heavy_chevy29

i have to get a new converter now that im going to use a powerglide.ive been looking around and i notice that there is the option of with a sprag or with out sprag. what are the ups and downs of both. also im trying to figure out my stall speed. can someone help me with that. my engine was dynoed when it was built and it made it peak torque at 4600rpm. my cam specs are .050 duration 252(intake) and 256(exhaust). i was thinking some where around 4000/4100 stall. does that sound about right.

AlkyIROC

Get a sprag. I run a TCS converter www.tcsproducts.com that has a heavy duty sprag. Although they offer spragless, they recommend using a sprag. Actually it's not really a sprag but a diode which is better. A TCS race converter has a 2 year warranty and the billet stator has a lifetime warranty.

What's the advertised duration of the cam? Street or street/strip or all out race?

heavy_chevy29

my cam card says

Duration at .020 tappet lift 283(int) and 287(exhaust)
duration at .050 252(int) and 256(exhaust)

the car is going to be more race than street. but the only street driving it might see is going down the road from my house to a cruize night(about 3 miles). but that would be very rare. so i would say full race.

AlkyIROC

For full race, a converter with a minimum of 4000 stall. Something in the 4500-5000 would be better.

heavy_chevy29

really that high. ok. thanks alot for the help.

AlkyIROC

Do you have the cam card? Where does the cam start to make power? For street use, a converter should stall roughly 500 rpm above where the cam starts to make power. For full race, 1000 rpm.

A camshaft in the 280-290 advertised duration range needs a converter in the 3500-4000 range for street use so for all out race, 4500-5000 is reasonable.

Although I've never had my engine on a dyno, my converter stalls at roughly 6000 rpm. When I launch at 6000, the rpms climb until I shift at 7400. The tach then drops to 6400 then climbs back to 7400 as I cross the finish line.

Pro Built Automatics

You will give up several mph when using a "spragless" torque converter, although they do ET a little better "sometimes". I do not like giving up mph though.......

Fast 383

iTrader: (2)

I think I can be of some help here. I work at Transmission Specialties as a race trans and converter tech. I have cut open thousands of torque converters and spec'd out thousands of race converters from Top Sportsman and Top Dragster cars to mild street cars.

Sprags are junk. If I showed you one of the hundreds of broken, worn, cracked and just plain shattered sprags I have seen you would be amazed. And thats just about EVERYBODYS sprags. Mechanical Diodes are definelty better but still fail and wear out. Probably good till about 1000 HP in my opinion.

Either way you will need to give your motor and car specs for an accurate stall recomendation. It will determine what size converter you will need and where it will need to stall. If you made peak torque at 4700 you are going to want to have the converters flash point be aprx 300 rpm's over youre peak torque. Thats where your car will react from a point of strength and fall to the same point through the low high shift.

Even know that sounds high you have to understand that PG's have low first gear ratios ex. 1.76 or 1.80 and need the high stall to bring the rpm's to the prime band of power. Hope this helps you. If you have any questions, ask.

BTW, without getting into a debate, there is not one single ounce of proof that a spragless stator will loose any HP, MPH or E.T. In fact, A sprag has nothing to do with that whats so ever.

Pro Built Automatics

I have worked with kris at Continental since 1980, and Terry at Precision Industries since 1996. Both tell me that the spragless will lose mph. Maybe on high horsepower they do not, but then I mostly work with motors in the 450 - 900HP range.

Fast 383

iTrader: (2)

There is no real way to address the issue without debate. I don't want that to happen. But I wouldn't believe everything you hear.

But to the origanal poster, I have thousands of guys from 500-2000 HP who claim perfect consistancy and 60ft's with no mph or ET drop as long as it's built correctly. If you have any questions you can Pm me and I will help you out. I have about 8 different PG models as well.