ZDDP for flat tappet engines WBX Aircooled etc- Itchyinfo

[itchyfeet]

For me, the point is that you need to know the actual level of ZDDP in the oil you are selecting as the base stock, as well as your target level, before you can decide on the dosage level, especially as too much can be harmful.

Agreed but as you can go up to 2500 for break in I doubt it matters if you are at 1700 with 1/2 a 3oz bottle if your oil is 850ppm

Marco chucks 6oz in a WBX for break in so his levels will be way higher and if it were detrimental he would know about it.

You don't get 500BHP out of a turbo WBX without knowing more than you and I

[937carrera]

I'll just drop this direct into the thread

Obviously, there’s a lot of wear when there’s not much ZDDP. As you can see to the left of the chart, no zinc equals no anti-wear protection and lots of abrasive and adhesive wear occurs.
Abrasive wear comes from metal on metal contact because there’s no ZDDP film to protect it. Those wear particles then travel through the engine and cause more wear. But, if you add the correct amount of ZDDP to an oil, you combat abrasive wear and very little wear happens. All good.So, if one is good, two must be better right? Wrong. If you have too much ZDDP, you start to see corrosive wear and cause another problem. Adding an excess causes the oil to become acidic, and before you know, you’re wearing cams, bearings and bushings because of too much ZDDP..

Race applications have quite different demands to road applications, as is the running in (or break-in if we want to speak American) period. I have specified mineral oil for running in purposes on race engines so that the rings bed in better rather than the normal sexy synthetic which is too good at eliminating friction, especially on hard rings with silicon coated bores. They also have more frequent oil changes...... maybe 300 miles between them, or 50 miles when running in. (so an excess for a short time while the metalurgical protection layer is getting made is OK)

AAoil are primarily focussed on racing fuels and oils, so they also know their onions.

While having the right level of ZDDP is a good thing, too much isn't good and the contribution I want to make is to help people be able to make an informed decision about what levels they run at, and over what period.

Pretty much everything is an engineering compromise

[itchyfeet]

Yes but for a break in you won't have the high levels there long enough for corrosion to be an issue and you will see corrosive wear is very much lower than abrasive wear anyway

No numbers on that graph make it pretty useless

[937carrera]

Yes but for a break in you won't have the high levels there long enough for corrosion to be an issue and you will see corrosive wear is very much lower than abrasive wear anyway

I think that's what I said, it depends how long the excess level is present for

No numbers on that graph make it pretty useless

While I would also like to see numbers, the key point of the graph is that too much of a good thing is bad and the optimum is to the lower end of the good range.

The absence of numbers is probably because the optimium number will vary with the materials of construction, valve spring pressures, tappet design and a whole load of other reasons

[itchyfeet]

While I would also like to see numbers, the key point of the graph is that too much of a good thing is bad and the optimum is to the lower end of the good range.

Yes we got the message loud and clear, other than this statement which comes from Marco building Turbo WBX I don't think anything says you should exceed the recommendations.

For a modified rebuild 2x 3oz bottle to each oil change on a WBX

So I have removed it.

[itchyfeet]

Thanks Kev
a nice diagram here, no timing chain in a WBX and they are horizontal pistons and valve gear but the principle is the same
http://www.cam-shield.com/acatalog/technical.html" onclick="window.open(this.href);return false;

Just to explain to a reader what ZDDP does.
It's all about the way the tappet (camshaft follower) camshaft lobe contact faces come together that causes wear.
The lifter bottom has a flat face and the camshaft lobe slides under it.
The camshaft is "case hardened" cast steel to assist in wear reduction.
.
The ZDDP assists the slide as the action is harsh on metal and oil molecule chains, unlike a modern roller bearing camshaft follower (tappet) which rolls over the surface.
Without ZDDP assistance the wear rate increases exponentially over the life of the engine, compared to an engine using ZDDP.

[itchyfeet]

Good find by Ian

http://forum.club8090.co.uk/viewtopic.php?f=37&t=169483" onclick="window.open(this.href);return false;