Fuel/Induction Page                                        Homepage        back to engines

[ nessa4 | nessa2 | engines | builder | farm | Home Page ]

How I installed a Quik Silver 34 mm slide carburetor, using pluming hardware off the self, an adapter plate was made to bolt up to the intake, this square plate was drilled & taped to 1.75" thread to take the under sink trap elbow, the "J" pipe was used to increase fuel pressure, by lowering the carb 18", it added 1/2 psi to the fuel pressure.

No float bowl, the hidden lever on the back side is a mixture control, a bad example of gascolator installation, the carb use to be mounted on top of intake manifold, this installation is supported by 3 big Lycoming engine mounts (dynofocal) three places, very smooth.

In 1990 I was flying with the fuel injection from the car, the problem today is that new vehicles the fuel injection is part of the Power Control Module, computers not only operate the fuel injection but shift the transmissions monitor fuel quantity in the fuel cell and pressure in the same fuel tank (leave the gas cap off your new car and it will turn on the SES light). These computers may be monitoring the vehicle speed, wheel speed; they have 02 sensors before and after the catalytic converter … in short they are not practical for our aviation needs.

If you are serious about an alternate engine take my advice; if you want fuel injection contact Racetech pay the money and go on. Racetech offers no B/S it does what they advertise they have an excellent quality product at a reasonable price, secured purchase program and they will deliver on time, I had my package with-in 48 hours of placing my order (from Calgary to rural Ontario) Racetech@cadvision.com    www.sdsefi.com

If you are on a budget try my waste spark idea and use a safe carburetors.

Carburetors

It will be hard to find an automotive carburetor to bolt on, and if you find one it may take you weeks if not months to tune in (replacing, finding, drilling jets) if you even understand what circuits operate what inside of carb.

Builders tend to take motorcycle carburetors and adopt, again if you try to use a carburetor that was one of four on the same engine and if the one was feeding a 250 cc pot it probably will not be able to feed your new 1300 cc.

Each horsepower will require minimum of .5 lbs of fuel per hour at full power. At cruise, depending on your installation things like cooling, timing, camshaft you may end up cruising at a power setting burning .375 lbs of fuel per hour, the best that you may hope for under ideal conditions.

The idea of being able to control fuel mixture from the pilots seat is important even in our installation on a hot day when your cooling system becomes marginal by allowing the engine to operate on the rich side you will be able to drop your coolant operating temp, just one example.

Carburetor choices

I have been flying with a Quik Silver 34 mm American built slide motorcycle carburetor more 900 hours. No choke required, to start even at -20° f, push mixture knob to full rich count to from 0 to 12, turn over engine and it starts like a car, it may stall once, crank it over again and it purrs, warm up the engine and go flying that simple. The tapered needle valve at the end of the hose supply to this simple carburetor is connected to a push-pull mixture device like the Cessna's have in their instrument panels. When one returns from flying shut-down of the engine operates the same way, pull the red knob all the way the engine starts to lean out and it runs out fuel, it quits. In this installation (Nessa II) no pumps are being used.

Revmaster Aviation sells this carb, Revflow carburetor ready with mixture control. www.revmasteraviation.com

Able Experimental Aircraft also sell a version of this carb, AltiMizer. www.altimizer.com

Edelbrock Motorcycle performance People may own the name Quik Silver they offer the carb as part of their motorcycle catalog www.edelbrock.com/motorcycle.

This carb is extremely simple as a car mechanic from the late 60 to 80s rebuilt hundreds of carburetors the first time I looked at a Posa or a Quick Silver I did not believe that it was possible for a simple device with out; pump, idle, fast idle or power circuit to operate, once I tried one I became converted. Mixture is adjusted by moving the needle valve up and down on the slide mechanism, the quicksilver needle will not rotate or move around in the slide, the needles are cut on the backside in a tapered section and allow precisely the fuel needed into the air stream.

