[Chad Harrington]

Thanks David, I’m looking for the detailed technical regulation but cannot find it.  Even on the WSK and CSAI sites.

When cadets have to carry a lot of ballast, is it normal to force all of it to be bolted to the seat? Or can it go to other places like the front or side of the frame, as long as it is all bolted down very securely?  Some cadets have as much as 45 lbs of ballast and there’s almost no place to put it, the seat becomes very overloaded and on a bumpy track the bolt holes get worn and the area around the bolt holes gets weakened from all the vibration of these heavy weights.  The seat wears out very fast and starts to crack.

We need to convince my ASN that it is safer to distribute the ballast a bit better, but they keep saying no and referring us to the CIK master regulations without providing us the document or .  But I cannot find any master regulations for cadet racing or Mini 60 racing!!

Can anyone help?

[Chad Harrington]

Thanks Chris, I’m very bad with electronics so will never be able to efficiently create a control system like that.  I will need to buy an existing solution to save time.

I’m not actually trying to run track simulations per se.  Only trying to simulate the 2 or 3 most common length straights, including aero load especially the higher speed straights, since aero load is the only load that increases exponentially with speed.  The linear loads can be adjusted with gearing on the inertia dyno.

[Chad Harrington]

Thank you guys for your sensible advice.  I agree on diminishing returns as we dive deeper into detail, but also want to look at how to maximize the money spent on an engine dyno.  I guess what I what I was hoping was a fast control engine dyno that can add the exponential aero load, without costing too much.  Since it is not rapid transient like track sim or for very powerful engines shooting through low gearing, but rather the opposite and just optimizing for the medium and long straights; such load control should not be difficult to create.  After all we can gear to add most of the aero load after best linear fit, and be very close in a specific range.

James, the data to simulate the load is easy – the straightway acceleration engine speed curves on track and dyno, just have to match closely.  It can be a 2  – 3 try iterative process, starting with calculation of the engine load, which will get close and make a good starting point.   Thanks for the aero numbers… how long ago were they reported?  Is it for current generation bodywork?  I plugged the numbers you provided and got the drag force shown in red.  The dashed line is target additional inertia load I would gear for (artificially tall) on an inertia dyno for best fit in the speed range that matters (most common medium to long straight speed range).

[Chad Harrington]

[quote quote=21079]Really? For kart motors? Do tell why…. [/quote]

Because you want to replicate load and know for that load range exactly what ignition timing and carb settings make the most power and power width.

From data we know that kart acceleration is not proportional to gearing.  In quite a wide range, you can go taller on gear and not lose any significant low end accel, yet gain massive speed advantage up high.  So we know that not just engine speed but engine load, and/or carb sensitivity to engine acceleration (engine speed derivative), are key factors in kart engine power width (at least for KF2) .

Walt, thanks.. when you change gears on an inertia dyno and overlay on-dyno engine speed vs on-track engine speed, do they line up perfectly?  Do you mind showing some examples?  Really appreciate it.

I tend to think the on-dyno engine speed trace will be closer to linear vs the on-track one mainly because of air drag increasing as a sqaure of speed, but perhaps in karts and at typical kart track ground speeds, it is small enough not to matter.

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