What HP loss due you see on the chassis dyno if you change rear ratios ?
03-27-2002, 10:29 AM
#1
Safety Car
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What HP loss due you see on the chassis dyno if you change rear ratios ?
It has been said many times before that if you change your rear gears you loose HP on the dyno. Does anybody really know what loss you will see if you change ? I mean going from say the 3.15 to 3.42, or 3.42 to 3.73, or 3.42 to 4.10 or 3.90 ?
03-27-2002, 12:48 PM
#2
Melting Slicks
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Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (Red98C5)
Hello Mr Dennis.......
3.42 to 3.73 swap is worth 8-10 rwhp.
3.42 to 3.90 swap is worth about 14 rwhp.
3.42 to 4.10 swap is worth about 18 rwhp.
Could be more of a loss with automatics due to different converters.
3.42 to 3.73 swap is worth 8-10 rwhp.
3.42 to 3.90 swap is worth about 14 rwhp.
3.42 to 4.10 swap is worth about 18 rwhp.
Could be more of a loss with automatics due to different converters.
03-27-2002, 03:35 PM
#3
Safety Car
Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (my00c5)
Could be more of a loss with automatics due to different converters.
03-27-2002, 08:26 PM
#4
Team Owner
Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (Red98C5)
I know it takes more HP to drive the dyno with tall gears and big tires but as we know dyno numbers mean nothing. It what you do at the track ;)
03-29-2002, 03:22 PM
#5
Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (robsvette)
Could be more of a loss with automatics due to different converters.
in my case my torque is much higher than my HP
in my case my torque is much higher than my HP
Regarding the gearing-dyno numbers, gears will only help your get your engine in to your powerband. I really don't think they will help by themselves make more power. If the engine is lacking,and needs to be spun a little higher, then of course a shorter gear will make that happen.
03-29-2002, 05:42 PM
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Melting Slicks
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Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (Red98C5)
We need someone from Dynojet to chime in here...
Physics tells us that F=MA (Force = mass * acceleration)
So, the mass of the drums is fixed, and your cars ability to spin and accelerate the drums through a given time period will ultimately give you a torque reading.
From what I understand, the chassis dynojets actually measure torque. Horsepower is then a derivitive of some calculation. What is that calcluation? I've seen it somewhere before.. the number 5252 sticks in my head and some multiplier and division and how fast the apple falls from the tree due to specific gravity. Well, not exactly. But, I'll do a search on the net and come back and modify this post. ;)
I FOUND IT!! Horsepower = Torque x RPM ÷ 5252
[Modified by EricVonHa, 4:50 PM 3/29/2002]
Physics tells us that F=MA (Force = mass * acceleration)
So, the mass of the drums is fixed, and your cars ability to spin and accelerate the drums through a given time period will ultimately give you a torque reading.
From what I understand, the chassis dynojets actually measure torque. Horsepower is then a derivitive of some calculation. What is that calcluation? I've seen it somewhere before.. the number 5252 sticks in my head and some multiplier and division and how fast the apple falls from the tree due to specific gravity. Well, not exactly. But, I'll do a search on the net and come back and modify this post. ;)
I FOUND IT!! Horsepower = Torque x RPM ÷ 5252
[Modified by EricVonHa, 4:50 PM 3/29/2002]
03-29-2002, 06:38 PM
#7
Re: What HP loss due you see on the chassis dyno if you change rear ratios ? (EricVonHa)
I FOUND IT!! Horsepower = Torque x RPM ÷ 5252