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135 bar injectors in a turbo?
by
87octane
on 15 Oct, 2009 14:52
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FrankenMotor rears it's ugly head again. All the injectors in my 1.8 gasser block diesel nightmare were rebuilds stamped 135 bar. The pump seems to be a legitimate 1.6 TD pump. I understand the injector could be shimmed and sprung to open at any bar, and flowing them on a test bench is required to know for sure what bar they open at. Please corrrect me if that's not right.
Assuming the 135 is accurate, what effect would that have on a turbo engine performance. Something you could feel in the seat of your pants? Some weird timing issue or maybe wrong flow volume or I don't know?
Obviously I plan on making some power out of a brand new 1.9 bottom end built right, so do I have to upgrade immediately to some built 155's?
And I plan on running grease sooner rather than later so does anybody have experience prothe's mercedes hybrid 155's?
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#1
by
burnt_servo
on 15 Oct, 2009 17:02
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don't use merc nozzles .... they have a funky spray pattern that will make the engine more smokey and less efficent.
find some gtd ( or is it gdt ??... ) nozzles with the proper vw spray pattern .
running a 135 bar pop pressure in a turbo motor can lead to the injectors poping off when the cylinder pressures get high enough to open the injectors rather than fuel presure poping them off .
if the cylinder pressure is poping the injector , you have little control of when it might occur .
thusly as you raise boost pressure you need to lift your pop pressure .
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#2
by
Syncroincity
on 15 Oct, 2009 19:47
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I have a set of brand new GTD injector nozzles for sale, if you're interested... $115 shipped.
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#3
by
Mark(The Miser)UK
on 16 Oct, 2009 03:48
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don't use merc nozzles .... they have a funky spray pattern that will make the engine more smokey and less efficent.
find some gtd ( or is it gdt ??... ) nozzles with the proper vw spray pattern .
running a 135 bar pop pressure in a turbo motor can lead to the injectors poping off when the cylinder pressures get high enough to open the injectors rather than fuel presure poping them off .
if the cylinder pressure is poping the injector , you have little control of when it might occur .
thusly as you raise boost pressure you need to lift your pop pressure .
Urban Legend?135bar injectors are fine IMO.
The opening pressure of an injector acts on the large surface area of the second step of the pintle needle. The needle seals on the small face just behind the spike, and needs say 10x the pressure of the fuel to open it. 2000psi of fuel well above 1000+ psi max of combustion, and compression pressure of 500+psi of cylinder compression....Which is what correctly injected fuel experiences...
You may need to retard pump slightly though...
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#4
by
Rabbit on Roids
on 16 Oct, 2009 08:37
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i ran 135 bar injectors with 35 psi boost. the engine ran great. never broke an injector, never messed anything up. it works fine. if someone tells you a 135 wont work in a turbo motor, they are smoking crack, and lots of it!
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#5
by
kaneb
on 16 Oct, 2009 09:24
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I have 135 bar in my NA/TD fraken engine with no issues and 18psi of boost. As this is my short term engine until my build is complete on the td.
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#6
by
jtanguay
on 16 Oct, 2009 09:33
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there was a thread a while back where someone reported better fuel mileage with the lower breaking pressure injectors... i have a pdf document that VW only increased the breaking pressure to "ensure safe fuel atomization."
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#7
by
Rabbit TD
on 17 Oct, 2009 00:12
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there was a thread a while back where someone reported better fuel mileage with the lower breaking pressure injectors... i have a pdf document that VW only increased the breaking pressure to "ensure safe fuel atomization."
I've been wondering about that myself as far as mileage is concerned. I had an old set of 135's in my N/A engine 1.6. I think they were in an Audi but had the same numers and markings as the VW ones. They had tons of miles on them but ran fine on the rebored and rebuilt engine and when I switched engines last winter the N/A was getting 52 mpg. This newly built T/D was rebuilt exactly the same way and even has the pump from the other motor on it with fresh 155's from Giles and it runs fine but the mileage is only 45 at best on the highway. Funny thing is the N/A smoked like a freight train and the T/D has hardly any but doesn't get near the mileage. How much of a mileage loss does the turbo actualy cause as a restriction at times or do they even act as a restrction. Obviously the mileage drop is due to one or the other or both
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#8
by
Op-Ivy
on 17 Oct, 2009 01:13
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135's will run fine in a TD. However you will have to retime the engine if you were previously running 155's.
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#9
by
smutts
on 17 Oct, 2009 07:39
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Intercooled SB turbodiesel. I had a set of my 155 bar injectors rebuilt by muppets. Two pissed out diesel where the muppets hadn't lapped the halves together. So those were swapped out for a pair of rebuilt 135 bar fleabay items that work fine. No holes in pistons or anything, but the engine sounds slightly more "naily" on two cylinders, so I would agree that the injection timing would need retarding when using them.
Perhaps due to the reduced drag on the timing belt, that also alows the pump to be more advanced, especially with aworn intermediate shaft bearings.
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#10
by
87octane
on 19 Oct, 2009 20:06
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My engine is a pile of parts on the shop floor. Does that mean I have to retime everything? Maybe I should buy some tools eh?
Just kidding, be calm....
So if 135's work just fine and get better mileage in a turbo, sounds like a winner. In that case, I only need to replace the single injector with the broken return line nipple, much cheaper. Maybe I'll reuse most of the gaskets as well, they don't have much mileage on them...
Now, to hijack my own thread, does the AAZ use the same ARP main studs as all the 1.6's ?
If so, does anyone have a main stud girdle you'd sell me? If so, please PM.
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#11
by
truckinwagen
on 20 Oct, 2009 11:33
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if you are going to use a girdle, the ARP studs are not going to work.
you need longer bolts/studs with the girdle, as it sits level with the bottom of the block, not the main caps.