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Q: Necessary modification for Diesel fuel?

T

thomaswimmer

Member
Hi,

a question to the sucessful integrators of a diesel engine: Did you need to exchange oarts of the fuel system to properly work with diesel?
The fuel sensor comes to mind, is the plastic usable with diesel fuel (ie does not swell)?
Any other pointers?


Thanks,

Thomas
 
Parts

Hi

The only thing we changed in the fuel system was was a capacitance fuel sender, as it is less likely to create a spark. With avgas/petrol the vapour in the tank becomes too rich to burn combustion is only likely to take place near the filler where the air weakens the mixture.

Diesel/Avtur is almost the opposite where the mixture is too weak to burn but can in theory hit the right fuel air ratio....

Also depending on which engine you are considering you may not need the electric boost pump. With the WAM engine the engine pump is more than sufficient, and even if it failed the electric pump does not have enough pressure to supply the injector pump.

One last thing again with the WAM you need a fuel return line which requires an Andair fuel switch.
 
More questions

WAM120RV said:
The only thing we changed in the fuel system was was a capacitance fuel sender
Click to expand...

Thanks for the answer.

I do have the quickbuild kit, so the capacitance fuel sender is no longer an option. Also there is the thing with the different dielectric coefficients for Diesel and Jet.

Did you exchange the fuel filler for a larger one? Jet fuel nozzles are usually bigger than Avgas ones.

I see that you also have an RV-9. Did you install a fuel trap like the acrobatic RV-7/8?

you need a fuel return line
Click to expand...

Where did you put the fuel return line on the tank: Also in the access plate or just in the end rib? How does the return line terminate inside the tank? Do you have photos?

Thanks,

Thomas
 
WAM120RV said:
Diesel/Avtur is almost the opposite where the mixture is too weak to burn but can in theory hit the right fuel air ratio....
Click to expand...

Diesel will not ignite unless it is compressed in the cylinder. It needs something like a wick to burn in open air.
 
We kept the fuel filler the same size. Many Jet-A1 nozzles are small enough to fit & for the few that aren't you can use a nozzle adaptor or a funnel.

The Wilksch engine needs a fuel return. We ran ours into a 90 degree bulkhead fitting on the tank end rib. We have an Andair double fuel valve to put the returned fuel into the tank you're running the engine from.

As the LAA in the UK were not happy with resistive senders due to the spark risk we fitted these Airworld senders. We had the bendable section bent up to the top of the tank and the measuring section going downwards at a 45 degree angle. They fitted in the tank access plates.

We've had no material compatibility issues and the WAM engine was very simple to install. The big problem was making a cowl for it!!

Which engine are you fitting, is it the WAM?

Dave
 
Last edited:
Dave_Boxall said:
The Wilksch engine needs a fuel return. We ran ours into a 90 degree bulkhead fitting on the tank end rib.
Click to expand...

Thanks for the info

Do you have photos of the install?

As the LAA in the UK were not happy with resistive senders due to the spark risk we fitted these Andair senders. We had the bendable section bent up to the top of the tank and the measuring section going downwards at a 45 degree angle. They fitted in the tank access plates.
Click to expand...

Are they really from Andair? Didn't find them on their website. How much are these? Can you hook them up to integrated engine monitors like the Dynon Skyview?

Which engine are you fitting, is it the WAM?
Click to expand...

Haven't decided yet, I'm still in the wing built phase, but want to incorporate the additional "diesel" features early on, even if I decide against it later on.


Thomas
 
Sorry, the senders are Airworld, not Andair. You can order them with either an output that mimics a resistive gauge or 0-10V so I expect you can link to Skyview.

I'll take a look for pics of the install.

Dave
 
Modifications

Hi Again,

Rather than going at this bit by bit, I suggest you make a decision about what engine you are likely to fit when you get to that stage. That will be when you start work on the fuel senders, or get to firewall forward part.

The good news with the WAM engine is that the stress analysis has been done on the engine mount for both the 9 and 9A, so that does not become an issue, for any other engine it will. Them having decided on engine if its a WAM chat with the people who have built 9's.

There are three basic design concepts out there at the moment for the cooling package, although the fuel systems are almost the same.

With our set up we separated the front mounted cooling package and placed the charge air cooler (intercooler) on the firewall, leaving the engine cooling rad on the front of the engine. This allowed us to use a smaller cooling radiator (less weight as less coolant) However, our inlet for the intercooler is not ideally placed as its in a restricted airflow in the climb, so we are about 5 degrees shy of optimum in the climb on a hot day. That means we climb out at high speed to increase cooling flow.

Kurt who followed our basic design, but who was able to relocate his coolant rad rearwards because he has a 9 and the nose gear is not in the way and who has larger inlet flaps on the intercooler inlet and exit has according to WAM the best cooling figures out there, and he is flying in 40 degrees ambient.

A second design relates the coolant and intercooler rads inside the cowl on the engine mount. This after some teething problems is now flying well.

The stock system with the front mounted intercooler an coolant rad is also working well, I think there is 500hours on that airframe now, but from the figures I have heard is slower than the other designs.

What you should have gleaned from this is there is now quite a bit of experience with the WAM set up. Both Kurt and 1 are working on further developing what we have, in fact I was waiting for the result of his experiments before proceeding with mine, but he is enjoying flying the 9 so much he hasn't got round to completing them yet.

So, if you go for a WAM there are lots of people who can help, put any other diesel in there and you have a heap of development work to do on cowls, cooling etc.

Ohhh, and without doubt the one with the best looking cowl is without doubt
Kurts. If you email me at [email protected] I can send lots of photos its far easier than putting them on here.
 
Hi,

WAM120RV said:
Hi Again,

Rather than going at this bit by bit, I suggest you make a decision about what engine you are likely to fit when you get to that stage. That will be when you start work on the fuel senders, or get to firewall forward part.
Click to expand...

Thanks for the detailed report, loved reading it.

My comment about engine choice was not which diesel, it was more whether diesel or gasoline engine. But good to hear that the WAM has an active (RV) development going on.
If I choose a gasoline engine (Lycosaurus) in the end, it will probabely be a fuel-injected one, so a return line installed for a diesel engine will not go to waste (although a bit over-engineered).

And yes, I am aware of cooling requirements for turbocharged, liquid cooled engines.


Thomas
 
Thomas

I've taken a look - but I can't find the photos.

We fitted the return line through the end rib using a bulkhead fitting, one of the Vans reinforcing disks and a bit of proseal, although it could just as easily go through the tank access plate.

I mocked up the fuel gauge with a bit of aluminium pipe stuk into a block of wood. I fitted the sender unit as high as I could in a blank access plate, bent the bendable section up to near the top of the tank, then it bends downwards so that the measuring section slopes down across the tank bay at around 45 degrees. From the mock-up I could establish the gauge length (bendable length & measuring length) to order.

Sorry about the photos.

Dave
 
What happens if you run a tank dry and the engine quits? :eek:
Will it start in the FAA required 8 seconds after you select a tank with fuel in it?
Or do you have to open the injector lines at the injectors to bleed out the air to get it to run again like a lot of diesel engines? :(
 
SHIPCHIEF said:
What happens if you run a tank dry and the engine quits? :eek:
Will it start in the FAA required 8 seconds after you select a tank with fuel in it?
Or do you have to open the injector lines at the injectors to bleed out the air to get it to run again like a lot of diesel engines? :(
Click to expand...


The WAM-120 bleeds the air out down the fuel return lines. I've not run a tank dry & attempted a restart in flight, though others have without problems. On the ground even with the fuel lines full of air the WAM-120 is still easier to start than a Lycoming :D
 
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