with high "spiking" pressures like you see with the Skypup turbo tweak) tuners will often have to change to higher pressure valve springs to keep the valves following the cam, because the intake valves get blown open on the intake strokes. When going well beyond the stock levels of boost (esp. Only the valve spring pressure keeps them closely following the cam profile instead of being blown open by the boost. Under high boost conditions, the boost in the intake tract is trying to push the intake valves open. Why would valve springs make a difference? I have no idea what the valve spring pressures are for the TDI, and how they compare. On lesser (gasoline) turbocharged engines, stock valve springs are only good for containing about a 5-7psi overboost against stock. There is one aspect (very possible gotcha) to increasing turbo boost that I've never seen anyone address on Fred's, so some of you might as well take a look at it now. It's probably not much different, but it could be. I haven't heard of what the limits are for the 5-cylinder engine. I won't get into the math unless you really want to know. If it's 130 bar, and with 19.5:1 compression, that means (roughly) you don't want much more than 1.2 bar of boost.
With the 4-cylinder engines, apparently the maximum recommended cylinder pressure is either 130 bar or 155 bar, I have conflicting information. There are two issues - the turbo, and the engine itself.ĭiesel des touched on the issue of the turbo itself, there is a maximum recommended speed which should not be exceeded, and there is a performance curve that will indicate at what pressure ratio this maximum speed occurs at. and the turbo (i think) is a KKK K14 (or KI4) 0-60 mph now I am at 13,2 sec., but i want to do better!!
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