[Dave Schiffers]

Please explain the difference between a tight, medium, and loose converters

[Dave Schiffers]

Please explain the difference between a tight, medium, and loose converters

[Lerry: The Body Ventura..]

Tight is close to a stock conv.,loose is a very high stall speed, and medium is somewhere in between.

[Dave Schiffers]

Where does torque multiplication come in here? I thought I heard some one say there is very little torque multiplication with a tight converter? Just trying to understand....please explain, "Torque Multiplication"?

[Skip Fix]

Torque convertors are a science(guess) in their own right.Torque convertors all multiply torque. The various fins on the inside determine how much fluid sheer or coupling they have. Imagine a water wheel with various angles of buckets that some spill more water than they carry- a simplistic view.

"Tight" =less slippage. You can have a loose 10" that drives similar to a tight 8". When my old 8" had some broken fins and was coupling poorly would almost rev to 3000 to pull the car on the trailer. alot of slippage. Current 8" that is a 5000 stall starts the car moving on the trailer at 2000rpm.

A really loose convertor whatever the size you can see the rpm fluctuate without the speed changing much. Drive a loose one up a hill at a constant speed that is below the stall(where it starts to couple)and you will see thr rpm rise as your speed is constant.

[Dave Schiffers]

So a 10" tight converter and a 10" loose converter will have the same torque multiplication ratio???......and will have the same ET at the track??? Only change will be street manners?
Thanks for the input guys.

[Dave Schiffers]

Also, in addition to the last post, please explain the advantages, and dis-advantages, of a 10" loose converter, and a 10"tight converter.
Thanks for the help......I need to decide soon.

[Skip Fix]

They might not run the same at the track. The looser one is not coupling as good as the tight one. A looser one may hit the tires softer, but slip too much to get a decent mph. Most guys with a really dialed in combination have at least three convertors on the shelf if not more, and most of them have been cut apart and changed!

There probably is some difference in torque multiplication but I don't know how to determine that.

[Dave Schiffers]

Can some one tell me how the torque multiplication would differ between a 10" tight and a 10" loose converter?

[johnta1]

try this link,it'll help explain a lot.

Torque Converters

[img]/infopop/emoticons/icon_cool.gif[/img]

johnta1
Pontiac Power RULES !!!
www.wallaceracing.com

[Dave Schiffers]

Thanks folks.....I have now read, Jim Hand's stuff, and TCI's, and now know more about converters.

Maybe I'm slow but I need to get it right.
Bare with me.

1. What, briefly are,
the benifits and drawbacks of a loose
converter, and,
the benifits and drawbacks of a tight
converter?

2. How does one decide wether thier converter
needs to be tight or loose?

Perhaps.....could it be said this way....tight or loose refers to the coupling effect before stall is reached?...and how quickly stall rpm
is reached.

A tight converter will move a vehicle easier with less slippage before getting to stall rpm. Friendier on the Street. Creates less heat, but will create more heat staging at the track because it is tighter.
And a loose converter will slip more, & quickly to stall rpm. So a very loose converter is designed for quicker ability to reach stall rpm? Will create more heat on the street.(ie. quicker reaction to a Pro Tree?)

3. If thats the case ...why run a loose
converter unless running a ProTree?

4. A loose converter will spin, (slip) upto
stall speed faster than a tight
converter....and therefore a loose converter
will have a greater torque multiplication???

5. So what about final slippage between the
tight and loose converter when crossing the
line at the end of the 1/4. The loose
converter will have a greater % of slippage
at the end of the 1/4 ???


Thanks
If this is not accurate.....PLEASE help clarify.

[This message was edited by grumpybear on December 23, 2002 at 02:15 PM.]

[torqjunki]

Let me try to simplify this as much as possible. Ideally, you want the engine to leave the starting line at or near peak torque RPM. So, if the dyno numbers say your torque peaks at say 3500rpm, you would want the converter to stall or slip just enough to allow the engine to reach about 3500rpm out of the hole with traction. AS far as slip down the track, ideally, the converter would slip 0% after launch. Unfortunatly, the design of the converter that allows the 3500rpm launch will create some slippage down the track. So how do you get a converter to stall off the line and lock as tight as possible down the track??? Simply open the wallet really wide and spend $650 to ?? for a quality, custom built converter hand picked and built for you using all your car info. My advise is to arm yourself with all your car info,(weight, tire diameter, gear, trans, just to name a few) and call someone like Kenny at PTC who knows Pontiacs. Let him decide what to build. BTW.. A while back, while I was waiting for my PTC converter to arrive, I installed a buddies Hughes converter that stalled about 3400 on his car. It was a 10" unit priced at about $275 a few years ago. It stalled 5000rpm on my car, but still managed a 10.45 pass with 10.25 being my best with the PTC. Question is, how long would it have held up? Anyone who knows me knows I am not an advocate of high dollar parts. I know some guys running real strong with carefully selected off the shelf converters. It really sucks when you miss it though. Good luck.

