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I doubt anyone currently on the forum is running a high stall converter, but if so I need to know if there are CEL concerns in doing so. This is out of the questions if it will throw an engine light because my need to pass Cali smog is paramount, and replacing the torque converter with oem for test time is too much work.
Some things I've been researching but am not finding jack for info on are:
What is an OEM GS300's stall speed
What is a good stall speed to run with 264 cams
And if anyone has info on codes coming up for slippage. etc.
My understanding is that as long as a locking converter is used and the TCC actually locks up, there shouldn't be any slippage registered as out of the ordinary. But as was the case for my vette, theoretics and real world are quite different, and a great deal of tuning was necessary to make a 3200 stall work for it. I don't know if any tuning is even possible for this trans if I did the work to install one and it acted up. So looking for as much info on this as possible.
I called BC and they told me that the 264 cams bring the rpm range up 500-800 on the low end and 1000 on the high end. And that a 3200 stall would be a great match for them. If it's anything like my vette, 3200 is very street-able. I actually needed 3400 for better 60 foot times, but I wont be drag racing this car. Problably will do 3200. And maybe maybe a smaller diameter for lighter weight/faster revs.
Next question. Is the OEM TC 10"? 11"? I ran a 9" in the vette and it was 20lbs lighter than stock! That alone in weight reduction in the drive train is a good upgrade.
Some thoughts, after doing some research on dyno sheets, for GE/GTE 256/264/272 cams (yes, I have no life...)
OEM, for the GE, you'll see 90% of your torque from 2k-6k rpm, with a 5% curve from 4k-5.5k... it's basically a straight-flat line. hp will rise linearly from 2k-5.5k, then gently curve down.
Reading the dynos for the cams, the torque increase will be across the range, yet nothing great. The hp increase is almost all on the high rpm... you'll see 2-5% across the rpm range...then rather then peaking at 5.5k and curving down, it'll continue to grow linearly until 6.5k then curve down. Almost looks like the hp/torque curve on a 3S-GTE, when you increase boost... the curve just keeps rising, until you hit max-boost... taking that engine from 12psi to 15psi didn't as much make more power, as let the curves continue for another 1000rpm, and you'd feel it.
For the GE, if we're talking about moving your TC from 2.7k to 3.2k, I'm seeing almost no change in torque, and maybe 10hp increase, no matter the cam, at that rpm range... I don't have enough experience with TC's to make a true judgement (the GS4 is our only auto car...!), yet that doesn't sound like enough to justify the time/labor, unless there was another factor in play... weight, cost, repair, etc.
If we were talking about a 2UR-GSE or 2JZ-GTE, where moving the stall would add 50-75-100hp/torque, that would be another conversation, yet guess the question is... how much more power justifies the cost/effort, for your application...?
BTW, Muffinizer, thanks for posting that... now I can say that the GS4 shifts in to 5th, at 130-143mph. : )
I dont ever expect a power increase when going higher stall. In fact higher stalls typically show less power on a dyno. It's what makes the power you have usable. The launch and the rpm being kept in the powerband is what makes an automatic move. I guess I can't really explain it, you'd have to feel my car. I was hoping I'd be able to install these cams and have everything be on point. I wasn't planned to go higher stall. But the powerband did move higher and the when you put the foot down, it really is notable how long it takes the car to really starts to pull. A higher stall converter will instantly put it to where it pulls hard. This is also why I want to put an LSD in the diff. The instant power will make a need for better traction.
Lets look at it like this (the way it make sense to me). Say we know OEM stall is 2700. And the 264 cams don't start to pull until around 3800-4000rpm which is what I'm seeing from various charts, and peak is close to 5500-6000rpm. Most experts say you want about 500 stall less than your peak power (This would be for all out racing). For street use, 500 less than the start of the operating range is good because you get to the operating range quickly, and have full use of it. Not just peak power for a short time. You'd be launching hard and have good 60' times, but be completely useless for streetability because you'd be running a 4800+ stall to have a setup close to peak power all the time. So because the car will move forward by force of the 2700 stall before the car starts to make power, it will (what we call) "dog" out of the hole. It will slowly raise rpm until it gets into the powerband and then start to pull hard. A 3200 in this case is right around that area of 500 less stall than where you want it to kick in. (close enough for a street car). This means that the car wont be forced forward until 3200 rpm is reached, and the car will be pulling hard forward instantly rather than ******* off the line. So it's not that I'm hoping to make power from a TC, its that my low end is basically not set up right. I am under powered until the cams kick in. This would make the car useless on the drag strip and spanked by anything that wanted to take me from a stop.
This is a chart I used when doing the converter in my vette. This is strictly for Chevy LS based V8s. But you can see the relationship between torque multiplication and stall. So you can look forward to a little bit of increased torque to the ground, however the main point is to be at your powerband.
So in example of my C5 Vette. You can see that going from 1800 stall stock to 3200 stall (The SS3200 on this chart) effectively increase the torque ratio from 1.9 to 2.1. The change will not be as extreme for the GS300. But I just wanted to share this to get a better idea of how certain aspects of a higher stall converter woork.
I'm looking for suggestions on brands that make converters for the a650e so I can research them etc. I seem to see people using this "dragon" converter a bit. Is that pretty much the "go to" for these cars?
Guess I'm in the "have to feel it to believe it" mode... with the cam change, this sounds like something you could have done pre-cam-swap, with the same effect/impact (statement, not criticism). A perfect situation would have been 1/4-runs by a solid/predictable driver, with slips before/after the TC swap.
Well it's not my first rodeo with cams and TCs.. I assure you, the two compliment each other quite well. It's a worth while swap. I have quite a bit of strip time on stalled vette. It's what makes the car even remotely competitive. Like I said, it all comes down to how the cams and TC work together. There's no power formula I look at on paper when I pick a TC. It's all about matching it to the operating range of the cams you are using. So ya, I guess you'd have to feel it..
I left Precision Industries a message about "The Dragon" converter. Seems they don't just sell them, you have to tell them your specs and they build it for you. I'll see what they recommend and what pricing is etc.
Well, hats off to someone willing to put the research in to a new solution... all I say is... measure, change measure... please measure before you make the change... : )
PI says the OEM stall is 2400.. I'm sure they know what they are talking about. Not sure if they mean brake stall or flash stall. I'll have to go test mine to see where both are at. They recommend a 2800-3000 stall for it and that it won't throw an engine light at 2800. This was by email. Going to call in for the finer details when I have a day off.
06-02-19, 09:17 PM
Torque converter stall
