Whilst I personally disagree with the change it is obvious to me that with 3 clubs in SEQ doing trials and with the majority of drivers seemingly in favor of the change that it was time to do some testing of my own.
My experience so far is limited to 2 race meets and one burnt out motor.
In preparation I did a race meet in 540 early in Jan (Logan the Holden v/s Ford meet ) and kept my times so I could have something to measure against.
Wednesday night 27th I ran 21.5 and the fast guys at that meet were Vazzo and Paul T. At the previous 540 meet I hadn’t been as quick as either of them but with the 21.5 I was right in the mix with them (quicker lap times) and I would say a tad faster overall – sadly I broke a pivot pin in the final. This was with a “normal” speed control no boost.
Saturday night 30th I ran it again in the regular 540 class (with Martin running a regular 540 ) Again overall I was as quick or quicker than Martin with this motor but hadn’t been at the V8 meet so the 21.5 was definitely faster for me.
I started the night with a normal speedie and geared at 47.34mmpr(4.18fdr) and had a TQ run in the first race – about the same as Wednesday night. Finished the race with a motor temp at about 68 degrees C. – I can live with that but it’s on the top side of where I like it. No alarm bells at that stage cause it was about the ratio I could run a 17.5 at – I was thinking surely a 21.5 can run a few teeth more on the pinion than a 17.5. With that in mind I introduced some boost and left the ratio where it was. It was immediately obvious that I was too high geared soon after the start of race 2 – felt sluggish and no performance – I did 6 laps and pulled in – the motor was about 80 degrees.
For the 3rd race I geared down to 42.76mmpr (4.63fdr) and it felt a lot better but let the smoke out after 12 laps and was very hot. So for me that was bad news, for the average 540 driver it would have been an expensive exercise – a years worth of 540 motors in one race. Was the damage done in race 2 or was it all teh race 3 ratio that cooked the goose.
For the final I ran 38.18mmpr (5.18 fdr) and the car was a lot closer to the speed of a good 540 but had them covered until a brain fade saw me upside down in the bushes loosing half a lap . Did some fast laps after that and my lap times were better than the rest. More detail when I see the actual result sheets from Sat night.
So what can we conclude so far from the test. The 21.5 will be as fast or a little faster than a good 540 so should make the whole field closer on speed (that still leaves handling and driving of course).
Some are going to burn the motors out looking for a little extra.
My deduction so far is that the 21.5 doesn’t have the torque in a TC that allows high gearing in the brushless motors we are used too (17.5, 13.5 etc etc) and will need to be geared conservatively for long life. If you have a regular Gen 1 or 2 speedie then start your gearing at about the same as your 540 (45mmpr) and go up a tooth or 2 on your pinion keeping an eye on the temp – you will be as fast or a tad faster than a good 540. If you have a Gen3 or 4 speedie I can’t advise you yet – more testing to do sometime.