gears vs tq converter

[burt ragio]

What might the difference be in a stock marauder zero to sixty time. One mod with 4:11 gears another with a 3000 stall converter?
Yes this may sound like a confusing question. I just don't understand why one would use lower gears to offset the weight of the car when a tq converter with higher stall speed will bring the motor into it's power band quicker and do the same thing ? Am I not correct in my understanding of the two mods ?

[JonW]

I have both 4.10s and a 3000 stall convertor, and I installed them both at the same time. Between those two mods and a tune, this car screams. I can spin the tires from a rolling start.

I'm sure someone with more technical knowledge than me will chime in shortly, but the TC is like icing on the cake to the gears. The torque multiplication and higher stall speed can probably best be likened to a supercharger for your rear end. It takes a good thing and enhances it to make it better.

If you do the gears, you will need a tune, no way around that. You should get one anyway, but the gears will require it. Not so with the TC. It can be installed as-is and you won't need a tune. If you're trying to budget, get the tune first, then the gears, then the TC. You can go back and change the tuner to accomodate the 4.10s yourself. You won't need another tune for that.

[Blackened300a]

I did gears first and a year later I did a 3K Stall T/C. Hands down, nothing puts you back in the seat like the T/C.

I felt a slight improvment with the gears without installing the tune but nothing like the improvement of the T/C.

According to a G-tech, with slight spinning Im pulling a low 5 second 0-60.

[MADRODER]

what brand of stall are you running? Any preference for the MM

[burt ragio]

Athtis time a stock converter.

[MADRODER]

Athtis time a stock converter.


Seems to me that the hardcore MM are running PI converters.....going to check it out.....

[RR|Suki]

Seems to me that the hardcore MM are running PI converters.....going to check it out.....

yup we are :D

[MADRODER]

Ahhh, yes and right on cue a HARDCORE MM.....and running a stallion.

[sailsmen]

The bulk of the TC is in the first 150'. Gears work through out the 1/4.

W/ Tune-4:10 & UD ran a best of 2.166 / 14.274. Added 3,000 PI & Cobra Exhaust and in similair air ran 1.9x / 13.74.:D

[HwyCruiser]

IMO the tc made a much bigger seat-of-the-pants difference than gears and a tune. I dropped 0.5 sec off my 0-60 mph time by adding the tc when I was still n/a. It's all pretty much overkill now.

[Raudermaster]

I'm getting my T/C installed probably a little before the beginning of April and I cannot wait.

[Blackened300a]

PI Stallion is the way to go. Many members including myself have been using it with great success.

[fastblackmerc]

PI Stallion is the way to go. Many members including myself have been using it with great success.
+1 on the PI Stallion.

[magindat]

I'd have gone with a 3500 converter and no gears.

I did a 3000 and 4.10 at the same time. I listened to a lot of advice and studied. Since then, I've learned to tune the transmission schedule myself and learned about what causes good and bad fuel mileage. I've also learned more about my own commute and driving likes and dislikes.

That said. I'd have stayed with 3.55's for highway mileage, gone to a 3500 converter and tuned my lockups and shifts accordingly for in-town fun.

It's not that I don't like what I have. I love it! I've just learned so much since then that my decision would have been more of a reflection of my OWN PERSONAL driving.

[JonW]

Magindat, care to share some of your tune secrets?

[Grifter]

a TC gets the RPM's higher when leaving from a stand still/idle. like stated above, it also has better torque multiplication, and even weighs a bit less, so the rotating mass is lessened. Gears help you move through the RPM's faster. getting the car trough the powerband faster, and into the next gear sooner.

[magindat]

Magindat, care to share some of your tune secrets?

No secrets. Just listened to advice and futzed around 'till I liked it.

Basically, I have no TC lockup at all in 1,2,3. At light throttle, though, I let it go to 4 pretty quickly and always lock 4. I have my downshifts scheduled so that I get a little engine braking.

I definately burn more gas in town. However, she'll git it from any speed in any gear. I basically can shift the tranny with my right foot. It's fun!

I made this chart to help me to start off. Chart (http://www.magindat.net/ssm/info/4r70wratios.xls) The rest was re-adjusting after driving a while. I'm sure it could still use a professional once over, but I like it.

[Blackened300a]

No secrets. Just listened to advice and futzed around 'till I liked it.

Basically, I have no TC lockup at all in 1,2,3. At light throttle, though, I let it go to 4 pretty quickly and always lock 4. I have my downshifts scheduled so that I get a little engine braking.

