What does it do? How does it add to performance? I'm thinking of trading my SS M6 for a C5 A4 but want to know what it will cost me to make it shift hard and have all the torque I enjoy with the m6.

 

The torque converter is the automatic equalizer. What it does is put your vehicle it's powerband and keep it there. I don't know exactly all the mechanics of it but I will tell you what I know about TC for LS1 vehicles. C5 may vary a bit so it might be wise to post this question on a vette forum too.

1). You want a minimum of 3500 true stall to really get the full power advantage. 3800 is as high as most will go with stock internals (i.e. heads/cam). With upgraded heads/cam then 4200-4400 stalls are ideal.

2). The higher stall you get the "looser" the car will feel. A lot of people think anything over 3800 is too loose for daily driving. So with a tight converter when you hit the gas a little the car will spring forward. That is feeling tight. With a loose converter when you hit the gas a little the car will move slowly/sluggishly. That is feeling loose. But when you punch the gas hard with a high TC then the car launches harder and accelerates better then it did before. So the advantage is there but you have to have a heavy foot to get it.

3). Then there is the STR. You can use this to help a higher stall converter feel a little tighter. The str ranges from 1.25 to 3.0 from what I have seen. The lower the number the easier the launch. The higher the number the harder the launch. So the advantage to the high str is that it'll make the car a little tighter for daily driving and give you a better 60' time. The disadvantage is that it hits so hard to the wheels you can easily roast DR's on the street. However I reccomend a higher str and then just learning to adjust your accelerating methods (you can't floor it but you can do say 50% at a dead stop and floor it when you are at a decent roll).

4). Yank and Vigilante are the top two brands as far as quality and satisfaction goes. But TCS is a good choice too. With a 3800 stall TC and say a 2.7 str on drag radials you could see a gain of .6 on the quarter mile and a 60' time of 1.6 seconds. Not too shabby and the 60' time is how autos get those awesome numbers and rule the track.

So anyway from my research I would recommend a 3500 stall with 2.3 str if you are staying totally stock internals and want a tight streetable feel. I recommend a 3800 stall with a 2.5-2.7 str if you want maximum performance and can live with a little looseness on the street and are staying stock internals. Both are great for spraying too BTW. I recommend a 4400 stall with 2.5 str if you are gonna make the car a track hound with little to no street driving and heads/cam work.

As far as costs go if you get the best (yanks are generally spoken off as the best) then you'll pay $900.00 for the new converter. Add another $80.00 for a trans cooler (a must have if you want your transmission to last more then a month with a high stall TC in it). Then figure about $300 for install. $1300 total should cover it. Now if you get the TC used or get a cheaper brand then that number will obviously drop but I recommend getting the best and brand new. This is not the kind of mod to go cheap on.

Also it is known that 3500+ stalls can cause you to hit rev limiters at wot so a lot of folks delete TM and or adjust shift points to make the shifts hard, fast and at the right rpm's. This can be done with ls1 edit, preditor or if a performance shop installs it then they would take care of that I would think. With a vette again this may very so a vette forum may have a better answer.

I hope this has helped some. It's the most worth while mod any auto can get. It can make you a torque monster from a dead stop or a roll to say 120ish. The M6 can still reel you in but not until very high speeds and generally not within the famous 1/4 mile. This is why M6's at the track will have the higher trap speeds but the stalled a4's have the better ET's.

Good Luck and I'm sure you'll love the vette if you get it. Just make sure you won't miss the M6 too much. The TC will make you faster then a M6 off the line but it won't replace the feeling of slamming through the gears yourself. Hehe but I already told you that in the other thread.

 

Hmm not to flame you or anything, but isnt a 3500 stall a weeee bit high for a stock internal/bolt on car? I have a buddy with a forged 383 (LT1) and mild 224 cam, running 11.4's in the 1/4, and he only has a 2800. This same guy owns and operates the local dyno/tuning shop... Then I have 2 friends with LS1's, one stock, not even headers, and one with a small cam, the cammed one running a 2800 (he's dipped into the high 11's now) and the stock one running 3200-he ran a 12.9 on street tires and the stock stall-he hasnt updated me on his post-stall times yet (he has a 224 cam being installed soon and will keep that stall.) All 3 of these guys run 1.5-1.7 short times easily.

