VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: malone on May 17, 2005, 03:11:15 pm
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I think this topic was briefly covered a few months ago but I can't find it again via the search.
I found a local seller with a non-turbo 1.6L solid lifter head + cam. I just want to get a spare head for porting, etc.
Brand new TD valves, springs, lifters, etc. will be installed. The camshaft may be reground (depends on the before vs. after specs, which will be discussed with the cam shop).
Straight to the point: Is a non-turbo 1.6L head inferior to the turbo version, and in what aspect? Should I be fine as long I'm using new TD valves and other parts?
Will there be room to work the 1.6L head to accept 1.9L valves? I don't have the full valve specs so if anyone has info to share, it'd be appreciated.
A complete 1.9L hydraulic head would be nice but it won't fit for obvious reasons.
Thanks,
Mark
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The TD head is a different alloy. There's a higher sodium content IIRC, for additional heat resistance.
If you plan to run the engine hard, I'd look for a TD head. Or, alternatively, you could throw the N/A head on your engine for a while (so you have the car to drive) and port the TD head you have on there now.
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Gotcha, you're talking about the entire head and not just the valves in regards to higher sodium content, right?
Anyway, I'll continue searching for a TD head.
Thanks for the quick reply.
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TD prechambers are different material and configuration too. (and used ones often cracked :( )
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Misinformation is widespread regarding NA vs TD differences. This has also been covered already.
From
http://www.vwdiesel.net/phpBB/viewtopic.php?t=357:
The part number for replacement head castings (that is, assembled with valve seats) of a 12mm head-bolt 1.6 NA head is the same as a 1.6lTD head.
If you look at the heads that actually came off 1.6lTDs and 12mm 1.6lNAs, the casting numbers actually cast into the heads (which don't correlate to any part number it ETKA ) are different. So, there is a possibility I suppose the metal content is different. Although there is also strong evidence (replacement part numbers being same in ETKA) that VW already incoporated the changes for turbo into the 12mm-head bolt 1.6lNA heads.
If you get a 1.6lNA head intending to put it on a 1.6lTD and have a chance to rebuild it, I'd recommend replacing the valves with turbo parts during the rebuild. Specifically, I think it's just the intake valves that ETKA lists are different vs the NA vs Turbo 1.6l heads.
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The diesel heads respond very well to porting. In the same way that the early 1.5, 1.6 & 1.7 gas heads did. My favorite "how-to" is an article from David Vizard in Hot VWs in 1981 or so. Gave great descriptions of where to port and what increase it gave.
The diesel heads flow just a little more than the comparable early gas heads, everything else being equal, and I believe it is from the additional down-draft that the airflow makes before getting to the valve. Basically, after the port makes its 90 deg turn towards the valve face, it travels further in a diesel than in a gas because the gas has a combustion chamber in the head and the port and valve is that much shorter. Can't prove it, but that is what the shop owner & I came up with eons ago.
I will try to dig out those old flow bench papers I have somewhere.
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Sounds great!
Interesting theory on the flow of the diesel head... I have never seen flow test numbers comparing the two, so this is really great info!
I would also imagine since the diesel head is "flat", there is less valve shrouding in a diesel head than versus a gas head with the combustion chamber in the head. I have noticed a sharp edge in the 1.6 diesel head along the inside radius of the runner by the way; it is definitely not optimal for flow out of the box. Don't know how the 1.5D head shapes up in this department.
Thanks in advance for the info, and welcome to the board by the way! :)