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#62
01-07-2012
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No it does make a difference.
The area of the hole on the flat face (which is of course circular) is smaller than the area of the hole on the tapered side (which is oval). Although a little over simplified you can think of it as a change in speed of the fluid as it passes through the hole. From big hole area to small hole area the fluid will have to speed up (same volume displaced, smaller area for it to flow through at the exit so it has to travel faster to get through in the same time). This change in fluid speed changes the point at which the shock 'packs up' relative to the other direction. With the tapper down effectively the pack point on the compression stroke is lower / earlier than that on the return stroke. This is also exaggerated by the fact that in use the return stroke will always be slower / lower energy than the compression stroke due to the balance of forces (this is also the reason you can't accurately gauge the pack point by bouncing the car on the table ... you need to drive it as you will never bounce it as fast as the suspension tries to move when hitting a bump on track). Tapered pistons mean that you can get a faster return Vs. bump stroke thus allowing you to use more pack than you could normally without slowing the direction change down as a parallel bore piston would ... with is why I say for our tracks tapered pistons are essential to get the performance out of the big bore shocks. There are lots of design considerations around pistons (even in our relatively crude rc shocks), they are far from a flat disc with a few holes in  Nick's pistons transform the Kyosho big bores, try the same piston sizes in straight and tapered back to back on the same track, same day same car .... I have a couple of piston related things I am working on which I will be talking to Nick about soon 
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#63
01-07-2012
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surely though this all works the wrong way arround you want really fast up travel in the shock and to be able to control the rebound. in reall life the last thing you want is any kind of pack or lock up i think the mip pistons are the propper way to do this
__________________
DO NOT BUY/SELL TO THIS USER.
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#64
01-07-2012
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We control roll AND big jump landings with our shocks and the cars use quite a large percentage of their suspension travel just in roll in a normal corner ... if they returned slowly it would take an age for the car to return to center let alone start rolling the other way.
Have a think about what we are trying to achieve with our very simple shocks and how our surfaces and track designs affect the car differently to say a 1:1 rally car.
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#65
01-07-2012
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We get what you mean roger however I would say the shape of the piston is forcing more oil around the piston rather than though a very slightly oval hole and this is why they seem to rebound quicker. Ive also done some back to back piston runs they both produced pretty much the same lap times but the tapperd IMO feel less consistant.
I would say don't waist your money on tapperd pistons unless your are at the top of the time sheets where those drivers can really tell the difference.
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