I traveled to another town and went to a knwon tuner to see his garage....
once he knew that my car put down 434hp he advised me to get an aftermarket tc like tci..
he said it will shave a significant delay in my car launch which is bothering me...
he told me that a tc is a must for an auto trans car modification
my question is that i am a street racer, would a tc make difference in my car launch especially with the sc...
any output about that ?

 

all of the stuff i have read says yes but not one that is to aggresive

 

You'll want a torque converter that flashes to rpm's where your engine makes peak torque. If you have a roots or twin screw blower which makes incredible power at lower rpm's, then get a fairly tame converter that flashes around 3,000 rpm's. If you have a have a centrifugal blower that makes its peak torque at higher rpm's (builds boost as rpm's rise), then you'll want a higher stall speed, say around 3,500 rpm's or higher.

I have a centrifugal blower and my stall converter flashes to around 4,700 rpm's, which is roughly peak torque for my engine, so this car hits the thick of the powerband instantly with this converter. Absolutely perfect for the combo of parts I'm running. When I bought this converter, it was rated to flash to 3,800 rpm's in a naturally aspirated engine. They flash higher when more power is put to them, so be careful not to buy too much converter for your needs.

Also be sure to buy a converter that retains the lock-up feature for 4th/5th gears. This will help keep fuel economy reasonable on the highway, and more importantly, it will reduce the amount of heat generated in the transmission at highway speeds.

 

THANKS GREY APPRECIATED

 

thanks a lot for the output
did you feel a change in your launch with the converter?

by the way we are exactly the same
07 alloy auto gt with sq s2 vortech.mine is also with aftercooler
it puts 434rwhp with 380 torque
my mods in addition is a complete jba exhaust with lt headres o/r h pipe and cat back
but i didnt change the gears ,is it beneficial?
what tires and exhaust are you running?


very happy to see guys like me

 

Very similar cars! My Vortech is the standard V-2 - no cooler on mine. I haven't had it on the dyno yet, but I suspect it'll be around 380 rwhp and 330 torque the way the car is now. Totally stock exhaust on mine, so that limits the total power I can expect.

The torque converter I chose really improved the launch of the car!!! Sixty foot times at the track dropped from 2.1's to 1.8's just by changing converters. Also, the car is quick to accelerate as the converter flashes instantly to 4,700 rpm's, which is peak torque.

I have 4.10 gears in my car, but I don't think changing gears is terribly necessary with the big stall converter. If you switch to bigger camshafts, though, they usually recommend a big stall converter AND more gearing (3.73's or more).

I still have the original wheels and tires on my car for daily driving, but have a different set (with drag radials) for race days. I've been considering using the drag radials every day on the street, too, unless the weather forcast calls for rain. You can't get enough traction with the supercharger!

 

This is a "for what it is worth post" I am N/A with the listed mods. I have been talking to Dave @ Brenspeed about this mod. They have a company stang that they put a 3500 rpm TCI torque converter in and he claims it is too loose. He said they changed it to a 3000 rpm stall converter and he thinks it is a better fit for a DD'er. Bottom line is I now believe that if you do not race and it is your DD'er and you don't want to leave every spotlight at 3500 rpm this may not be a mod for us DD'er's. There seems to be little beneifit if you don't accelerate hard from every stoplight. At least that is my impression to date!! But he says at the drag striip it seems to be worth maybe .5 seconds.
Scott

 

He Scott, worth noting is that you don't leave every stoplight at the rated stall speed. Under partial throttle, you actually leave at near normal rpm's. Give it more throttle and the stall speed increases, accordingly. It's much like slipping a clutch in a stick shift car. You can choose to slip more or less, as needed. Of course, hammer it to the floor and it'll instantly flash to the stall speed.

I've owned several cars with big stall converters. I consider them a "must-have" for any automatic equipped car that sees any drag racing action. They are very "daily-driver-friendly" as long as you don't buy a higher stall speed than necessary to match other components of your drivetrain. I think most N/A cars or roots style blown cars would be awesome with a 3,000 rpm stall converter. Something that thrives on higher rpm's (i.e. centrifugal blower or turbo) can really benefit from more stall speed (i.e. like the 3,800 rpm stall converter I bought that is now flashing to 4,700 rpm's with the extra power underhood). Again, it all comes down to matching components for a specific rpm range you have in mind.

For under $1,000 (parts & labor), there are very few mods that will improve your sixty foot, 330 foot, and 1/8 mile times at the drags by .3 second and the 1/4 mile by .5 second. Get a lock-up style converter and you won't even affect your highway fuel economy. What's not to love?

I would really encourage anyone to drive a car with a good converter in it to get a real-world feel for what they do. It's terribly hard to describe them in writing.

 

Your last two sentences are why I have not pulled the trigger on this mod. I really would like to drive one of these cars with a 3000 stall converter so I could feel what you are talking about. Coupled with Dave's opinion of this mod on a daily driver. I truely believe this is a great mod if you are racing the 1/4 mile. Just not convinced for a DD'er. At least not for at least 1K investment without a test drive!
Scott

 

As you seems to knows the torque converter, can you check my thread ?

Thanks.

http://forums.bradbarnett.net/showthread.php?t=469820

 

I posted a few thoughts just now on your thread. What really stands out is that the weather is so very different between last October and your runs a few days ago. That is likely a big part of the problem overall with your timeslip. You can compare more directly by calculating the Density Altitude for runs in the cold October air versus the hot humid air this summer. Might be an eye opener if you've never done this.

You also need a good sticky tire that's heated up properly to eliminate tire spin from the equation. You mentioned you can't hear through the helmet whether your spinning. 1.90's for a sixty foot time are OK, but with your mods you should be in the 1.70's with proper traction.

Make sure the traction control is off during any racing. It will pull timing and fuel, which in turn hurts performance at the dragstrip. Check the tune or check the switch on the dash. Also, while checking the tune, be sure your speedometer is calibrated correctly so the transmission shifts properly at the right time.

I have no idea how an MSD launch control works, but I'd ditch that to sort out the other mods first.

 

Scott, I posted a short 45 second video clip of my 07 GT online so you can hear it take off fairly normally, then a blazing launch from a stoplight. You'll notice a big difference in rpm's between the two...

http://s294.photobucket.com/albums/m...07GTLaunch.flv

This was filmed before the supercharger, so it's just 4.10's, stall converter, and a canned 93 octane Predator tune.

 

Thanks Brian. I can tell that the engine does not rev up like I had a concern of it doing. I hope to see the Brenspeed gang at a meet on Aug 2nd in Indy. I will talk to them more about doing a converter. Hopefully they are bring a couple of there shop cars and the one that they done a converter in. Maybe I can talk them into taking me for a spin to get the feel.

 

LMAO, great mental image of someone burning out at every light.