I definately burn more gas in town. However, she'll git it from any speed in any gear. I basically can shift the tranny with my right foot. It's fun!.


Sounds exactly like the way Sal from PSP set up my car. I didnt buy this car for gas mileage

[ctrlraven]

I'll be sticking with my 3.55 gears but hopefully sometime this year a 3000 PI will be installed.

[88LTDCV351]

Mine is stock for now. I think I want the TC first and maybe the 4.10 in the future. What is the stall that I should ask for on a stock MM?

[Blackened300a]

Mine is stock for now. I think I want the TC first and maybe the 4.10 in the future. What is the stall that I should ask for on a stock MM?

I was using my car as a daily driver so I went with a 3000 stall. It didnt hurt the drivability, just allowed me to melt tires off the line at 3/4 throttle.

[Power Surge]

One thing that nobody has mentioned yet, is that gear and converter go hand in hand. The big issue with the MM, is the motor is a higher rpm breathing motor, but the car is heavy and not setup to take advantage of the motor's powerband.

Doing the 4.10s will let the car accellerate quicker, thus getting into the motor's powerband sooner.

A stall converter works similarly, but it lets the motor slip into it's powerband sooner, the car is not actually accellerating to that point.

The idea behind the stall converter is to be able to get the motor into it's powerband while the car is standing still, so you can launch the car in it's powerband instead of having to accellerate into the powerband.

But your gears need to match the converter for the best performance. The 4.10s should definitely be used with the stall converter at the same time.

If it were me, I'd do the 4.10s first, then the converter later.

[RaceLegend79]

I have been pondering this for a while myself. I want the 4.10s and tune but the stall had never crossed my mind. If it is true that the stall is what is supposed to be then which would be best for the occasional road trip car that also will see the track every once in a while? The 3000 stall or the 3500 stall. BTW please forgive my ignorance with any of this I just learn as I go and this is my first that I am mostly doing myself. My first tune was mostly orchestrated by a master wrench turner who went to the Navy a few years back and that I havent seen since.

[magindat]

I'll be sticking with my 3.55 gears but hopefully sometime this year a 3000 PI will be installed.

I'd do a 3500 with 3.55's and turn the idle in drive up to 1000 to get your 'creep' back. Also helps with the alternator charging while at a light.

[magindat]

A stall converter works similarly, but it lets the motor slip into it's powerband sooner, the car is not actually accellerating to that point.

A good brand (like PI) of converter will also MULTIPLY torque at a factor of about 2.2-2.5. This is why you can melt tires standing still. A car measured at 260ish RWT on a dyno with TC locked will now show 500+ RWT to the ground with the aftermarket converter unlocked and RPM's in the power band!

[Power Surge]

A good brand (like PI) of converter will also MULTIPLY torque at a factor of about 2.2-2.5. This is why you can melt tires standing still. A car measured at 260ish RWT on a dyno with TC locked will now show 500+ RWT to the ground with the aftermarket converter unlocked and RPM's in the power band!

It doesn't quite work like that ;) .

[magindat]

It doesn't quite work like that ;) .

Really?




THE TRUTH ABOUT STALL TORQUE RATIO
STR has been talked and argued about for many years. The following information is what we at Precision Industries have found by doing our own testing to be helpful for you to try to understand this subject. Our competitors must have a crystal ball to figure the STR of their torque converters. There are a couple of companies in the performance torque converter business that do have the capability to test STR, MOST DO NOT! Precision Industries happens to be one that does have. Our test dyno has the capability to test from 200 ft. lbs. of torque up to 900 ft. lbs. of torque. The other companies use dynamometers that vary from 100 ft. lb. of torque to approximately 300 ft. lb. of torque. There is an old GM printed sheet that has floated around our industry for about 10 years showing the STR of stock GM torque converters that were built back then. Our competitors either use this sheet or are guessing because they have no way of knowing what the STR really is. They also advertise STR’s of 2.7, 2.9, 3.0, 3.2, etc. this is pure BS. All torque converter companies use the impellers, turbines and stators that come in the factory torque converters. In our tests we have never seen an STR over 2.55. Precision Industries do have torque converters with STR over 2.55 but these units have specially machined stators in them and are not worth the high cost for a street/strip application. If our competitors try to tell you differently just ask them to show you a picture of their test machine, not just a printout. The formula for STR is EXACT OUTPUT TORQUE ÷ EXACT INPUT TORQUE = STR. This requires a known power source and a data recovery system. STR is just what the name implies. The ratio of torque multiplication at stall. As soon as the turbine rotates (car moves) the ratio starts dropping rapidly until enough RPM has been reached for the ratio to drop to 1:1. The RPM that the ratio reaches 1:1 varies depending on other factors in and out of the torque converter such as impeller exit angle, stator design, impeller to turbine clearance, input torque (engine), etc. A fact that most everyone overlooks is that a torque converter does not make torque! It takes the torque the engine produces and multiplies it for a very short period of time. This is why some cars perform better than others with the same torque converter.

