Torque converter question.

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Torque converter question.

Post by MileHighMan » Sun Aug 20, 2006 6:24 pm

Hello guys, I got a question about the converter in my car. Your probably gonna laugh, but I've got very good service out of it. It is a B-M 3600 holeshot, I bought from jegs about three years ago. In my car, at 6-7000 feet of air it went 10.94 @124 mph. not bad. I bought a name brand 5000 stall converter for it, and the car slowed down, both et, and mph. I put the B-M converter back in, and picked back up. The old combo was a 468ci,.660roller,13.1cr, 1050 carb, brodix heads,and super-comp hedders. The new combo is a 555ci, 13.1cr, .700+ roller, Dart [pro-1 325s]heads, 1050 carb,and same exhaust. The trans is a th400, no brake[ I do have a huge oil cooler on it ] and 4.10 gear. Now! Do you guys think the converter is gonna live in the new combo? Any info please! Thanks, Dan.

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Post by Transman » Sun Aug 20, 2006 8:33 pm

What did you get for the new converter? If you can give me the brand and part number or better yet stator type and fin angle I can see what is off. If you're curious, go to my site in the link below and click on the 'converters' page for a basic insight of the inner workings of a converter. It may give you some ideas... but the Holeshot will be something that will probably not have a long lifespan behind a 555, lol.
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awesomebill

Re: Torque converter question.

Post by awesomebill » Wed Aug 23, 2006 6:41 am

MileHighMan wrote:Hello guys, I got a question about the converter in my car. Your probably gonna laugh, but I've got very good service out of it. It is a B-M 3600 holeshot, I bought from jegs about three years ago. In my car, at 6-7000 feet of air it went 10.94 @124 mph. not bad. I bought a name brand 5000 stall converter for it, and the car slowed down, both et, and mph. I put the B-M converter back in, and picked back up. The old combo was a 468ci,.660roller,13.1cr, 1050 carb, brodix heads,and super-comp hedders. The new combo is a 555ci, 13.1cr, .700+ roller, Dart [pro-1 325s]heads, 1050 carb,and same exhaust. The trans is a th400, no brake[ I do have a huge oil cooler on it ] and 4.10 gear. Now! Do you guys think the converter is gonna live in the new combo? Any info please! Thanks, Dan.
Fisrt, what was your RPM crossing the finish line with the B&M and then with the other converter? Not all converters are the same. You have a fairly large engine, lots of torque and a pretty heavy car. You do not need a loose t/c.

What tire size, and what rpm are you up to and any point in the run where a shift light comes on and stays on. I use the light as an indicator of where my engine sees max rpm. If I am at the 800 ft. and my 7000 rpm light is on, I know my converter was made improperely. You need to know this before buying any converter from any one.

Some at best are a very poor design with sprags that fail all the time with the larger engines and heavier cars with tall tires and gears. Give me a ring today and I will go over it with you in detail in what to look for. I can also build a custom converter for your car that will not break and just about last forever with little to none converter slippage and warratny it for 2 years against breakage.

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converter

Post by MileHighMan » Wed Aug 23, 2006 11:44 am

I agree with you that I don't need a loose converter. As you can see, the smaller cyl heads, and carb,and the cam is 278/282@.050. I built this thing for alot of torque. My car with me in it weighs 3340lbs. I think I want a converter to hit at about 38-4000 rpm, and basically lock up after that. Remember I have a 4.11 gear, and tire size is 29.5 tall by 10" footprint. Any suggestions? Thanks, Dan.

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Post by Transman » Wed Aug 23, 2006 12:11 pm

You need a fairly tight 8" converter that does not have excessive torque multiplication. I'd recommend a CCX200+ 8" if you run at altitude. This will give you a converter with sufficient stall speed (really needs to be near or barely under the peak torque if footbraking it...) and it will do two other things: it will not be a violent hit due to your smaller tire size, plus the CCX stator will have the benefit of being more efficient downtrack. If you need more information or details, let me know...
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Post by MileHighMan » Fri Aug 25, 2006 9:56 pm

Thanks Bill, for your time on the phone. Transman, I thank you also. The guy I have, is gonna set up a converter the way I think it should be, based on your info. He said we could go spragless. But said it might slow the mph down a little. Here's the deal. I want a converter to get me off the line, but once rolling, I want little or no slippage. I want to load this thing all I can to go fast. I want your opinions here. The reason I am looking at a local deal is just that. I feel more comfortable dealing with somebody that I can look eye to eye, and he's been here forever. Race parts are worth almost nothing used. Man! Guys if you see anything I'm doing wrong, Please, let me know. And again,Thank You very much! Dan.