[Bad-Goat]

torqjunki, real good explaination.I have a few things to add. The size determens how much stall.
Stock convertor 12" will stall around 1200-1500 rpms. 11" around 2200-2500 rpm's and so one. On a Pontiac you want your convertor to stall around 300 rpms above were the motor makes peak torque, The chevy usually stall around 600 rpms above peak torque, they like a little loser convertor. If your picking a cam that makes peak torque at say 3500 rpms,then that's what you shoot for.

It really depends on the motor and how efficient
it is, so it's not exsect but most convertor companys can come pretty close. I like Coan because they've done a lot of Pontiac convertors
and they seem to get it right the first time

[Dave Schiffers]

Thanks Torqjunki and One-Bad-Goat, I think I'm getting it...but no one has touched the issue of tight, or loose.

So,....whats all the business with

10"tight vs 10"loose

What is the difference.

Is a 10" tight just a lower stall than a 10" loose(higher stall rpm than a tight)?

Is this right....or wrong again?

I really appreciate the help.......Thanks.

[This message was edited by grumpybear on December 24, 2002 at 09:15 AM.]

[Skip Fix]

A looser than stock convertor can help smooth that lumpy idle as the convertor isn't starting to couple its freewheeling some.If you have a very stock motor you don't need much extra stall.GM had a special convertor for the L-88 BBC with their big cams that was a little looser.A motor that idles a 1200 and has a torque peak at 4500 you need alot looser one. A recent Pontiac Super Stock raceer I talked to said they have recently found a convertor that flashes ABOVE their torque peak is faster if it will couple good.

I just dug out some old notes and Lee Bannister a local stocker with a 72 Formula runs a PTC and said it really picked the car up.My machine shop says alot of their racers have had good luck with Precision Convertor's "Vigilante" line. They run in the 8s with one in their car.

Just alot of trial and error.

[David Holmberg]

Skip, Almost all of the LS1/LT1 guys I know run the Vigilante converter. They all Love it!

[johnta1]

The difference between a 'tight 10" converter and a 'loose' 10" converter would be that the 'tight 10" would be more locked up at higher rpm's.The 'loose' 10" would still be slipping.

The stall can be the same on either converter,the converter is still multiplying torque until it 'locks up'.A tight converter will start putting more HP thru without the converter slipping.Pontiacs being a lower rpm torque engine doesn't need the extra slippage after it gets into it's power range.

Whereas a ch*vy might still need that extra torque and slippage to keep the rpm's up.

Most Pontiacs work better with a 'tight' converter because of their higher torque output.
[img]/infopop/emoticons/icon_cool.gif[/img]

johnta1
Pontiac Power RULES !!!
www.wallaceracing.com

[AIR RAM]

The loose converter will act like your riding the clutch on a standard trans. It will allow your engine to Rev higher and stay in the chosen RPM range while allowing the transmission to "slip" creating more torque to the rear and much more heat. There is much more to the science than that but that’s the gist of it.

The tight converter will lock up at a lower RPM putting a load on the engine before it reaches its peak torque. This would be better for a streetcar where it is difficult to launch from a light at 3500 RPM's. Traction would be almost impossible on street tires. A tighter converter would offer better street manors.

Heat plays a big factor because the looser the converter the more it will slip the more torque it will deliver but it will also deliver more heat. Transmissions do not like heat so again it is a total science. [img]/infopop/emoticons/icon_rolleyes.gif[/img]

SPEED SAFE, AIR RAM



Im putting together a .040 455 with Edelbrock heads (72cc), Eagle Rods, FLAT top J&E Pistons for 12:1, Harland sharp roller Rockers, Fluidampner, Edelbrock Performer RPM intake, and 750 Demon Carb. "GOT TRACTION"

[Bad-Goat]

Actually here's what happens, most convertor company's will size your convertor to a one fits all type of deal. Here's what I mean, lets say you order one for a BBC 454 They need to lock up a little higher then a Pontiac 455, So you'll get the same convertor the BBC guy order. You won't really notice the difference, because it's only 300 rpms, when you will notice is going through the traps.

Let's say you've gear and size your tire's to go through the traps at 6500 rpm's to make peak hp, you may end up going through at close to 6800-6900 rpms, when that happens your losing mph plus ET. A lot of company's do this,that's why I say it pays to go with some one who knows Pontiac's. Now On the street both 10" convertors will react almost the same. You won't be able to tell the difference between the two, but for a Pontiac 300 rpms is a lot.