blue11 Posted May 23, 2011 Report Share Posted May 23, 2011 How much does the stall rate on a turbo 350 torque converter come into play on a 3400# big body car. What stall should I be running? Link to comment Share on other sites More sharing options...
abrungot Posted May 23, 2011 Report Share Posted May 23, 2011 I run a stock converter with no issues.. Just make sure you get a SFI FlexPlate & use Locktite. Link to comment Share on other sites More sharing options...
jwmbishop Posted May 23, 2011 Report Share Posted May 23, 2011 Rule of thumbs are: Stall should be about 300-500 rpm higher than the no load rpm at which your cam makes 16-18" vacc. and stall should be equal to the rpm difference in the 1-2 shift (for drag racing). Of course rule of thumb are basically just the starting point for tuning.n a cicle racer there is nothing to use as you are going from 3K range to 6k range and back - idle quality and shift points are fairly irrelevant. For example my 383 pulls 12"@850, 16"@1200 and 18"@1350. Stall converter is 1500 - a little on the low side but 1800 was the next stall and I did not want that high because it would shock the drivetrain when putting the hammer down with a load (this is in my tow veh). To smooth the idle and maintain power brake I have to set it at 950 (13") - a stock stall would be trying to go at the red light. But boy does that bad boy sound sweet loping at 850! Of course then I also run out of brakes as soon as the engine hits idle Not good for towing! Word of warning: the higher the stall the more elongation deflection the converter will see (gets thicker under sudden high loads - like launching or hard shifts - the main reason for having flex in the coupling). I just learned this one last summer the hard way (with the help of TCI technicians) when I destroyed a .14 thick (supposedly heavy duty) Scat flex plate on just the first tow (9,000 lbs total weight and a mere 415 bhp\430 ft lbs torque)! Spider cracks at every bolt hole and the center ripped completely out. TCI late one piece seal HD plates are .18, most HD's are .14-.15 and stock truck is .13 stock pass is .12. The Scat SFI heavy is .14! Link to comment Share on other sites More sharing options...
abrungot Posted May 23, 2011 Report Share Posted May 23, 2011 Yeah what he said... I run a stock converter (11"), SFI FlexPlate & use Locktite, with no issues.. Link to comment Share on other sites More sharing options...
F5RACING Posted May 23, 2011 Report Share Posted May 23, 2011 Nogalitos gear recommended a stock converter out of a oldmobile. It supposedley had more stahl which according to them was what you need at higher rpms. I think that is the svery simple way compared to jwbishop's response. If this is not correct maybe jwbishop can put it in simpler wording. Link to comment Share on other sites More sharing options...
blue11 Posted May 23, 2011 Author Report Share Posted May 23, 2011 Yeah what he said... I run a stock converter (11"), SFI FlexPlate & use Locktite, with no issues.. Stock is a relative term Aaron. Every time I go to the parts store its a guessing game as to the year parts I need. I was just wondering if a higher or lower stall had any advantage in circle track. If I understand at the rpms we run the stall really dos'nt matter much. Link to comment Share on other sites More sharing options...
Hansen99 Posted May 24, 2011 Report Share Posted May 24, 2011 LOL put the one you had back in just clean it back up yeah yeah yeah lots of loc tite stock thats the word lets go we need to put a bounty on that dam TBS lol grrr man the torpedoes Link to comment Share on other sites More sharing options...
abrungot Posted May 24, 2011 Report Share Posted May 24, 2011 Bobby.. what are you talking about.. i haven't won a race in nearly a year~! LOL put the one you had back in just clean it back up yeah yeah yeah lots of loc tite stock thats the word lets go we need to put a bounty on that dam TBS lol grrr man the torpedoes Link to comment Share on other sites More sharing options...
jwmbishop Posted May 24, 2011 Report Share Posted May 24, 2011 Stall also equates to "slip". For example a 1500 stall the engine would have to be running 1500 RPM higher than it would with 0 stall to be fully engaged. For example when driving look at your tach - while accelerating as you pass 30 mph say your tach says 3000 - yet while cruising at 30 (no throttle load) tach says 2150 (in same gear) - the difference is a direct result of stall speed (does not quite split in half)! So why would one want a higher stall on a circle racer? Simple - with a stick there is no difference from accel, cruise, and decel when measuring RPM vs MPH (unless the clutch is slipping). This can be harder to drive correctly as the transition from accel to decel, and from decel to accel (you are never cruising right - the apex should only be a point of transition from decel to accel - the shorter that point the faster you are) can be harsh and it takes practice, patience and a ton of driver discipline to modulate this. With an auto trans you can be smoother without regard to what your right foot is doing! increasing stall rate smooths you out more - much like shocks smooth out the the transition by spreading weight transfer over more time (rate of transfer)! This my friends is legal traction control! Yes the BPO converter is slightly higher in stall (mainly because the olds sedans are A heavier and B have less power - so higher stall gets you into the power band sooner), and yes a higher stall is easier to drive at higher RPM (lift out of throttle at 3K is softer than lift out at 6K - so it only makes sense that to smooth the lift out at 6 one would increase the stall) Link to comment Share on other sites More sharing options...
thumper Posted May 24, 2011 Report Share Posted May 24, 2011 This is why most vehicles now have a lock up converter at crusing speeds.It removes the converter slip and acts like another gear. Link to comment Share on other sites More sharing options...
