Hi all, recently went to a new track after racing on one track the whole year and gearing was a complete disaster. We were off pace for the whole weekend until the last 2 heats when we finally figured out the gearing somewhat. However I have several questions about gearing on the VLR.
Does changing the front sprocket do anything? I’ve seen 10,11 and 12 teeth front sprockets available, so would say a 12 be better at a high speed track compared to a 10? From what I’ve heard it doesn’t make a difference.
What RPM should I be aiming for? I’ve heard various numbers thrown around, 16000, 16500, etc. What minimum RPM should I have? On the Vortex website it says around 9800, so I am presuming somewhere around there?
Gearing seems pretty important as my best laptime went down almost a half a second once we figured out the gearing in just 1 practice session (after almost 6 sessions before with barely any improvement), so I really want to get this sorted and hopefully be faster
The front sprocket changes the ratio just like the rear sprocket, but in reverse and with bigger results. A smaller front sprocket will increase the gear ratio (more RPM, more acceleration) and a larger front sprocket will decrease the gear ratio (less RPM, more top speed). The reasons for changing the front sprocket typically are if you’re having to put a really large rear sprocket on to get the RPM you want, and you would rather run a smaller rear gear to reduce the risk of it bottoming out on the track. In that case you could put a smaller front sprocket on and in turn could run a smaller rear sprocket to keep the ration the same but have more ground clearance.
I don’t know specifically the VLR’s RPM range and powerband but max RPM definitely shouldn’t be 9800. I’m assuming Vortex is talking about peak torque with that number. In general with any engine you want to gear so you spend as much time in that peak torque number as possible. To do that, you will need to “over rev” and run higher RPMs so that you can take advantage of that torque curve as often as possible through the lap. So on the end of the straights you are running more RPM and not making as much power there but the rest of the lap the engine is right around that 9800 mark and making max power for most of the lap.
On the similar KA engine, we aim for 15.5-17k RPM for max RPM. I’m guessing it’s about the same range for the VLR.