automatic trans. strength

[2s4x0]

Roughly how much hp/torque can a stock auto transmission on a 98 240 take? Anyone with experience with this would be very helpful. I searched and I'm sick of having to say i searched so i dont get flamed. I know there has been talk about this before but I want people with experience to answer and not an argument on why its gh3y to have an auto ka-t.

[WDRacing]

Should withstand 400 without any problems. I had that much on my Skyline and it has the same transmission. You'll want a good transmission cooler though. Anything from Summit will work well.

WD

[2s4x0]

what about without the cooler?

[WDRacing]

The cooler will extend the life, thats all.

[240SicknessX]

Should withstand 400 without any problems. I had that much on my Skyline and it has the same transmission. You'll want a good transmission cooler though. Anything from Summit will work well.

WD

i have an auto also that will be boosted in about 2 months, its good to hear a definitive answer from a knoledgeable person about the strength of the auto s13/14 transmission. for some strange reason i had the weird number of 240whp before the converter starts to get unhappy.

WD is the stall on the auto skyline converter set @ 1800 as the s14 auto? you power braked it to build boost with that low of a stall to launch from the line or neutral drop at the track.

how much power was your skyline making and how were the shifts, progressivly getting softer as the bands get weaker, signifigantly? or the wear would be expected with the amount of power, not prematurly.

NA auto s14, on a good day ill chirp second in d shifting, just wondering if it will still have that hard good crisp shifting charictoristics.

[2s4x0]

yes it is nice to hear the answer straight up. I really appreciate it. I remember seeing that 240whp number also, but that was in the flaming auto thread i was talking about not wanting this one to turn in to.Thanks WD!!

[WDRacing]

Yeah, I put a stop to that flaming auto thread, as soon as I called everyone out they seemed to just stop posting for some strnage reason.

I couldn't honestly tell you what the stall speed is of the convertor. But I did power brake to build boost everytime I drag raced. I had to use the ebrake to help hold the rear tires though.

Shifting was never sharp in between gears, I don't think I chirped any gears in mine. You'll get a weird flutter inbetween shifts with an auto, sounds funny, cause your on full boost. It may actually be compressor surge.

Get the cooler though, she'll last alot longer.

[Structure240sx]

the auto transmission can take some decent abuse.

i had boosted mine to about 10psi before swapping motors and to 5spd. the transmission was jsut fine, only problem is that it shifts kinda soft. other than that you're good to go

[WDRacing]

My skyline always shifted rather soft for some reason, but every model I drove shifted soft. You could rework the valve body and crank up the line pressure for sharp quick shifts.

Ivan from S&P is using an auto in his drag car and has done lots of wok to it.

[2s4x0]

theres also that plug right on top of the drivers side wheel under the hood that makes it shift hard and quick...would it be alright to just unplug that during races.

[240SicknessX]

theres also that plug right on top of the drivers side wheel under the hood that makes it shift hard and quick...would it be alright to just unplug that during races.

actually dont do this, unplugging the drop line resistor will lock the torque converter on acceleration and deceleration, the torque converter isnt made to be locked on deceleration. When you are at WOT the torque converter has the same charictoristics as if you have the drop line resistor unplugged. I have not seen anyone gain ET from unplugging the resistor, and i personally havnt gained ET on the gtech either. Its not worth shortning the life of your transmission if it dose not benefit you. correct me if im wrong.

WD, about adjusting the line pressure in the transmission in order to shift harder, i understand the s14 transmission uses TPS values (voltages) to determine when to downshift, and then it matches the TPS + engine rpm +wheel speed? or actual load? to up shift. can you manually turn up the line pressure, or dose the ecu monitor that. and if this is all possible, could you turn up the line pressure with the factory valve body to an extent?

im probably wrong on some of that, correct my inaccuracies ^^^

[WDRacing]

I'm no slush box guru, but I know the ecu uses all those readings to control the transmission. I'm pretty sure you can manually increase the line pressure though, for harder shifts.

[240SicknessX]

maybe ivan can help? plz

would there be a benefit to increasing the line pressure without ungrading the valve body? would this shorten the transmission life signifigantly? would the gains be signifigant enough to warrent this?

if i were to somehow figure out how to up the line pressure, this would be more harsh on the converter inbetween shifts, should i be conserned with the added stress on the converter, or it shouldnt be much of a problem. for the time being, i est 240hp.

[WDRacing]

I'd boost your car and see how it responds, if you want to mess with the transmission after, the deal with it. Put a call into Ivan at S&P, he's always at work.

[bradd]

You just need to add one of these handy Ford C4 transmission adapters, Just kidding . I have seen a post I think about Ivan talking about his auto, It was vary pricy to build up, and I think the main reason he is doing up a Nissan auto is because he wants to race in some sort of class where it has to be all Nissan stuff.

[GEO]

^^^^^^^^^ WTF. He wants to braket race at NOPI.

[WDRacing]

He's racing in Turbo4, All nissan equipment. the transmission is basically a 240 shell with 300ZX internals.