Question for: PTC converter users

How does shift 2-3 shift feel? Do the gears feel like they blend instead of hit. Almost feels like clutch slipping but no flair. Bizarre Thinking that I'm blowing through the converter but Dusty says if anything it would be too tight.

On a log when I punch it, the rpm flat lines around 5000-5200 while speed goes from 70 to 100 mph.

Trans was just freshened up. I don't know if that good or bad but none the less I have this issue. Not letting full power get to the wheels. Thats for sure.

Thanks for the reply Dusty. Thats exactly what it feels like. (Flashing to 5000rpm) I think thats a little high for my combo. Can you adjust that to say 3800-4000?

Here is a log with a third gear pull.

Most that run a 9.5" arent shifting at 5200. My converter flashes to 5400-5500@26psi. Therefore if im in second and shift at 5400 the rpm will not drop at all. My peak torque is at 5600 rpm based on injector dc. If i shift at 6400 it drops to 5400. That flat line of rpm is good after ratio change. I have tremendous g force when during that time. Then before you know it the engine rpm is climbing rapidly as the converter couples and the slip % drops. Mine goes under 5%

Looks like it might be about 100-200 rpm low for your combo to be honest assuming the parts i see in the sig. 3800 will kill the performance. You should be able to rev to 5800 and still make power with those parts. I had a tiny 212 hydraulic roller in one that pulled to 5800 and the converter flashed to about 5200 at 28+psi. The engine turned out to be one of the quickest and fastest stock bottom ends ever. The converter made a huge difference. Slip was only about 3% at 134mph in 3rd. Another nice thing about the converter when dialing in a car with fuel maps is that you dont have to waste many cells below the flash rpm unless they are being used for drivability. You can use them where the engine is spending most of its time.

Looks to me like you have the same problem Chris. 2nd to 3rd blended together. No rpm drop. I bet my log will look alot like this. I don't like it.

Hydraulic roller here. I'm not seeing a rpm problem. Just have not pushed that far. I'll get a good log today and we'll take it from there.

Thanks bison, I appreciate your input. Here is the problem IMO, My car makes a ton of power between 4000-5000 rpm. If the converter is not coupled hard to the trans at that point, It just dumping the power off as heat.

Not entirely true.

Below the point where the converter 'couples' part of the 'slippage' is generating torque multiplication.

The only way to know the true efficiency is with a torque converter dyno.

Thanks for chiming in Bob. So what do you think of Chris's log?

if you look at the RPM trace you will see a point where it stops being a flatline and starts to climb again. This is the coupling point where the stator sprag uncouples and you are no longer multiplying torque. Below this point, the torque coming out of the converter is higher than the torque going in. Slippage above this point is true efficiency.

The coupling point RPM changes with the square root of applied torque. If you increase boost and raise your torque 10%, your coupling RPM will go up 4.9% (1.0488 is the square root of 1.1).

You must shift above this RPM, and the RPMs will drop back to about this point.

The converter looks like its doing its job to me.

Bob