764 Nozzles; Power Plus or DLC?

R

Rrusse11

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From what I can glean from trolling the net, the big difference between the 2 types of the 764 nozzles is that the PP has 7 holes while the "new and improved" DLC764 has 5 openings. Slightly increased overall flow (87%>103%) on the PP's, but to my surprise I find that DBW lists both as being DLC coated. The PP's are ~ $50 cheaper.
Is there a consensus as to whether there is any significant advantage
to a 7vs5 hole orifice?

With DBW's option of increased flow rates with spring setup, ie. a DLC764 could be bumped up to the same rate as the PP(DLC)764.

I'm also considering the 10% plus stage 1 injection mod as well,
according to Pete it would improve lower down spooling & torque.
I'm not looking for the ultimate high rpm horsepower, more low down grunt for towing a small tear drop camper (~1200#) around the country next year. With an 11mm pump my goal is on the order of 160-170bhp/300'#s.

I'll be picking up a 17/22 turbo this weekend, and an SBC2 End clutch. The combo should be more than capable of dealing with the bigger nozzles.


Thoughts, input, and experience on the 2 types greatly appreciated.
Cheers,
R*2
 
Seatman

Seatman

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Don't think either is really worth it if you're fitting that turbo unless you're going with the 11mm pump too.

Personally I had the PP764's, found the extra torque alone was excellent even without a tune. Most I could get out of them with bigger turbo and mapping was about 165-170 at the crank.

But yeh, definite boost in oomph
 
R

Rrusse11

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Seatman,
Got the pump already, check my signature for a list of mods.
The torque/low end power is what I'm after, thanks for the input!
Cheers,
R*2
 
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bobbiemartin

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On my Golf, I have DLC764, Stage 2 flow with modified pilot injection. You can see the mods in the link. I'm happy with them. It has pretty good low end and a very strong mid range.

I corresponded with my tuner and DBW for recommendations on the best nozzle for my application. Once we settled on the nozzles, the tune was written for the nozzles and other modifications. That is probably the best way to sort out what nozzle to use. If you don't retune after making the turbo swap, nozzles, etc you really won't get the most benefit out of what you have.
 
R

Rrusse11

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Bobbie,

Thank you sir for the input! Great work on your car, very impressive. So a VNT17 ehh, that was where I was headed, but when the deal for the combo 17/22 & the SBC popped up, I couldn't resist. My understanding of the 17/22 is that it delivers better low end spooling that the VNT17. Just what I'm after for my application.

I want to maximise the power band of the diesel, low end grunt/torque. My take is most modders seek to replicate the high rev/peak power aspects of gas engines. Realistically they might be better off playing around with the 1.8T motor.

With the increase in pilot injection, and I'm thinking with the finer atomisation of the 7 hole PP injectors, these tweaks should also be giving a boost where a diesel motor is at its best. I doubt if I'll be needing a StageII increase.

I'll be using Jeff of RC for tuning, Peter of IDparts speaks highly of
an RC3+, a turbo specific tune. Not looking to max out the car,
figuring that if I run a dialed back setup, I should be good for long term reliability/durability.

Thanks, good to hear your happy with 764s.

Cheers,
R*2
 
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Enabled

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The VNT17 spools faster than a 17/22, 17/22 has more volume and a little higher capacity at high end...
 
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Enabled

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The difference isn't huge between the 2 turbos. But a lot of the VNT17/22 benefits are at high rpm. (I don't think it's worth the extra $400-500 price, but that's an opinion)

Either way, high torque (read high cylinder pressures) puts huge stress on head and head gasket. So you don't want to aim only for high torque low hp, unless you've strengthened a lot of it. Even then, increasing rpm will be safer for utilizing the power.
 
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Rrusse11

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Enabled said:
The difference isn't huge between the 2 turbos. But a lot of the VNT17/22 benefits are at high rpm. (I don't think it's worth the extra $400-500 price, but that's an opinion)

Either way, high torque (read high cylinder pressures) puts huge stress on head and head gasket. So you don't want to aim only for high torque low hp, unless you've strengthened a lot of it. Even then, increasing rpm will be safer for utilizing the power.
Click to expand...
Ahhh, just the kind of info this neophyte appreciates!
Cheers!
 
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bobbiemartin

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If it's low end torque you are after, you might consider keeping the VNT15. Look up some post by Peter (IndigoBlueWagon). He really likes the VNT15 for road cars. You won't get the top end HP, but it might be better for your application.
 
Seatman

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There's also the GT1749VA as found on our PD130 over here, same turbine bigger compressor. It can handle a bit more boost but still spools fast.
 
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Nevada_TDI

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R*2, I'm with enabled on this one. The 17/22 is in a vnt-20 cold side, which tells us you can expect your full spool to be approximately 300 RPM higher than you "want."
Check the link to this page, and look at the chart on the bottom of the page:
http://www.darksidedevelopments.co....56vk-turbocharger-with-vacuum-conversion.html
But according to the chart, all may not be lost here; you are not running a 26PSI tune, you will be running a 20-ish PSI tune I believe with a Stage 3+ so you don't really need 26 PSI; with the right nozzles and tune you should have lots of low-end grunt.
 
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Rrusse11

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Nevada,

Yep, seen the chart. I know the current VNT15 isn't handling the nozzles I got. Took me a while to realise that the actuator was causing
a LOT of boost spiking. I think they must set the auto tranny turbo differently. It didn't hit the stop until 26"Hg on my Harbor Freight
"brake bleeder". Now starting to move the vanes at 3", hits the stop at 17". It was throwing oil. I'm regarding the turbo as compromised.

Guessing here that a 17/22 set around 22-24# max should give me plenty of power for what I'm after. Also guessing that it'll max out the current nozzles. 764's set conservatively and the above boost limit I'm hoping should give durability/longevity with plenty of grunt. Not looking for a race car. Without a load, car's not bad as is.
But my feeling is trying to do a couple month trip with a camper would be questionably reliable.

Only have a couple years experience running TDI's, and never been a motorhead, so it's a steep learning curve here. Now if you want to talk about the finer points of old meter boats, or powdering claybirds, got a lot more experience. {:eek:)

Thanks all! Just the kind of experiential input I need.
R*2
i

 
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Nevada_TDI

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Due to the fact that turbo moves more pounds of air at the same pressure as a vnt-17, you should not have to worry about EGT problems even when towing. Yes, we want bigger turbos that make more boost, but PSI for PSI, (pound for pound so-to-speak) the bigger turbos should be able to run minimal boost at freeway speeds while still having plenty of air moving at the same time.
 
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Rrusse11

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Nevada_TDI said:
Due to the fact that turbo moves more pounds of air at the same pressure as a vnt-17, you should not have to worry about EGT problems even when towing. Yes, we want bigger turbos that make more boost, but PSI for PSI, (pound for pound so-to-speak) the bigger turbos should be able to run minimal boost at freeway speeds while still having plenty of air moving at the same time.
Click to expand...
Interestingly on the same subject of EGTs, my query to DBW on the benefits of increased pilot (stage 1) injection, he spoke of improved
combustion that also would lower said temperatures. Win win!

Currently cleaning my spare intake in preperation for turbo install.
Got a SS braided oil line, a turbo inlet adapter from IDparts.
Don't know if I'll need an adapter for the intercooler connection
yet. I'm planning on just using my stock SMIC piping if possible.
 
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Nevada_TDI

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I replaced my stock pancake pipe with one from a 1.8T; I don't really know if it makes a giant difference in the airflow but the interior cross-section is significantly larger and I am sure it can't hurt anything seeing as I have a larger than stock turbo.
 
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