Three brand new EVO engines were run in on Friday and then testing started in earnest on Saturday morning. Kohen Bam drove the Junior Max, Julian van der Watt the Senior Max and Luca Canderle the DD2. Testing started with 2014 spec engines setting a base line on new rubber and then one by one the new components were added (and removed) to get a feel for what the effect of each upgrade is. This article is not intended to be a conclusive or formal report but just an overview that competitors may find useful in choosing which upgrade(s) to do first and explaining why these upgrades were done in the first place.
The carburettor was the first item tested and all the drivers reported that it was much easier to drive and more forgiving if you made a mistake. The lap times were only slightly quicker but I think it is very important to note that we were comparing the EVO carb out of the box to top class existing carbs being driven by experts – not your average competitors carb – so the benefit may well be a lot more for the average racer. The jetting still needs refining but the Junior was good on a 116, the Senior around 118 and the DD2 around 128 (all at sea level – sizes will be smaller inland). Rotax and Dell'Orto spent time developing an optimum and easy to use carb set up that is competitive and to save you having to pay an expert to modify the old carb before it performs well. The carb is definitely a “want to have” that should improve your race time significantly.
The EVO ignition system transforms the Junior Max – much smoother and the engine “breaks through” without hesitation. Rotax developed the Max engine in 1997 and mapped an ignition curve to suit this.
Five
years later the Junior Max was produced by simply making a cylinder with a smaller exhaust port and shorter duration. The ignition was never calibrated for the Junior engine hence the problems encountered when the engines often resist revving on beyond 12400 rpm making tuning extremely critical. The new ignition now has an ECU specially programmed for each class of engine so this problem is solved. In Bam’s opinion this ignition is the first item on the wish list for Junior Max.
The electronic power valve was a big hit with vd Watt (Snr) and Canderle (DD2) who both reported that the power valve worked predictably and decisively every time unlike the old system where they never felt confident that it would react as it should. Again both said that race times would improve and that the EVO exhaust power valve was far more forgiving. The exhaust power valve has been an important part of Rotax’s performance and low revving reliability secrets but with the vision of hindsight the operation of the power valve using pressure in the exhaust system was too sensitive and very difficult for the average competitor to master. The electronic power valve is actuated by vacuum and an ignition triggered by a solenoid so it opens and closes precisely all the time irrespective of all the other variables. The EVO ignition system is required to actuate the electronic power valve. Both drivers agreed that this would be top of their list of upgrades.
The new exhaust systems were tested but as predicted seemed to make no difference. All the drivers commented that it was quieter.
The new EVO base motors were finally fitted in each class and proved equal to the top 2014 motors (fitted with all the 2015 bits) used in the test. This would not normally be so because traditionally the new motors from the factory were assembled with small clearances and needed many hours of running before delivering optimum performance. The EVO engines are now built with “racing” clearances so no need to have them blue printed (artificially aged) by an engine tuner. More importantly we can confidently confirm that this demonstrates that a 2014 (or much older) motor can be upgraded to the exact same spec and performance as a new EVO engine.
Our sincere thanks to Joy, the SAKRA team, Kohen and Henry Bam, Julian and Deon Van Der Watt and Luca Canderle for their time and efforts on Friday and Saturday.
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