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Post by Transman » Fri Aug 25, 2006 10:07 pm

I believe the CCX200+ would be what you want to use. You don't want an agressive hit on the line, you want the stall speed as required, and lastly you want efficiency downtrack. IMO this is the combination to run. Not sure but I imagine you must be in the Denver area? I always did enjoy running Bandimere... just about as much as the Morrison Inn's maragitas, lol. Make sure your converter either has an investment cast front, or a good anti ballooning plate up front, as well as one in back. Furnace brazed fins and a good B-W sprag will do well. I still keep in contact with some guys out your way: the Baldwin brothers, Mike Lupfer, Henry Sliwinski, etc. When I get my dragster back out next season I'll probably stick a bit closer to home than I did years back when I chased NHRA Div 5 points pretty seriously. Went from running Super Street in 90 (won Div 5 title) right to Super Comp the next year. Anyhow... have your converter guy look at my recommendation and he can probably also explain why I said to use that combo...
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awesomebill

Post by awesomebill » Sat Aug 26, 2006 12:05 am

MileHighMan wrote:Thanks Bill, for your time on the phone. Transman, I thank you also. The guy I have, is gonna set up a converter the way I think it should be, based on your info. He said we could go spragless. But said it might slow the mph down a little. Here's the deal. I want a converter to get me off the line, but once rolling, I want little or no slippage. I want to load this thing all I can to go fast. I want your opinions here. The reason I am looking at a local deal is just that. I feel more comfortable dealing with somebody that I can look eye to eye, and he's been here forever. Race parts are worth almost nothing used. Man! Guys if you see anything I'm doing wrong, Please, let me know. And again,Thank You very much! Dan.
Dan, I would stay away from the 8" stuff with a 555 and the heavier car. You will get into some bad converter slippage with those things. Been there and it does not work very well. Maybe a very light dragster or something but even then it would be 300+ unit and as tight as it could go. Stay with the 9" because you most certainly will go to a track with better conditions and will hammer the thing harder when you make more power. 8" converters are really done with about 800 hp and 700 lbs tq and staying with light cars. I have seen some work pretty good with the big engines but with very low tq and high hp engines that spin over 7500 rpm. Not what you need for your combination.

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Post by Transman » Sat Aug 26, 2006 8:39 am

Ever see what happens at altitude to stall speed? I have. I've run in 9K ft corrected altitudes before in Denver. :wink:
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Altitude

Post by MileHighMan » Sat Aug 26, 2006 11:49 am

Transman, Please explain. Also, I'm not in Denver, but rather the high desert of Alb New Mexico. It's called the land of enchantment, but getting down the track is another story. Like Denver, we are about a second slow. Remember the converter that didn't work? I was gonna have my guy cut it open and make it stall where I want it, and do whatever it is to make it not slip going down the track. As you can read, I know very little about what goes on inside a converter. Alot of the racers around here use this guys product, and he has a good rep. Also, my converter is a 10". If I am making a mistake, PLEASE let me know. Thanks, Dan.

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Post by Transman » Sat Aug 26, 2006 12:12 pm

You want to run the smallest diameter converter that will do three things for you:

1. Provide optimum stall speed

2. Provide adequate yet not excessive torque multiplication

3. Provide decent downtrack efficiency.


The first one is easy to attain with a variety of methods including core size, stator choice, fin angle, and clearances. The second you need to work at. It's very easy and common to have too much torque multiplication with some combinations, and just as easy to have too little. Last one is a compromise that you have to attain the first two. The stator design not only affects torque multiplication, but also downtrack efficiency as well. A cut stator will be more efficient downtrack compared to an uncut one. If you move to hand-fabbed steel stators then there's even more room to work with things. I see far too many racers with big motors being led like sheep to the '9" is the way to go' myth. Don't get me wrong; there is a use for them. Just not as often as most think. With your car being footbraked, having exhaust on it, and other issues such as the altitude you run at, I'd run the converter combination I suggested. Many racers are using a C200+ or C250+ converter with similar combinations to get stall speed up in the area of 5000 (or more...), which is what you need with those heads. When you take this combination up in altitude you'll easily lose a fair amount of stall speed. Thus, moving to the CCX stator will give you 500-700 more in stall speed which is needed at altitude. Plus it gives the benefit of better efficiency downtrack. There are a lot of opinons on stall speed. My preference is to have stall speed right about at the torque peak with a footbraked car. With a transbrake there are some other things to look at. I usually want to see stall at least 300-500 over the torque peak most of the time. Marv Ripes at A-1 and I spoke about 7" converters as I'll be using one behind my new small block. He said what he looks at for choosing stall speed is the horsepower curve of the motor primarily, and the torque curve second. He wants to see stall speed at the point where the motor is down roughly 40-50 hp from the peak. He also said he likes to see a more narrow rpm operating range. My new motor has a peak at just about 6200, so if you use my thought on stall speed it should be 6500-6700. Going from Marv's recommendation and looking at the hp curve, I'm down 40-50 hp at 6800. This is pretty close either way you look at it. I intend to have stall speed at the 6700-6800 area. Anyhow, it's not really the 'black magic' most think inside a converter. Rather, it's knowing how they work and guiding the customer to provide you real numbers and a realistic goal for you to make the choice for them. Talk to your converter guy, and have him explain the workings of the two main stators in use; C and CCX. Hopefully he will give you a good peek at what they do and why. Good luck with your project!!!
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