VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: Turbofan on January 16, 2013, 05:30:50 am
-
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.
-
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.
-
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.
-
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.
-
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).
-
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.
-
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..
-
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?
-
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..
-
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.
-
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.
-
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.
-
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..
-
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..
-
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.
-
Scrounger If you are thinking the 20 bar difference is only 10% increase then check this out.
155 bar = 2 248.08493 pounds per square inch
135 bar = 1 958.00946 pounds per square inch
20 bar but 290 psi. 290/ 1958 = .1481 or roughly 15% of the base value.
I would have to guess a bit more work needs to happen to get that increase. How much HP? I can't tell you that, I have no way to calc it.
-
The GTD nozzles are different. Giles told me that they are not that much different in function, but they cost about 4x as much per nozzle. I have never seen the GTD nozzles, but they are the ones that came in the GTD cars. They had them in Europe I believe and they were intercooled and had more HP than what we got in the US in the TD cars. IIRC the GTD may have had a water cooled turbo, but that doesn't affect the nozzle discussion.
-
If your interested in GTD nozzles one place you can get them is at Greaseworks (google). They are made by Bozio and supposed to be pretty good...Justin could probably help with GTD questions.
:)
Some folks swear by Monarks for Mercedes diesels; i run Elsbetts for Mercedes (for vegetable oil) and they have been a big improvement over Indian Bosch nozzles when running 50% diesel too. They are troughed, like Monarks
-
So if 135 bar nozzles give better mileage than 155 why not go down further. Surely 100 bar would give less pumping loss. My point is why would an engineering team choose the 'wrong' pop off pressure.
I have always used 14.7 psi as standard pressure (1BAR). The 'new think' is going with 14.5. Not sure why std units are not used.
I wrote to the Mercedes source who I was told was the distributer for monach and they told me that they couldn't help me with tuning a set of injectors for my vw.
-
I wrote to the Mercedes source who I was told was the distributer for monach and they told me that they couldn't help me with tuning a set of injectors for my vw.
That's weird...i bought a set of Monarks from Mercedessource.
Here is the quote from my e-mail box one of the e-mails (i bought a set then, but then i got the Elsbetts instead...blah, blah):
"Yup the 261 cross references directly to my monark nozzles for the mercedes from 1968-1985
https://mercedessource.com/node/4757"
They were referring to DNO SD261 which is different from the usual DNO SD293 Boschs i had before of course.
Merc nozzles are set to 115 bar for non-turbo; for the Elsbetts, i set them at 135bar for the 1.6 NA since my pump is set at 1.00. Don't know why that wouldn't work for Monarks but i am not the one on this forum to rely on about this.
D'oh! now i see the link has them sold out right now
:-[
-
Here is a copy of my msg and theirs (Mercedessource)
HI Dave
I am sorry we do not have any monark Nozzles for VW
kaia
On Jan 13, 2013, at 7:01 AM, [email protected] wrote:
Dave sent a message using the contact form at http://mercedessource.com/contact. Can I get a set of 4 nozzles tuned to 155 bar for my 1986 1.6 Jetta TD? Thanks.
-
this is the e-mail the above was a reply to:
Kaia,
The source i read for the info lists the Mercedes nozzle that would fit the VW as:
DNO SD261
So i think that i am looking for the Monark nozzle that replaces that Bosch part.
The usual VW nozzle part number(s):
DNO SD273 and also listed as DNO SD293
-
I have tried 150 bar and 160 bar injectors with new nozzles in the same engine. I always set the timing using a diesel pulse adapter and strobe to 12° BTDC and so the actual start of injection is the same. The 160 bar got dramatically worse mileage (approx 15%) with similar driving. I have also used the 135 bar nozzles, but not as scientifically. I believe there is a point of diminishing returns with dropping the injection pressure where the atomization gets bad enough to waste more fuel from the incomplete burn than is saved from the pumping losses. I also believe that the trend to higher break pressures is not for performance or fuel economy but rather for emissions. I have always wanted to take the time/money and make up several sets of injectors in order to find the peak for these engines but have always had higher priorities.
-
There was someone on here long ago that did some testing using the long drive to work.
And found 125 to be the most efficient.
With efficiency dropping off below that.
I couldn't begin to find the post but it stuck in my mind.
Yeah I know, it's not scientific proof so believe at your own risk.
Not sure if that was TD or not.
-
I also believe that the trend to higher break pressures is not for performance or fuel economy but rather for emissions.
Seems to be.
Some mention of that in this overview:
http://files.nequam.se/greenCarLecture.pdf
More on combustion & modeling:
https://www.princeton.edu/cefrc/Files/2012%20Lecture%20Notes/Reitz/Princeton-CEFRC7.pdf
http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/adv_combustion/ace001_musculus_2012_o.pdf
http://www.transportation.anl.gov/pdfs/EE/715.PDF
-
Nice links Tyler, but a bit complex, and mostly related to direct injection engines! Turbofan, what exactly happened to your last engine? there are a few rules to follow for better engine life!
