Torque Converter causing a 5-10% drop in RWHP?

[BlownSRT8]

In my post about my 6.3 motor someone responded and said that a high stall converter (mine is only 2600rpm) would cause a 5-10% drop in rwhp, but that it would also show an increase in rwtq....

Is this true? Has anyone else heard of this?

[Meister]

I've heard the same thing stated, then others refuted it pretty much out of hand.

Last I saw the refuters were winning.

[Chrispy]

My car lost RWHP with a stall versus stock converter but it depends on a lot of factors.

1) Diameter of aftermarket torque converter (ie: 11, 10, 9, 8 inch)
2) stall speed
3) STR (torque ratio)

There are converters out there that are MORE efficient than stock so it all depends on what you started with and where you are going.

I had a Yank TP4200 stall that flashed to 5000rpm on the dyno and made 460RWTQ and only 390RWHP in my formula when I had a mild heads/cam. Car ran 11.30s @ 122mph with that combo at 3600 pound raceweight. I could ignite the tires punching the gas at 60mph. It wasn't all that streetable but it was a beast at the track with 4.10 gears

Cheers,
Chris

[Sled]

After a recent cam install with headers and catback exhaust (running stock heads), I made 433 rwhp @6400 rpm and 395 ft-lbs of torque @ 4800 rpm with a stock torque converter.

It's a big cam 228/232, 0.6in lift, LSA 112 so it was pretty much a dog at anything less than 3000 rpm with a stock converter.

Without changing anything in my setup, I swapped the stock converter for a ProTorque 2800 stall. At the dyno, I made 411 rwhp but 447 ft-lbs of torque. It really woke the car up on the street despite the dyno numbers. I haven't taken it to the strip yet but other nearly identical GTO's running drag radials are laying down 11.5's @ 118 mph.

In this instance, dyno numbers don't tell the whole story. The same would be true for your 300C.

[Kaisersteiner]

I also would not worry too much about RWHP at 6400rpms or peak rwhp so to speak. I would worry about the car staying at a moderately high level of power throughout the powerband (say 3800 to 6000). That's where you'll lay a beating on people. Peak RWHP is only touched when shifting and most of the times it starts to fall off anyways. The converter should be helping at the wheels were I am talking about.

[BlownSRT8]

Originally Posted by Chrispy

My car lost RWHP with a stall versus stock converter but it depends on a lot of factors.

1) Diameter of aftermarket torque converter (ie: 11, 10, 9, 8 inch)
2) stall speed
3) STR (torque ratio)

There are converters out there that are MORE efficient than stock so it all depends on what you started with and where you are going.

I had a Yank TP4200 stall that flashed to 5000rpm on the dyno and made 460RWTQ and only 390RWHP in my formula when I had a mild heads/cam. Car ran 11.30s @ 122mph with that combo at 3600 pound raceweight. I could ignite the tires punching the gas at 60mph. It wasn't all that streetable but it was a beast at the track with 4.10 gears

Cheers,
Chris

It's the APS 2600stall converter.

It's made from the stock converter, so it should be the same diameter.

I don't know the torque ratio.

[Chrispy]

Originally Posted by BlownSRT8

It's the APS 2600stall converter.

It's made from the stock converter, so it should be the same diameter.

I don't know the torque ratio.

You'll likely lose a bit of RWHP but pick up peak torque when the converter flashes on the dyno/street.

[Jaybo]

Remember torque is what gets you out of the hole.....


Jaybo