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Homebrew Diesel (Built by Elden DuRand 2018)

David Jones

Registered
Elden DuRand was a member of the Smokstak community and frequent poster. Like a lot of you, I followed him here and on his website www.eldensengines.com, often commenting and providing suggestions on his various projects. I especially liked his Homebrew HVID engine and frequently encouraged him to build a true injected diesel engine. Elden was very fond of diesels so it did not take much encouragement to get him to build what I have named the Homebrew Diesel.

July 31, 2017, was his first official post suggesting that he would begin working on a diesel design. Elden studied various methods of developing a simple injection pump and injector. In addition, he constructed an injection tester so he could evaluate his injector designs. By late August, 2017, metal shavings had begun to fly at the Hoyt-Clagwell & Company (name of Elden's machine shop) facilities, Port Saint Joe, Florida.

After several attempts at making a successful injector, he decided to start building engine parts and lay the injector aside. He wanted to do more research on an injector design, something he could construct given his limited machining capabilities.

Construction of the engine continued at a rapid pace, and by May of 2018, the basic block and crankshaft assembly were complete. He posted a need for some small valves, so I harvested a pair from a 4-stroke weed eater and mailed them to him. On May 27, 2018, he had first ignition--from a naphtha soaked rag held against the engine intake port.

He then turned his attention to the injection system. Another follower named "Doc" had sent him some Lambordini pump parts. After studying these parts, Elden decided he could incorporate them into his pump housing. By June 12, 2018 the injection pump was complete.

Focus now returned to the pesky injector. After a couple of attempts he was able to construct an injector that worked. He was not happy with the spray pattern, but felt it was adequate.

June 22, 2018, saw the engine on skids with an Elden signature brass radiator mounted and plumbed. Two days later, he was able to get the Homebrew Diesel to run under its own power ("off-the-belt," as Elden would say). The injector continued to be a problem, so a new poppet style was constructed.

June 26, 2018, was the first attempt at engine operation with a working governor. After adjusting the timing the engine was able to sustain itself at a governed speed. The video:

https://www.youtube.com/watch?v=HihqXrPmU1A&feature=youtu.be

June 28, 2018, Elden turned his attention again to improving the injector. Using his Dremel ,he was able to reface the injector poppet and get an improved spray pattern. However after just a couple of hours of run time the engine would loose compression and quit. Removal of the head revealed the valves had carbon buildup and were not sealing. In addition, the piston rings were full of carbon sludge, causing them to stick.

Several more run attempts were made, all resulting with the engine quitting due to carbon build-up under the valves and loss of compression. Elden tried many things, various angles on the valve face, stronger valve springs, heat-treating the head, and even valve rotors. None of the changes corrected the problem. During these modifications, he constructed a fuel tank, lift pump and day tank using a Lukenheimer oiler jar which had been given to him at the Florida Flywheeler show in Zolfo Springs.

Another poster had suggested to Elden that it could be the exhaust valve duration was too short. A new cam was machined and fitted to the diesel. After about an hour of running, it lost compression and quit. Here is the last video of this engine made by Elden.

https://www.youtube.com/watch?v=ZnvGMFiKNdA&feature=youtu.be

Elden continued to refine the injector. He increased the popping pressure to 1500 psi which improved the spray pattern, yet the engine would continue to clag up the exhaust valve and quit. August 22, 2018, Elden posted that he had been given "light duty"--doctors orders. He was having health issues and would need open heart surgery.

October 10, 2018, Hurricane Michael was a direct hit on his home and shop in Port Saint Joe, Florida. It totally destroyed everything. This was two weeks before he was scheduled to have the heart surgery.

October 27, 2018, Elden contacted me and advised me he was getting rid of everything and wanted me to have the Homebrew diesel. He did not have a place to store or keep it, and I needed to pick it up within two weeks as it was exposed to the elements in Florida. My wife Angie and I got in our trusty 1996 VW Passat Diesel wagon and headed to Port Saint Joe Florida. We were unprepared for the decimation and destruction we encountered. Homes, businesses, utilities, and trees, had all been reduced to piles of rubbish with automobiles, boats and the like entombed together. Elden and Elaine were living in their motor home parked in their driveway. We spent the day visiting with them and their friends, (from Kentucky) who were there assisting them with removal and cleanup. We loaded up the Homebrew diesel, said goodbye and headed back to Texas.