Tuning of mixture is simple turn a screw in less fuel, turn it out more fuel, they also have different tapered needles available. Unlike the Posa the flat side is indexed down stream, many Pilot have experienced fuel delivery problem on a Posa because after adjusting the mixture the needle was not facing the down stream of the carb.

The RevMaster unit is best for a gravity system, no float bowl; they may have a fuel regulator available when fuel pumps are a must. Today I would purchase 38 mm.

Posa Carb, it will work they are simpler then the above mentioned but the mixture adjustment may be deadly.

Aero-Conversions make Aero Carb it looks simple as well www.aeroconversions.com

It may be an up dated design from Posa I dont know www.sonex-ltd.com

Ellison  throttle body injector, also an excellent product www.ellison-fluid-systems.com

My installation at first, the Quik Silver was installed in the same place as the fuel injection throttle body, it worked Ok until I started to play with exhaust systems, the short story, as the engine increased in performance my gravity system did not supply the amount of fuel that the engine required, by moving the carb about 18" down from the top of intake manifold the  fuel pressure increased by ½ psi, it solved my fuel supply problem (in my installation). Yes I went to a hardware store to buy the "J" pipe and the elbow, later I had to solder a 5/16 copper tube around the 1.5" "J" tube to keep the icing down by feeding hot coolant from the engine. This system has accumulated over 800 hours of trouble free flying.  At first it also had a carb heat system, after flying for over 4 years with out using it, it got removed.

Carburetor Heat Requirements

Please note in my installation the way the carb is mounted to the engine block, icing is not a problem (four years of testing) but if I change the cowling or anything else it may not be the same. Recommend to always install a carb heat box to be able to de-ice your carb, many, many people have died over this.

In Canada it is mandatory to have carb heat, unless you can prove that it will work with out (amateur-built airplanes). People that tell you that you do not need carburetor heat may not be flying! Even Ellison people recommend carburetor heat device.

Things to consider in a fuel system:

• Never use paper element fuel filters, water will plug/restrict flow

• Should use a gascolator (separates water and pre-filter)

• Fuel pumps should be up-stream from gascolator (debris will fail pumps)

• Fuel pumps do not suck, they pump liquids only

• If engine requires a fuel pump to operate, an aux pump should be installed and a fuel pressure gauge.

• If a mechanical fuel pressure gauge is used always isolate fuel from going into cabin (to instrument panel). Even hot rods use this approach

• Always use a fire wall fitting to cross the fire wall with a fuel lines

• Keep heat away from fuel lines, pumps, filters, and gascolators

• Fire sleeves buy time in the event of a fire

• When fuel injected is used, the fuel return line from the fuel rail should have a one way valve, is close as possible to returned tank, this may prevent fuel leaks in a forced landing condition.

• Fuel valve to shut off supply of fuel in the event of an engine fire. In High pressure fuel circuits it should de-pressurize the fuel lines/rail for safe force landings, also helps when servicing, try to replace the fuel filter in your modern vehicle after you shut it off, you will be surprised how much fuel it will spray and for some time.

• Always do a fuel flow test, use aircraft practices 150% flow for gravity and 125% for pumps .55lb x hp/6= Us gallon x the safety factor, remember to look at the rating of your pump, if you purchased a 30 gal/h pump it should give you close to that don't accept a much lower reading.

• On automotive fuel injection application take the reading from the return line going back to low pressure, it will insure that the pump not only is able to overcome the regulator setting but also give you a surplus. If the pump does not over come the fuel regulator you will end up with a vapor lock, injectors are not good vapor sprayers, if your fuel rail percolates the fuel, your engine will quit! One reason to have a fuel pressure gauge and a back-up pump.

• One last test before attempting flight. Tie down the airplane in a climb attitude, climb on board, warm up the engine and then give it full throttle for 10 minutes 5200 to 5400 rpm assuming that the proper propeller is bolted on, if your installation passes this test with out overheating or miss-firing leaking or vibrating/shaking, it may ready for one circuit, but will you?

In case your wandering what is up with my attitude look up my experience Builder.