Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

diff gears in relation to dyno output result

old mate

New Member
Joined
Aug 18, 2009
Messages
738
Reaction score
7
Points
0
Age
30
Location
Gippsland, Victoria
Website
www.facebook.com
Members Ride
VB Sedan / GU Patrol
haha no worries, i was bored and was a good excuse to mess around. it wont be 100% accurate but it does give a good indication of the shape and size of the curves.

it must feel pretty linear to drive i reckon.
 

ari666

250,000 hits
Joined
Mar 10, 2009
Messages
11,829
Reaction score
119
Points
63
Location
melbourne
Members Ride
1966 impala, R32 GTR
it must feel pretty linear to drive i reckon.
the weird thing is that its one of the most stupidly happy cars i have ever driven. i dunno how to explain it. even if the graph says its weak, there have been times i would swear that graph is way off.

but yeah, you answered the question above and beyond what id hoped for so rep your way.
 

peterg2121

New Member
Joined
Jul 22, 2010
Messages
24
Reaction score
0
Points
0
Location
sydney
Members Ride
VR
diff gears

hey guys i dont know if this is an old post but in relation to diff gears ive had first hand experience and i work as a mechanic they dont increase your torque or your horsepower what happens is basicly you have a smaller ratio so you take off harder only letting your torque kick in earlier so running down the quarter would be great

so say if a car has 200 horsepower and 150nm (nm is newton meters) torque e.g like how tight you do up a wheel nut 90nm if you ran your car on a dyno on the standard set of diff gears say the car on those gears has a max speed of 200kmh

a smaller set of diff gears whitch is good for your drag racing you use the same power same torque but just the car always seems to have torque becouse it doesent require as much to push the car forward on a smaller set of gears

a tall set of gears will help your top speed but they end up being harder to turn and etc

if you look at a dyno sheet with a torque curve reading
1) standard set of diff gears you might say see a say 45 degree diagonal line
2) short set of diff gears you will see the line shoot straight up say a 70 degree line all it is is the power coming on all in one go rather then gradually
3) tall set of diff gears you will see a long line say a 30 degree line

but its a curve not a perfectly straight line

thats what i know dont bag me out just trying to help if you dont understand ask me and i will try and explain it better
 

bauer5152

New Member
Joined
Jul 25, 2011
Messages
1
Reaction score
0
Points
0
Age
33
Location
bauer5152
Members Ride
bauer5152
From my Mechanical Engineering knowledge, Power (KW or HP) is power the engine can create and is usualy constant. Changing dif gears would increase torque but lower the maximum RPM that can be acheive thus the overall power of Engine (Torque*RPM) is still constant. So would have no effect on final maximum HP/KW.

I dont have any Direct experience with Dyno's and testing though so whether this translates to real world experimental data as there are other factors to consider that effect power output such as friction losses etc that vary with RPM. Need a dyno guy to give us the answer to this one. But i would expect it to be a small variation.
I also think so.
 

old mate

New Member
Joined
Aug 18, 2009
Messages
738
Reaction score
7
Points
0
Age
30
Location
Gippsland, Victoria
Website
www.facebook.com
Members Ride
VB Sedan / GU Patrol
here is an interesting fact. the torque curve and HP curve should always intersect at 5252rpm or the dyno reading is false :)

true story bro.
note the word intersect in this statement, not the torque peak cannot be over 5252rpm which is completely false.
 
Top