i tried to search for relative info but still a bit confusing, so why not ask here

i know with the TC it will raise the idle rpm a bit, is that right? and that will also give more hp at the wheel? what's the idle rpm, from what i read it's adjustable? now does that mean if i start my car, run it for 10 mins until the car is at normal running temperature, and i sit at the red light, the rpm would be at like 3000rpm? wouldn't that be high and quite noisy? and isn't that be quite bad for fuel economy?

and with lsd (say trd), what's the advantage above the stock one? what exactly does it do and how does it help traction, hp, etc... with an upgraded tc?

thanks guys, i figure i will never do intake or exhuast on the gs4, but these two, i am interested

 

well what it does is spin both wheels instead one. puts more power to the ground, so i hear. yet to get 1. i am keeping the exaust stock for now too. but i definatlly reconed getting a better airfilter. trd or k&n make stock replacements. definatly better then the stock filter, and isnt noisy. hope that helps , good luck

 

the TC is mostly for increasing efficiency through the drivetrain, you know, that 20-22% loss of bhp and rwhp. so, it increases effective hp like you said.

that 3000 rpm thing isn't true, i don't think. cause you're right, that's very very high. i think you're referring to the stall, which is 2400rpm or 2800, depending on which lsd you get. 2400 works with one lsd, 2800 works better with another lsd(ratio).

i think this is the guts of it. the TC will toss more power at your wheels, and you'll just spin them wildly with TC alone. the lsd puts power to the grippier wheel(say for cornering really), but together, they'll just launch you faster. you get the extra power and extra grip that needs to go with it.

i hope that is accurate and helpful

 

From a previous post on CL - an excellent write-up on how a torque converter "works".

In summary, a higher-stall TC will:
1. not give more HP
2. improve torque multiplication
3. not raise idle rpm
4. raises transmission fluid temps (most recommend trans cooler w/higher stall converter)
5. can lower gas mileage (on the scale of 1-2mpg Lexus 2800 stall application).

Good write-ups on LSD can be found here, here, and here.

After riding in two TC-equipped GS4's and a few stock GS4's, the Dragon TC would be the best bang-for-the-buck performance mod IMO

 

In your opinion, can the TC benefit be realized without the LSD, or will the hard launch capability go "up in smoke"?

 

wow, thanks guys, great info, i have a much better idea now damn i wonder why i never get what i want with searches but you guys always come up with some good stuff.

gotta learn more about stall rpm more tonight. i always thought it's the idle rpm when your car is idle, guess it's not huh?

 

I can't specifically answer this question as I have never spent time in a TC-equipped GS4 without the LSD.

From posts regarding this subject by GS4 owners with TC / without LSD, I get the impression that an improved 60' (vs. stock TC) is more difficult to achieve on stock rims/tires vs. the typical aftermarket rims/tires package.

Hopefully someone here that has has experience with TC / no LSD can answer your question better than I have.

 

The TC does not affect the idle rpm. The (performance) TC does raise the rpm at which the momentum from the flywheel is transferred to the transmission. In a manual car, that would be equivalent to giving the car more revs before letting out the clutch: you can give very little revs and start gently (or stall ) or you can rev it up and let the clutch out and the car will lurch forward. TC is sort of a "clutch" for an automatic. Your fuel economy will suffer a bit, as more of the engine revs are now used to churn the fluid inside the TC and tranny, creating heat (under normal driving). People recommend getting a tranny cooler as well, to keep long-term reliability.

 

Quick defnition of stall speed, referenced from the link I posted above:

"If you're not familiar with stall speed, it is the maximum rpm at which the engine will turn before the converter will allow no more slippage. In other words, it's the maximum speed at which the impeller will turn before the turbine starts to move."

"A higher stall speed generally gives more torque multiplication, which improves acceleration. The highest amount of torque multiplication is achieved when the engine reaches its maximum stall speed just before the car starts to move. It peaks out as the transmission starts to turn, and then diminishes as the speed of the turbine wheel catches up with the impeller."

 

After the hight stall TC installed, due to the higher torque multiplication, you'll spins your rear wheels at hard start or corners all the time. With the LSD, you can pretty much eliminate those un-necessary wheel spins and get your power to the ground efficiently.

I had the LSD installed 2 months after the TC, I'd say both of them should be must have straight from the factory.

 

I drove my GS without the LSD but WITH TC for almost two years, then added the LSD. The answer to your question is "it depends" .

Most of the time you'll get the benefit of the TC without the LSD. Definitely quicker off the line, but you can experience wheel spin (aka burnouts) depending on a number of variables including:
- grip of your tires (remaining tread, softness of tire compound, heated, etc)
- road surface (including hard straigh-line launch, dips in road, angle of launch uphill)
- other variables that impact the power output of your car (my GS runs much stronger in the cool weather, for example)

I would not hesitate to recommend getting the TC installed without an LSD. IMO it's by far the biggest bang-for-buck performance mod you can make to your GS. However, if I had the opportunity and means to do them both at the same time I would certainly go ahead and do it.

I honestly did not feel the need to get an LSD until I went to a quarter mile track with my GS. The track surface was less-than-ideal with lots of rubber and some fluid, and I had severe traction problems. Although I put on a good show for the crowd by lighting up our tires in a HUGE cloud of smoke, leaving burnt rubber all over the back underside of our cars , it didn't leave me with the good ETs I hoped for. I went looking for options for better traction immediately after that event and added the LSD and new wheels.

 

pretty informative thread this has turned out to be

 

I just bought a new GS430 and I thought that it already had an LSD, but I have noticed that it seems like the paassenger wheel it the only one spinning on a corner. DOes anyone know for sure whether I have an LSD or not?

 

its a mod, but maybe if you bought it used from the right person?

 

No, there is no LSD from the factory.