There are some people who do and think its fine and others that would want a higher stall speed. This is why we recommend 2.5 for stock converter guys just to be safe. It depends on you and your driving habits and where you live
gptunning stage 3 on stock converter?
Anyone running gptunning stage 3 on stock converter?
How do you like it, and should I just put a converter in it before I finish putting it All back together?
How do you like it, and should I just put a converter in it before I finish putting it All back together?
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One of my customers i was talking with recently had told me there is a chance of burning up the trans pump by running to small of a stall. This info made me rethink rather or not if I should get a higher stall converter now before I put it all back togetherThere are some people who do and think its fine and others that would want a higher stall speed. This is why we recommend 2.5 for stock converter guys just to be safe. It depends on you and your driving habits and where you live
I dont think there is any concern besides some idle and drivability annoyance that as I said bothers some more then others.
What is the drivability of stock vs having a stall beside the pushing through the brakes.I dont think there is any concern besides some idle and drivability annoyance that as I said bothers some more then others.
Stock stall will have no power till a certain power range?
High stall will the tires break loose easily?
Doesnt need a high stall just higher then stock. Id say try it with the stock converter first. There are many that run it that way.
Fwiw- I’m running a 3000 stall Circle D with an equivalent cam. Should have the car back on the road tomorrow and will let you know.
Sweet yea let me know!Fwiw- I’m running a 3000 stall Circle D with an equivalent cam. Should have the car back on the road tomorrow and will let you know.
How is it so farFwiw- I’m running a 3000 stall Circle D with an equivalent cam. Should have the car back on the road tomorrow and will let you know.
Well the shop got the push rod / lifter preload wrong on 3 holes, so misfired. Should have it sorted by Wednesday. More to come…
BTW- I’m running the 1.8 rocker for gross lift of .675”. 236/249 duration
BTW- I’m running the 1.8 rocker for gross lift of .675”. 236/249 duration
I wouldn’t call that an equivalent cam since the lobes, duration, lift at both lobe and valve, LSA etc are all different then the OP.Well the shop got the push rod / lifter preload wrong on 3 holes, so misfired. Should have it sorted by Wednesday. More to come…
BTW- I’m running the 1.8 rocker for gross lift of .675”. 236/249 duration
Regardless of that a 3000 stall speed in 245-265mm will cover it but how it drives has other factors depending on converter options. You do not have to have a loose driving converter to allow a reasonable idle rpm for cams a little larger then what a stock converter works best with. Power still comes in at low rpm so you don't need to setup it up like you would with an NA build or Centrifugal blower.
Just a bit of info which might help you, or others.Well the shop got the push rod / lifter preload wrong on 3 holes, so misfired. Should have it sorted by Wednesday. More to come…
BTW- I’m running the 1.8 rocker for gross lift of .675”. 236/249 duration
Don't know what heads you have, but. . .
The LS3 Heads don't flow well (wet flow) after a net lift @ the valve, of much more than convergence lift. After convergence lift the mass charge (fuel & air / wet flow) tends to shift to the wrong side of the port. This is why some use a vein, or wing in the intake bowl, which compensates for this.
If the valve is 2.165", then convergence lift will be (2.165 * 0.25)= 0.541".
So the targeted net valve lift should be ~0.541".
Net valve lift is different from gross valve lift.
Here is how I and others approach this.
Multiply the gross lift by 0.87.
Your gross valve lift is specified at 0.675".
=> (0.675 * 0.87)= 0.587"
If the engine does not perform as you expect, and you cannot get the tune you desire, ditch the 1.8:1 rocker arms for the 1.7:1 rockers, and see what happens.
=> 0.675 / 1.8)= 0.375 lobe lift. <= That's a good number for this engine.
=> ((0.375 * 1.7)= 0.638 * 0.87)= 0.555"
Good Luck..
Here you go, copied this just for you..lolWhat is the drivability of stock vs having a stall beside the pushing through the brakes.
Stock stall will have no power till a certain power range?
High stall will the tires break loose easily?
Flash stall refers to the amount of rpm observed when you initially hit the throttle with the vehicle under load, the opposite of sitting up against the converter while matting the foot brake during the brake stall test. This initial hard acceleration can cause the converter to flash at an rpm higher than its brake stall speed.
---------------------------------------------
It's a bit confusing, but the paragraph above pretty much describes the term 'Stall'.
With a Trans-Brake and a Glide, your pretty much just dealing with what I call 'Flash Stall' at peak torque. This eliminates the issue of stall associated with the brake pedal.
Dang I'm about to measure mine 😬Well the shop got the push rod / lifter preload wrong on 3 holes, so misfired. Should have it sorted by Wednesday. More to come…
BTW- I’m running the 1.8 rocker for gross lift of .675”. 236/249 duration
Did it mess anything up
So the brake stall will act like normal. But the car won't move until the higher flash stall has been reached? Causing a delayed take of in part throttle driving?Here you go, copied this just for you..lol
Flash stall refers to the amount of rpm observed when you initially hit the throttle with the vehicle under load, the opposite of sitting up against the converter while matting the foot brake during the brake stall test. This initial hard acceleration can cause the converter to flash at an rpm higher than its brake stall speed.
