Torque converter efficiency?

[DNeinstadt]

I have a BBC, TH400, 10-bolt '71 Chevelle that has an unknown rpm stall converter in it. At a recent visit at a performance shop, I was told that a lower stall may be helpful for street driving.

1. Would a lower stall make my car more efficient for street use?
2. Can you tell anything from a dyno sheet?
3. How can I accurately verify what my stall is at?

School me on TC's?

Dan

[old vette dog]

Yes on one, I bought a tight one
Yes on 2
Brake stand or load at the strip.

[DNeinstadt]

:)

Ok. Thanks. :)

[MR.hp]

I have a BBC, TH400, 10-bolt '71 Chevelle that has an unknown rpm stall converter in it. At a recent visit at a performance shop, I was told that a lower stall may be helpful for street driving.

1. Would a lower stall make my car more efficient for street use?
2. Can you tell anything from a dyno sheet?
3. How can I accurately verify what my stall is at?

School me on TC's?

Dan

Dan I know for a fact that when running a BB chev engine that the tq. makes more stall also inc. weight in the mix. I have an 11" tci in the bird and it's pretty good with the BB it stalls around 2900 rpm and with a SB it 2100 rpm.
If you want to find close to your stall speed get the car into high gear and go along at about 30 mph and stab the throttle and look at the tach and see where it jumps to. Generally 11" converter will stall around 3k. I think the best way to check would be to take the converter to a trans place such as precision to test it as I think they have a way to check stall speed.

Also believe this or not tci told me that they can make an 8" convrt. that is more efficent than a 10 or 11" convert. and that was due to fluid sheer in the convert.

[DNeinstadt]

Looking at this converter:

Diameter: 10 Transmission: TH MP: STD Stall: 35-4000
10" STREET PERFORMANCE CONVERTER

I think my existing is a bit higher... closer to 4500/5000?

Dunno, had some fun tonight in it so not sure what I'm going to do yet..

Dan

[old vette dog]

and what are they rating the stall speed against?

I just bought a 4200 stall that was behind a 1050 hp 598 ci bbc which is tighter than my current stall of 3500 on just motor w my 550 hp 502
which also stalls at 5200 on 250 shot last year.

A good stall company will find out more about your current configuation so they can be more accurate on #'s

[DNeinstadt]

I have no idea what the existing one is as it came from the previous owner of the motor, he planned on racing with it I think.

Anyhow, 602hp, I jumped on it in D at about 40mph and it went to 5500 quickly and stayed there until my pooper puckered up. Does that mean I have a 5500rpm stall? If so, would a 3500-4000rpm stall be more fun for the street? I would see the track maybe 1 or 2 times a year, most driving done on the street..

Thanks guys. I don't claim to know it all but I enjoy learning from those that do..

Dan

[MR.hp]

Anyhow, 602hp, I jumped on it in D at about 40mph and it went to 5500 quickly and stayed there until my pooper puckered up. Does that mean I have a 5500rpm stall? If so, would a 3500-4000rpm stall be more fun for the street? I would see the track maybe 1 or 2 times a year, most driving done on the street.

Dan

Try this Dan and you will need to make sure the tires hook this is from a website I found>.


You cannot check the stall speed of a torque converter by pulling the transmission into gear, holding a vehicle with the brakes and adding power -- the drive-wheels will begin to spin long before you reach full-power. The proper way to check the stall speed is to make a standing-start, abrupt, foot-to-the-floor acceleration run and note the RPM shown on the tach at the instant the vehicle begins to move. This test actually measures "flash stall", but this is usually very close to the true stall speed of the converter. Also, this test is only valid if the tires do not begin to spin and if the engine can develop sufficient torque to actually reach the rated stall speed. If the tires spin, the apparent stall speed will be high. If the engine does not develop sufficient torque for the converter, the apparent stall speed will be low.

Level 10 performance is where I found this at.


I still check mine in high gear even at the track and stab the throttle.
I just put a 350 in my firebird that has a 11" tci as I mentioned and that 350 engine came out of the camaro with an 8" tci and although the 350 flashed to 4900rpm in the camaro, Now that the 350 is in the bird it stalls at 21 to 2300 and pulls way better as it has a chance to stay in it's usable powerband longer.

One of the best street converters I ever had was a 10" tci super street fighter and on the street it acted like a stock converter untill the gas was hit hard. I had a BB 461 and it ran 12 teens @113mph. The next year I put in a 10" vega converter that I thought would be the hot ticket as on the street it would stall at 4500. A funny thing happend the car still hooked good bur at the track it was 2ths. slower and lost 5 mph and felt like I was spinning a rubber band. It was as they say like some women loose.

[torkflight]

Coan and other converter companies will tell you to pull out your launch chip, hold the trans brake button and floor that fucker, wherever it revs to and holds is what you have for a stall, so all you clowns with no trans brakes, TO FUCKING BAD!!!

[old vette dog]

I has a tb and gonna use it this year

[DNeinstadt]

It runs to 5500 and stays there. The tires spin A LOT already so there's no way I'm hooking up right now.

I suppose I could just swap converters and test it out?

I'll try to get some video tonight maybe...

[DNeinstadt]

Anyone got any input?

That converter I was looking at was at Coan:

#06010
Diameter: 10 Transmission: TH MP: STD Stall: 35-4000
10" STREET PERFORMANCE CONVERTER $300.00

Thinking this would be good for the street?

[MR.hp]

Coan is top notch stuff so that is a good converter, Also take a look at Yank they are more exspensive but when they make them to your specs Yank delivers. I have a guy with one in a car wit a turbo 400 and he swears by it.

I see that is a factory refurbished converter, But I think the stall speed is too high as with big block converters almost always tend to stall on the higher side due to the tq.

[DNeinstadt]

#0840
Diameter: 11 Transmission: TH MP: Stall: 2500-2800
11" STREET PERFORMANCE CONVERTER, TURBO SPLINE $175.00


Hmmm... worth it maybe? What's "turbo spline" mean? I know it means you have to do something with the input shaft, likely won't work?

[DNeinstadt]

Found this:

Some "less technical" guys probably aren't familiar with the definition of "turbo spline"...so here is a quick lesson. The OEM powerglide input shaft has 17 splines on the end that goes into the torque converter. The popular TH350/TH400 transmission input shafts have 30 splines. Its a no-brainer that more splines are better and stronger, so in order to keep up with today's high horsepower engines, transmission companies decided to put the popular "turbo splines" on the powerglide input shaft. By doing so, you gain a lot of durability with the added splines, but it also allows you to use any standard TH350/TH400 torque converter in your powerglide transmission.

So it sounds like the converter on their site should work?

Which is better for a BBC on the street? 3500-4500 or the 2500-2800? I'm used to manual transmissions!