Is there a difference between N/A injector nozzles and Turbo nozzles?

[Turbofan]

I just reringed my engine (again) and I want to make sure I'm not going to kill it as fast as I did last time. I'm upgrading my IP from a pumped up NA pump to a proper TD pump, and I want to make sure my injectors are correct. Is there a difference between nozzles, or is the difference in the cracking pressure of the injector? I seem to be finding conflicting information.. Thanks.

[scrounger]

It seems to me that vw engineers designed the pop pressure 294 psi higher with the TD injectors. Would not using the lower pop pressure give you a less vaporous mist and less efficiency.

At full boost the the intake pressure reflects about 9 psi giving you about 207 more compression psi than a NA engine. 14.7x23=338, compared to 23.7*23=545psi. Of course my numbers are just calculations not real world.

[libbydiesel]

While a lower break pressure will give worse atomization it robs less power from the crank to push the fuel.  In testing various injectors I have found the best fuel economy (after adjusting timing for various break pressures) from LOWER break pressures.  I believe the trend towards higher break pressures is to lower emissions from a more complete burn at the cost of losing efficiency.

To answer the OP, I believe the nozzle is slightly different but many have used the N/A nozzles, myself included, without any untoward effects.  

[scrounger]

Hi Libby
I can see your point about less frictional losses with a lower pop pressure. A couple questions?

What kind of mileage do you get running lower psi injectors? What kind of mileage does the TDI get running much higher psi injectors?

My last fill was 47 mpg (US), the worst in a year. Of course it is winter.

[Turbofan]

Thanks. I like the idea of not having to send my injectors our to be recalibrated. Here's a follow up question, are the injector lines the same? I.E. Are the delivery nozzles on a turbo pump the same dimensions? (I don't have the pump yet, just want to be prepared when it shows up).

[bbob203]

While a lower break pressure will give worse atomization it robs less power from the crank to push the fuel.  In testing various injectors I have found the best fuel economy (after adjusting timing for various break pressures) from LOWER break pressures.  I believe the trend towards higher break pressures is to lower emissions from a more complete burn at the cost of losing efficiency.

To answer the OP, I believe the nozzle is slightly different but many have used the N/A nozzles, myself included, without any untoward effects.  

Id be interested in knowing what timing your running with the lowered breaking pressures.

[R.O.R-2.0]

Myself personally, i like the feel of n/a injectors..

ive run both flavors in my engines...

myself personally, i think thats part of my ultra-good mileage..

i have NOT gotten under 45mpg since doing my engine swap, and i have BEAT on that car hard a few times..

still running 1mm of timing..

[EcoTX]

This guy was simply asking if there was a difference in the nozzles, not how it affects his mileage or efficiency.
Already on the 2nd post, someone brings in the breaking pressure/efficiency discussion.

That issue has been discussed and talked about not only on this forum, but many diesel forums.
Trying to figure out if 130 bar injectors are better than 155 bar in a TD motor is pointless to me.
There are just way too many variables to contend with when gathering fuel mileage data, especially from multiple people.

Unless we all had identical motors with identical compression, identical timing values, identical pumps etc, and we all drove the same roads at the same speeds on the same day...it is just crazy to take someone's word for it as the tell all end all truth.

Are there any cold hard numbers and data with pictures of anyone doing this type of experiment?  I haven't found it.
That means I take it with a huge grain of salt, like a lot of stuff you read on the internet.
If you really want to know, experiment yourself on your car on your roads with your driving style.
Otherwise take someone's word for it and be forever happy thinking your 130 bar injectors are a MPG upgrade.
Hell might as well throw 100 bar injectors in there for like +15 MPG upgrade going by the logic "lower is better" right?

[R.O.R-2.0]

This guy was simply asking if there was a difference in the nozzles, not how it affects his mileage or efficiency.
Already on the 2nd post, someone brings in the breaking pressure/efficiency discussion.

That issue has been discussed and talked about not only on this forum, but many diesel forums.
Trying to figure out if 130 bar injectors are better than 155 bar in a TD motor is pointless to me.
There are just way too many variables to contend with when gathering fuel mileage data, especially from multiple people.

Unless we all had identical motors with identical compression, identical timing values, identical pumps etc, and we all drove the same roads at the same speeds on the same day...it is just crazy to take someone's word for it as the tell all end all truth.

Are there any cold hard numbers and data with pictures of anyone doing this type of experiment?  I haven't found it.
That means I take it with a huge grain of salt, like a lot of stuff you read on the internet.
If you really want to know, experiment yourself on your car on your roads with your driving style.
Otherwise take someone's word for it and be forever happy thinking your 130 bar injectors are a MPG upgrade.
Hell might as well throw 100 bar injectors in there for like +15 MPG upgrade going by the logic "lower is better" right?

good thing you didnt ask the question

now quit your b!tch!n..

