Ive noticed that the stock auto/M/T dynos have been puting very similar power down to the wheels. What I dont understand is that isnt auto tranny power loss alot greater then a M/T? . I remember back in the day I was observing a stick/auto stock dyno comparisons on civics,preludes,corollas ect and the difference in power was a large margin. Example was a 2000 auto corolla putting down 90-95 hp to wheels while a M/T put down over 105-110 on the stock 125 hp engine....This is boggling my mind. Btw I used the search function.

 

Give the car about 100k miles and then compare. It's mainly the "wear and tear" that will start to take it's toll on power in any automatic.

 

ok.. Is there anything that we can do to keep it performing like new? or is just normal? it has to wear out,

 

The bulk of the frictional losses come from the torque convertor slip and the power required to drive the transmission ATF pump. Gears are gears.

Losses vary based on the ATF temperature [viscosity].

External inline filters, external thermostatically controlled heat exchangers and frequent replacements of ATF [when additives are depleted or overheated] will extend the AT life beyond the 100,000 cycle design.

Cold driving away,failure to warm to 176F operating temperature before agressive driving is the main wear item............just like engine.

 

Yaup, that's pretty much it. Just keep up with your maintenance and you should be alright, along with common sense as in letting the car warm up properly before going crazy.

 

I don't think the original poster is talking about wear and tear at all. He's talking about drivetrain losses compared to the 6MT.

 

more moving parts=more drivetrain loss

 

The higher drivetrain loss is actually a function of the difference in speed between the torque convertor and the input shaft. A locked torque convertor will result in the same if not less drivetrain loss than a manual transmission.

 

The TC frictional loss is a function of the differential speed between input and output.

"A torque converter is not just a wet clutch, think of it more as a hydraulic pump driving a separate hydraulic motor.

If the pump and motor are made to displace different amounts of fluid per revolution, it is possible by design to get speed or torque multiplication."........

"Slippage by itself merely means that heat is being generated and wasted. What happens is that the stator blades REDIRECT the oil flow AFTER it passes thru the driven turbine such that the oil is moving in the same direction as the pump--at least near the inner area of the pump section. The return flow acts to help the engine rotate the pump--more torque. There is a HP loss but a torque gain."

"At lower RPM and light loads hypoid gearing can be very inefficient."

 

USE Militec-1!!!

 

The way I understood his question is that Zs and Gs dyno numbers are much closer than other cars comparing MT to AT... he's wondering why our cars MT and AT HP are so close - when dynos from other cars he's seen MTs are much higher that AT.

I understand his question because I have an AT G sedan and it has always dyno'd close to MT with similar mods...

 

An efficient torque converter.

/thread

 

That's not true, stock 6mt g35/ Z dyno consistently higher than the corresponding 5AT by at least 10 hp and tq

 

My post stated:
"I understand his question because I have an AT G sedan and it has always dyno'd close to MT with similar mods"...

How is it "not true" that the dynos I've done with similar mods haven't been close to MTs?... 2 stillen day dynos, 2 Churches Dynos and 1 dyno in SD (can't remember the shop) have proven this to be true... I never mentioned "stock" - in fact I have very rarely seen a stock dyno.

 

Hmm ...my question still seems to be unanswered. ...maybe noone knows other then the car god.

 

Some cars have different power setups for auto's - RX8 is a perfect example. The auto model had a redline much lower than the manual. And boy is that thing a slug!

A lot of modern vehicles have similar numbers between the auto and manual - 3-5% difference. It isn't that significant.

-Mark

 

A lot of auto transmissions cant handle high RPMS, e.g. RX-8. If a car has to have its rev limiter reduced, odds are it'll reduce the max hp. this is the reason most of the hardcore vtec honda's dont come in auto. Also older autoboxes are a lot less efficient. Brand new auto's dont loose nearly as much HP as older units.