Jtrain

iTrader: (11)

About to pull the trigger on a VB upgrade and tranny cooler.

Wondering what a TQ converter really does or why I would or wouldn't want it. (I understand it creates heat issues)

Also what brand VB upgrade seems to be the best.

rcdash

iTrader: (18)

GTM or SGP. Talk to Sam (GTM) and Thomas (SGP) and discuss with them.

I had a hard time understanding why a TC upgrade was necessary but Sam strongly advised to do it, so I didn't argue too much. As I recall (the conversation was a while ago) he felt it was required to help with smooth torque transfer. GTM strengthened some of the internals and raised the stall. It will run hotter so a good external cooler is required.

If you learn something additional, please post up...

roncfpz

iTrader: (15)

Here's a good explanation from Pro-Torque. You might want to check out their site as they have some good FAQs on there. BTW, they make an awesome TC as well.

Why is a torque converter an important performance upgrade when installing a turbo system?
Theoretically, for maximum acceleration the stall speed of the torque converter should match the peak torque rpm of the engine. If a high performance engine makes power at a higher rpm, then a higher stall speed torque converter is what you need to put more power to the ground quicker. When the same vehicle has a turbo installed you want to make sure that you are transferring power to the ground at the best possible rpm and best boost levels. If the stall speed of the torque converter is too low there can be some associate “turbo lag” or delay until the engine rpm comes up and the turbo starts to build boost. The correct aftermarket performance converter that is properly matched to the turbo system will allow for maximum acceleration. In many cases a performance torque converter will take .4-.6/th’s off of your quarter mile ET with no loss of drivability.

DanielW

iTrader: (27)

i THINK the TQ converter is the equivalent of slipping the clutch up to a higher rpm level so it will spool better

rcdash

iTrader: (18)

Well, yes, that's all good if the goal is to achieve the *absolute* maximum torque output, but you can always increase torque output by increasing engine output, right? The other side of the argument is that since you have a LOT more torque being transferred through the drivetrain, you can set the stall lower to help with traction and economy. Why maximize performance at the expense of disregarding a balance between driveability, performance, and economy?

I talked with Andre at Edge Racing and he recommended: "lowering stall", "tightening clearances", "strengthening internals". All in all, more efficient and stronger at the same time.

Many others (Sam and Thomas included) recommend increasing stall.

So there you have it. Hope you are now as confused as I am

EDIT: I present this for argument's sake really. Those who really know what their doing can increase performance, driveability, and sometimes even efficiency all at the same time through a TC upgrade. That's why I just decided it's best to leave to the experts and move on.

Jtrain

iTrader: (11)

Yeah I'm not really any closer to making a choice-- I like being able to take .6 seconds off my 1/4 mile.

I'm still not sure what the "stall" is however...

rcdash

iTrader: (18)

It's where the engine rpm is going to sit when you launch - it is that torque that will be applied when the car starts to move. Well there is also torque multiplication of 2 at that point. So obviously a higher stall (higher rpm) means more torque to the wheels at launch.

coachk

iTrader: (21)

In MY CAR this statement is correct, because my stall is set at the same PSI that my boost kicks in and in a review thread I did about my TC,I was able to take off .2-.3 ths off in the quarter.

coachk

iTrader: (21)

[QUOTE=rcdash]Well, yes, that's all good if the goal is to achieve the *absolute* maximum torque output, but you can always increase torque output by increasing engine output, right? The other side of the argument is that since you have a LOT more torque being transferred through the drivetrain, you can set the stall lower to help with traction and economy. Why maximize performance at the expense of disregarding a balance between driveability, performance, and economy?

I talked with Andre at Edge Racing and he recommended: "lowering stall", "tightening clearances", "strengthening internals". All in all, more efficient and stronger at the same time.

Many others (Sam and Thomas included) recommend increasing stall.

