Kit Aircraft Modifications

Well I did it. I purchased the LS1 crate engine last Monday. I purchased a FAST intake and Nick Williams 92mm throttle body as well and had them shipped to Michigan where I am going to go in a couple days to pick it up. I saved a bundle by purchasing it in the states even though I have a GM discount. I got it for $900 less there. Amazing!!

Here at home I have started constructing an engine test cell. I am doing this because I have a couple of things I want hashed out before I install the engine in my airframe.

The ignition is the primary reason that I want to put some time on the engine in a test cell. We are planning to develope a dual ECM set-up and I want to get some hours on the system before installation in the airframe.

The cooling system is the second reason. I am going to go with a dual electric water pump set-up that will require some engine test time to determine whether a thermostat is required. As well, we need to determine how effective the electric fan will be on the cooling when the engine is operating at various loads and speeds.

All of this is better tested on the ground under controlled conditions rather than in the air. I am determined to improve upon the set-up that Bud Warren is using at Geared Drives. I have decided not to go with the OEM computer, water pump and Bud’s cooling system. All of this will require some validation and I am going to do this the right way.

Dave

I have been in discussions with Dan Yager of quickheads.com and we are working on putting a package of parts together for the Quickie series of aircraft.

My company, Effectus AeroProducts manufactures accessories and components for kit aircraft and I am pleased to be able to work with Dan on getting these parts made available for these aircraft that no longer have factory support.

We’ll announce the availability and parts lists here on the blog when they become available.

Dave

I have been spending a lot of time lately thinking through the cooling system and specifically the water pump. On a liquid cooled engine the water pump is a single point of failure. A pump failure means that you are coming down and sooner than you would like.

The other thing that needs to be considered when choosing an automotive engine for an aircraft is that a pulley driven water pump is optimized for a very specific RPM range and that is usually around 1000-2200 RPM. This is where the automotive engine spends most of its operational life.

You want a liquid cooled aircraft engine to flow as much coolant as possible at its cruise RPM and for the LS1 married to a Geared Drives psru that turns out to be about 3300 RPM. This is much higher than the optimized speed of the OEM water pump. If you turn that pump faster you end up simply wasting horsepower and not getting an equivalent increase in coolant flow.

There are a couple of ways around this problem. The first has been used in racing circles for years and that is to under drive the pump by changing its pulley size. This works well when running at cruise speed but unfortunately means reduced flow at idle. This doesn’t bode well for the long taxi on 104 deg. F afternoons in Texas.

The second is to install an electric motor driven water pump in lieu of  the OEM water pump. Meziere makes a  number of bolt on replacement pumps that have an idler pulley built in to maintain your existing belt geometry.

The electric pump accomplishes a couple of things that are positive for automotive engines in aircraft. First, it eliminates the need to physically drive the coolant pump using a belt. This will net you 15-20 horsepower at the propeller. Second is the smoothing out of coolant flow over the entire range of engine RPM. This means that you are getting optimum cooling flow when you are taxiing down to the end of the 12,000 foot runway as well as when you are throttle to the firewall.

There have been numerous instances of automotive engines over temping on the ground while taxiing and I have to wonder whether this inefficiency of the coolant pump at idle RPMs is a contributing factor.

The last bit I am going to talk about today is in regard to redundancy and failure modes as mentioned earlier. I am going to be installing dual electric coolant pumps in my RV-10. The main pump will be mounted to the engine in place of the stock unit. The aftermarket unit from Meziere duplicates all of the hose connections of the stock unit and maintains the belt path and operation. The secondary unit will be run in series with the main unit and will be mounted onto the radiator where the bottom rad hose bung would normally be located.

This will eliminate a major failure mode in the installation of a GM LS1 engine in my RV-10 and give me the peace of mind that I need for the  future flights into IMC that I plan to make after getting my instrument rating.

 Have a great time building and modifying!

Dave

Greetings,

Here in Canada we have to install a gascolator in our aircraft to establish a low point for fuel on the engine side of the firewall. I decided to install one of the Van’s Aircraft designed Gascolators as it wasn’t expensive.

It was challenging to find a place low on the firewall of my RV-10 because of the design of the  engine mount. The mount I am using for my LS1 installation as well as Vans original design have a tube that runs the perimeter of the lower firewall. This meant that I had to devise some sort of standoff that would allow me to mount the unit and at the same time have the drain clear the mount tubing.

