dirtdragguy Posted September 18, 2009 Report Share Posted September 18, 2009 (edited) Good evening, I was reviewing this thread saw the "my dyno will out run your dyno" argument. I will go ahead and tell everyone that I am NOT an expert tuner of drag ATVs. I do review a large number of dyno pulls for a large private fleet's road tractors, they have to be dyno pulled before turn in to the leasing company. So I do know a little about dyno's and their results. First that dyno's don't "read" horse power, that number is a figment of the operator and computers imagination. They only read torque which is twisting force on the drum only. Then you have to look at what size drum & how much weight of the drum & what is the calibration or lack of on the unit. If you have a dyno that is calibrated for 500 ft. lbs. with 1%. Then drop back to the atv range let's say 50 ft.lbs. just to make the math easy say 50 ft lbs. now we could be 10% off now. Their is also the "weather station" & corrected h.p. when I see this on a dyno sheet it is highly suspect. The operator can move them where ever you want. That is where the amazing results of the mobile dyno guy comes from at bike shows. They pull your bike on their make a pull then screw with the carb correct the weather numbers & now you get 10% more horse power WOW! So in closing a dyno is just one tool for helping in racing & tuning. Because how many hours & fun at the track would be lost screwing with jetting & or timing. When you could go to a dyno & tune right their. This has got really long & looks like crap grammar, but oh well I am drunk. Edited September 18, 2009 by dirtdragguy Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted September 18, 2009 Report Share Posted September 18, 2009 I dont use a chassis dyno, heck I dont even use a sprocket dyno. I use a crank dyno. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 18, 2009 Report Share Posted September 18, 2009 Look...final answer, firehead is still the king of drag. Settled. Quote Link to comment Share on other sites More sharing options...
dirtdragguy Posted September 18, 2009 Report Share Posted September 18, 2009 I dont use a chassis dyno, heck I dont even use a sprocket dyno. I use a crank dyno. A crank dyno is still a water brake unit. It just mounts to the crank instead of a drum, everything else I said applies the same. Quote Link to comment Share on other sites More sharing options...
bigborebanshee Posted September 18, 2009 Report Share Posted September 18, 2009 (edited) I dont use a chassis dyno, heck I dont even use a sprocket dyno. I use a crank dyno. I agree,considering the type of "drive chain" can alter output,the less variables to consider..the better A crank dyno is still a water brake unit. It just mounts to the crank instead of a drum, everything else I said applies the same. Yea,but now you can subtract the traction,gearing,tire and drivetrain factor...much more accurate on an engines performance numbers.Chassis dyno add too many variables that if not calculated correctly will reflect on output numbers. Not to mention crank dynos that are designed for smaller engines are better than +/- 10% on accuracy. What your doing is comparing a carpenters ruler to a machinist scale. Edited September 18, 2009 by bigborebanshee Quote Link to comment Share on other sites More sharing options...
BB3 Posted September 18, 2009 Report Share Posted September 18, 2009 I always wonder why when the track gets loose, I always run like crap; but you still got guys knocking off 3.60s like clockwork on the same loose track. I'm that guy that can't tune the setup of my bike, or can't ride, I guess. Put my 50 lb lighter buddy on there and he picks up 3 tenths. Heck ya if i had Jeff as a jockey id be Fast as well....lol....j/k bro... congrats on the 0-650 class...that was a awesome Time you ran and i dont see a 4 stroke running that kind of Time. Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted September 18, 2009 Report Share Posted September 18, 2009 The crank dynos are way more accurate than anything else, there is a huge difference in the way it samples the motor. There is no clutch, no gears, no chain, and no sprocket. The correction programs are alot easier to use as well. So by far its nothing like running on a drum. Drums dont even have an engine break either. Quote Link to comment Share on other sites More sharing options...
dirtdragguy Posted September 18, 2009 Report Share Posted September 18, 2009 I agree, A crank dyno is more accurate, but I just checked on land & sea and they claim .5% accuracy at the point of calibration. This is at a point at the top of scale. They stated that below a certain point their isn't enough water flow for measurement. this was around 30 h.p. or 15 h.p. per rotor. So I wouldn't claim anymore accurate than say a Machinist rule to a tape measure. LOL! But wasn't this a drag racing thread & haven't we just "jail house raped" somebodies thread? So I will remove my self from this topic. Quote Link to comment Share on other sites More sharing options...
JMADD Posted September 18, 2009 Report Share Posted September 18, 2009 Heck ya if i had Jeff as a jockey id be Fast as well....lol....j/k bro... congrats on the 0-650 class...that was a awesome Time you ran and i dont see a 4 stroke running that kind of Time. Well, I don't even own that bike (in my sig) anymore. I gave it way.. er.,sold it to Eric. Quote Link to comment Share on other sites More sharing options...
BB3 Posted September 18, 2009 Report Share Posted September 18, 2009 Well, I don't even own that bike (in my sig) anymore. I gave it way.. er.,sold it to Eric. oh my bad sorry, it ran good last weekend right when it counted. Quote Link to comment Share on other sites More sharing options...
JMADD Posted September 19, 2009 Report Share Posted September 19, 2009 oh my bad sorry, it ran good last weekend right when it counted. No need to apologize. Just kicking myself for selling it. It ran its best pass ther last week. Nothing different done to it since I had it. Hoping my 16 cheetah runs even better. And, to stay on subject of the thread. I'll again say that a good setup 421 cub, or even 397, will stomp any raptor on the track. you could run the cub on a stock chassis and the raptor on a drag chassis on motor. Quote Link to comment Share on other sites More sharing options...
2K1Banshee350 Posted September 22, 2009 Author Report Share Posted September 22, 2009 how much hp can u get out of a gas 350? i ask because of this http://www.quadracerhq.com/forum/showthread.php?t=9292 Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted September 22, 2009 Report Share Posted September 22, 2009 how much hp can u get out of a gas 350? i ask because of this http://www.quadracerhq.com/forum/showthread.php?t=9292 70-75hp. Quote Link to comment Share on other sites More sharing options...
2K1Banshee350 Posted September 22, 2009 Author Report Share Posted September 22, 2009 70-75hp. what about a gas 450 4 stroke Quote Link to comment Share on other sites More sharing options...
shanYE west Posted September 22, 2009 Report Share Posted September 22, 2009 yeah.. I'd say about 75ish give or take.. I've never seen a triple port on gas though.. so I'd have to say it could see 85ish hp on gas... Quote Link to comment Share on other sites More sharing options...
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