So you may want to research a stall a bit more before you decide on one..I think everyone will have a different opinion on what stall speed is good for what application...maybe call around to some speed shops also. I love an auto for the consistancy and awesome 60's, but I cant give up my M6

 

I in no way took your comments as a flame. To answer your question, No 3500 is not too much. In fact most people with A4's that get a 2800-3200 TC later upgrade to 3500+ or verbally say they wish they had gone higher. I'd say 3500 is perfect and 3800 is max for stock internals. If you check out ls1tech.com you'll find a ton of info in the manual trans section on this subject. The gurus there will basically all agree that 3200 is minimum if you want to be happy but 3500 is the most talked about stall for stock heads/cam.

Some may think it is too high but 9 of 10 will say get a 3500 (myself included). But the 3500+ has one downside I failed to mention. The car will stall this rpm so cruising through a parking lot at 5-10 MPH can be very annoying with a high stall TC if you have a loud exhaust. I would have to say that if you want a 3500-3800 stall as I do (saving for one as we speak) then a quieter muffler may make it more streetable from that point of view. I may ditch my dynomouth for a hooker catback at that point but I'll try it first and then decide.

Don't get less then 3000 stall. It would be a waste and you would likely regret it later. But a 3000 or 3200 stall would show you a decent performance gain and be much more stock feeling in the looseness and sound. But again I'd say 4 out of 5 3000 stall guys say they wish they went higher (or spend more $$ and actually do it).

Hope this helps.

 

the biggest str is 3.7. that is what is in my car a 3800 VIG with a 3.7 str. i pulled a 1.8 60 on bfgs that were still spinning and my car short shifted into second before the end of the 60' mark. they are well worth it

 

I'm running an ST3800 It's not to bad on the street and it's a monster at the track. Check my sig for the numbers.

 

darrens99formul ,

That's the best info I've ever read about torque converters. You really explained it well so newbies (me) can understand it good. When you go for a 3500 stall converter, what size is the best to get (10", 12". etc.)? Would a larger converter with a high stall create more heat than a smaller one? Thanks a lot for replying to that, helped me out a lot!

 

No problem. I do a lot of research on my mods and future mods. Plus I have a automotive guru at work I always bug with car questions. I enjoy passing the info along to help others out.

The question of converter size (10", 12") is pretty simple. Smaller is better. In general the smaller the converter the more effiecient it will be. So a 3500 stall 9.5" may have a effienciency rating of 97% where a 12" 3500 stall may be 92% effiecient. Higher effiency allows more HP to get to the wheels when the converter is unlocked. Now Yank does have some new converters that raise the effiency on 12" models. I don't think it'll be that big of an issue however. Just make sure you get a good model, stall and str for your needs and I wouldn't worry about how many inches you have (hmm that didn't sound right).

high stall = more heat generated. Heat kills transmissions. Simple enough right? All the big converter companies recommend a trans cooler with any converter 3000 stall and up. I recommend one period. Even if you never get a TC it's a good idea to get a trans cooler. It will prolong the life of the 4l60e. With any 3500 stall and higher it is crucial to get a trans cooler or expect your 4l60e to blow up within a month or two. However with that $80 investment, a little common sense and a little luck you can have a trans + 3500 TC + trans cooler last a long time.

Do not kid yourself though. A higher then factory stall torque converter will shorten the life of a transmission. But I would rather have a kick a$$ TC that allowed me to have fun with my car for 50K miles then the stock one with dead spots for 70k. 4l60e transmissions is a wear and tear car part as far as I'm concerned. It will die before the rest of the car and most have to rebuild or replace at least once. When mine dies I'm gonna take that as an opportunity to upgrade to a better tranny.

Hope this answered your questions.

 

this is very interesting stuff..im glad this question was askes..cuz i just went from a m6 to a a4..keep opinions coming....

 

First off, Great thread.

Right now I have a GM peformance Parts Tranny in my 93 (4l60 aka 700r4) with a stock GMPP 1800-2000 stall. I also have a B&M 3200 HS sitting in my garage. That stall was originally put in the car about a year and a half ago. Well, It kept killing the tranny. The tranny was redone 2 times, then sold the car to a friend of mine who rebuilt it once more then put in the GMPP Tranny minus the Stall. I bought the car, and the GMPP tranny crapped out with the 2000rpm TQ. I just got the car back with a brand new GMPP Tranny (thank good for 3 year unlimited miles warranty). I want to put the 3200 back in but I don't want to kill my tranny. Was the fault lying in the heat destroying the tranny because I live in the city and have no tranny cooler?? Tranny cooler is on the immediate GET list. Will it now be safe to put in the 3200 once I get the Cooler?? *note that the 3200 TQ voids the warranty