Chassis dyno question
06-09-2007, 03:30 PM
#21
Senior Member
DYNO OPERATOR
Join Date: Mar 2007
Location: Texas
Posts: 525
buffjhsn I was wondering if you got some ball park #'s I came up with 620 hp at the rear wheel an 689 hp at the flywheel. I think these calculators are close but I dont know about being spot on. Wesley
06-10-2007, 02:41 PM
#22
Member
CRAFTSMAN
Join Date: Mar 2006
Location: Ohio
Posts: 58
well i have a formula i use to get rear wheel hp.... it is as follows
hp=weight*200/et*et*et
hp=2750*200/8.962*8.962*8.962
hp=550000/719.8
hp=764
i went to tim mccamis like you said and used the calculator. it says that i have
755.1 rwhp and 981.63 at the flywheel.
i just have a hard time believing this pooch of mine make almost 1000hp... i also have a hard time believing i lose 230 horse to the tires....
i have used my formula on a buddies dragster that makes 900 hp on the dyno and he had 900 horse at the rear wheels on his best pass....so thats why i wanted some input. making 1.512 horse per cube is respectable outta a 505 with box stock heads and intake.
i don't believe that you lose 25% to the tires. i understand it takes hp to initially turn the drive train but everything you put into the rear gears, converter, and trans is multiplied to the tires. granted you lose some through converter slippage, but 25%???
once you get the mass moving in stays moving (newtons law)....
anyone have any thoughts on this???
hp=weight*200/et*et*et
hp=2750*200/8.962*8.962*8.962
hp=550000/719.8
hp=764
i went to tim mccamis like you said and used the calculator. it says that i have
755.1 rwhp and 981.63 at the flywheel.
i just have a hard time believing this pooch of mine make almost 1000hp... i also have a hard time believing i lose 230 horse to the tires....
i have used my formula on a buddies dragster that makes 900 hp on the dyno and he had 900 horse at the rear wheels on his best pass....so thats why i wanted some input. making 1.512 horse per cube is respectable outta a 505 with box stock heads and intake.
i don't believe that you lose 25% to the tires. i understand it takes hp to initially turn the drive train but everything you put into the rear gears, converter, and trans is multiplied to the tires. granted you lose some through converter slippage, but 25%???
once you get the mass moving in stays moving (newtons law)....
anyone have any thoughts on this???
06-10-2007, 02:53 PM
#23
Member
CRAFTSMAN
Join Date: Mar 2006
Location: Ohio
Posts: 58
Originally Posted by woodsman
buffjhsn I was wondering if you got some ball park #'s I came up with 620 hp at the rear wheel an 689 hp at the flywheel. I think these calculators are close but I dont know about being spot on. Wesley
06-10-2007, 03:38 PM
#24
Senior Member
DYNO OPERATOR
Join Date: Mar 2007
Location: Texas
Posts: 525
buffjhsn1 I used Wallace Racing Calculators (hp from 1/4 mph,et and weight calculator) I think they are the closest. I just put your et and weight in to get the #'s if you put in the MPH than you come up with 755hp as you did and that looks much better. Sorry if I stole some of your pony's. I am a little new at this and did not input all the info. Well I have learned another good lesson on RJ. Wesley
06-10-2007, 05:17 PM
#25
Member
CRAFTSMAN
Join Date: Mar 2006
Location: Ohio
Posts: 58
Originally Posted by woodsman
buffjhsn1 I used Wallace Racing Calculators (hp from 1/4 mph,et and weight calculator) I think they are the closest. I just put your et and weight in to get the #'s if you put in the MPH than you come up with 755hp as you did and that looks much better. Sorry if I stole some of your pony's. I am a little new at this and did not input all the info. Well I have learned another good lesson on RJ. Wesley
no big deal, i dunno what is right or wrong. all i know is what it runs in the 1/4 and what it weighs.
06-10-2007, 06:26 PM
#26
Senior Member
DYNO OPERATOR
Join Date: Mar 2007
Location: Texas
Posts: 525
buffjhsn1 I think I am trying to help to soon. So will just sit back and let the boy's that know what they are talking about give the advice. And thanks for your understanding. I love this stuff and will get great enjoyment out of it. Thanks again. Wesley
