned Exhaust System will include 4 headers, cabin heat shroud, extractor system, muffler, support rod, STC, instructions and all necessary hardware for the installation. Hardware includes nuts, bolts, No-blow gaskets, etc. Your system may require some additional optional equipment which may be unique to your installation, such as heat shields and strap hangers, which will be determined when you place your order. Most installations are bolt-on and require little or no modification to the existing aircraft cowl. On some Cessna 172 installations a small 1.5 inch hole is required in the cowling for a support rod. The addition of a Ceramic Coated Muffler upgrade with your order will eliminate the need to continually polish the standard stainless steel muffler.

100% Guarantee

Power Flow Systems come with a 100% satisfaction money-back guarantee for 60 days after installation. If you are not happy with the product, return it for a full refund of the purchase price. This guarantee does not include shipping and handling charges or installation labor. Contact us at Aero Resources, Inc. for return instructions.


Power Flow Systems are also covered with a one (1) year or 500 tach hour (whichever comes first) warranty providing repair or replacement (our choice) for any defective part of your tuned exhaust system. This warranty does not cover outside labor, shipping or handling expenses. Any alteration to the product or deviation from the approved instructions may void the warranty and will not be in compliance with FAA approvals and may render the product not airworthy.


Which aircraft are Certified (STD'd) with the Power Flow Exhaust?

Cessna 172 I, K, L, M, N, P with Lycoming O-320 engine
Cessna 172 I, K, L, M, N, P with Lycoming O-360 conversions
Cessna 172's on floats with Lycoming O-320 engines
Cessna 172's on floats with Lycoming O-360 engines
Cessna 175 with Lycoming O-360 conversions
Cessna 177 (1967-68) with Lycoming O-320
Cessna 177A with Lycoming O-360, Fixed Pitch Props
Cessna 177B with Lycoming O-360, Constant Speed Props
Grumman Traveler (AA-5) with Lycoming O-320, Fixed Pitch Props
Grumman Traveler (AA-5A) with Lycoming O-320, Fixed Pitch Props
Grumman Tiger (AA-5B) with Lycoming O-320, Fixed Pitch Props
Grumman Tiger (AG-5B) (1990-93) with Lycoming O-360, Fixed Pitch Props
Mooney (M20B, C, D, G) with Lycoming O-360 engine
Mooney (M20E, F, J) with Lycoming O-320 engine
Piper PA28-140 with Lycoming O-320 engines
Piper PA28-150 and PA28-160 with Lycoming O-320 engines
Piper PA28-180 with Lycoming O-360 engines

The following aircraft models are currently under advance product development:

Cessna 172R & SP Models with Lycoming O-360 and IO-360 engines
Cessna 210 with Continental IO-470 engine
Robinson R-22 and R-44 Helicopters
Kitplane RV-6, RV-7, RV-8, and RV-9

Can I get an FAA Field Approval for my aircraft?

No FAA Field Approvals are currently being done. Please call us back for updates.

What type of performance gains can I expect?

During Dnamometer tests at LYCON, data obtained from an O-320 powerplant configured like a standard
Cessna 172 indicated that the Tuned Exhaust provides:
Gains of up to 23.75 Horsepower over the stock exhaust
Average fuel savings of up to 2.2 gallons per hour
Lower Cylinder Head Temperatures
Other benefits reported by customers include:
Climb rate increases up to 250 feet per minute
Service ceilings increased at least 2500 feet
Quieter and smoother running engine

What were the conditions during the Dyno test?

The test was professionally conducted at one of the premier aircraft engine performance overhaul facilities, LYCON. They are well versed in the world of aircraft engine repair and testing. They are extremely careful to maintain an accurate test environment. The test environment was carefully measured for barometric pressure, temperature, and even fuel specific gravity.

Will I get an increase in climb or cruise performance?

After installing your Power Flow Systems tuned exhaust, you will immediately notice an increase in climb performance and available power.

For a constant speed prop application, the Power Flow exhaust will allow you to generate the same amount of power as before, using less throttle. Therefore if you set the same power settings with manifold pressure, mixture and RPM, you will achieve that power with less fuel flow. It will allow you to generate more top end airspeed and increased airspeed if you choose to use the full throttle position. Currently customers report an airspeed gain of between 3 and 8 miles per hour at the top end. Your fuel flow will be higher than you are used to because it is generating more power than it ever did before.

For a fixed pitch prop, at cruise, airspeed is directly related to RPM. During each rotation of a fixed pitch prop, the prop can only pull the aircraft forward as far as its effective pitch. If you generally cruise at a specific engine RPM, say 2300, the prop turns at 2300 RPM and still provides the same airspeed. You can utilize the extra RPM our exhaust provides to increase airspeed, but you would have to allow the RPM to increase. Your only possible alternative is to consider "re-pitching" your propeller.

Will it increase my RPM?

For fixed pitch propellers, it will increase your static RPM from between 70 and 150 RPM. On a constant speed prop, it will not increase your available RPM.

Will I go over RPM Redline?

On a constant speed equipped aircraft, you will not exceed redline.

On aircraft equipped with a fixed-pitch prop, is more likely that you may exceed redline at full throttle at varying altitudes. Power Flow recommends that you do not exceed redline. You should reduce throttle accordingly to to match manufacturers recommendations. Some customers have reported that experienced prop shops have repitched their propeller to obtain a better cruise performance by sacrificing some of the improved climb performance from installing a Power Flow Systems Tuned Exhaust.

Will I get altitude or service ceiling increases?

Some customers have reported servicable altitude increases of up to 3500 feet. Power Flow Systems, Inc. does not guarantee any increase in the aircraft service ceiling nor do they recommend exceeding the manufacturers' specified service ceiling.

Will my EGT probe fit in your exhaust?

The Power Flow exhaust is manufactured of thicker than original tubing, but EGT probes can be mounted in the exact same manner as they were in your previous exhaust. They will operate normally.

What type of fuel saving should I expect?

Power Flow has several systems on flight schools and flight clubs. They all report an average fuel savings of 1.12 to 1.95 gallons per hour.

Does the tail pipe have to stick out of the cowl?

Yes. The basis of tuning an exhaust is tubing length. This length is required to keep exhaust gases separate from each other and inside their respective tube for maximum cylinder scavenging.

Does this tube increase drag?

Power Flow has accomplished flight testing and found that drag caused by the tailpipe is overcome by the thrust coming out of it. During testing they examined the use of fairings to overcome apparent drag in the system. Their data indicated that any drag created by the exhaust tube was overcome by the small amount of thrust put out by the tube. Your net effect is a zero loss or gain from the drag of the pipe.


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