Hot Bulb and Glow Plug Difference

[John LovegroveParticipant @johnlovegrove20877]

Thanks Jens Erik

I did not realize that there were so many manufacturers of hot bulb engines in Norway. I had heard of Dan, Grei, Rap and Wichmann, (I saw one of the latter in a visit to your country in 2008.) It seems that almost every significant port had someone making these engines.

We will be visiting again in July this year, are there any museums or collections that I should try to visit?

John

[Niels AbildgaardParticipant @nielsabildgaard33719]

The paper SAE 2002-01-0115 describes test results for a lot of early engines from Sweden.

The latest glowhead engines reached 35% thermal efficiency.

 

Edited By Niels Abildgaard on 23/05/2018 05:34:05

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Posted by John Lovegrove on 22/05/2018 16:03:52:

Thanks Jens Erik

I did not realize that there were so many manufacturers of hot bulb engines in Norway. I had heard of Dan, Grei, Rap and Wichmann, (I saw one of the latter in a visit to your country in 2008.) It seems that almost every significant port had someone making these engines.

We will be visiting again in July this year, are there any museums or collections that I should try to visit?

John

Yes, it was about 120 difference brands of hot bulb engines produced in Norway, both from factory and black smith.

About engine museum in Norway, see this map.. **LINK**

[Jens Eirik Skogstad 1Participant @jenseirikskogstad1]

Posted by Niels Abildgaard on 23/05/2018 05:33:35:

The latest glowhead engines reached 35% thermal efficiency.

Edited By Niels Abildgaard on 23/05/2018 05:34:05

Glowhead? We call it hot bulb who are correct in english..

[John LovegroveParticipant @johnlovegrove20877]

Sorry not to have replied sooner, I have been busy with some other things the last couple of days. Concerning Niels mention of the SAE paper, I did download a copy of this and was quite surprised about how well the hot bulb engines compared with the diesel and spark ignition engines tested. The one doubt I have is that the author is clearly analyzing information from tests carried out by others and has drawn an arbitrary distinction between "hot bulb" and pre-chambered diesel engines (presumably with glow plug heaters for starting.) He works on the basis that an engine with a compression ratio of less than 13:1 is hot bulb and above this it is a diesel. Most people would regard a "hot bulb" engine with a compression ratio of more than 6 or 8:1 as a "semi diesel".

Regarding the terminology; in English "hot bulb" and "semi-diesel" are the words normally used. I know that in German they use the term "Gluhkopf" which means glowing head – similar to your own terminology.

Jens Erik – thanks for the information on museums.

John

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