Gear ratio/final drive vs torque

[j_l200s]

I've been googling around and still don't quite understand their answers to my question.

-Does changing gear ratios/final drive directly affects (as in increases/decreases) engine torque? For eg. 5 speed gearbox changed to 6 speed gearbox.

-Some people said if u change to shorter/closer ratios, u'll increase the engine's torque.

-Some people said the max (stock) torque in the dyno chart will be shifted.

-Some people said ECU (piggy or standalone) need to be re-tuned again cos torque already has been afffected.

I'm confused. My question might be stupid but i'd be happy if any sifus can shed some lights here. Don't give too technical terms as me or some forumers might not understand it. Try to be as simple as possible

thanks in advance!

 

[nappx]

i also not really undertand about this..but this link might help a bit laa..

Cusco - LSD - Type RS - Nengun Performance

Cusco - LSD - Type MZ - Nengun Performance

http://www.cusco.co.jp/en/catalog/pdf_catalogue_lsd.html

 

[D7zul]

Engine & Gear are two different component..

if u change gearbox, it wont effect the engine (hp & torque)..

What changes is the 'transfer of power'..

it's quite difficult to explain..

but close ratio gearbox is more efficient in race..

read this HowStuffWorks "How Gear Ratios Work"

 

[D7zul]

more info on this..

below is a dyno chart..

close ratio gearbox will make the rpm drop around 15%.. so, if u rev until 7k rpm & change gear.. it will drop the rpm to 6k.. more or less.. thus, not loosing much horsepower and u get to the finish line faster..

Normal ratio gearbox will make the rpm drop around 25%.. so, if u rev until 7k rpm & change gear.. it will drop the rpm to 5k.. more or less.. thus, loosing more horsepower and u get to the finish line slower..

Gudluck

http://www.turnermotorsport.com/image/engine/engine_pulley_dyno.jpg

 

[cuscostrutbrace]

I've been googling around and still don't quite understand their answers to my question.

-Does changing gear ratios/final drive directly affects (as in increases/decreases) engine torque? For eg. 5 speed gearbox changed to 6 speed gearbox.

-Some people said if u change to shorter/closer ratios, u'll increase the engine's torque.

-Some people said the max (stock) torque in the dyno chart will be shifted.

-Some people said ECU (piggy or standalone) need to be re-tuned again cos torque already has been afffected.

I'm confused. My question might be stupid but i'd be happy if any sifus can shed some lights here. Don't give too technical terms as me or some forumers might not understand it. Try to be as simple as possible

thanks in advance!

-Does changing gear ratios/final drive directly affects (as in increases/decreases) engine torque? For eg. 5 speed gearbox changed to 6 speed gearbox.
Yes and no,change in final ratio will increase torque seen at the wheels,but the torque the engine can produce is unchanged.Thats why we use 2nd gear rather than 5th gear to go up hill

-Some people said if u change to shorter/closer ratios, u'll increase the engine's torque.
Closer ratio does not increase engine torque,but increase torque at the wheels(if there is change in overal ratio)

-Some people said the max (stock) torque in the dyno chart will be shifted.
I dont think so,chassis dyno machine measures rpm and wheel speed,then calculate torque and power

-Some people said ECU (piggy or standalone) need to be re-tuned again cos torque already has been afffected.
No need retune,but a re-tune might give better performance to suit the new ratio

 

[j_l200s]

Thanks guys for giving your thoughts.

 

[lkeong88]

The dyno results also depends on whether you are using inertial dyno or load dyno. Inertial dyno are affected by gear ratios

 

[D7zul]

I think we need to study Engineering before we can understand all this..

 

[nnik]

-Does changing gear ratios/final drive directly affects (as in increases/decreases) engine torque? For eg. 5 speed gearbox changed to 6 speed gearbox.
Yes and no,change in final ratio will increase torque seen at the wheels,but the torque the engine can produce is unchanged.Thats why we use 2nd gear rather than 5th gear to go up hill

-Some people said if u change to shorter/closer ratios, u'll increase the engine's torque.
Closer ratio does not increase engine torque,but increase torque at the wheels(if there is change in overal ratio)

-Some people said the max (stock) torque in the dyno chart will be shifted.
I dont think so,chassis dyno machine measures rpm and wheel speed,then calculate torque and power

-Some people said ECU (piggy or standalone) need to be re-tuned again cos torque already has been afffected.
No need retune,but a re-tune might give better performance to suit the new ratio

million credit to sifu......................

 

[xtremeleo]

shorter gearing allows u to stay in the engine's optimum power band a lot more in term of time compared to a longer gearing. for a shorter gearing, u will likely still be in the optimum power band when shifting up, compared to a longer ratio.

plus, the transfer of load is way better with a shorter ratio, with a limit to speed limit at the same engine revv, simple..

 

[nnik]

err mine asking....what if the 4agze engine using 4age gearbox...from wat i knew, tat 4agze engine got lot of tork..and compare 4agze n 4age gearbox, 4age got close ratio...so my Q is isit compatible with normal driving??? any pro n con???? mind to share...how the performance wise...

 

[xtremeleo]

performance wise, the combination shud be good. i dunno about the reliability, dat depends on the gb material i guess

 

[pcmoddingmy]

nnik: I think 20v MT gearbox can take the beating... see those 20v turbo monsters, running 5spd or even 6spd gearbox without much hassle. For SC, i think it should handle it easily. Just make sure you get it with LSD as SC kicks in quite early.
Also, it is better to tune (piggyback) the 4AGZE with 20v gearbox to improve its power delivery as the ratios are different. But hey, you no longer have to worry bout SC driveshafts anymore as 20v shafts are plenty and cheap.

 

[D7zul]

err mine asking....what if the 4agze engine using 4age gearbox...from wat i knew, tat 4agze engine got lot of tork..and compare 4agze n 4age gearbox, 4age got close ratio...so my Q is isit compatible with normal driving??? any pro n con???? mind to share...how the performance wise...

woo.. i wont do that if i were u..

yes, it will fit nicely..

but what i'm worry about is the driveshaft.. 4age driveshaft is thinner that 4agze.. so, it wont last long..

i even heard 4agze driveshaft break when its used hard..

 

[nnik]

anyone had try this setup before...esp thos using 4agze engine....