Some great sounding stuff you should pass by...
1. Teflon buttons. Sounds like a good, idea, but they are constantly rubbing against the piston walls, removing oil. They can also get damaged and leave pieces exactly where you don't want them. Circlip type snap rings work (install them the right way) and I have no reason to believe "Spirol lok" rings won't do what they claim. Put your trust in metal over plastic, or buy a rice burner...
2. High lift rockers with needle bearings. OK, I don't think they are around any more, but I couldn't leave this one out. About ten years ago it was hard to find after market rockers without needle bearings. Think about the action of the rocker, the pushrod is pushing up on one side while the spring is pushing up on the other. So the rocker is riding on just a few of these rollers for it's entire life - instead of spreading the pressure across the solid bearing, it is concentrated on a few very fine edges. Combine this with the fact that this design does not provide for adequate lubrication through to the valve end (if any) and oil tends to leak out of the roller bearing anyway these were a prety guaranteed way to shorten the life of your valve train.
3. "Magnetic" oils. These claim to be able to adhere to the engine in order to provide lubrication during startup, before oil is pumped up from the sump. Sounds like a great idea, but our engines rely on oil flowing across parts in order to provide much of our cooling - having a layer of oil holding heat onto the metal would be counter-productive. I have also heard from reliable sources that these tend to coagulate on the oil screen and can even clog filters. See my notes on oils, the thinnest oil our engine can cope with is a better bet for the VW.
4. PTFE (teflon) additives. Very popular when I was younger, and still to be found on the shelves in this day and age, when the jury is in. These additives do not stay long term where they are needed most, and have a high propensity for gathering where they are not - blocking the passage of oil to parts of bearings or even the engine, clogging oil screens and filters even sometimes causing pressure control valves to stick.
You can't drive a VW for very long without oil, no matter what you have put in it - it will overheat! And sieze - my poor 69 Kombi's engine died in less than 8km (that's about 5 miles in the old imperial measure.) Pistons, cylinders, crankcase, crank machining and a rod (clever VW-trained mechanic actually made up a "balanced" set from his spares,) all bearings of course.
5. Spark Plug indexing washers. OK, these aren't snake oil themselves, but some of the claims are. There is evidence you can get a little more power by pointing all your sparkplugs the right way - but you probably won't know which way that is for your particular engine. The other problem is that the required washer may be moving the plug further into the head than is optimum, exposing boss threads or shrouding the plug.
The main way these can be useful is if your plugs protrude too far into the head, exposing threads on the plug or maybe even getting too close to the piston. This may be due to wear, an overenthusiastic head job, or incorrectly made sparkplug (we won't name names here, but some of these were getting around a number of years ago.) Otherwise, concentrate on using quality plugs and make sure your deck height is low and combustion chamber well shaped.
6. Full Circle Crnankshaft. If you look at a stock crankshaft you can't help but notice that the arms for 1 & 4 in the middle are on the same side, as are the outer arms for 2 & 3. centrifugal force is pulling these out and as the engine is revved higher this is putting a bending force on the crank. A stroker increases both the weight and the length involved, magnifying the effect. To counteract this counterweights are added to the opposite sides of the crank on stroker cranks, or stock length designed for high rpm use.
In two stroke engines, the crankcase volume is used to pump the mixture into the cylinder, so a full circle crank can help top reduce volume and increase this effect. This does of course affect the balance of the engine and increase the rotating mass and books have literally been written on how to overcome these problems.
As every manufacturer soon realised they must add counterweights to their cranks, the problem was how to create a point of difference so people will buy your cranks? Some obviously saw what was being done in the two stroke and HD scenes and, not really realising (or caring) what the counterweights were for, decided that continuing them around the crank would be (or at least appear) better! One manufacturer, Bernie Bergman, even tried to counteract the increased mass by drilling holes on the counterweight side! Any increased strength in the crank would be offset by the increased imbalance and mass, resulting in a weaker than stock crank.
A variation on this that did actually appear to have some success on rebuilt stock cranks was to cut a counterweight which extended, while narrowing, up the opposing web to add strength. These apparently were a bit stronger than stock and did not have as severe an imbalance issue. The main concern here is the stresses put on the previously forged crank by the welding and re-machining - these days we can have a new counter-weighted crank forged from strong alloy in China for a lot less money...
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