What I did was take a chunk of aluminum the same size as the base of the gascolator and deep enough to allow the drain valve extension to clear the mount. I then drilled the block to accept a threaded brass extension which was then threaded into the gascolator. The threaded brass extension was then fed through a hole in the firewall and the gascolator was bolted through the firewall as well.

On the inside of the firewall I threaded an aluminum 90 deg AN fitting on to the brass extension and clocked it to be parallel to an angle brace that runs diagonally across the firewall. I secured rigid flared tubing to this brace and ran it between the output of the high pressure Walbro pumps and the 90 degree fitting on the firewall.

I now have a low point for fuel in the engine compartment and have the drain valves for both the gascolator and the header tank side by side so they can be easily checked for water contamination during the pre-flight inspection.

Thanks for taking this in. I would appreciate your comments on this blog. Please feel free to drop me a line or two.

Dave

Hi Everyone,

The fuel in my RV-10 is located in three tanks. Left and right wing tanks of 30 gal. each and an auxiliary tank located in the baggage compartment.

As mentioned earlier I have installed a header tank on the cockpit side of the firewall. This header tank needs to be full of fuel all of the time as it supplies the high pressure Walbro fuel pumos that charge the fuel rails on the engine.

I have installed two Facett fuel pumps in the bottom of the center tunnel on a bracket that has them angled up from horizontal 45 degrees. This is necessary to make sure that bubbles in the fuel do not congregate in or around the pumps. This also helps stave off vaopr lock if the fuel gets too warm. I shouldn’t have too much trouble with this as I am returning unused fuel back to the tank supplying the system.

I have run the two pumps in paralell in the same fashion as the high pressure Walbo pumps. I am building an IFR capable aircraft with all of the necessary redundancies of which dual fuel supply and pressure pumps are a part.

I used aluminum tubing with AN flared fittings throughout the installation and made sure that all of the lines were supported and isolated from other items in the center tunnel. I took great pains to make sure that the fuel lines were routed away from heat sources such as the cabin heat exchanger.

Each of the Facet pumps will have its own power supply from independant sources so that an electrical system failure won’t put me out of business.

Here is a picture of the tunnel with the pumos in the center bottom.

Dave

I have been asked to make up some fan grills for other builders like the ones I posted a week or so ago. They can be customized to your specific aircraft type or I can put your aircraft identification number in the design as well. They are 4.5″ x 4.5″ and have a bolt pattern that is 3.5″ x 3.5″(this can be varied depending on your specific fan size).

Contact me if you are interested in having thes made for you. Approximate cost for 2 grills made from 20 guage 304 stainless is US$ 50.00

I ship them flat which means that you have to bend out the louvers. They will have a mill finish as most builders will want to powder coat or paint them to their specific color of choice.

Here is a picture of the one in my plane.

Dave

With a liquid cooled engine now in the works I had to start thinking about how to modify the cabin heating system. The RV-10 has installed tee shaped ducting in the center tunnel that is connected to the heat muffs on the exhaust pipes in the original configuration. I wanted to maintain the same outlets so I had to fashion a heat exchanger and plenum that would allow me to connect 2″ SCAT tubing towards the forward endo of the tunnel as well as aft.

I found a MOCAL heat exchanger that along with banjo fittings would fit into the tunnel while laying on its side. From there I made up a stand that Would allow me to anchor it to the floor as well as have it at the proper height for the SCAT tube runs. They run quite high in the tunnel.

I had to make the whole thing removable as it is the last piece of the puzzle to be placed inside the tunnel and I need to be able to get at everything else in there during annual inspections and for maintenance.

The heat exchanger is connected to 90 deg. bulkhead fittings on the firewall (3/4″) with braided teflon hoses and I have insulated the lines as best as I can to keep the heat down in the tunnel. I am going to be making a bypass valve on the firewall side that will allow me to vary the amount of fluid that is going through the exchanger.

On top of the heat exchanger is a 4″ SPAL fan that I have pulling air through the fan into the plenum. This fan is of high quality and it seems to move the air quite well through to the two distribution tees in the front and back footwells.

I haven’t decided whether I am going to vary the speed of the fan with a thremostat or whether it will simply turn on and off. I still have some thinking to do on that.

