More About Prechamber Inserts

[Gizmoman]

Thanks for the reassurance and the upgrade pointers Libby. I'm way over on expenditures though.
BTW, my gearing already stinks.

Also, For your records, my engine has a K14 turbo - don't know if it is stock for the engine, but it was on the van when I bought it.

[vwzzuk]

Libbydiesel,

I had the same thing happen with my AAZ in hole number one. Ended up replacing the pistons and head of course. The amazing thing was it would run like that though pretty bad.

[Rock3tman]

Libbydiesel/all -

here's my data:
Casting #068 103 373E (original German head from 1983 Jetta 1.6TD)
Mechanical 12mm studs, TD 1.6 w/Garrett T3
Magnetic status unknown, but likely inconel
All cups cracked, most in two places
32mm diameter
No dimples.

The precups seemed tight in the head, but cracks in all four, 221,000 miles on the head, and my plan to run 15-18 peak psi boost,
led me to replace them with interference sized Eurocar Togliani cups (32.5mm).   I had the head bored with approx .002 interference fit,
heated the head to 350F, froze the precups, and then staked their perimeter in 5 or 6 places away from headgasket areas.  Engine
is still on the stand for install later this spring. 

[libbydiesel]

I got word back from Grupo Baron, one of the sites I linked in my initial post.  They list the 1.5 and 1.9 precups.  I also asked if they could make some 1.6TD ones.  Here's their response:

Prices for the chambers as follows:
GB-014 VW GOLF 1500 $4.17 each F.O.B.
GB-065 VOLKSWAGEN POLO 1.9D $4.13 each. F.O.B.
 
We can manufacture your samples, you can send them to our U.S. Address, below, the chambers are usually oversize 0.010”, if you want STD, chambers you should let us know.  Minimum order is $1000.00.  The chambers are made from an alloy, which we melt carbon 0.42-05, Iron balance, Manganese 0.6-0.9 Phosporus 0.04max Sulfur 0.05max, after machined they are heat treated.  We export to Guatemala, Honduras, Costa Rica, Panama, Nicaragua, Barbados ,New Zeland, United States, Argentina, Dominican Republic, etc.  If you are in the states import taxes are 0% due to the free trade agreement.

That all sounds very encouraging except it would take 100 heads before it was worth it. 

[bajacalal]

I got word back from Grupo Baron, one of the sites I linked in my initial post.  They list the 1.5 and 1.9 precups.  I also asked if they could make some 1.6TD ones.  Here's their response:

Prices for the chambers as follows:
GB-014 VW GOLF 1500 $4.17 each F.O.B.
GB-065 VOLKSWAGEN POLO 1.9D $4.13 each. F.O.B.
 
We can manufacture your samples, you can send them to our U.S. Address, below, the chambers are usually oversize 0.010”, if you want STD, chambers you should let us know.  Minimum order is $1000.00.  The chambers are made from an alloy, which we melt carbon 0.42-05, Iron balance, Manganese 0.6-0.9 Phosporus 0.04max Sulfur 0.05max, after machined they are heat treated.  We export to Guatemala, Honduras, Costa Rica, Panama, Nicaragua, Barbados ,New Zeland, United States, Argentina, Dominican Republic, etc.  If you are in the states import taxes are 0% due to the free trade agreement.

That all sounds very encouraging except it would take 100 heads before it was worth it. 

How do you figure? I think the value of these precups is at least $50 per set, if they're good parts, and 4 per head, assuming you could buy them at about $5 each, and sell them as sets for $50, you would recoup your initial minimum investment after selling about 30 sets.

Would they sell? I don't know. Owners of old VWs are notorious cheapskates and would probably just want to replace one or two... When I worked at a Napa, it was always the diesel Volkswagen owners who would try to buy just one brake pad or brake pads for one side of the car only... It's something that kind of frustrates me about this community.

