Hi Bushie and all Husaberg friends!
As I'm slowly recovering from a MAN-COLD (Yes friends, a near death experience), I have time to kill with browsing this thread and noticing how fast it all went bonkers!
Somewhat entertaining but more worrying.
My last dyno result was 88 RWHP (not for comparison with results from other dynos) and that was with these specs:
Bore: 104mm
Stroke: 80mm
Cylinder volume: 680cc
Intake valve dia: 41mm
Exhaust valve dia: 34mm
Intake max lift: 13,0mm
Exhaust max lift: 12,0mm
Intake cam duration (@0,050" lift): 256deg (little less on exhaust)
Geometric compression ratio: 13,5:1
EFI: Megasquirt III
Throttle body and injector: Ducati 1198
Maybe that gives some reference on what a 680cc thumper is capable of putting out? When i started stop calling it a Husaberg?
Well, the crankcases, covers, gearbox and clutch are still Husaberg... -ish.
Well, now I will not participate in leading this thread any further from the topic!
My 50-cents:
Porting job and flow testing does not tell near half the story, when it comes to finding as much power as possible. With that being said, if you are not changing anything else, nice ports WILL of course give you some positive effect. If that is the case, I'm sure any skilled, experienced head porting company will do it for you! Just correcting possible edges in the casting and ensuring smooth transitions from carb/throttle body to intake to valve seat, will help a lot. Some are tempted to cut off the valve guides, which will increase flow but reduce technical life span. I would have to advice against that, however it might be OK for a dragracing engine. Some are tempted to polish the intake, but it will not increase flow but cause fuel to condensate on the shiny walls (poor air/fuel mixture which needs to be compensated with a richer jetting than necessary). The Husaberg intake is of "dump" type (not "tumble"), so porting should make the most out of that (which is not bad at all). Trying to port it more like "tumble" will not give the benefits a "tumble" type intake normally is associated with. So keep away from taking material from the "floor" close to the valve guide and downstream! All this is yesterdays news to anyone claiming to know their stuff. A nice service minded attitude from your head porting company will maybe be just as important to the whole experience?
If you are feeling free of the boundaries of the OEM design, another world of opportunities to spend money is available to you!
The whole shape of the intake plays a big(biggest?) role and second to that, the exhaust system. To my experience the total length (velocity stack to valve seat) and the areas all the way through the intake (not causing any sudden pressure changes), is more crucial than just the flow test results. I have made the largest leaps in gaining power at the dyno, trying out different intake and exhaust lengths. Once I discovered that the velocity stack was a tad too small, causing the air flow going super sonic! Just enlarging the stack (costed me just a couple of hours in the workshop and two cups of coffee) was rewarded with some 10 RWHP! I have more examples, but it´s supper time in Sweden now!
Good luck with Thumper Racing, Big Berg, and may the force be with you!
@Thorgan: "stock 84mm stroke"? Is that true for a 2008 650? Didn't know that! To my knowledge the 644 cranks were 82mm and the 628 cranks 80mm.