[theman53]

I think what Giles told me was that there is no difference in the N/A vs the TD nozzles. The GTD nozzles they are different.

[scrounger]

Hi Theman53 and others,
What are GTD nozzles? We all want the most efficient! With the price of diesel approaching 3.80 a gallon, who wants to waste it.

So the consensus on this list is that there is no difference in running with pop pressure, once you account for the advance in timing that the lower pressure gives? It is just for emissions? There seems to be a mathematical basis for having higher pressure, were the German engineers who designed the engine not doing their job?

It would make for an interesting test trying various injectors in one engine.

I wasn't able to get better than 55 mpg or worse than 54 all summer I was running old bosch 155 injectors, every time it would start it would leave a black spot on the ground at the exhaust. Starting this tank I am running new Chinese un-tuned injectors, their saving grace is that they cost 14 dollars each. So far ok.  No black farts on the ground. I am going to get my old ones rebuilt. The weather is now super suck, 5-30 degreesF.

[Turbofan]

Thanks for all your thoughts. I guess confirms my suspicions. The higher cracking pressure on the turbo injectors makes perfect sense, as you are overcoming boost. For some reason I spaced that aspect. I'd be curious if lower cracking is actually mote efficient  though. I see what you are saying about less power taken from the crank, but inefficient combustion/atomization is exactly that, inefficient. I guess the real way to see this is by calculating bsfc on a dyno with each of the injectors. Then, we could put that debate to bed.

Again, I greatly appreciate everyone's contributions. Thanks.

[R.O.R-2.0]

Hi Theman53 and others,
What are GTD nozzles? We all want the most efficient! With the price of diesel approaching 3.80 a gallon, who wants to waste it.

So the consensus on this list is that there is no difference in running with pop pressure, once you account for the advance in timing that the lower pressure gives? It is just for emissions? There seems to be a mathematical basis for having higher pressure, were the German engineers who designed the engine not doing their job?

It would make for an interesting test trying various injectors in one engine.

I wasn't able to get better than 55 mpg or worse than 54 all summer I was running old bosch 155 injectors, every time it would start it would leave a black spot on the ground at the exhaust. Starting this tank I am running new Chinese un-tuned injectors, their saving grace is that they cost 14 dollars each. So far ok.  No black farts on the ground. I am going to get my old ones rebuilt. The weather is now super suck, 5-30 degreesF.

higher break pressures DO negate performance..

lower break pressures take less power from the engine to pump the fuel to that pressure..

just think of it, higher break pressure requires the pump to produce a higher line pressure, and in turn, it takes more power from the engine, to turn the pump..

so, in theory, you should get better power and economy with lower break pressures, rather than higher break pressures..

higher break pressure will atomize the fuel better, but we run IDI diesels, they have swirl chambers where the fuel is atomized EVEN MORE than when it comes out of the injector.. we can get away with lower break pressures, and larger fuel atomization..

[scrounger]

Oh great thanks Ror.
What MPG info do you have when you have run 135 vs 155?
My data  points are lacking.
My car was giving the Hershey squirts with the old injectors.  They were marked 155BAR but I assume were lower and were worn. My new injectors are made in China, are supposedly set to 155 but who really knows. I figure that any fuel that is not atomized just goes out the exhaust as liquid.

I wonder if injecting a fraction of a gram of fuel at 10% higher pressure actually adds that much more resistance.

Hi Theman53 and others,
What are GTD nozzles? We all want the most efficient! With the price of diesel approaching 3.80 a gallon, who wants to waste it.

So the consensus on this list is that there is no difference in running with pop pressure, once you account for the advance in timing that the lower pressure gives? It is just for emissions? There seems to be a mathematical basis for having higher pressure, were the German engineers who designed the engine not doing their job?

It would make for an interesting test trying various injectors in one engine.

I wasn't able to get better than 55 mpg or worse than 54 all summer I was running old bosch 155 injectors, every time it would start it would leave a black spot on the ground at the exhaust. Starting this tank I am running new Chinese un-tuned injectors, their saving grace is that they cost 14 dollars each. So far ok.  No black farts on the ground. I am going to get my old ones rebuilt. The weather is now super suck, 5-30 degreesF.

higher break pressures DO negate performance..

lower break pressures take less power from the engine to pump the fuel to that pressure..

just think of it, higher break pressure requires the pump to produce a higher line pressure, and in turn, it takes more power from the engine, to turn the pump..

so, in theory, you should get better power and economy with lower break pressures, rather than higher break pressures..

higher break pressure will atomize the fuel better, but we run IDI diesels, they have swirl chambers where the fuel is atomized EVEN MORE than when it comes out of the injector.. we can get away with lower break pressures, and larger fuel atomization..

[745 turbogreasel]

I figure that any fuel that is not atomized just goes out the exhaust as liquid.

No, it sticks and burns a hole in the prechamber.