What stall speed for PT?? - Lateral-g Forums

deuce_454 · #1 03-06-2008, 03:50 AM

I am installing an LS1 in my 79 malibu.. the engine is recieving a head/cam package in the form fo a set of patriot CNC ported stage 2.5 5.3L heads and a tourquey cam (224/228 110LS) ive asked the question on ls1tech and they all recomend 3600-4000 rpm stall.. but while that might be great for dragracing doesnt that get OLD quick in a street/pt car??

im considering a yank3200 converter but i still think it might be a bit on the high side??? what to do??

**Steve Chryssos** · #2 03-06-2008, 06:00 AM

Need...
Final drive ratio:
Rear Tire Dia:
Vehicle weight:
Trans Type: 4L60E?
Min cruise RPM:
Max RPM:
Throttle Body size:
Cam Lift:
Will you dyno the engine?
Computer Type (can you adjust lock up control?):

**Steve Chryssos** · #3 03-06-2008, 06:02 AM

Copenhagen altitude is at se level, yes?

deuce_454 · #4 03-06-2008, 06:24 AM

Final drive ratio: 3.5 or 3.73... advice.. again its a PT car
Rear Tire Dia: 27 inches
Vehicle weight: 3450 wet with driver
Trans Type: 4L60E? yep!
Min cruise RPM: 2200
Max RPM: ?? 6500
Throttle Body size: 78mm stock 2002, (=ls6 IM)
Cam Lift:.580
Will you dyno the engine?.. yep
Computer Type (can you adjust lock up control?): stock 2002.. will have manual override switch
Will install a TCI controller and a shrifter eventually!!
oh yeah.. no road in denmark above 350 ft above sealevel... copenhagen is aprox 20-30 feet in elevation

**Steve Chryssos** · #5 03-06-2008, 09:09 AM

3.50 or 3.73 won't matter much on an FI LS motor with regards to throttle response. Given that it's a 27" tire, I would go 60/40 in favor of the 3.73's.

Will you be drag racing this car at all? If you will only take the car to the drag strip once in its life, I would disregard maximum drag strip performance in favor of part throttle acceleration. Powering out of a corner at part throttle is way more important. To that end, I would suggest a 9.5" 2600 stall converter. Throttle response will be awesome--even at 2000rpm. That's particularly important because at 45 mph with the car in overdrive, you don't want the car to feel soggy. If you feel I am being too conservative, go ahead and choose a 2800 stall converter and be sure to run the 3.73 gears. 3000 is pushing it. There are many circumstances where a pro-touring car needs to work right at 2500-3000 rpm--especially if you choose a 3.50 gear. Also be sure to specify that you will be manually locking up the converter and therefore insist on a heavy duty lock up clutch.

I can build you exactly what you need. Price for this particular MuscleDrive converter is $759.00 including a billet front cover, anti-balloon plate, torrington bearings, machine welding, furnace brazed fins, big ass lock up clutch, and 3 year warranty.

deuce_454 · #6 03-06-2008, 10:11 AM

I knew it... there had to be some reason for my gut feeling that 4000 or 3600 rpm stall wasnt great for a DD, would there be a wisdome in getting a 2800 stall for the occational (often) stoplight dash.. and then programming the transmission to stay in lockup whenever its in "manual" mode and the paddles are being used to shift??

i just think of my step dads old 325 bmw that would bog at a stoplight and only really take off halfway accross the intersection once the rpm's got up in a range where that straightbanger actually made any power!!

but ill definately give you a call and well spec the converter.. thanx a million for the reply

**Steve Chryssos** · #7 03-06-2008, 11:34 AM

Quote:

Originally Posted by deuce_454

....would there be a wisdome in getting a 2800 stall for the occational (often) stoplight dash.. and then programming the transmission to stay in lockup whenever its in "manual" mode and the paddles are being used to shift??

Not exactly. You only want the lock up to engage above stall speed, so you must work the math backwards to determine how stall speed rpm relates to vehicle speed. For example, my 2500 stall 9.5" converter is set to lock up at 45 miles per hour. Lock it up at 30mph (under 2200 rpm) for example, and the drivetrain overloads the engine (which in my case is carbureted). 2600 or 2800 won't matter much for stoplight dashes. It is more important that--when you are hauling ass on a road course or auto-cross, that stall rpm be exceeded and lock up be available. In this environment, you are employing lower gear selection and therefore higher rpm. You might be in second or third gear. You might be pulling 3200 rpm or more at 60 mph whereas, on the highway, you would only be pulling 2200-2400rpm in top gear at very light load. It is under these higher rpm circumstances that you want torque converter stall to be over and done with.

Imagine that same road course scenario with a 3600-4000 stall converter. It would be the equivalent of riding a clutch pedal while trying to power out of a corner. And that high stall converter will generate excessive heat. There are many companies building awesome converters--Yank is one of the best by far. But none are considering the above "pro-touring" scenario on a daily basis. Drag Race-Drag Race-Drag Race. They have blinders on. Call up the average tech guy and he will think you are nuts.

deuce_454 · #8 03-06-2008, 11:48 AM

ok im sold! ill call in a week...

**Steve Chryssos** · #9 03-06-2008, 12:34 PM

Cool. When you're ready, send me an email so that I can reply with a detailed list of questions regarding vehicle specifications.
Thanks
/Steve

tyoneal · #10 03-07-2008, 12:27 AM

Quote:

Originally Posted by streetfytr68

Cool. When you're ready, send me an email so that I can reply with a detailed list of questions regarding vehicle specifications.
Thanks
/Steve

==============================
Steve:

Have you ever dealt in any, "Switch Pitch", converters?

Those would seem to be the ultimate for street/strip applications. I had been told that they discontinued them back in the 60's because of the expense. Since people are building these, "Not so cheap", cars, it seems like the Switch Pitch would be a viable Technology.

What are your thoughts?

Best Regards,

Ty