Dave

The LS1 requires a fuel rail pressure of about 60 psi and as such needs to be supplied by an aftermarket Walbro Fuel pump. With most low wing aircraft there are two pumps to supply the engine with fuel. There is the engine driven pump and an auxiliary pump that is used during take-off and landing.

To maintain this redundancy and because the LS1 doesn’t have an engine driven pump, I have installed dual Walbro high pressure pumps to supply the fuel to the fuel rail. These pumps are gravity fed from a long cylindrical header tank mounted above them. This ensures that the pumps are wetted in all but the most extreme of flight attitudes.

I have plumbed them in paralell and have wired them to two separate power supplies. I will have the primary pump running all the time and the secondary will be switched on by my Vertical Power system based on flight mode. I have wondered whether or not I will change the designation of primary and secondary at each annual inspection so that any one pump isn’t overused.

I mounted the two pumps on brackets that I mounted to the co-pilot side of the centre tunnel. Each pump is secured to the bracket by two stainless steed worm gear clamps. They each have a check valve so that they can operate in parallel independently.

The fuel is routed from the tee just past the pumps up out of the centre tunnel and forward to the firewall where it is secured to the stiffener rib running diagonally down and outward where it turns 90 degrees through the firewall and into the back of the gascoaltor.

Tomorrow I will explain the dual low pressure pumps.

Dave

Hi Everyone,

The fuel system is the first area that I had to address because it is very different from the one employed for the Lycoming. The LS1 requires that pressurized fuel be supplied to the injectors via a fuel rail. This is a looped system with more supply capacity than will be used by the engine. The unused fuel is depressurized at the termination of the fuel rail by a fuel regulator. It then returns to the supply tank. This differs from the lycoming set-up in that there are no return lines required.

So to begin with we are adding complexity to the fuel supply system. There are quite a few more lines involved in the LS1 set-up that have to be bent and flared to get the fuel to the engine and back.

Header Tank

On a component basis I am going to start with the header tank. I installed a quart sized header tank on the cabin side of the firewall on the pilot’s side. This tank serves a couple of functions that are very important.

The first function is to keep the high pressure pumps always wetted. Automotive style high pressure fuel pumps do NOT like to be run dry. This would be a very real possibility should you mount them in the wing tanks.

The second function is to act as a collector and distributor of two streams of low pressure fuel. the low pressure pumps feed fuel to this tank and the pressure regulator returns depressurized fuel back to this tank. This keeps the fuel cool. Allows for any bubbles in the fuel to move away from the high pressure pump intake ports and provides a path for the fuel to be returned to the supply tank.

The photo above shows a large portion of my fuel system including the header tank, supply lines, return lines, twin high pressure supply pumps, and fuel transducer.

Next post I will describe the high pressure pumps and how I have installed them.

Dave

Now that I have changed my mind and decided to install the LS1 package from Geared Drives I needed to change a bunch of things and start thinking about a whole bunch more!

I had already attached the engine mount and front gear leg to the fuselage so that had to be removed. This left the fuselage without a front leg so I called Bud Warren and he fabricated an engine mount for me and I picked it up from him at Oshkosh AirVenture 2008. This saved me a bunch in shipping.

After I removed the engine mount I had to remove the oil cooler mount from the firewall. This wasn’t an easy task as I had the firewall covered with a special fire blanket insulation mat. I ended up cutting the oil cooler bracket apart leaving the aluminum feet attached to the firewall. I didn’t want to have to plug all of the rivet holes and this made for a fairly neat result.

The next big job was to go through Van’s firewall kit and determine what I’d used and what was still in there. I put the kit up for sale and I had a guy out in British Columbia  purchase it. I ordered all of the consumed items from the kit and had them sent to him direct.

Next was the fuel pump and filter assembly which I had already installed and now no longer needed. All of this was removed in preparation of the installation of the twin Facet fuel supply pumps and the twin high pressute Walbro pumps.

A ton of thought went into the placement of the pumps, fuel transducers, fuel valves, fuel lines, wiring, heater core, shroud and air ducting. All of this had to be fitted into the center tunnel and it all had to be able to be serviced and inspected.

I will talk about each of these installations in more detail next and will add some photos for clarification.

Dave