View Single Post
Old 04-17-2014, 03:29 AM   #415
JMo (& piglet) OP
Gone a bit Baja
JMo (& piglet)'s Avatar
Joined: Apr 2007
Location: Somewhere west of Laramie...
Oddometer: 4,445
John sent me a coupe of print-outs from the first dyno test...

This is the stock KTM 690 Enduro - 40,000 miles so nicely bedded in!

Max figures for the 654cc bike are: 59.1hp @ 6843rpm and 46.4lb/ft torque @ 6250rpm.

The first run on the dyno for the LC4-50 conversion produced this in comparison:

Max figures for the 449cc bike are: 47.1hp @ 8261rpm and 33.7lb/ft torque at 6811rpm.

Of course max figures only tell part of the story... what is clear from the notation on the LC4-50 chart is that there is a nice level* torque curve from around 3800rpm right up to the rev limiter, with no real drop off - indeed 82% of the maximum torque is available pretty much everywhere, with the mid range 5000-7000rpm following a similar curve (albeit with less overall torque) to the 690 engine - which is why I'm sure everyone who has ridden both says the LC4-50 still 'feels' like a 690 in the way it delivers it's power.

*Yes, there is a slight fueling glitch at around 4800rpm on the first run... Despite the dip in the graph, John says that in reality, a seat-of-the-pants road test revealled it was barely noticable... nevertheless, this is being sorted with a second dyno session tomorrow (Friday 18th April) once the custom map has been tweaked by Dave at DWR.

So in conclusion, the curves are broadly similar, albeit with around a 12hp reduction for the LC4-50 at any given revs (and similarly a deficit of 12-13lb/ft torque) - to put that in perspective it's around 20% less power from 30% less capacity - so I'd say that is pretty efficient all things considered! - and ultimately the numbers for the LC4-50 are towards the upper level of what you can expect from a similar capacity production 450cc enduro bike engine...

Perhaps most importantly, the mid-range is particularly strong and level (which is what we want for a rally bike) while there is still plenty of torque available at the higher revs even if we decide to chase maximum power at the top end...


JMo (& piglet) is offline   Reply With Quote