---------------------------------------------
It's a bit confusing, but the paragraph above pretty much describes the term 'Stall'.
With a Trans-Brake and a Glide, your pretty much just dealing with what I call 'Flash Stall' at peak torque. This eliminates the issue of stall associated with the brake pedal.
The converters for these cars are much tighter then something for a 3 or 4 speed. If you flash ot it will jump up in rpm but normal driving is close to stockSo the brake stall will act like normal. But the car won't move until the higher flash stall has been reached? Causing a delayed take of in part throttle driving?
Don't buy a converter based on stall speed. Brake Stall/ Flash stall etc are not predictable and are best guesses. In the days of 8" vega converters it was the best guestimation you could get, but the "science" of converters has improved and there are other more desirable characteristics at play. You could change pulley ratios in your car or add or take away timing and change the "stall rpm", but the converter would still drive the same. In turbo cars the converter can stall higher and higher depending on what boost (torque) you put to it.
Call the manufacturer or whatever shop you are buying from and tell them what you have and let them spec what you need. You could get three different sized cores and all can have the same "stall speed", but all drive differently.
Call the manufacturer or whatever shop you are buying from and tell them what you have and let them spec what you need. You could get three different sized cores and all can have the same "stall speed", but all drive differently.
Nope, don’t think so. I personally think they can adjust preload a little better. I think they were trying to keep it at exactly.030” ( no plus or minus)Dang I'm about to measure mine 😬
Did it mess anything up
Brake stall rpm, is quite different than peak torque flash.
MeanMike is correct, but in reality the only way to accurately set converter flash for a car using a Trans-Brake', was to first dyno the engine and note peak torque, as well as peak torque engine rpm. Then you put the converter on a 'Transmission / Converter Dyno' and build out the converter until you get what you desire.
We used to carry several different converters in our trailer for different tracks. For different tracks at different altitudes, or even for adjusted altitudes at the same track. Headed down the track you never want the transmission to shift below peak torque. You always want the engine operating above peak torque.
-except when leaving the starting line-
This is what a 'Slipper Clutch' provides for when leaving the starting line. In order to not spin the tire too much the clutch slips. You launch the car below peak torque, get the car up on the tire, and then the engine rpm moves past peak torque. Usually this is done without the driveshaft engine rpm moving more than about 1500 rpm.
Now to kind of finish this off; the entire chassis, particularly the shocks and 4-Link must react to the clutch or converter locking up, particularly on the starting line.
Small tire cars need much more of an instant chassis hit / shock, then do the higher powered cars, which are allowed to use a larger tire.
The small tire cars tend to not use wheel speed to get the car up on the tire. The higher powered cars using a larger tire like to generate some wheel speed before the car gets up on the tire.
Frankly there are not many secrets in drag racing. Most use many of the same parts. But the 'Combinations' run by the winners, tend to be just a little more sophisticated, than the losers..lol
Cheers
MeanMike is correct, but in reality the only way to accurately set converter flash for a car using a Trans-Brake', was to first dyno the engine and note peak torque, as well as peak torque engine rpm. Then you put the converter on a 'Transmission / Converter Dyno' and build out the converter until you get what you desire.
We used to carry several different converters in our trailer for different tracks. For different tracks at different altitudes, or even for adjusted altitudes at the same track. Headed down the track you never want the transmission to shift below peak torque. You always want the engine operating above peak torque.
-except when leaving the starting line-
This is what a 'Slipper Clutch' provides for when leaving the starting line. In order to not spin the tire too much the clutch slips. You launch the car below peak torque, get the car up on the tire, and then the engine rpm moves past peak torque. Usually this is done without the driveshaft engine rpm moving more than about 1500 rpm.
Now to kind of finish this off; the entire chassis, particularly the shocks and 4-Link must react to the clutch or converter locking up, particularly on the starting line.
Small tire cars need much more of an instant chassis hit / shock, then do the higher powered cars, which are allowed to use a larger tire.
The small tire cars tend to not use wheel speed to get the car up on the tire. The higher powered cars using a larger tire like to generate some wheel speed before the car gets up on the tire.
Frankly there are not many secrets in drag racing. Most use many of the same parts. But the 'Combinations' run by the winners, tend to be just a little more sophisticated, than the losers..lol
Cheers
My bad. I was under the impression OP was looking at cams that put you in the 700+ range. Looking back I do have a totally different set up-way more lift and duration. Circle D built the trans and recommended, along with Mamo not to go more that 3000 stall. Just slightly more than stock which is ~2000 because it will idle a little higher than stock.I wouldn’t call that an equivalent cam since the lobes, duration, lift at both lobe and valve, LSA etc are all different then the OP.
Regardless of that a 3000 stall speed in 245-265mm will cover it but how it drives has other factors depending on converter options. You do not have to have a loose driving converter to allow a reasonable idle rpm for cams a little larger then what a stock converter works best with. Power still comes in at low rpm so you don't need to setup it up like you would with an NA build or Centrifugal blower.
1 - 20 of 29 Posts
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