Cruising with a high stall converter

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WyKev

WyKev

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First, this could be a dumb question.

I'm planning on a fairly stout cam in my 340. 284/484 approx. My engine guy told me I would need to run a 2500stall conv minimum to make it work right.
Trans is a '70 727TF. I'm planning on running 3.91 gears and a gear venders OD unit. (I already have the OD). This will change my ratio to approx. 3.00 to1.

My highway rpm will be around 2k, give or take. Will the converter slip/try for higher stall? I need educated, and come to the experts.
 
Depends on the converter. A good converter shouldn't be too much of a problem. A cheaper converter will tend to slip below the stall RPM.

Why not give Dynamic or one of the other top shelf converter shops a call and talk to them.
 
Gear vendors has this covered in their common questions section on their website.



Can I run a high stall converter in overdrive with a 3.42 axle?

Yes, this is one of the most often confused questions (even when you ask people you would think would be knowledgeable). Here is the detail. Our example could be this 3.42 Chevy guy. In overdrive he is going to be a 2.67 final drive ratio. He is a Cutlass body with 27 inch tire and so at 75mph in overdrive the motor will be turning 2484 rpm and he has a 3500 stall speed on the back of a pretty nicely built 350ci motor making close to 400hp. 95% of the people you would ask (even tranny guys) would say no-way and yet we know this is an awesome package (drives wonderful, no high temps in the trans etc) why does it work? When his converter was made it was set up to stall at 3500 with 400hp. However if you put 600hp to it it would stall at something like 4500. Conversely if you only put 125hp to it (as when you are just crusing at 75mph not accelerating) then the stall is way down at 2,000 rpm. So his stall with a 3500 converter is not 3500 at cruise because he is not making 400hp. Car drives wonderful. If he romps on it while cruising then the trans is going to downshift to a lower gear and get him into the powerband. (note: read gear vendors passing gear in this section) So, this is why you never lie to you converter builder (because if you overstate your hp you will not get the stall you wanted).
 
good explanation,so if im cruising at 3000 rpm in a 3700 pound car with 570 horse my converter that was built for a 400 horse 360 in a 3200 pound car should not slip much because im only pushing 300 horse at it till i punch it?
 
Well, that was a great explanation. Now I need to figure out what my 340 is going to have for hp. Any ideas? Big cam, stock heads,edelbrock performer intake, carter carb, and currently stock manifolds($).

Looking at it there, I'm thinking 325hp? Dreaming?
 
I run a gear vendors unit on 3000 TCI stall with no problems. My rear end is 3:73 and 550HP at the crank. Gear vendors is a solid unit.
 
As a side note, ALWAYS run an aux. tranny cooler !! The ones on Dippy cop cars work great and they are MOPAR!
 
If you are planning an OD build, why not simply use a cam that makes power in the range you'll be driving in? With a typical 27" tire, your cruise at 70mph is 2800rpm with the GV engaged. That 484 in a 340 will feel soft. A more modern design cam would get you power from idle up, make the same peak power at the same rpm as the 284, and let you run a more friendly convertor. When you're cruising in a car that has a 3K stall, and your at light throttle, and you say... hit a long grade, or want to pass something... What happens? You press the pedal, and the car feels like a wet sponge. On a car that is a street car first, you are MUCH better of setting the stall speed under the cruise rpm. Better for noise, wear and tear, and fuel mileage. I've re-stalled several Dynamic "9 1/2" units that were just too soggy at lower rpms. Tighten them up, lower the stall, and the car gets much more drivable and fun with no loss of the grin factor.
 
Personally I would call around to dynamic, ptc and ultimate and see what they recommend. make sure you are completely honest and accurate about your combo and intended use. I would think the converter on a od car would be a little tighter then on a non od car.
 
Spoke to Ultimate about this, except I used an 800 hp efi Hemi in my example. Len told me that he is working with someone in Vegas that is attempting this. When he has the convertor tight enough so that the torque does not make the convertor slip at freeway speeds climbing hills that the car suffers at the strip, when he has the convertor loose enough so the launches well at the strip, it slips out on the road. Might want to contact Supershaft, he is a member here and sells the gv unit. I am sure he has an opinion on it....
 
Well there is always some kind of compromise when trying build a dual purpose car like that. Some times ya have to decide what you are gonna do most with the car and let the other suffer some.
 
Don't cheap out on a convertor...driving enjoyment will far out weigh the price...
We put an 8'' steel stator PTC in the 273 for Vic's 67 Cuda and it's got a 2.90 gear...He'll drive it every where.

Ultimate Converter Concepts or PTC are my go to guys....SUPER CUSTOMER SERVICE from both...!!! in the long run that's what REALLY counts...IMHO
 
i run a ,4400rpm stall, dynamic 9.5" converter, very nice and when the throttle is held steady like at highway cruise seems to slip very little, I would say you would need a stall in the 3,500 rpm, no headers, and the performer, is going to hurt your HP without headers i would say your right at 325hp add a 750dp, rpm manifold , and good headers then that cam will work good and should put you at 400hp
 
Not sure if this would work or not, but have you considered using a lock-up transmission? You should still be able to get a good converter for it and I would think that the lock-up would make the stall speed of the converter a non-issue on the highway.
 
I had a tci Breakaway, that thing slipped! At a stoplight I had to hold the brake down on a slight hill to keep the car from rolling back. This was like 10 years ago. I then used factory "high stall" converters for $100 and learned how to go fast by making hp, lol.

Well this summer I got a tci Streetfighter, a 10 inch 3,000+ rpm stall. Was worry how loose it feel, its tight! So tight I have to hold the brake down to stop it from creeping forward when stop. I can pull the car enough to keep up after the light with traffic most times and its at 1,500 rpm.Yet when pushed hard it goes right to 3,000 rpm or higher. Even on wot up shifts where the lowest rpm is 4,000 it pulls great. 2nd to 3rd gear is a killer for most trying to stay with me, ha ha.

I would highly recommended the 10 inch tci converters. Yeah I heard the bad talk about tci but only one Summit had in stock. My converter was made in April 2010, maybe tci has its act together now? I do know Comp Cams brought tci a few years back.
 
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