So there you have it. Hope you are now as confused as I am

And this also is true about "lowering the stall" if you don't plan on drag racing and are looking for what Andre says. So if you don't plan on launching the car hard, IMHO then you can leave the OEM TC just the way it is.I believe if your going to step up the stall, you better get a tranny cooler.

marques1

iTrader: (5)

this might be a dumb question but a is a stall converter the same thing as pushing the brakes and hitting the gas on a launch to get your rpm's up except on the stall converter you don't have to hold the brake?

coachk

iTrader: (21)

NOPE... I would explain it but RCDASH can explain it better than I...he's very smart and I'm just a drag racer. If he doesn't then I will

coachk

iTrader: (21)

Even with a stall conv. you have to push on the brake to keep the back wheels from spinning. I think your talking about a trans brake, which I may put on my Z someday.

marques1

iTrader: (5)

oh ok so how high can a stall converter be set at for a daily driven FI car, thanks ahead of time.

coachk

iTrader: (21)

I don't know for sure, ask roncfpz.His is a daily driver, mines not.

roncfpz

iTrader: (15)

Mine is not a DD either but I don't see why there would need to be a difference. My stall is set at around 3200 and the driveability is virtually the same as stock. My SGP race trans is just like stock except for the hard shifts from the valve body upgrade.

BTW, Chucky is selling his Edge Racing 3500 stall TC for anyone looking for a high quality converter.

coachk

iTrader: (21)

Just remember the stock TQ specs are between 2600+- and 2900+- or real close to those numbers. 3200 is a slight bump up from stock and probably works ok for street driven cars. If your looking to drag race a higher stall is good,just has more heat issues.

rcdash

iTrader: (18)

Every torque converter has a stall speed. You can get a measure of the stall speed for your tc using the method you describe. Here is an excerpt from the SummitRacing website that provides a pretty good description of stall speed. This explains why the stall speed is a range and not a single value and also illustrates that there is more than one way to measure "stall":

The most misunderstood aspect of torque converters is stall speed. Many people think if a converter is rated at 2,500 rpm, their car will rev up to that rpm and then take off. That's not how it works. Stall speed is a function of engine rpm. The more torque an engine makes, the higher the rpm the converter will stall, or lock up at, and transfer that torque to the transmission.

There are two types of stall speed-foot brake stall and flash stall. Foot brake stall (or true stall) is the maximum rpm that can be achieved with the transmission in gear, the brakes locked, and the engine at full throttle. The rpm reached before the vehicle moves is the true stall speed of the converter.

The problem with foot brake stall is that you will end up overpowering the brakes and suspension before you reach the converter's stall speed. The only way to really measure true stall is by using a trans-brake. This will keep the vehicle from moving, allowing the converter to absorb 100 percent of the engine's torque. Race classes that do not allow trans-brakes are often called foot-brake classes. In this type of racing, the rpm obtained when the brakes are applied and the vehicle is not moving is considered to be foot brake stall. When the brakes are released, the engine goes to full throttle and “flashes" the converter.

This brings us to flash stall. It is the maximum engine rpm reached when you launch a vehicle from a dead stop at full throttle, no brakes applied. Flash stall is always lower than foot (true) stall because there is less load on the converter. Changing the load on the converter can change the flash stall rating. Additional engine torque, a higher(numerically lower) rear axle gear, or adding vehicle weight will increase flash stall. Less torque, a lower (numerically higher) gear, and less weight will decrease flash stall.

Another factor that gets confusing is converter slip. Slip is basically a measure of converter efficiency. Due to the difference in rotating speeds between the impeller and the turbine, there is usually a five to 10 percent efficiency loss at cruising speeds for non-lockup converters. Because a converter gradually slips, or creeps up, to full stall/lockup rpm, the higher the stall speed, the more slippage you get. On a street-driven vehicle, that can lead to poor idle and low end performance, worse gas mileage, and most importantly, greater heat buildup-the number one killer of converters and transmissions. If you do run a high stall converter, a good transmission cooler is a must.

marques1

iTrader: (5)

thank you that was very good and answered my question. On my 03 auto i guess the stall speed is about 2500 because anything after that my car will lurk forward a bit. I think im still confused though why you would want a stall speed of for example of 3500 rpms how is this useful if your brakes cant hold up to this rpm level unless you have a trans brake.

coachk

iTrader: (21)

See I told you RCDASH was smart..I gave you the short version but all in all we said the same thing..Your brakes will hold a stall of 3500....

OK now its RC's turn to give the smart version.

marques1

iTrader: (5)

how the hell would my brakes hold a stall of 3500 rpms i guess i was not pushing down hard enough on my brakes or something?