Mike TexaSS

iTrader: (2)

Ok i have some questions about stalls. Right now in my Impala SS i have a 3600 Vigilante stall. On motor it flashes to about 4400. On the gas it flashes to about 4800-5000 rpms. This converter is very loose. If i switched to a Yank (dont know which one) 4000 rpm stall with no flash will it make my car faster?

Patrick G

iTrader: (14)

Typically, you want your stall speed to be about 400-500 rpms below peak torque of your motor. If your motor makes peak torque at 4500 rpms, you would go faster with a 4000-4100 stall converter. If your motor makes peak torque at 5000 rpms, you would want a 4500-4600 stall.

When your converter stalls above your torque peak, you often lose valuable torque multiplication and efficiency. Basically, the motor is driving through the converter. Yank is a small company, but they are very very good at custom tailoring converters for your specific application. Stall speed is just one of the parameters. Shift extension, stall torque ratio and converter clutch engagement are also very important features you'll want to take full benefit of.

Mike TexaSS

iTrader: (2)

So with a 409 on gas. My tourqe curve shoud be way below 4400 right?

Patrick G

iTrader: (14)

I would expect so, but if you have a huge cam, it still may be higher (but doubtful).

Your large motor with a big shot of nitrous is probably a good candidate for a larger 258mm converter. This would have more holding capacity when running on the juice. Something to consider.

Stu

The weight of that beast is gonna affect your stall speed also. I had a Vig 3600 in my 3600 lb Z and it only flashed to 4000.

Stu

Dom

iTrader: (2)

Yeah, heavy cars flash higher.

F8L Z71

Question.

I currently have a PT-4400 and I am cutting crappy 60's in the high 1.5s or worse lately.

I used to have some defective ARE S2 heads and a 226/234-.554/.575-112 cam. I was making peak TQ right around 4400rpm but it was hard to tell if I could have had more down lower because of the damned high stall on the converter.Now on this combo I would say that I might have been better off with a 4000 stall or so right?

Right now I am doing a combo with GTP S2+ heads (319cfm inatke, 220exhaust @.575) and the Piglet cam 223/.591/112. This setup is supposed to make power pretty high up in the rpm range, peak power being in the 6400rpm area? Will I need to change converters, or should I say, after I dyno, how will I know if I needed a smaller converter if I can't acurately read anything below 4400rpm because thats where my stall flashes to?

I am thinking of having my TC redone to a PT-4000 since that would help out on nitrous too.

Did I confuse the hell out of ya?

<small>[ October 31, 2002, 11:05 AM: Message edited by: F8LPONY ]</small>

Patrick G

iTrader: (14)

F8LPONY,

I would keep the converter a PT4400 if you want the best 60' times, but if you plan on running the jug, a reduction in stall to a PT4000 will help you out.

F8L Z71

Cool, thx Patrick. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

ToplessTexan

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by F8LPONY:
<strong> how will I know if I needed a smaller converter if I can't acurately read anything below 4400rpm because thats where my stall flashes to?</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">How about pulling with it locked up?

Kevin Winstead

Mike Texass,
You could send your Vig back to Precision and have it restalled. I recommend a #6 impeller (like the Vig3200). That would make the converter more driveable and more efficient on the big end.
Kevin