Some car enthusiasts put all kinds of money in the engine, transmission, torque converter, NOS, rear end gears, etc. then want to cripple the torque converter by lowering the STR to try and prevent wheel spin on take off. This is as foolish as pulling off one of the plug wires. Why don’t they finish the project and work on the rear suspension? Trying to tune your car by using STR is probably not very smart seeing how our competitors don’t have a clue about what STR their converters have, after all the stock torque converter you took out of your car has a STR of 1.9-1.94. The best way to get the right torque converter for your car is to buy it from a company that has a large database of previous sales for your kind of car. Then tell the sales person what mods you have made and what mods you intend to make and let that person help with the decision. The key words here are large database. The “Johnny come lately companies” have no large database or experience with what works with these late vehicles. Why try to reinvent the wheel with your hard earned money when there is bound to be someone in our database that has the same mods as you do and their torque converter/engine combination ROCKS! At Precision Industries we found out 10 years ago that STR is not the most important consideration when deciding on a torque converter it is the whole COMBINATION!



http://www.converter.com/index.htm



Over-simplified, maybe. But, takes TORQUE to spin tires. So, if you can't spin tires today and add a TC and super-smoke tires tomorrow, what makes that happen? It certainly isn't the measly 25 torque gained from moving the stall from 2400 to 3000!


It's taking the 125-150 ish torque measured on a NA car on the dyno at 2400-3000 RPM and multiplying it by 2.2-2.5 ish and laying 200-375 ish torque to the rear wheels and more as RPM's increase.

This is part of the reason a good tranny tune makes the MM so much faster. It takes the stock 1.9ish torque multiplication and allows it to do it's best work by modifiying lockup (STR of 1:1) times and shift points.


We feel this more in the MM (than say, a mustang) because we NEED torque to move our WEIGHT.

All this said, a torque converter NEEDS a good tranny tune to realize it's full potential.

[Power Surge]

I know how TCs work, and I know a thing or two about tuning ;) .

Your statement about adding a TC to a 260 rwt car and having it now make 500 rwt on a dyno is just not true.

Obviously there is a performance gain from adding a good TC. But the ability to light the tires up after adding the TC usually comes from the shock effect. Since the converter is now looser, when you whack the throttle, the TC allows the motor to quickly rev up and then it hits the point where it starts to lock up. It's sort of like doing a neutral drop, but it's all happening in the converter in a split second.

If a TC really doubled your rear wheel torque, then there would be no need for a higher stall.

[magindat]

I know how TCs work, and I know a thing or two about tuning ;) .

Your statement about adding a TC to a 260 rwt car and having it now make 500 rwt on a dyno is just not true.

Obviously there is a performance gain from adding a good TC. But the ability to light the tires up after adding the TC usually comes from the shock effect. Since the converter is now looser, when you whack the throttle, the TC allows the motor to quickly rev up and then it hits the point where it starts to lock up. It's sort of like doing a neutral drop, but it's all happening in the converter in a split second.

If a TC really doubled your rear wheel torque, then there would be no need for a higher stall.

It doesn't really start to 'lock up' it comes to a point where the impeller and rotor are turning the same speed. That's what 'stall' IS.

I AM saying though, that compared to the LOCKED state when tested on the dyno and then taking the STR into account due to being unlocked, there is a huge torque multiplication at least for a moment. I could see your comparison to a 'neutral drop'. A good deal of that 'shock' comes from STR. It is one of the few advantages than can be exploited with an auto vs std shift.
Perhaps we are simply debating symantics... :beer:

[ctrlraven]

I'd do a 3500 with 3.55's and turn the idle in drive up to 1000 to get your 'creep' back. Also helps with the alternator charging while at a light.

Thanks for the tip.

[KillJoy]

Boost...FTW!

:D

KillJoy