Injector HP Fuel Line - How to Make?

[Wotname]

Originally Posted by Ecos

They don't even use the good stuff for those Perkins injector hoses. Probably really meant for emergency repair.
You could TIG weld some -3 JIC fittings to the end of the old line, use MIL-spec fittings with 3000psi hose.

Interesting to know that hose is used by Perkins...

Originally Posted by Ecos

That kind of hose has a 10 year life, how about your warranty?

Hmm I'm not sure if I want to know but I will alter my warranty statement to have a lifetime warranty

[Wotname]

[QUOTE=Ecos;2976868][QUOTE=Compass790;
Can't guess at his personal warranty but I'd rather have an engine he rebuilt than any regular commercial enterprise rebuilt engine with a warranty provided his labour hours weren't included in the asking price

Do you remember the time he was refurbishing a fuel cap?[/QUOTE]
You have just reminded me that I am spending too much time at the keyboard

[Wotname]

Originally Posted by Jim Cate

Hey, I've seen that cap and the tank that it seals... and they are beautiful to gaze upon.

And at his hourly wage of 0.00 AUD, it was a bargain!

Jim

Aww gee



My shout next time you get this far south

[Wotname]

Originally Posted by RaymondR

You cannot use hose.

The reason that the injector lines are so thick walled on these little motors is not because of the pressure they experience, the burst is probably around 12,000 - 15,000 psi, it is because with the miniscule amount of fuel pumped each time the compressibility and line expansion would probably result in none through the injector nozzles.

Originally Posted by Jim Cate

^^^^^

That would be my opinion as well, unless there is some sort of super hose that emulates the properties of heavy walled steel tube. Just having a high burst pressure ain't enough!

Jim

This was my initial thoughts also but I'm happy to listen to posts that are pro and con.

So please keep slugging it out and I'll make my mind up later to see if the idea is worth pursuing (i.e. who is right and who is wrong). - mind you, most of the time with black and white statements, the devil is in the detail.

[Compass790]

It's not my opinion because I've seen flexible diesel injection lines for sale.
The way I suspect they work is the injection pump would pump them up to their expansion limit or the injection v/v opening limit ( or both) & the delivery v/v ( non -rtn) in the pump holds that pressure until the next squirt of fuel.
But it's only an opinion but they must work for whatever reason if they sell them.
Anyway it's a moot point as Wotname will be buying or making steel lines I bet.

[RaymondR]

Originally Posted by Compass790

It's not my opinion because I've seen flexible diesel injection lines for sale.
The way I suspect they work is the injection pump would pump them up to their expansion limit or the injection v/v opening limit ( or both) & the delivery v/v ( non -rtn) in the pump holds that pressure until the next squirt of fuel.
But it's only an opinion but they must work for whatever reason if they sell them.
Anyway it's a moot point as Wotname will be buying or making steel lines I bet.

Flexible hose injector lines would be allowable on common rail injector systems because the fuel metering is done at the injector and the supply to the injector is held constant at the injection pressure by a single high pressure pump. In fact the fuel computer on some systems with trigger a warning at a substantial reduction and eventually shut the engine down on some common rail systems if the supposedly constant pressure falls bellow a certain value.

The upsets on the ends of large pipes are usually formed using induction heating. The pipe is placed in a holding jig and the induction coil positioned at the start point for the upset. A narrow band of heated circumference is bought up to forging temperature and pressure applied to the end of the pipe swelling the heated circumference. The induction coil moves slowly towards the end of the pipe heating as it goes.

Piece of cake Wottie, all you need is a powerful RF generator and a coil, chuck the pipe in your lathe and use the tail stock to apply the swelling pressure.

[Compass790]

Originally Posted by Wotname

This was my initial thoughts also but I'm happy to listen to posts that are pro and con.