F5RACING Posted May 24, 2011 Report Share Posted May 24, 2011 Stall also equates to "slip". For example a 1500 stall the engine would have to be running 1500 RPM higher than it would with 0 stall to be fully engaged. For example when driving look at your tach - while accelerating as you pass 30 mph say your tach says 3000 - yet while cruising at 30 (no throttle load) tach says 2150 (in same gear) - the difference is a direct result of stall speed (does not quite split in half)! So why would one want a higher stall on a circle racer? Simple - with a stick there is no difference from accel, cruise, and decel when measuring RPM vs MPH (unless the clutch is slipping). This can be harder to drive correctly as the transition from accel to decel, and from decel to accel (you are never cruising right - the apex should only be a point of transition from decel to accel - the shorter that point the faster you are) can be harsh and it takes practice, patience and a ton of driver discipline to modulate this. With an auto trans you can be smoother without regard to what your right foot is doing! increasing stall rate smooths you out more - much like shocks smooth out the the transition by spreading weight transfer over more time (rate of transfer)! This my friends is legal traction control! Yes the BPO converter is slightly higher in stall (mainly because the olds sedans are A heavier and B have less power - so higher stall gets you into the power band sooner), and yes a higher stall is easier to drive at higher RPM (lift out of throttle at 3K is softer than lift out at 6K - so it only makes sense that to smooth the lift out at 6 one would increase the stall) Thank you for explaining. That definitely helped me understand. Now if I could just keep the tranny from burning up, Id be ok. I heard something on here a bout a flow problem on the 350's in first gear. Is this true and could it be why Im burning them up. I have checked lines and coolers for blockage and have none, but cooler is mounted on rol;e cage by rt shoulder. I am moving it to front by radiator. It is a 6x10 at fins. Is this large enough. I also have a 18x20, but that is too large to mount in front without too much work. Thx. Link to comment Share on other sites More sharing options...
JohnnyT66 Posted May 24, 2011 Report Share Posted May 24, 2011 Gotta disagree about wanting slip on a circle car....Aftermarket circle racing converter are tighter so as there is no slip coming out of the hole...If rules allowed it, you would see transmissions like i stocks run,DIRECT DRIVE....Most look at a stall on a heavy circle car of about 2800 to 3200 rpm....Now on a drag car, we ran a stall of 5200, but its a different world.....Frank Torres...... Link to comment Share on other sites More sharing options...
thumper Posted May 24, 2011 Report Share Posted May 24, 2011 I wonder if its possible to enguage the lock up clutch with a switch once your underway on a roundy round car.That would also help it run cooler while providing the same as a direct drive would do.My concern is if the lock up clutch is strong enough.What do you think? Link to comment Share on other sites More sharing options...
JohnnyT66 Posted May 24, 2011 Report Share Posted May 24, 2011 I always wanted to try the 700r and try that.....Just never did...frank t Link to comment Share on other sites More sharing options...
jwmbishop Posted May 24, 2011 Report Share Posted May 24, 2011 I want the driver to have the control and learn to modulate it as well. The best driver does not just slam the throttle shut and slam it back open. Unfortunately not all find that fine line or have access to (or openess in reciept of) good coaching. Which is why not all go on to Cup careers either. Don't get me wrong - not meant to be insulting to anyone in anyway - tis just the way it is. I know for me after just a couple attempts -I decided screw it I'll just stay outta the drivers seat so as not to make more enemies than friends (I am not very level headed when the paint starts swapping and quite ashamed at the first response that came to mind when someone touched me)! I would make a good demo derby driver! The only autos I ever ran were Renegades - powerglides with direct connects, bypass valve and no second gear at all - not just for this reason though. With higher stall speed and the subsequent slip comes increased risk for accidental over revs during the transition period! If you increase your stall speed 500 - you just increased your rpm 500 to make the same mph! And I (as well as my drivers) always seemed to like running em on the bleeding edge rather than the cutting edge. But its a personal preference thing. Playing with stall is a band aid not a cure - much like using crossweight, static camber or static caster (or even rear axle steer) is as opposed to getting the roll ctr working for you and letting your statics be as minimal and straight rolling as possible. But band aids do work when one can determine when and how to apply them! Seems to me the lockup would work also - yes a toggle does the trick, there are many articles available on how to setup a lockup in a street rod with a toggle. Downside would be the el trannys are not as economical. In order to get the strength of the 350 internals one has to spend close to 3 times as much! As to burning up - can't help much other than to offer up the basics. Lots of flow, correct fluid (high friction fluids like trick shift do run hotter), change fluid often and lots of surface area on a high efficiency cooler etc. Link to comment Share on other sites More sharing options...
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