I continued to correspond with Elden via e-mail and text. He was eagerly awaiting his heart surgery, now scheduled in Birmingham, AL, as his local hospital had been damaged by the hurricane. On January 9, 2019, I was notified by Elden's nephew that he had died January 6, 2019, due to complications from his surgery.

I, like many of you, will miss Elden's frequent posts and updates to his web pages. My goal of this thread is to continue to allow his readers the opportunity to follow the development of the Homebrew diesel. The picture attached is of Elden and Elaine sitting on the back of our car with the Homebrew diesel as we were getting ready to depart for Texas.

David L. Jones
 

Attachments

David Jones

Registered
In my discussions with Eldon, he believed the clagging problems were associated with incomplete combustion due to fuel not being atomized by the injector. I agreed with him and my initial focus will be to attempt to improve the injector design using a pintle style injector. I have attached some of my initial designs and will show the construction progress of the new injector.
 

Attachments

David Jones

Registered
Making progress, have slightly modified the design as I go. The size of the parts make machining very difficult given my skills and equipment. The allen screw is a 10-24 and it will have a lock nut when finished. The end of the pintle will need to be trimmed flush. The pintle style injector relies on the fuel pressure to lift the pintle to allow injection to occur. If the clearance is too great between the pintle and the housing, the fuel will bypass the pintle and just exit the return line to the tank. I lapped the pintle to the housing but still have too much clearance. I can only build 400 lbs of pressure before the fuel leaks by and exits via the bypass (return). Next step will be to explore the use of an O-ring on the pintle piston.
 

Attachments

TekNik

Registered
David,
Thank you for continuing the work on Elden's diesel.
I followed the project on Elden's website, and will continue to follow it here.

Thanks,
TekNik
 

David Jones

Registered
Brief update. I machined a groove on the pintle piston to accommodate the installation of a size 60 O-ring. The bore of the injector is .203 and a size 60 O-ring is .250 OD. After installation I used my Dremel and the lathe to grind it down to work in the injector bore. This picture was taken after it had been in and out a few times and was showing wear. The O-ring has solved the bypass leak I was having. I am now able to adjust the injector from 0 to 1,500 psi. I seem to get the best pattern around 800 - 900 psi. I am getting more of a stream instead of the fog I was expecting. I re-installed the injector and attempted starting the engine. Could not get any injection exhaust smoke, so I backed off the injection pressure adjustment until I got smoke in the exhaust. I then removed the injector and checked the pressure setting. It was around 200 psi. Above that pressure I am not getting any injection to occur. I now need to look at the pump to figure out why I am not getting high pressure. Regarding the injector pattern, my pintle has a straight section after the seal flange. I may need to re-design it where the seal area is at the very tip of the injector. I believe the straight section is why I am not getting more of a fog.
 

Attachments

David Jones

Registered
I disassembled the injection pump and re lapped the surfaces between the barrel and injection pump discharge valve. I got the pump working again, however not at the pressure I am targeting. I would like to get the injection pressure between 1,000 and 1,500 psi. I was able to get the engine to run with the injection pressure of 600 psi. However I had to retard the injection timing to get reliable injection to occur. I believe that compression pressure exceeds the injection pressure and therefore I don't get injection. By retarding the timing cylinder pressure decreases and allows injection. Due to the retarded timing, the engine is very smokey (white smoke). Seems to make adequate power. Elden limited the stroke of the pump trying to make it flow less fuel. The limited stroke causes the injector pump to dump fuel before it reaches high pressure. I will do some tweaking and see what I can come up with. I will try and post a video of it running in the next couple of days.

Any thought or ideas appreciated.

