Mini diesel engine.

Help Support HMEM:

Peter Twissell

Well-Known Member
HMEM Supporter
Joined
Nov 13, 2019
Messages
299
Reaction score
136
Location
United Kingdom
Some steels, generally the lower strength grades like EN8, are very difficult to achieve a good finish with.
EN24 and EN16 can be finished to a mirror like condition by polishing.
 

weir-smith

Bruce W-S
Project of the Month Winner
Joined
Jan 30, 2015
Messages
63
Reaction score
58
Location
Perth Western Australia
Minh

I refer to my original comments re injectors and the difficulty of getting a good seal with the injector nozzel. I would suggest that you spend a few dollars typically $10 Au and purchase an injector nozzel via ebay of the pintle type or see if you can scrounge one from an injector repair shop. The pintle pin can be used on its own with your injector body.
The pin has been ground to a level that you will never achieve and I have found them to work very well op to 2000 psi.

Bruce
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
764
Reaction score
453
Location
Viet Nam
tim9lives !
Thanks !
Peter Twissell !

are very difficult to achieve a good finish with.
That's the problem I'm trying to solve .

weir-smith !
Minh

I refer to my original comments re injectors and the difficulty of getting a good seal with the injector nozzel. I would suggest that you spend a few dollars typically $10 Au and purchase an injector nozzel via ebay of the pintle type or see if you can scrounge one from an injector repair shop. The pintle pin can be used on its own with your injector body.
The pin has been ground to a level that you will never achieve and I have found them to work very well op to 2000 psi.

Bruce
Thank you for the advice! It is definitely an option if I cannot make needles and nozzles airtight
I have several options for making needles and nozzles and can change to a different injection style
Anyway, there's no time limit, so I'll find a way to do it, I hope so :)
 

Mechanicboy

Well-Known Member
Joined
Jul 10, 2013
Messages
747
Reaction score
246
With patient, you did the injector airtight. Next: test to see the fuel is atomized. :)
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
764
Reaction score
453
Location
Viet Nam
ajoeiam !
Please - - - - I'd like to see a pic of the injector spray pattern . . .
I'll look for the needle, but that's faulty I'll take a picture for you, it's the same.


Mechanicboy !
Yes, I will try it when I make pump.
When I cleaned and assembled and completed it, I tested injection with fuel by pneumatic pressure, I felt it was quite good , everything seems right, I hope so..
 

ALEX1952

Well-Known Member
Joined
Jan 17, 2018
Messages
86
Reaction score
22
Location
SCOTLAND
Please do not be tempted to put a finger over or near the spray pattern fuel will enter your body, worst case it can kill. I am no expert but I did spend 40 yrs in diesel fuel injection manufacture, and this is the first thing you are told.
The snoring noise is the imjector opening and closing, pump produces pressure, injector opens, pressure decays, injector closes. It takes a high speed camera to capture one cycle. One problem you will have is getting it to open and close quick enough, hence the exremmely high pressures (more than stated here) and high spring pressure. iIts one of the reasons why diesel went electronic (common rail etc) where injection is controlled by actuators. Its also easier to tinker with if its not producing the desired results. Sorry to waffle.
 

minh-thanh

Well-Known Member
Joined
Dec 29, 2016
Messages
764
Reaction score
453
Location
Viet Nam
ALEX1952 !
Please do not be tempted to put a finger over or near the spray pattern fuel will enter your body, worst case it can kill. I am no expert but I did spend 40 yrs in diesel fuel injection manufacture, and this is the first thing you are told.
Thanks for your advice and warning !
"Expert " :
I don't need you or someone must be an expert to give advice or warning ....
Any suggestions, comments,... based on experience or knowledge ... that is good for me.


One problem you will have is getting it to open and close quick enough, hence the exremmely high pressures (more than stated here) and high spring pressure. iIts one of the reasons why diesel went electronic (common rail etc) where injection is controlled by actuators. Its also easier to tinker with if its not producing the desired results. Sorry to waffle.
"getting it to open and close quick enough" : I am learning about this
although I do know a little bit about electrical circuit, but first: i need to make a diesel engine that it can run (i hope) and then i can think more about injector control by electric

Thanks !
 

ALEX1952

Well-Known Member
Joined
Jan 17, 2018
Messages
86
Reaction score
22
Location
SCOTLAND
Lucas diesel systems which became Lucas Varity then Delphi the last two being American.
In minh-thanhs last post I don't understand the comment in bold, if it is to chastise for making a comment that was made with good intentions then it could have been better. this is a forum for helping each othe,r whether the advice be good bad or indifferent and comments in reply should at least be civil. I'm getting a bit sensitive in my dottage (my attempt at humour}.
 

ozzie46

Well-Known Member
Joined
Dec 12, 2008
Messages
1,232
Reaction score
40
I think he is saying a person doesn't need to be an expert to offer advice. Anyone is welcome to comment.
At least that's the way I take it.

Ron
 

grahamgollar

Member
Joined
Jan 14, 2020
Messages
19
Reaction score
9
Further to the comments by Alex1952, when I was at sea on vessels with propulsion engines up to 40,000BHP we regularly overhauled injectors. Once reassembled and connected to a (hand operated) test pump the pressure was applied slowly up to just before the point of injection and held there for 30secs. this was to check whether there was leakage between the pintle and its seat. If there was no evidence of fuel from the spray holes then the pump was fully depressed to check the spray pattern. These tests were carried out using MDO (Marine Diesel Oil) but once in service the injectors were operated on HFO Heavy Fuel Oil) which had 180 or 380mm2/sec viscosity so if the injectors worked well on MDO they were sure to be ok on this boiled treacle! Fingers were never put near the nozzle tip during the tests!

Oh - by the way, definition of an expert: an EX is a has-been and a SPERT is a drip
 

ALEX1952

Well-Known Member
Joined
Jan 17, 2018
Messages
86
Reaction score
22
Location
SCOTLAND
It was a full time job for one man to set up enough injectors using the hand pump you mentioned with a test oil to satisfy all the test machines about 100 of them each taking from 3 to 8 injectors all to different specs. with regards to the drip which is why a lot of vehicles have high smoke the plintle (we called it a needle) and nozzle were match ground, and to a certain degree provided a seal, the contact area between pintle and nozzle is very small as are the holes down to .2mm if memory serves and as you say probably more than one. You are obviously talking about the good old days when you could recondtion things and not chuck them as is the norm today. As an aside the needles make superb centre punches they just never need regrinding.
 

Richard Hed

Well-Known Member
Joined
Nov 23, 2018
Messages
1,001
Reaction score
220
Location
Seattle
Lucas diesel systems which became Lucas Varity then Delphi the last two being American.
In minh-thanhs last post I don't understand the comment in bold, if it is to chastise for making a comment that was made with good intentions then it could have been better. this is a forum for helping each othe,r whether the advice be good bad or indifferent and comments in reply should at least be civil. I'm getting a bit sensitive in my dottage (my attempt at humour}.
No, no no no, Minh Tahn was not chastising--please let it go. He was explainng that YOU do not needs to be an expert in order for him to take your hint and warning. That is, anybody giving good information on safety is accepted.
 

Latest posts

Top