Gears and HP

[SquadX]

Ive seen on here that gears lower overal hp. Some one posted a dyno graph the other day with 3.55 gears. In the comments, someone mentioned if you had stock gears, the hp would be about 30 more rwhp. So my question is, if going from a 3.07 to a 3.55 takes hp away, would going from a 3.07 to a, say 2.55 (making stuff up here) gain hp over the stock gears.

Many high performance cars have higher gears like the z06 (3.42), but why do the SL65 AMG and the lambo murch. have lower gears, 2.__? Just trying to get an understand of the two questions. Every one says the viper would be perfect with 3.55 but when the murch and amg have gears lower then the viper, and they accel. quicker off the, thru the 1/4.

 

[SquadX]

Bump bump bump

 

[gb66gth]

does'nt make sense to me. Horsepower should remain constant regardless of gears, as long as you could reach the same rpm level. For example, if you took the motor out of the car altogether and put it on an engine dyno, unattached to any transmission at all, it should give realtively the same bhp rating...No?

 

[SquadX]

that's why I bought this up as u stated...hp should stay the same. I'm I reading the comments out of text that gears hurt hp? I'm speaking of rwhp if that was unclear.
Also what benefit did lambo and the amg get with using taller gears (2.__)?

 

[Bandit3]

I have always heard that "gears" will not affect HP in anyway, but will affect acceleration/deceleration.

 

[JonB]

I have always heard that "gears" will not affect HP in anyway, but will affect acceleration/deceleration.

Bingo.

This topic is possibly the MOST documented topic on this site, and eminently searchable.

 

[SquadX]

That's what I believe but wanted clarification since some have posted otherwise.

 

[JonB]

.............many High Performance Cars Have Higher Gears Like The Z06 (3.42), But Why Do The Sl65 Amg And The Lambo Murch. Have Lower Gears, 2.__? Just Trying To Get An Understand Of The Two Questions. Every One Says The Viper Would Be Perfect With 3.55 But When The Murch And Amg Have Gears Lower Then The Viper, And They Accel. Quicker Off The, Thru The 1/4.

if They Had The Vipers Low-rev V-10, And The Same Viper Tranny, They Would Also Have Different Gears Than They Chose For Their Own Driveline.

 

[pe5787]

Also what benefit did lambo and the amg get with using taller gears (2.__)?[/QUOTE]

I think the trans ratios in the AMG & Lambo are shorter and make the overall gearing closer to the viper.

 

[2001 GTS]

Joseph Dell said something about the 3.55 gears adding more friction to the drivetrain loss, hence reading a slightly lower number than the 3.07s.

 

[DEADEYE]

Shorter gears will change the way the dyno interprets the HP curve. Your actuall hp stays the same.

 

[IEATVETS]

I've got a writeup about this that I will post as soon as I scan it. Basically what it says, if memory serves me, is the HP isn't affected at all, just the TQ. I will post it later on and let you guys decide.

 

[SquadX]

I've got a writeup about this that I will post as soon as I scan it. Basically what it says, if memory serves me, is the HP isn't affected at all, just the TQ. I will post it later on and let you guys decide.

cant wait to read it.

 

[IEATVETS]

 

[BOTTLEFED]

this is almost more confusing
it seems to be saying that torque increases with a gears swap??
can someone clarify this?

I'm wondering about this as I have 3.55s and with the S/C now, I feel like the 3.07s would be more drivable and make launches more controllable

 

[DEADEYE]

Shorter gears multiply torque at the wheels, not the engine. Since HP is a function of torque, it is also affected at the rear wheels. Next time you dyno your car, dyno once in 3rd gear and again in 4th gear. You will get different results. Not because of the engine though, the change takes place at the gear.

 

[ShadowLight]

In simple terms, think about it:

Shorter gears punch harder off the line, what causes the punch? TORQUE and there is more of it.