What Model Dynojet did you test on?

ATV, 248C.......?

 

Not sure about the crank vs. RWHP? I assumed that everybody was testing RWHP, that would make up the difference. I dyno'ed on a Dynojet 168/188 with the WinPEP software.

 

Any suggestions or explanations? Trinity, Raptor720?

 

ZRWHAT
On a rear wheel dyno you are obviously checking horsepower to the rear wheels, Any drag or problem will show up as a lower hp # , example: tire deflection on the dyno wheel ( low pressure, tied down to tight, The wider the tire the worse the problem ) also too tight of chain, bad chain, loose chain, bad rear bearings, brakes draging, etc. Consistency is the key to doing good dyno work. If you aren't consistent from bike to bike then the comparisons are void. The tires are the biggest variable, We use a special tire that gets good bite on the dyno wheel and we always run the same tire pressure. This eliminates tires out of the equation. All the other problems would have to be addressed on the bike itself.
Tire slip on the older Dynojet dyno's shows up as a broken or incomplete curve, the operator then has to hit the f8 key to "fill in the blanks" so to speak. At least that’s the way it worked on my Dyonjet( I now have a Superflow SF 240 ). Horsepower also can vary dyno to dyno and will also vary from different dyno manufacturers ( they calculate final hp differently ) It's well known that a Dynojet reads about 10% higher hp figures than a Superflow. (Superflow claims that their calculations and correction factors are more accurate ) I purchased the Superflow because it could do more for me as a tuning tool. ( more bells and whistles ) Rear wheel dyno's are tools used to evaluate performance changes, verify and tune. And unless certain guidelines are met can't be ACCURATELY used to judge one bike against another using different dyno's.

 

ZRWHAT,

Some dynos are setup to calculate horsepower at sea level and some are non calculated ! What was the weather and altitude, this will make a big difference if they didn't calculate it to sea level. I'm sure Harry can tell us if his does or not to give an Idea of some numbers. Like harry said if they set it to auto calculate it to sea level then the numbers look more consistent from place to place.

 

Well, I think #'s are just that, #'s. You said that you felt a night and day difference compared to your previous mods, So that is whats important, As long as you can ride it, and FEEL like you got your moneys worth, Than who cares about #'s. ALL that really matters is that it gave you enough power to beat your buddies, RIGHT?

Biggerisbetter.

 

Most dyno's have a weather station built in and will update as you go. Others require initial setting daily then continue to calculate on the fly. The typical correction factor (CF) is calculated based on the absolute barometric pressure, air temperature and water content of the air used for combustion by the engine. It attempts to predict the horsepower that would be developed if the engine were tested at sea level under standard pressure and temperature conditions.

 

ZRWHAT, I can assure you that the numbers in the mags are HP @ the crank and not the rear wheels. The mags always rate it there unless otherwise stated. Of course it sounds better with the higher number. The stock Raptor (Cal. model) puts out 34.6 ponies according to the mags...I'd bet my left n_t that it ain't at the rear wheels.

You got one bad a$$ bike there dude - be proud of it...very proud of it!

 

2strokeDiehard: The dyno had a weather station, or at least it had readings for temp/hummidity/barrometric pressure. I am unsure about the correction to sea level, but that shouldn't be a factor because we are at sea level here in Indiana.


biggerisbetter: I deffinitely felt a difference between the previous mod's and the new motor build. It kind of felt like going from a Spree to a R1, well maybe not that drastic.

eRAPTOID: I don't know about the rwhp? Everyone that I have heard numbers from on this forum refer to rwhp and not HP at the crank. Does anybody know what dyno was used in the last pipe shootout that CT did for dirtwheels?

 

If it is on tire dyno it is at the rear wheels!