I guess we all install the torque converter (T/C) straight out of the box after spending some time figuring out the best position in which to bolt it to the engine for our application.
We try to figure out the best gearing ratios and leave it at that but Bill Carter in the US CycleKart newletter has just posted the most interesting little appetite wetter I have seen for a while. It's on tuning the T/C to get the best out of it for your Kart given its weight, your weight, driving style and what you use it for.
My biggest issue with the Renault for example is due to it’s overall weight which results in poor acceleration out of the corners, where it really matters. That is why I am tweaking the engine a bit to take it up around the 10h.p. level.
So here I am spending all this time, effort and money on the engine whilst totally ignoring the real gains that can be had by tuning the T/C.
I am not going to lift Bobs article so pop across the Altantic and read the article for yourself, the least we can do.
Many thanks Bill.
It’s prompted me to look into the subject and when I really know what I am talking about, I’ll write an illustrated article.
The main thing is to have the clutch bite at around (above a bit actually) the engines max torque.
A standard T/C starts biting at around 2,200 rpm and since max torque on a standard GX200 is around 2,600 rpm, we suffer the engine being pulled down below max torque, resulting in low acceleration, significantly less then it could be if only the T/C cut-in at around the max torque. On my rebuilt engine that's going to be round 3,500 rpm so something has to be done.
Well the good new is that you can quite simply get the T/C to-cut in at that point by changing the springs within the clutch for some Blue/silver springs and you can change the spring in the output clutch (not sure of the correct names for these parts but I will find out) for a stronger one and you can change the tension of that spring too.
Also, the weights in the clutch can be changed so there are a whole bunch of alternatives to have a go at.
I have just ordered a set of blue/silver springs and the yellow spring for the other end on Gemini's advice. That should give me a biting start of 3,600 rpm (max torque) and the stronger yellow spring will hold it down keeping the engine in it's power band longer but allowing ten thousand rpm so yippe!
In Bills posting he included a spring engagement chart for the 20 and 30 series T/C's and Gemini have promised to send me one which explains things a bit better.
I must point out that this information is for my use only and MUST NOT be used by anyone in CycleKartsGB.
It’s not all about winning you know!