David L. Jones
 

David Jones

Registered
I got a chance to work on the Homebrew Diesel today. I am trying to develop a reliable way to determine the actual injection timing and be able to adjust it accurately. I also removed the head to clean and lap the valves. I took some pictures with the head off, my timing indicator, and clag on the exhaust valve.

I also made a video showing the pintle injector spray pattern. My drill battery was about dead and kept shutting off during the video. That is the strange sound you hear which caused the engine to slow down.

https://youtu.be/IR59cyIruys
 

Attachments

Thaumaturge

In Memory Of
Age
68
Last Subscription Date
07/12/2019
David: I'm the "Doc" follower you mentioned in your first post.

The injection pump and parts I sent Eldon were off a 6LD435 Lombardini. The complete shop manual for which can be downloaded here: https://drive.google.com/file/d/0B1p7xJAXmwbWTVo5ZWw5a1kycFk/view?usp=drivesdk off my gdrive.

The parts were from an engine that suffered a catastrophic failure with around 635 hours on it. I mention this strictly as an indicator of possible wear.

There is a section in the manual that covers specs and testing for the pump and other injection components.
Hope this is of some assistance to you.
Doc
 

David Jones

Registered
Thanks "Doc", I will download and study the manual. It appears that Elden shortened the stroke of the pump from it's original design. As such it dumps (spills) the fuel very early in the stroke. The parts do not appear to have any noticeable wear, if the plunger were to bypass fuel (leak) it would accumulate in the injector pump cam follower. I have not seen any leakage.

Looking at the pump stoke, the 6LD435 originally had a stroke of 9 mm or .354 in. Based on the drawings Elden gave me it show a max stroke of .0065, this is the elevation of the cam lobe. My theory is this limited stroke causes the plunger to spill the fuel prior to reaching a high injection pressure. Thanks again for your input, all ideas appreciated and welcomed.

David L. Jones
 

David Jones

Registered
Adjusted timing trying to figure out the best setting. Using the timing procedure from "DOC's" Lombardini manual, it appears that the Homebrew Diesel prefers 5 to 7 degrees ATDC. Advance it any more and it really hammers and will not produce any power. With the timing close to TDC, ignition comes easily. As I retard the timing I have to assist with heat before it begins to fire. With timing retarded 5 to 7 degrees it does produce power and will accelerate and run against the governor. Once the governor reduces the fuel the engine starts to stall and then the governor takes the fuel setting to max and it recovers only to repeat the cycle again. Elden had added a fuel limit stop and I suspect he was having the same problem. I am waiting for warm weather as I cannot run it in my shop. The smoke gets heavy very quickly. Hope to post a video next time I work on it. Stay tuned.

David L. Jones
 

Oil Power

Registered
Davd: Some notes about your injection pump. Delivery will commence when the top of the plunger closes the spill port in the side of the barrel, on the up stroke. Delivery ceases when the lower edge of the helix uncovers the port. When a plunger is worn it will be worn on the helix and allow fuel to leak past the helix. This wear occurs usually in a narrow area where the plunger has been working. Fuel leaking past the helix will by-pass back to the fuel feed gallery within the pump and not from the base of the pump. A worn plunger will only build up pressure when rotated to the excess fuel position used for starting. This could cause the behavior you describe as when the governor cuts in the pump will not deliver until it returns to the starting position.

I am not sure how Elden modified the pump to work with such a short stroke. Perhaps he shortened the plunger by grinding off the top. This would have made the helix very narrow and make it hard to build up sufficient pressure. Normally those pumps would have no problem in building up a high pressure. If you have the pump apart you can judge the condition of the plunger & barrel by holding a finger over the top of the barrel and checking how the helix holds pressure. A worn plunger will allow air bubbles to escape as the plunger is raised in its working position. Just some thoughts.
Hugh
 

