As the title says, does anybody have know the most amount of power than can be put to the ground through a '99 4-speed auto?

I don't want to start doing the mods that I'm planning, only to find that the first time I put my foot down the auto grenades itself.

by design automatics are much stronger than manuals, as they have rotational(planitairy) gearing which distributes torque through more than just the 2 gears like in a manuals box. That said, there might be something still weak in there, but i would say anything you can throw at it wont break it. You should look into a manualised valve body at very least. Go to the wreckers and see if you can get a car with a buggered auto so you can play around with it for a few dollars, you will learn bulk.

http://turbocharade.kicks-ass.org/images/other-cars/dean-torry/torry/images/IMG_0316.jpg

This thing runs a manualised valve body and a big shifter, i put standard clutch packs in it just with the better valve body and it cherps 3rd at 140kph it shifts that solid.

well if the auto's are stronger than the manuals then i do belive booya had his car at 250 atws with standard manual yes?

I have very little clue on the "actual" working of auto's but I am assuming they use a series of clutches and the auto trans fluid as a method of cooling and lubrication?? If I am correct, the more power you push through an auto, the more friction your likely to induce in the clutches, therefore, more heat, therefore tranny fluid has less effect, therefore, more wear, therefore detonation?? I might be way off the mark here, but given a standard auto box, throwing heaps of power through it given its design cant be good. I know that when giving my car a bit of a hammer, I can force gear changes by lifting off the throttle and then jumping back on it. When doing this it sounds like its slipping, does'nt sound good in any case. Given the amount of auto gearbox failures people have had here over time, I dont think it was meant for heavy duty use somehow? :confused:

Besides, if your going to throw enough money into your car to be producing serious power why the hell do you want an auto with only 4 ratios for??? Damn, I'd be looking at getting a 6 speed manual fabricated to bolt up to the engine....

im not sure what you meant by a clutch system on an auto.

Automatics Explained With Diagrams (http://auto.howstuffworks.com/automatic-transmission.htm)

and i think the liqiud is moved with a pump?
i havent read the article in ages, and im still to learn about them in school, so i could be wrong..

']im not sure what you meant by a clutch system on an auto.

Automatics Explained With Diagrams (http://auto.howstuffworks.com/automatic-transmission.htm)

and i think the liqiud is moved with a pump?
i havent read the article in ages, and im still to learn about them in school, so i could be wrong..
You provide the link to the very question your asking?? wtf? :nuts: :doubt:

well there ya go

Auto's for big power, like the motor ive pictured in the torana, are the best option for times. Turbos need load, and a big turbo like that doesn't come on boost very easily, so with long gears and no close in throttle body an auto is ideal.

For highly strung NA motors with only 2000 usable rpm lots of gears are needed, to keep the motor "on cam" as they put it. Turbo motors make enough torque to have longer gears, gearing is then just set per use.

to keep the motor "on cam" as they put it.
Or in its power band to use another term....

I knew autos were favoured for drag racing coz they can be modded like in the torana. From the little I know about autos, it's not torque or power that kills them directly, but the heat instead.

The only time I'll be rebuilding this transmission is when it dies. And hopefull that will be never. I don't want my car to be a drag strip only beast thats a ***** to drive on the streets. I want to preserve all the drivability goodness while having a fair bit of power

I knew autos were favoured for drag racing coz they can be modded like in the torana. From the little I know about autos, it's not torque or power that kills them directly, but the heat instead. Im sure that if you built a gearbox from scratch, you could make it withstand as much power as you want. Whereas the magna gearboxes would not have been built to sustain a lot more power than they come with stock. The auto boxes may be able to withstand a 50% power increase, but pumping any more than that through a auto magna gearbox is just asking for trouble.

The manual boxes are a lot more power friendly but, as we have several examples of 400hp cars with no tranny problems. Wheres Mitsiman when you need him.

The easiest way to make a standard auto box auto perform well is as follows.

1. have the main drum machined to a mirror finish and replace the primary drive belt with a heavy duty aftermarket kevlar based belt. this will last far longer than the OEM stuff and provide a better shift too.

2. swap out several of the steel disks responcible for the shift between second and 3rd with more friction plates for a stronger and more sudden shift.

3. fit a MV Automatics shifter box. Allows you to shift as if the vehicle were tiptronic (1 is 1st gear, 2 is 2nd, D is 3rd and overdrive is 4th)

4. ramp up the stall converter to a higher rpm.

5. fit a transmission cooler.

This may not make sence to you but look out www.howstuffworks.com and search automatic gearboxes.

I think I remember reading that the Sprintex kits didn't have a problem going on car with a 4sp auto, and I'm sure they wouldnt sell a product to people that was gonna make their car spontaneously combust. Sprintex s/c's make around 220kw+?

I was going on the 50% rule as well....around 210-220kw at the crank. I'm not leaving myself much tolerance with what I'm planning.

I guess if it breaks, theres always a recon'd auto that could be gotten and slightly toughened.

When in doubt, thrash it. If it breaks, it needed replacing anyway :D