firechicken76

iTrader: (14)

i was talking to someone recently about autos and manuals and he said that autos make less hp but more torque than manuals, is this true?

smokeshow

iTrader: (17)

More or less. Its not the auto trans that increases the torque, its the torque converter.

firechicken76

iTrader: (14)

so would it be more so on a smaller converter/ higher stall?

smokeshow

iTrader: (17)

Technically, yes. But the conversion isn't linear. A torque converter isn't as efficient as a torque-amplifying gearset, so you lose energy as heat.

Oldsmobility85

iTrader: (1)

The converter only really does so in stall range but yes it multiplies tq do to the rout fluid flow through the stator and impeller and then hits the case in the same direction as the engine is spinning thus helping it rotate more easily.

01ssreda4

iTrader: (96)

I would read the stickies here to help you out or try the info over on Yank's website. Both should be pretty informative.

c0ncEpT

iTrader: (4)

Yes a torque converter will multiply torque on the initial hit and tapper off until it couples.

firechicken76

iTrader: (14)

sooo, if autos make more torque and manuals make more hp, then why are autos slower from the factory?

01ssreda4

iTrader: (96)

Simply put because a torque converter is a trade-off. In order to multiply torque it is not 100% efficient meaning all your hp does not get to the wheels. Stock converters multiply torque just not very much, because they are trying to reach the highest efficiency on the top end. Aftermarket converters multiply more torque but tend to be less efficient then stock converters in most cases. Also, the auto trans itself robs more power. Manuals have more gears to accelerate with also. Combine all 3 of those and the auto gets beat every time, especially from a roll. That is, when comparing stock cars.....modded cars is completely different.

c0ncEpT

iTrader: (4)

The factory torque converter isn't optimal for performance. There are very large trade offs when it comes to performance and streetability with a factory vehicle.

If all LS1 fbodys came with a 9.5" 3600 converter from the factory it would be a completely different story.

Anthony Williams

iTrader: (3)

Manuals until recently were more efficient in power transfer than autos, but with the advent of electronics and 7 speeds autos have caught up with manuals.

thunderstruck507

iTrader: (18)

Because from the factory the cars are made to be MPG efficient and the stock converter is too tight for performance application. They also use more HP in drive train loss than a manual.

The exact reason people should not cam a car with a stock converter...it's already "too small" out of the box and the cam makes it significantly worse.

Matt 00' T/A

iTrader: (2)

Nice thread. Did not know the difference myself.

joecar

If the converter is matched to the cam, on acceleration the converter allows the engine to spin up into the rpm range where it makes most of it's torque (around peak torque), this avoids loading/bogging the engine down at the lower rpm's;

also during each upshift, the converter allows the engine rpm to stay up higher and avoids the rpm being pulled down at the end of the shift;

in both cases the converter is slipping some amount which means it is multiplying engine torque (close to peak torque) into the transmission (by virtue of changing fluid motion creating force);

so not only is the engine operating close to peak torque, but the converter is multiplying this torque into the transmission until the load (the vehicle) catches up with the engine (which happens very quickly);

properly matched converter and cam makes a very quick car.