It's called 'random chance'!
And it's simple!
All manufactured things are made to 'tolerances'. For example, if you order a 6 inch ceramic tile to replace a broken tile in your kitchen, you would be quite happy for it to be 6.0009 inches, or 6.009 inches or 6.09 inches but you'd throw a RIGHT WOBBLY if it turned out to be 6.9 inches! In this case, your 'tolerance' is about 0.1 inches so anything between 6.09 or 5.91 would PROBABLY be ok for you!
It's the same with engine components, the EXACT value might be MUCH tighter, you being only willing to tolerate 0.0001 of an inch on the piston diameter but anything up to 0.1 of an inch in the postioning of the inlet 'duct'.
However, it may WELL be that the engine with it's inlet duct 0.1 of an inch HIGHER up the barrel gives more power than one 0.1 in DOWN the barrel! Both barels are WELL within the allowed 'tolerance' but one works BETTER than the other. And that's JUST the positioning of ONE 'component' from your whole engine! It's made of HUNDREDS of 'elements' of those 'components' and, if you are LUCKY, you might buy a motor that has been STAGGERINGLY lucky with ALL the tolerances at their LIMIT and ALL in the 'more power' 'direction'. If you find THAT motor, it'll be a BL**DY quick one!
So..... one way to get such a motor is to buy 100 of them and Dyno tham ALL selecting the ones that was the quickest from the batch and selling the rest. You still wqould be VERY lucky to get one with ALL the tolerances in the RIGHT direction but you will have select one with a pretty GOOD set of 'tolerances'.
The next choice is to buy HUNDREDS of motors and select the components from each of them which you already KNOW (by being a brilliant and experienced tuner of TKMs) work best at 'tolerance limit' X for one component and Y for another, etc.. You now build THOSE bits into a single motor and sell the remaining motors off being brand new.... which they are!
That last method is MUCH more rare but IS done.
There is a FINAL option! Get you tuner to adjust the gaskets and other ALLOWED items within your engine so that they all 'push' the engine into the areas where they work BEST! For example, if moving the inlet HIGHER up the barrel helps, then fit a couple of gaskets under the barrel and machine the cylinder head DOWN by the 'same' amount. That's what LEGAL tuning is in a TKM!
TKM is special, you are onloy allowed an EXTREMELY tight tolerance and there is NOT a GREAT deal of extra power to be gained in this way. There is SOME but it ain't a LOT! Good!
Finally, be assured that if you HAVE chosen TKM, then you will suffer LEAST from these problems of 'meeting' a BALLISTIC motor on someone else's kart than almost ANY other class. The reason is that the tolerances are VERY tight in TKM and there is only, perhaps 1bhp differeces between a well set-up SLOW motor and a well set-up BALLISTIC motor. In OTHER classes (no names here!) you can find about THREE bhp difference! And that WILL cost you!
I hope that explains it!
Ian
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TKM engine query by 'ranny' (04 Nov 2008 @ 18:17)