-
Honestly, nothing significant happened. Over the summer I ripped the head off it because I wanted to fix the oil leaking from the head gasket, as my gf was less than thrilled about the oil mark in the driveway. I too wanted to fix the oil leak, as I deal with enough leaky motors at work (where I wrench on Land Rovers). While the head was off, I cleaned the piston crowns by adding a bit of diesel to each of the cylinders. I found 2 cylinders (1 and 3 I think), wouldn't hold fluid as the others did, so I pulled the pistons, ball honed the cylinders and re-ringed it. It seemed fine, and had good power (I could more or less keep up with my gf's 2010 tdi on the highway) and was getting decent mileage, but something was still off.
http://www.vwdiesel.net/forum/index.php?topic=31754.msg289801#msg289801 (http://www.vwdiesel.net/forum/index.php?topic=31754.msg289801#msg289801)
Basically, it would idle fine when cold and I first started it, but it would smoke like hell.If I put a load on it, it would miss for the first 15-20 seconds. I should mention at the same time I did the HG, I had the injectors professionally rebuilt, with Bosch nozzles. I decided to go over the basics, and bought a compression gauge from GSI (http://www.gsiindustries.com/cgi-bin/Order/data.pl?id=6610 (http://www.gsiindustries.com/cgi-bin/Order/data.pl?id=6610)) (they will sub out the gm 6.5 adapter for the tdi adapter for no charge btw!) and found that compression was not as even as it should be, and ranged in the 300's with one cylinder at 400. I think the Bentley suggested the wear limit was 400, so I was effectively below that on all cylinders. So as I was on break from school, I pulled the Golf in once again and pulled it apart, this time having the machine shop check the bores (which ended up being perfect). They cleaned it, honed it, and once again I bought some new rings and put it back together. I started this post as I finally bought a TD IP from another member, and was wondering if it would be worth it to have the correct TD nozzles on my injectors and have them adjusted to the correct break pressure. I'm hoping for the ability to get better than 42 mpg. I was running a AAZ camplate in my IP, which I will swap over to my TD pump, and I was gov modded, BUT I also new how to drive with love and respect. I suspect my NA pump was just pumping too much fuel into my motor (though my EGT's remained in the safe zone).
So here's a new non-related question. Have any of you ever run into a crack gear that had a small amount of play on the crankshaft? Neither the key on the gear nor the crank look worn at all. Interestingly, whenever I played with my timing, I couldn't quite get the timing pin into my IP, and I'm wondering if the gear was off by a little bit. I should be able to find out the conclusion to my exciting story on Friday, when I work again and put it back together.
-
......................
So here's a new non-related question. Have any of you ever run into a crack gear that had a small amount of play on the crankshaft? Neither the key on the gear nor the crank look worn at all. Interestingly, whenever I played with my timing, I couldn't quite get the timing pin into my IP, and I'm wondering if the gear was off by a little bit. I should be able to find out the conclusion to my exciting story on Friday, when I work again and put it back together.
There should be no play between crankshaft and crank sprocket. Did you remove the cam sprocket when you set the timing? You have to do that in order to get the timing exact and get the timing pin aligned in the IP sprocket.
-
So if 135 bar nozzles give better mileage than 155 why not go down further. Surely 100 bar would give less pumping loss. My point is why would an engineering team choose the 'wrong' pop off pressure...
Lower breaking pressure gives better mileage to a point, just like thinner oil gives you better mileage, to a point, and that point is when you cause excessive wear and/or seize your engine by running too thin oil..
Like others have mentioned, higher breaking pressures are mostly for reduced emissions. Also, on a TD, the cylinder pressures are higher under boost, so injectors that spray with more pressure might be beneficial.
-
I did a hone/re-ring on an idi some years ago, the ring end gap was right at the large end of the manufacturers tolerance, (60 thou), the engine took a good 10,000 kilometres to break in, and then still had a small amount of blowby (I got a bit carried away with the hone). Starting that engine from cold didn't result in any missing until I retarded the camshaft timing around 6 degrees (for better top end breathing), then on the 0 degrees c. mornings it didn't quite have enough cylinder pressure/heat to light the charge for the first 10 to 20 seconds on 1 or 2 cylinders as retarding the camshaft means that the intake valve closes a bit later on the comp. stroke, allowing some reversion. Any other missing on cold startups has always been because of air finding it's way into the injection pump on my vehicles. Surely your new injectors have had their pop pressures set correctly, unless you got them done on a friday afternoon when everyone is in a rush to get to the pub, or monday morning when most folk are still in recovery mode!!
-
I do loosen the cam sprocket when I retime the pump. I'm wondering if it was a fuel issue at this point. My car was at the point where I rarely used the cold start lever, unless it was around 0 (c), or just above. When my injectors were rebuilt, the rebuilder told me they were so bad they weren't really atomizing fuel anymore. Time will tell if the problem is fixed. I'm preparing myself to find out my new used pump will need a rebuild, or reseal at the very least. I'll look at the guts tomorrow when I throw the camplate in.
-
The cam timing doesn't change when the pump timing is adjusted.
-
I do loosen the cam sprocket when I retime the pump. I'm wondering if it was a fuel issue at this point. My car was at the point where I rarely used the cold start lever, unless it was around 0 (c), or just above. When my injectors were rebuilt, the rebuilder told me they were so bad they weren't really atomizing fuel anymore. Time will tell if the problem is fixed. I'm preparing myself to find out my new used pump will need a rebuild, or reseal at the very least. I'll look at the guts tomorrow when I throw the camplate in.
If you loosened the cam sprocket when the timing was set with the timing pin aligned, and you could not get the timing pin in on subsequent timing checks, then something is not right. If you have play between the crankshaft and the crank sprocket, that could throw the algnment of the timing pin off.
-
Agreed. My guess is the last time I did I had it apart, I didn't notice the play, and when I put it back together, it was a bit off, which is why the timing pin would no longer fit. I'm going to see if I get it back together right just so I could drive it, and in the mean time look for a replacement cog. I REALLY hope it's the cog that's beat, and not the crank.
**Yay!** Just found a replacement sprocket from GAP for $17. It'll be here on Saturday, so I guess I won't just slap the thing back together. My guess is this was probably my problem all along. When I originally turbo'ed my engine years ago, it went like crazy until one day when it just had a little less power, which is how it stayed. I'm guessing that the timing between the crank/cam timing was a little off, but luckily not off enough to mash valves. I can't wait to get this back together. Funny that I can get excited about driving a car that came with less power than my '67 Type 1 had.