Quote:
Originally Posted by tapemonkey
I don't think those are percent gains, I think they're HP gains.
If the figures are correct for the 35/70mm combo then the increase at 6000rpm is almost 9%. Sounds pretty good to me and perfect for a road bike.
Tapemonkey.
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Hi TM -
Correct - The hp numbers are are definitely "HP" gains - not percentages.
All the Factory Pro dyno tests are full, steady state tests and the hp scale is
True HP scale (that's why the HP numbers are
lower than djhp)
Hi Robw#70 -
The sv650 dyno charts were tested every 1000 rpm, as is common for loaded, steady state testing - that is probably why, if you are used to looking at a simple sweep tests (ala dynojet and dj clones) would see it as "odd" looking - but really - it's a better way to test - even when tuning FI, the bike's only at full throttle for less than 10 seconds at a time
And instead of only 1 sample at many rpm points (dj style), each rpm point has 100's of averaged torque and hp samples at each point for better accuracy.
You could actually do steady state testing every 100, 250 or 500 rpm, but it would cause more "engine run timer".
Another thing about stacks - They will always change power output when you change lengths. Better or worse, in one rpm band or another - And - the shape of the flare and inner diameter of the stack are equally important.
I've always seen carbs react to length changes - BUT - stack changes DO affect the way a carb delivers fuel and jet size required for Best Power.
Quite often the power changes that the diff. stacks cause are masked by the changes in the carb jet requirements -
That's another reason to use steady state testing and a 4 gas EGA, rather than a simple o2 sensor in a sweep test to help tuning -
Also - keep in mind (for the tinkerers) that what stack configuration works best on a stock engine may not be the correct stack configuration for a ported or cammed or big-bored engine -
Marc Salvisberg
415 491 5920
www.factorypro.com
marc@factorypro.com