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October 2005
4,6 and Rotary Wars
We fronted for the local Motorplex 4,6 and Rotary Wars on a perfect day, to find quite a few hard hitters out despite the overall low numbers. This was the first time out with the new PSI blower, and we we keen to know how our design plans would pan out.
Starting the blown 20B for the first time gave us an indication of what this combo would do. Even though I had it so rich it was killing people with the alcohol fumes, it sounded oh so tough. First pass out was fat and lazy with some rough running, and we slipped through for a 9.909et @ 103mph - nice and safe. Blown alcohol tuning is far different to tuning electronic turbo combo's, as we cannot do any dyno testing to get the tune fairly close. The huge magneto's tend to fry the dyno computers, and it really is too noisy and "out there" to get any successfull tune. So we start with a fat tune, and work our way safely back on each pass, until the engine "comes on". Once the engine "comes on", the power really increases a huge amount. Too far and the burst panel will pop.
For the second run, I took a little fuel out to progress down that path, and after a strong burnout I got muddled on the start line and took off in second gear! Trans brake did not work, and it was a slug off the line. I rolled through with the engine screaming - blown alcohol engines are turned off by pulling the fuel shutoff lever - starving the engine of fuel. The PSI was behaving strangely when I did this - revving it's head off. May be because I had it so fat.
Back in the pits we found the eccentric shaft brace a little loose, so re-torqued that and took a little more fuel out. Plugs were still showing a rich tune, so we were still way safe. Third run she sounded a little angrier, but still with very little boost, but took off out of the hole and screamed through first gear to 10,500rpm (caught me out), and when I hit second the engine started to miss, so I pedalled (the 8/71 used to blow the burst panel when this happened, so I was very cautious) slowly about three times, and ended up rolling through at 142 mph. I could not believe my ears when Peter Glover told me I had done a track PB 8.97.
Back in the pits the drama started. A quick inspection showed the crank support had broken in two places, putting us out of the event. We had put huge 11mm solid core ignition leads on, and the spark was so big the external coils were shorting together, causing the missfiring. Then ANDRA got involved, effectively banning the car due to excessive noise. The track had measured us at 120db, and the ANDRA brass were insisting on imposing the new exhaust rule - un-turbocharged rotaries must be below 98db.
At the end of the night, the crew and I pondered the car's future over a few beers. The PSI experiement was a total success. Incrementals on the 8.98 run showed it could have done a mid 8 easy, and with the right tune a 7 would be possible. Our attempts at muffling the car in the past had all been unsuccessful. Restrictive mufflers choke the rotary, not allowing the engine to rev past 5,000rpm. Standard mufflers and hot dogs took very little noise out due to the nature of the supercharger. Bigger mufflers are a safety concern, as they fill with alcohol and turn into bombs at any moment. Maybe the blown3rotor is dead?
Purchase photos from High Octane Photos
Archived Newsletters:
August Report 2005
July Report 2005
May Report 2005
April Report 2005
March Report 2005
Nov/Dec Report 2004
Sept/Oct Report 2004
July/August Report 2004
May/June Report 2004
April Report 2004
March No 2 Report 2004
March No 1 Report 2004
February 2004
January 2004
December 2003
November 2003
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