[libbydiesel]

Yeah, my math was screwy.  It actually might be worthwhile. 

[theman53]

We could set up a group buy??? I would approve. That way we could all get a set or 10 and be happy. I would probably only get a few as I will go to the 1.9L engines after this 1.6.

BTW, great info Libby. I was incorrect in what my research had found in the TD being 30mm only. Just happens that every head I had that was TD had 30mm.

[libbydiesel]

I was thinking that it might also be worthwhile to design a pre-chamber insert that would fit the 1.9 head, but result in the combustion chamber size of the 1.6.  That would allow easy use of the new OEM 1.9 heads  on 1.6TD blocks without the downsides of the smoke and harder starting caused by the low compression of a franken.

[RabbitJockey]

I was thinking that it might also be worthwhile to design a pre-chamber insert that would fit the 1.9 head, but result in the combustion chamber size of the 1.6.  That would allow easy use of the new OEM 1.9 heads  on 1.6TD blocks without the downsides of the smoke and harder starting caused by the low compression of a franken.

wouldn't that require a reshaping of the dome inside the head?

[Rock3tman]

Re: Libbydiesel's suggestion of 1.6L volume sized prechambers for 1.9 heads is a good one, I guess that I'd personally rather see the effort towards 1.6L oversize  pistons in a TDI configuration though.  That should really jump start the m-TDI pump, strengthened clutch & 02A/02J transmission transplant businesses...and also enable 15 percent better economy in all the 1.6L hydro blocks we have.  My $.02

[libbydiesel]

I was thinking that it might also be worthwhile to design a pre-chamber insert that would fit the 1.9 head, but result in the combustion chamber size of the 1.6.  That would allow easy use of the new OEM 1.9 heads  on 1.6TD blocks without the downsides of the smoke and harder starting caused by the low compression of a franken.

wouldn't that require a reshaping of the dome inside the head?

I don't think so.  I think that it would be possible to make the bowl of the precup less deep to compensate for a deeper dish in the 1.9 head.  I will do further measuring/comparing as time allows. 

[libbydiesel]

Re: Libbydiesel's suggestion of 1.6L volume sized prechambers for 1.9 heads is a good one, I guess that I'd personally rather see the effort towards 1.6L oversize  pistons in a TDI configuration though.  That should really jump start the m-TDI pump, strengthened clutch & 02A/02J transmission transplant businesses...and also enable 15 percent better economy in all the 1.6L hydro blocks we have.  My $.02

I'd love to see oversize 1.6TDI pistons, but precups are a lot less expensive than custom pistons.  1.9TDI engines are fairly readily available and a 1.9TDI tuned to the power output of a 1.6TDI would get virtually the same fuel economy.  I think most people currently choosing a 1.6TD vs a 1.9TDI would balk at the cost of custom pistons, a TDI head, mTDI fuel pump, etc...  

[Rock3tman]

great points Andrew; you've covered it well why my idea blows.  Anyway, I'd be in for a couple of sets of tailored prechambers for use of 1.9 heads on 1.6 blocks with a more suitable compression ratio, especially if the fallout issue could also be addressed someway better as well.

[libbydiesel]

I didn't mean to say that a 1.6TDI was intrinsically a bad idea.  I think it would be very cool and have done considerable thinking/investigating in the past on how to accomplish it.  I just keep coming to the conclusion that it's not really cost effective.

[RabbitJockey]

I didn't mean to say that a 1.6TDI was intrinsically a bad idea.  I think it would be very cool and have done considerable thinking/investigating in the past on how to accomplish it.  I just keep coming to the conclusion that it's not really cost effective.

i agree, it has been done with 1.5 crank and tdi pistons before, but that is quite a different 1.6.  it would be sweet but i don't see the point, and i can't imagine it would get much better fuel economy the only difference would be less energy wasted moving air ur not using except at full pedal, and more energy lost on friction with the cylinder walls from the larger bore and longer stroke.