How fast can a scooter really go? Dyno Data & Sprint Sim....

[Darrell Taylor]

Heres something i thought i would share, only a snippet or 2 though as its hard earned data about my group 6 race scooter that ive built over the last year, from its performance on race track/scooter shootout/elvington mile meeting as well as dyno data and sprint simulation data that ive pulled together.

This is the info i pulled together when Ian Campbell visited me, i put his weight and my gearing data in and the revised power figure it made with the fan removed (43.6bhp) to do the Elvington 1-mile sprint. The data below is as per Monday's runs at 117 and the 2nd day we ran just 1 tooth less on rear and it ran 118.6mph. This is as per rich settings as ran on Dan's dyno, apart from fan removed. It didnt get up to temp on that jetting so dropped a few jet sizes to acquire the correct temps and the times came good.

The basis for this data was worked from info i acquired from the scooter shootout 1/2 mile runs we did with Joe on board doing 112.9mph my software workings from that were within 1mph of actual results so got it dialled in really well, you can get some great data from this as to what is needed, remember this is group 6 chassis with improved aero and small light rider.

[Darrell Taylor]

Heres a full bodied with 35bhp, gearing on this chart isn't optimised, the trick is to follow the grey resistance line and check speed and hp requirements.

[Arcadia]

This is really interesting, please can you explain a bit more about it?

So you take a dyno graph and input the info into some other software, and add in some additional figures like weight and gearing, and the software tells you what top speed you will do? Is that right?

So how does it know things like frontal area of a Lambretta compared to say a motorbike with fairing which would clearly be more aerodynamic?

[drunkmunkey6969]

Darrell....ive not seen software like this before, can it 'work backwards'? By that, i mean if you know another scooters speeds/times....can you calc back how much power they have? Presuming you know their gearing for example?

And what factors go into calculating the drag/friction curve?

[Darrell Taylor]

Arcadia.....the software is well used in the sprint scene around the world and its result are well respected, i started using it first a few years ago on a fizzy project to calculate methods of achieving spread of power against the available gear ratios, it lets you know if the high power you have is useable over the gears available or if the hole in the power curve results in a actual slower speed or lap time for example. The first lamby i tuned, i studied this area first to evaluate what spread was needed and tuned accordingly, it allows you to input your dyno graph/gear ratios /final drive/machine+rider weight/loads of other data too but had no bodywork data to work from, so i did the crafty thing and used the dyno graphs of the very successful JB Tuning tuned bikes of Tim Lee and Keith Hudson that were posted on here and collected the times they were doing and adjusted the data until it tallied with the 1/4 times and speeds (thanks Jon/Tim/Keith), then when we started sprinting started collecting our own data, the first meeting on Eric copes scooter i told James Lancaster who rode it at 2012 shootout what times it would do before the meeting and were only fractions off.....

[Darrell Taylor]

Dan......you can do a quick recky of what would be needed, pick either the group 6 or road scooter graphs then look at the drag and friction curve to the power and speed graph lines.

eg - for the group 6:

40 hp = 112mph
50 hp = 122mph
60 hp = 130mph

There are, on the day, variables to consider. eg - head or tail wind and the graphs are simply adjusted with these different inputs...

[drunkmunkey6969]

Dan......you can do a quick recky of what would be needed, pick either the group 6 or road scooter graphs then look at the drag and friction curve to the power and speed graph lines.

eg - for the group 6:

40 hp = 112mph
50 hp = 122mph
60 hp = 130mph

There are, on the day, variables to consider. eg - head or tail wind and the graphs are simply adjusted with these different inputs...

So you can actually asses what power is needed to hit a certain speed?

I know Avantone did a bit on this and am waiting to hear back from him, i cant remember what his calcs said but im sure he had some sort of graph/resistance curve also???

[Darrell Taylor]

ps we ran a huge 3.7 gearing on the group 6 look at the huge drop 1st to 2nd




quote Dan.So you can actually asses what power is needed to hit a certain speed?

yes pretty much now i have found a working formula as i said b4 from others dyno/regular sprint results and my own i can asses power requirement to achieve speed

ive just finished a new very hi torq motor ill be interested to see how it fares.

[mick1]

Does the riders weight effect these results, if so how is that inputted as a variable ?

[Adam_Winstone]

"ps we ran a huge 3.7 gearing on the group 6 look at the huge drop 1st to 2nd"

So, running a 5-speed (if one proves to hold together in such a powerful motor) and the right ignition profile, so that it is back onto the power quicker between gears, and you could ride it without feeling the massive dip in power between changes? Long gearing and the power to span the changes, now there's an idea

Adam