Saturday, October 12, 2013

Project update: quarter-mile time and estimated power figure...

Recently I had the opportunity to use a performance tracking device to get some timed runs of my project Sigma. It was a very wet day so I wasn't able to do many runs (only did three passes) and on two of the runs I got a fair bit of wheel spin, to my surprise!
The first run was basically just a trial run, to setup the timing equipment and to work out what rpm to stall the car to before letting go of the brakes. The car registered a quarter-mile of 19.521 seconds @ 112.84kph. So I dug up some old car magazines and found a performance test of a stock standard 1979 Sigma SE 2.0 3spd auto (same as my car when it was stock) and it did the quarter in 18.9 seconds @ 123kph.

On the second run the rain had stopped, but the surface was still quite wet. Despite a little bit of wheel spin, my Sigma managed to set it's best elapsed time of the day: 16.565 seconds @ 113.75kph. The terminal speed tells the story here, showing that the initial wheel spin did hurt the elapsed time and final trap speed a bit.

So on we went for a third (and final) try, but the rain only increased and so did the wheel spin off the line. The car still managed to run a 17.517 @ 111.04kph quarter.

So what did I learn? I want more power! Using an old drag racing formula, we got a power figure of 107hp at the rear wheels (give or take a few hp). Not bad considering the Sigma I got the new engine from had a factory standard power figure of about 115hp at the engine. Keep in mind the engine is no longer stock. The previous owner told me that when it was reconditioned, they increased the bore, fit a "better" crankshaft and balanced the bottom end, plus who knows what else. The stock Mikuni carburettor has been modified and the stock exhaust from my Sigma flows a little better than the one on the donor Sigma...

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