Cut Delivery Valves: Has anyone done it? - Page 6 - PeachParts Mercedes-Benz Forum

Diesel911 · #76 02-09-2010, 02:28 AM

Quote:

Originally Posted by mytmousemalibu

Well im gonna go out on a limb here... Im actually colorblind, LOL!

The Yellow dot? center dot on the right picture. the tapered surface. It seals against the DV holder. If that surface gets damaged, it wont seal properly and the injection charge can back bleed. If its leaking, its going to make each injection pulse be forced to refill the line with fuel and residual pressure charge when it should be poping the injector open. So that means less fuel injected. You can even see in that pic the thin line/wear band on the seat surface where it seals to the holder.

In between the Yellow/green dots, is the collar, now the MBZ ones look basically the exact same. The collar is a super close fit to the bore in the holder. With it that way, I presume very little fuel gets past that collar till injection pressure forces the valve out of the holder far enough the collar is pushed out. If the collar is modified by removal or cuts, you can visualize that the injection pressure forces more directly against the valve seat area so it only needs to be pushed up ever so slightly for the injection charge to get past it. Lookin at it from that point of view, the fuel injection should occur sooner (timing advanced) and the valve only being pushed out a bit less, it should close faster. That may possibly trap more residual pressure in the line that way? Maybe a diesel injection expert can comfirm that, but i can kinda see how this may be working out now.

I was reading this thread out of curiosity.
The collar/ring on the Delivery Valve is there to cause something called "Fuel Retraction".

And, it is actually there for use at the end of Injection to modify and deminish the pressure wave created inside of the Hard Line.
It is one of they ways they use to keep the Hard Lines from erroding from inside out and to reduce vibration in the Hard Lines.

OM616 is on the mark concerning the diaplaced volume;that is what dampens the pressure wave I was speaking of.

tomnik · #77 02-09-2010, 07:03 AM

Ian,
the 6.5mm MW elements are my own creation.
I can sell a piece for 75 EUR.

Diesel911,
the "thickness" and location of the collar together with the spring makes the difference. The volume above the collar to the cone is the volume that is retracted, the more the safer regarding second injection but also decreasing the fuel that exists the injector.
Then there is the collar height or thickness which provides different DV plunger lift until fuel gets into the hard lines.
From my understanding a low and thick collar is responsible for moving a certain amount of fuel just back and forth.

Tom

Ian White · #78 02-09-2010, 11:12 AM

Tom, what kind of luck have you had using these?

Diesel911 · #79 02-09-2010, 11:34 AM

Quote:

Originally Posted by tomnik

Ian,
the 6.5mm MW elements are my own creation.
I can sell a piece for 75 EUR.

Diesel911,
the "thickness" and location of the collar together with the spring makes the difference. The volume above the collar to the cone is the volume that is retracted, the more the safer regarding second injection but also decreasing the fuel that exists the injector.
Then there is the collar height or thickness which provides different DV plunger lift until fuel gets into the hard lines.
From my understanding a low and thick collar is responsible for moving a certain amount of fuel just back and forth.

Tom

Thanks for the more extensive explanation.
When I was in Trade School they simply gave us a simple explanation for the Collar. And, the focus of the School was to repair things to Factory Specs so they did not delve into more than that.

OM616 · #80 02-10-2010, 12:08 AM

I came across this the other day. It is out of an old Bosch manual but the principals are there.

tomnik · #81 02-10-2010, 12:43 AM

Quote:

Originally Posted by OM616

I came across this the other day. It is out of an old Bosch manual but the principals are there.

Too small, can you post large pics or the pdf?

Diesel911,

repairing these things is a good step for tuning them in sense of understanding.

Ian,

the luck is that the elements are running very smoothly and I have the bench data that confirms the perfectly balanced delivery and an out put of nearly 80ccm/1000 revs, but the VTG boost control is still missing on my car so no test run except some night driving down the street with boost control via foot.

Tom

Ian White · #82 02-10-2010, 12:51 AM

Did you have these source to Myna? I assume these are not hardened like the factory samples. I imagine this has taken quite abit of time on a test bench and quite a bit of greenbacks.

OM616 · #83 02-10-2010, 01:14 AM

Quote:

Originally Posted by tomnik

Too small, can you post large pics or the pdf?

Tom

Here is the link to where I found it.

http://www.oldengine.org/members/diesel/Injection/AmbacMenu1.htm

tomnik · #84 02-10-2010, 07:31 AM

thanks for the link.

Ian, you mean that the MW6.5mm come from Myna?
No, they only sell M, not MW (as far as I know).
I took stock 5.5 elements and increased the bore to 6.4..mm.
New plunger with custom control edges and both matched.
The raw material of the plungers follows the Bosch tolerances for the material, as well as the hardening treatment.
The barrels are hardned through and except the fuel supply bore and lubrication grooves no more modification.

Tom

Ian White · #85 02-10-2010, 08:05 PM

Wow,

What sortof machine shop did you have the work performed at? This stuff is way too small for my shop's capability.

Ian

tomnik · #86 02-11-2010, 01:56 AM

Quote:

Originally Posted by Ian White

Wow,

What sortof machine shop did you have the work performed at? This stuff is way too small for my shop's capability.

Ian

I can't tell but you need special machines. An universal machine shop will never be able to do all the steps (material, hardening treatment, precision,..) or you just can't pay it. The manufacturer is a big company and not working for private people (it was a long lasting discussion and at the end I had to meet the general manager to get my things done).
An universal machine shop does not know where are the key functions and how to do quality tests, besides all the test equipment, no chance.

Tom