Average lap rpm senior rotax

rotax_max

(Christopher Ramnauth) #1

Anyone have any figures to share for what I should be aiming as my average per lap rpm in race studio? Engine is rotax senior pre-evo. This surrounds gearing right for any particular track


(Tony Zambos) #2

Between 13 and 14.5K. Closer to 12.5K for road racing and 14.5 for sprint. For road racing, the Rotax had a good mid-range and you want to use that to your advantage. You can turn that engine over 14.2 but there’s not a lot of power there.


(Christopher Ramnauth) #3

Tony I think you’re referring to peak rpm, I’m talking about the average channel feature in race studio, it averages the rpm over the entire track and this is a more effective way of getting your gearing right regardless of track config. You just adjust gearing until it’s where you know is optimal. I’ve heard 9800 is the number, just wanted to know if anyone else has done testing


(Tony Zambos) #4

Chris, for most of the road races we did, around 10.7 K was the value the average channel. At one track, the value was 11.1. Have no idea how this value would translate to a sprint racer.


(Christopher Ramnauth) #5

Oh wow that’s quite high…I’m on 11x83 gearing and only doing 10500 or so average. But I’ve been told I’m geared way too short and that I should aim for around 9800. Got this from someone working BRP, but I too found it sounded a bit on the low side


(James McMahon) #6

I’m very sceptical of average RPM being a useful data point. It’s not so much how long you spend at certain RPMs, but a matter when you are using them to most effect. Inclines of course a one example as well as how critical a particular turn may be in terms of lap time. Turns that precede long straights for example


(Christopher Ramnauth) #7

I get what you’re saying James, but the engine has a characteristics power and torque curve and that is fixed regardless of the track. The point of gearing is to be able to keep the engine geared where it’s making the best use of that power/torque characteristic.

I can see in some instances though where using the average feature may not be the way to go, but for most instances…I think it should be a pretty good starting place to arrive at the optimal gear. that’s my thinking anyways…good to hear you guy’s take though…this was the point of the post

If you have any data from rotax senior from different tracks where you know you were on the quickest gearing…can you for info sake double check what your average per lap rpms looked like? I’d be interested to see other people’s data…


(Tony Zambos) #8

Your method may have some merit and it would be great to pull a number off of RS and have the perfect gear. But the power curve of your engine will not remain the same. The power output of an engine is predicated on air temperature and air density. Neither remain constant during a single day at a track, let alone between multiple visits to a track.
A better tool or tools IMO is a stop watch, a barometer, tire pressure gauge, a stack of gears plus pen and paper.


(Christopher Ramnauth) #9

Understood Tony. On that note, since you seem to have some knowledge on both rotax and gearing. I was asking on another post about gearing vs jetting requirement. Have you ever experienced the scenario if you gear longer vs shorter so you’re hitting less max revs that the engine could use a leaner main hence produce more peak power vs if you geared shorter and revved the engine all the way out to 14200 it wouldn’t take that lean a jet…it’d begin popping and ask for a bigger main?


(Tony Zambos) #10

The short answer is no. Tuned the engine to atmospheric conditions and tested for best gearing.


(James McMahon) #11

I think the first thing you need to do is clean up the data so you are only measuring average RPM under acceleration only. Yes what goes up must come down, but again you need to measure it where it matters, including inclines.