Subaru Diesel....

[210TC]

I almost forgot, Diesels create a frequency vibration much different than a gasoline engine.
I will bet that many panels will crash and burn as a result of this harsh vibration. I have not considered how this will effect nuts and bolts?

[Andy_RR]

Originally Posted by 210TC

I have found that if you ever run one DRY it is a son-of-gun to restart.

I have asked Mark Wilksch about this - he reckons it is down to design and configuration of the injection system. He says it isn't a problem on the WAM engines and that they will restart after inadvertent fuel starvation in a timely fashion - I can't remember how long he said it took, but it was definitely quick enough to put it in the non-issue basket - unlike the Thielerts, from what I have heard.

A

[210TC]

I will believe it when I see it.
Diesel injection requires apx 3000 plus psi (and UP) and if a small air bubble inters the system you have got problems, on the other hand the less efficient systems used on the old cummins and detroits supply fuel to the injector via a low psi pump and the injector becomes the pump. Cam lobe operates the rocker arm which pushes the plunger down in the injector and presto vaporised fuel, just like the intake and exhaust valves work. This is the choice system for restart.
If they make a system like this with a fuel supply line to the injector AND add a full flow return line to the tank I will take a big LOOK. The return would allow bubbles to exit the system with ease. The Germans have used return flow for many years and all have copied, automotive only. Both engine's mentioned have return system's that could use a small amount of improvement.

[Andy_RR]

I appreciate that you remain to be convinced, but I don't think you need to teach Mark or a lot of people involved in these diesel engines how they work.

I was interested to know how this issue was dealt with so I asked Mark - I'm sure that he wasn't bull****ting when he answered me.

FWIW, the WAM diesel combustion/injection system is 'closely related' to german automotive IDI technology

A.

[Dave_Boxall]

I'm installing a Wilksch (we cast the bottom cowl this weekend). The procedure for starting a brand new engine is to turn on the electric pump, wait for a short while then a few seconds on the glow plugs before hitting the starter. There's no bleeding the fuel system or any other funny business - and the engine will self-prime if no electric fuel pump is fitted.

I guess a restart after running the engine dry can't be any worse than that.

The Wilksch has a fuel return line all the way back to the tank.

Dave

[Syncrogreg]

Originally Posted by rv6ejguy

Unless they are going to MMC blocks and heads, this will just be too heavy for RV7 though 9s. Might have some application for RV10s if the long block weight is under 350 lbs. Going to be a few more years before these show up in bone yards. The modern electronics on diesels are extremely complicated and interconnected with chassis electronics to a large degree. A real mess to transpose into an aircraft application unfortunately and make it work properly.

Hi,
i have one unit in my garage here in TN.

The long block weigh less than 300lbs

http://www.vanorama.com/

GSB

[kgood]

Originally Posted by Syncrogreg

Hi,
i have one unit in my garage here in TN.

The long block weigh less than 300lbs

http://www.vanorama.com/

GSB

How did you get it?? I've been trying to get one for quite some time.

On another subject, earlier in this thread, there is some concern expressed about a diesel's ability to re-start after an in-flight shut down.

Last year, I inadvertently ran my Wilksch WAM 120 out of fuel on one tank while cruising at about 7500'. Scared the heck out of me, but once I determined that I had run one tank dry, I simply switched tanks. Before I got my hand off the selector, the engine was running perfectly, no sputtering, missing, nothing. In less than 3 seconds, it was as if it had never shut off. Kerry from WAM had told me early on to just try that some time, and that I would be amazed at how quickly it re-started. I was!

Back to the Subaru: please let me know how I can get one, I'm really interested in seeing how it would do in a plane. It is lighter than I thought it would be, but still heavy, once you add in a cooling system and gearbox. I'm sure some parts can be lightened to make it a viable aircraft engine.

Kurt
RV9 / WAM 120 diesel, 209 hours

[Sig600]

Originally Posted by 210TC

I have owned an opertated well over 100 peices of diesel equipment and I have found that if you ever run one DRY it is a son-of-gun to restart. Given this problem I would NEVER put a diesel in an airplane until they prove to me it will restart like a gas engine.
I think anyone who runs a plane out of fuel in flight should loose the ticket for a period of time. Yes, I toooo have forgot to switch tanks, the most stupid mistake I have ever made. I was at altitude and nobody but me knew about it. Don't tell anybody that pilots forget to switch tanks....

You're correct about it restarting. If you run a tank dry in a gasser, you just switch tanks. A diesel however because of the setup of the fuel system the injectors have to be bled. The fuel atomization is incumbent on pressure. If there is any air in their you're pretty much screwed. Like anything else in aviation, don't screw it away.

Never mind, just read page two and you know all this.

[robpar]

Most if not all modern automotive diesels use the Common Rail type of injection system. This has a "Rail" which is basically a pressurized pipe where the fuel recirculates and the injectors are fed from this rail. Since the fuel recirculate any air that gets into the system is purged. If the system is run dry, not recommended as the pump is also dry, when the tank is switched the pump will pick up fuel very similarly to a gasoline system and will purge any air.

The older style Bosch systems that may still be used on some small diesels that do not have to meet emission requirements do have to be manually purged to get them running again, and definitely would not be recommended for aircraft use.

I wonder what the marine people did as they had the Bosch injection systems and running a boat motor out of fuel could be just as dire as an airplane.

BP

[kgood]

My Wilksch diesel has the old-style, lower pressure fuel system, of WAM's own design - not a high pressure common rail system.

As I mentioned above, in post #17, when run dry, it restarts IMMEDIATELY. The injection pump was designed for Jet A, so it is lubricated with engine oil. It's not such a big deal to run it dry.

We did some testing years ago with our Cessna 180 with Cont. 0-470 gasser, to defend ourselves in a lawsuit. We ran it dry many times (unported the selected tank) to see how long it would take to restart, and sometimes it would take up to 2 1/2 minutes before sputtering back to life. Believe me, that 2 1/2 minutes seemed like an hour....

I'll take the diesel any day!

Kurt
RV9, WAM 120 diesel, 210 hours