turbo head vs. non turbo head

[westcoaster]

Is there a way for your average layperson to tell the difference between a head that was meant for a turbo engine vs. a head for a NA engine?
I understand there is a difference in the materials used to make the head in that the turbo head can tolerate heat a little better.

Thanks,

[Rabbit on Roids]

part numbers!

[westcoaster]

Ugh,

It appears that anything with an "N" at the end of the part number is a turbo head.

I am getting a 1.6TD engine done for me and am finding a pile of "substitutions" have been made. Apologies, but this is a bit of a time critical thing. The posts I had found with the search "head casting numbers" really didn't turn up anything I could pinpoint as specific for a 1.6TD engine.

[vanbcguy]

Isn't the size of the prechamber different on the 1.6 NA versus 1.6 TD head?  I thought I read that somewhere...

[Kantdrivefast]

Isn't the size of the prechamber different on the 1.6 NA versus 1.6 TD head?  I thought I read that somewhere...

Big enough difference that you cant use them in a new hydro head...

Ive got a non turbo head on my turbo engine... no troubles so far.

[westcoaster]

Am I correct with my assumption that head part numbers that end with an "N" are for turbo motors?

[Rabbit on Roids]

my turbo engine has an N at the end of the casting number. none of my other 1.5 or 1.6 heads have an N. and my engine has a known turbo head on it.

[theman53]

The flat red rabbit was an N at the end and it was N/A. That being said I am with Andrew and since they used the same for both I really don't think it will matter. Guys with N/As are putting turbos on so it "should" be ok. Just guessing though.

[Peter]

several yrs ago I had read ..might have been on vwdieselparts.com (not sure) that there was NO difference between the n/a & turbo heads starting from 1986

[dieseltech]

after 86-87 all are the same, basically the hydro heads are the same NA and forced induction. pre 86 the NA had a much larger pre chamber than the turbo, this was to allow a greater amount of air to be mixed with fuel to create a cleaner burn, the turbo used the same size pre chamber as the na1.5l the reason why they used the smaller pre chamber in the turbo was to try and prevent cracking between pre chamber and exhaust valve by allowing more aluminium head surface to be exposed so hot spots didn't form between the steel inserts and the head and since it was forced induction, it didn't need as much volume in the pre chamber because there was more than one atmosphere of pressure in the cylinder under boost conditions.

[saurkraut]

pre 86 the NA had a much larger pre chamber than the turbo, this was to allow a greater amount of air to be mixed with fuel to create a cleaner burn, the turbo used the same size pre chamber as the na1.5l the reason why they used the smaller pre chamber in the turbo was to try and prevent cracking between pre chamber and exhaust valve by allowing more aluminium head surface to be exposed so hot spots didn't form between the steel inserts and the head and since it was forced induction, it didn't need as much volume in the pre chamber because there was more than one atmosphere of pressure in the cylinder under boost conditions.

Were does this information come from?  Its the first time I've seen anything about smaller swirl chambers in the TD.

Seem very counter intuitive to raise the compression ratio on a forced induction motor.

here's what the VWTD white paper says:

“A cross-section through the combustion chamber with the position of the injection nozzle, glow plug and swirl chamber inrert, as well as the shape of the piston cavity can be seen in Figure 12. Numerous investigations on the combustion chamber parameters were carried out. For example the angle of the injection nozzle with respect to the cylinder axis, the position of the glow plug in longitudinal engine direction, as well as its penetration were optimized. Other parameter studies concerned the effect of the volume ratio between the swirlchamber, the cross-sectional shape and rise of the connecting port between the two combustion chambers and the sire of the injection port. By considering the best compromise of engine power, fuel consumption, soot formation and exhaust emissions the configuration shown in Figure 12 was obtained. Experimental results will be discussed later in this paper.”

“During the course of the combustion chamber optimization program the opening in the cylinder head between the injection nozzle and the swirl chamber was increased from 7 to 13 mm. The advantages for soot-number and fuel consumption are shown at 2000 and 3000 rpm and plotted versus start of injection, in Figure 40. This improvement was first found during an investigation of the 4-cylinder naturally aspirated Diesel engine and has later been checked and incorporated into the turbocharged Diesel engines.”

Sure doesn't sound like "hey Hans, go grab a 1.5 head for the 1.6TD I'm working on and we'll try that"

Link:
http://www.4crawler.com/Diesel/SAE/vwtdsae.shtml

I have all three heads in my garage (1.5, 1.6NA and 1.6TD)  I could CC them and see for sure.

[saurkraut]

I just knocked out a 1.5 swirl chamber cover and a 1.6TD mechanical swirl chamber cover.

1.5:  flange diameter, 1.183",  barrel diameter, 1.002"

1.6TD: flange diameter, 1.177",  barrel diameter, .995"

Close but not the same, and not interchangeable.

[Rabbit on Roids]

i set a 1.5 cup on top of a 1.6 turbo cup thats out of a turbo head for sure. these ones are the same size. so it seems there was no standard in the early eighties with these engines. at least the damn japs were consistent on the engines they built.

[Dean Erickson]

I rebuilt a 1985 turbo diesel engine from a Jetta. The pre cups had bad cracks so I knocked the pre cups out of a 1.5 head and put them in my turbo head. They were the same size. I have been told if the valves have a ruff surface then you have a turbo head. Ruff on the large flat part.

[fatmobile]

“During the course of the combustion chamber optimization program the opening in the cylinder head between the injection nozzle and the swirl chamber was increased from 7 to 13 mm.

It sounds like they aren't talking about prechambers here,..
 more like the aluminum area the injector heat shields sit against.
It used be be a very small hole the injectors shot through, later when you remove an injector and look down the hole it is much larger.

 I think the real TD heads have dots on the prechambers.
 I'll be slamming all the prechambers out of my junky old 1.5 heads before I scrap them. I had read earlier that they fit but it's good to have it confirmed.