ronm

Subscriber
Last Subscription Date
07/10/2019
A pintle injector is just not the best choice for a direct injection engine. Every direct injection I've ever been around uses a multi-hole injector that sprays a spread pattern into a chamber machined in the head of the piston. A pintle-type is used in a precombustion chamber where the straight or cone-shaped spray shoots into the length of the prechamber.
I think what's happening is the spray from your pintle injector is impinging right on the head of the piston, where it just splatters out, becomes big globs, gets the whole combustion chamber wet, cools off & doesn't burn clean, if it burns at all. The excessive carbon buildup supports that premise...
The standard procedure on most Diesels is to have injection END at TDC, not begin.(common notation on pumps is "TIMED END OF INJECTION")... Diesel fuel doesn't ignite instantly, & if it's already past TDC when it's injected, the compression ( and heat) is going away before it has a chance to burn.
I know, a multi-hole injector is VERY hard or near impossible to build on a small scale, but maybe a small one, like a RoosaMaster pencil, could be adapted.
I approached Elden, rest his soul, a couple times early in the thread about the pintle vs. multi-hole subject, but got no traction.

Edit: I wrote this edit last night, but for some reason it didn't post...
In reading Elden's notes on his web page, I see he did do some experimenting with a Roosie pencil injector. I still think that's the tree you need to be barking up, or else pursue a precombustion chamber setup...
 
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David Jones

Registered
Thanks for the input. I have not had time to work on the Homebrew diesel. I will check the pump plunger for wear, what you describe is comparable to what I am seeing. Regarding the injector, I am sure a multi hole injector would work much better, just not quite sure how to go about building it. I will spend some time thinking about it to see what I can come up with.

Thanks again everybody for your suggestions. Hope to get back to work on it soon.

David
 

BTurney

Registered
One basic thing that affects timing and delivery volume of fuel in mechanical diesels on initial start up is always the "Hydraulic / Nitrogen accumulator effect" you get in elevated injector lines that will not properly bleed out all the air. With that high arched line it can take extra effort to bleed all the air out of the line so that you have a solid liquid fuel space which gives you the correct injection volume and not a delay in the injector opening because of the SPRING VALUE of the gas trapped within. Furthermore when you have a gas bubble trapped it may over fuel your engine after your intended injection timing on the stroke because the injector continues to flow fuel from the gas pressure within the injection line past the point that the injection lobe has reached top dead center..
I know Eldon and yourself have already overcome this issue but for someone who cant get a diesel to start by hand when its run out of fuel this is always the first thing I check on mechanical injectors. Sometimes we can start and engine with one injector bled fully and it may take several minutes under elevated load and speed to clean the air out of the other cylinder lines. Any air at all in a injection line will keep the larger percentage of mechanical pump diesels from starting especially if they are small displacement with small pumps and over sized lines for the job. I have had tractors run rough for up to 45 minutes when the engine was in a hot condition and fuel viscosity was thin at which point I finally bled the single lines at a time while running.
Very seldom do you see and injector line that rises above the injector with much elevation or distance on a commercial engine because of this reason or do you see a injector line that makes a turn downward in the direction of flow to bypass an accessory , it can happen but for the most part engineers avoid it. Now that I have said that, I understand there are some engines with injection pumps on top of the engine and everything is down hill but when you look at most commercial single or inline multi cylinder engines from reputable companies it is mostly avoided so that the operator/ service department can more efficiently overcome a air lock situation after running out of fuel or maintenance on the fuel system.
Just posted this here in case someone else is building a diesel pump & injector
I suppose that to manufacture a multi hole injector you would have to drill it with a precision EDM drill
 

Dustin D Ehli

Subscriber
Age
35
Last Subscription Date
12/20/2019
Thanks for continuing this work, I miss Eldon and his commentary.
Glad to see one of his engines is in good hands, hope is true for the others as well
 

mcmlvii

Subscriber
Last Subscription Date
04/17/2020
Thank you David for posting this information. Truly tragic what Elden went through with the hurricane, and then his sudden passing a few months later. I wish you much success in refining the Homebrew diesel.
 

Motormowers

Subscriber
Age
55
Last Subscription Date
07/13/2019
Speaking of Elden. I wonder what will happen to his web page if it expires? Is there a way to save it all so all those videos dont get lost to history?
 
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