I have a friend who is telling me getting new gears or "changing the gear ratios" increases horsepower and torque. I told him it doesn't, and it just feels that way.
Someone clarify.
EDIT: He just says it increases torque, not horsepower.
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Gears are normally used to transmit torque from one shaft to another. These shafts may operate in line, parallel to each other, or at an angle to each other. These different applications require a variety of gear designs, which vary primarily in the size and shape of the teeth.
'89 LX 5.0 Hatchback
For accuracy on your track times. GO TO THE TRACK!
8.1 with 5spd et streets
AOD all motor 8.8@78 mph street tires
125 shot nitous 7.51@91 mph street tires
http://www.mustangregistry.org/Tech/...6/chap_06A.htm
If you want to feel an increase in acceleration, get some gears. Again, these do not make more BHP, they just improve acceleration by getting the 5.0L to its peak power output RPM sooner. A stock '87 to '93 Mustang came with 2.73 gears while some were optionaed 3.08 and 3.27 gears. For the street, the 3.27s are a nice step up from the 2.73s. However, if you visit the high end of your tach often, go with the 3.55s or 3.73s. These are a popular modification with late model mustangs.
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'89 LX 5.0 Hatchback
For accuracy on your track times. GO TO THE TRACK!
8.1 with 5spd et streets
AOD all motor 8.8@78 mph street tires
125 shot nitous 7.51@91 mph street tires
Gears are normally used to transmit torque from one shaft to another. These shafts may operate in line, parallel to each other, or at an angle to each other. These different applications require a variety of gear designs, which vary primarily in the size and shape of the teeth.
If i may say something about that, You referenced to howstuffworks.com as did i and i read it. http://science.howstuffworks.com/gear.htm As i will quote directly from this page.
"With a gear reduction, the output speed can be reduced while the torque is increased."
I will disagree. WILL NOT SHOW ON DYNO. .... Peak Torque will not increase. It will move in down the "dyno graph" if any. If someone can post some proven facts. LIKE own experience than I will agree.
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'89 LX 5.0 Hatchback
For accuracy on your track times. GO TO THE TRACK!
8.1 with 5spd et streets
AOD all motor 8.8@78 mph street tires
125 shot nitous 7.51@91 mph street tires
On our race bikes (01' 996 and a 01 aprilia rsv) gear changes do change dyno readings on both torqe and horse power but only by about 1%, wich on those bikes is about 1.5 hp.
a ratio change will not increase produced torque. It will increase the mechanical advantage of the rear end. Therefore it feels like the car is producing more torque. It also gets the engine into it's powerband quicker. The downside it goes out of the powerband faster also.
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Sometimes I think that government fits that old-fashioned definition of a baby: An alimentary canal with an appetite at one end and no sense of responsibility at the other.
- Ronald Reagan
I will agree with you 150% Bluestreak 03 that is what I wanted to say. But couldnt quite say it like that. THank you.
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'89 LX 5.0 Hatchback
For accuracy on your track times. GO TO THE TRACK!
8.1 with 5spd et streets
AOD all motor 8.8@78 mph street tires
125 shot nitous 7.51@91 mph street tires
still no one has explained this clearly. If it improves times, how is there no power gain? Is it because it reduces top speed, so on a dyno it balances out or something????
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Performance: C&L CAI with Xcal 3 Tuner. 93 Race tune by Bamachips. GT sway Bars. 8.8 Rear axle with 4.10 gears. Dual Magnaflow Exhaust.
Not performance... 7 inch In dash Pioneer DVD/touch screen deck, Shaker 500 system, Chrome taillight trim. Sequential taillights. Window tint, Viper alarm with remote start. Cobra radar detector with GPS. Black 18" bullitt wheels with Sumitomo High Performance HTR Z II Tires.
how I pay for my mods: andydew.myvi.net
It reduces top speed for more acceleration, just changes the output speeds of the transmission to the wheels so no HP or Torque is added just acceleration
It does improve HP and torque, as measure on the chassis dyno. It does NOT change the power output of the engine. So, follow me on this.
- The chassis dyno measures the amount of torque applied to the rear wheels. It does not measure engine output directly.
- HP is not measured. It's calculated from the torque and rpm readings.
- Any increase in torque will also show an increase in hp.
- All gears - except 1:1 - will change torque application. OD devides torque, and UD multiplies torque. That's why all dyno runs are done in 4th gear; which is 1:1.
- A gear drive is like a lever. think of a 3.00 bar gear as a 4' bar, with the fulcrum at the 1' mark. A 4.10 gear is a 5.1' bar with the fulcrum at the 1' mark. "Give me a long enough lever, and I can move the world."
- goin from a 3.00 gear to a 4.10 gear will change torque application at the rear wheels. That's why the car is quicker. Torque gets you moving, hp keeps you there.
- Whenever I go to the dyno, the tuner wants to know what the rear gear and tire size is.
Do new gears increase horsepower and torque? 
