My GS455 has a relatively stock Stage 1 rebuild with the number's matching Turbo 400 and a stock converter. (13 inch?). Gears are 3.42 posi. The foot brake stall is less than 2000 and the car is lazy from a dead stop. Would this basically stock GS benefit from a higher stall converter like the 9.5 one Jim sells? If so, how much stall should I ask for? And, if I later add about 100 HP (heads, cam, intake, tuning, etc. will the converter need to be re-stalled? This car will be 90% street with maybe 2 or 3 trips to the track a year. (and, I hate mushy converters, by the way)
My set up is stock 455, turbo 400, rebuilt with a TCI level 1 shift kit and a supposed 2300 stall (500 over stock or RV) converter. It works great for street. If I was racing, I would probably go to 2800 ish. When I got the car, it was "mushy". Now it really launches and shifts like a street car should. Actually, it was a little harsh at first, but I adjusted the modulator to correct some of that. I also have plans to rebuild the engine a little stronger and I expect to change the converter, if and whenever that happens. I doubt if I would race it unless I would ever get down to Bowling Green or some other event. Also, this is my first auto trans in a muscle car, so I am no expert. Just relaying my experience. Add: I also have a 3.55 posi
Ray, You really need to call Jim and talk to him. He has been doing these converters for awhile now, so he knows what you need. All you need to do is tell him what the car is now. I can tell you this, the converter he sells is likely 15 lbs. lighter than what you have now. Just that amount of weight off the crank will produce seat of the pants feel.
The converter and your axle ratio can be tuned for level of performance. But a higher stall converter will require reving the engine higher for all driving, using gas and wearing the engine. I would not recommend pulling a heavy trailer up a mountain with a higher stall. Its your choice. Here I resort to a switch pitch converter, which helps get going without sacrifice the rest of the time. But these do not have the range for serious performance. Bruce Roe
What you want is an efficient converter that will stall where you need it when you get on it. That is having your cake and eat it too. You are unlikely to find that with an off the shelf converter, unless you are lucky. I can tell you about my experience with Jim's converter. In regular street driving, it feels like a stock converter, but when you punch it, it goes right to the sweet spot. It is hard to believe it's a 9.5" converter.
Too bad there isn't a 9.5" lockup 2004r convertor available. Maybe there isn't enough room for the lockup function with the 9.5" case.
Not surprised. Can you tell it's a high stall converter when it isn't in lock up? Is it otherwise efficient/tight under light throttle street driving?
I am of the opinion that this new generation of converters, configured properly, will dramatically help even an otherwise dead stock combo.. Simply because it's nearly as efficient in light throttle driving as the big converts, but under power, the stall speed will increase and the torque multiplication is so much greater.. In many cases, about 50 ft lbs or more.. When I put the test car together here, hopefully next spring, I am going to build it all stock to begin with, it's going to be equipped with data acquisition equipment, so we can quantify driveshafts speeds/rpm/accel G forces ect, and then do the street and track testing to get the real world results and numbers. JW
And to clarify, I can build the 9.5" in TH 400/350/200 configurations, as well as the 200/700 and 4L60E and 4l80E lockup or non lockup units.. The lockup units use a 3 disc Kevlar clutch setup, that can be locked up reliably at full power. The lockup converters are $769.00 plus $40 shipping to the continental US. Non Lockup units for the 4 speed transmissions are the same cost as the non lockup units, they are exactly the same, except with a different hub and impellor.. That cost is $629 plus $30 shipping to the 48 states, JW
Larry, Its great unlocked around town. I leave it unlocked unless I'm tooling down xway usually over 70 mph. Locked below 55 with my cam/setup/gear, it'll chug and lope. Much more performance than the D5 I was running. I think a 3,6k stall would be just fine on the street. Trans cooler is important for any additional heat buildup while driving unlocked. I'm happy...