So please keep slugging it out and I'll make my mind up later to see if the idea is worth pursuing (i.e. who is right and who is wrong). - mind you, most of the time with black and white statements, the devil is in the detail.

happy to avoid chores & keep slugging it out

One example of the supposedly " not possible " flexible diesel injection line..https://www.ebay.com/itm/Emergency-D...AAOxyzHxRJm1rI

I'm sure there are plenty more examples out there but that was 1st hit on google. Ecos already said they are avaliable for 4108 Perkins which I dont believe are common rail.
I just say it's possible not desirable, as it says in the listing, " not intended for permanent replacement"
As you say the devils in the detail
Keep working on that 6mm o.d., 2mm i.d. certified steel pipe hunt Wotname whilst I await the next salvo

[RaymondR]

Originally Posted by Compass790

happy to avoid chores & keep slugging it out

One example of the supposedly " not possible " flexible diesel injection line..https://www.ebay.com/itm/Emergency-D...AAOxyzHxRJm1rI

I'm sure there are plenty more examples out there but that was 1st hit on google. Ecos already said they are avaliable for 4108 Perkins which I dont believe are common rail.
I just say it's possible not desirable, as it says in the listing, " not intended for permanent replacement"
As you say the devils in the detail
Keep working on that 6mm o.d., 2mm i.d. certified steel pipe hunt Wotname whilst I await the next salvo

A couple of decades ago there was an Australian naval vessel where the steel injector lines had been modified to flexible hoses. A failure of a hose caused an engine room fire which killed two of the crew. The coronial inquiry attributed the cause to the hoses being unsuited to long term exposure to the extreme levers of deleterious pulsation, that is a combination of high pressure pulses with rapid and extended application causing fatigue failure of the subject hoses.

These factors may be overcome with design but at some point the use of steel piping becomes more practicable.

[wsmurdoch]

The frequency of failure of high pressure injection lines on large diesel engines is large enough and the consequences disastrous enough to require double wall tubing on the solid injector lines. The outer tube contains the leak directing it to a safe location and sounding an alarm.

https://en.wikipedia.org/wiki/Jacket...injection_pipe
Fuel lines - Fluid Mechanics

[model 10]

So à Perkins at 2000 rpm is pulsing eaçh çylinder 500 times per min to 1600 psi max? That is so lame. 3000 PSI systems do that in Mill seconds, with hoses.

[model 10]

Now I'm thinking you could forge new ends on a piece of tube. It would take a little practice, but you could chuck the tube in the lathe, heat up the end and forge a lump on it. Then it would be a matter of machining it to the right shape.
Piece of cake.

[Wotname]

Originally Posted by Ecos

Now I'm thinking you could forge new ends on a piece of tube. It would take a little practice, but you could chuck the tube in the lathe, heat up the end and forge a lump on it. Then it would be a matter of machining it to the right shape.
Piece of cake.

Hmm... might be a possibility if I can't find an easier way. I have an old injector body that is otherwise useless and I could use that as a former when bashing the heated pipe. That should get it close to the proper size and then machine accordingly.

Maybe a piece of cake for you

But just doable for me

Thanks for the idea!

[RaymondR]

Originally Posted by Ecos

So à Perkins at 2000 rpm is pulsing eaçh çylinder 500 times per min to 1600 psi max? That is so lame. 3000 PSI systems do that in Mill seconds, with hoses.

Common rail systems provide fairly consistent high pressure to the injector which does not cycle from zero to the injector breaking pressure. The computer on the common rail diesel system in my van will shut the engine down when it senses a significant pressure drop on the common rail interpreting it as a stuck open injector which would damage the engine through pre-ignition.

In contrast the pump on a conventional diesel pressures the line to the injector breaking pressure and drops it back to zero on each power stroke of the cylinder.

[S/V Adeline]

Originally Posted by RaymondR

You cannot use hose.

The reason that the injector lines are so thick walled on these little motors is not because of the pressure they experience, the burst is probably around 12,000 - 15,000 psi, it is because with the miniscule amount of fuel pumped each time the compressibility and line expansion would probably result in none through the injector nozzles.

When we had a steel line fail we got a high pressure 'hose' custom made to get going again.
Seems to work fine.
We purchased 4 new steel lines and are keeping the hose for an emergency spare, as it will replace any line (and cost twice what the full set cost)

[Wotname]

Originally Posted by RaymondR

.....

In contrast the pump on a conventional diesel pressures the line to the injector breaking pressure and drops it back to zero on each power stroke of the cylinder.

I'm curious (and pedantic) - does the pressure really drop back to zero?

I always understood it only dropped back to just below the injector breaking pressure with that pressure being held the non return valve at the outflow of the pump - maybe I have the horse by tail of course.