selecting a torque converter stall speed



selecting a torque converter stall speed

Postby grumpyvette » May 21st, 2009, 9:55 am

reading thru the links will provide you with a good basic understanding on torque converters, the basic object of swapping to a higher stall converter speed is to allow the engine to spend a good deal more time in its most efficient power range without needing to build rpms slowly up in the lower engine speed ranges where there's a good deal less usable power available, IF your thinking of swapping to a higher stall converter,you should be able to answer the questions, listed below as it will be to your advantage to do so, by simply asking yourself ...those questions, but be aware your transmission gear ratios and rear gear ratio effect the correct choice in converter stall speed.one of the most common myths about high stall torque converters , is that the car won,t move under part throttle until near the rated stall speed is reached by the engine, think about that a second, then think about how your current car reacts to part throttle and realize your stock converters stall speed is probably 600-700rpm higher that the rpm that effectively moves your car at part throttle.
the first thing youll want to do is test your current converters stall speed and find out what your currently dealing with, so you have a few facts and a start point!
if YOUR NOT SURE DO YOURSELF A FAVOR AND CALL AT LEAST 5 DIFFERENT HIGH PERFORMANCE CONVERTER MANUFACTURERS AND ASK FOR RECOMMENDATIONS BASED ON YOUR COMBO, that way your bound to at least pick up some basic info and ideas.


READ THIS RELATED THREAD

viewtopic.php?f=71&t=741

BTW IF you have a dyno graph of your cars engine power curve selecting the correct matching stall speed is much easier

(1) was the current converter stall speed performing well?
(any problems or things you did not like) and at what rpm do you normally cruise in top gear?)

(2) what if anythings changed that makes you suspect a higher stall will improve things?
(if you floor the throttle from an idle in gear is there a significant time lag before your car accelerates, hard? does the car bog down if you floor the throttle at idle or does the car accelerate rapidly?)

(3) whats your current engine power curve?
(where does the engine start to really come alive, and start pulling hard, in the rpm band., at what rpm does power start to rapidly drop off?)

(4) whats your rear gear ratio?, whats your tire diameter? youll spend much less time in each transmission gear range with a 4.11:1 rear gear than a 2.87:1 rear gear so thats an important factor?

(5)are you planing mod mods that make you suspect you'll require a higher stall speed, are you planing on installing larger diameter tires? a longer duration cam?

(6) do you have an auxiliary transmission cooler installed and whats your normal trans fluid temp range?

(7) have you called at LEAST 4 different converter manufacturers and ask for their input? suggestions?


before buying any converter discuss the combo with the converters manufacturer, AND YOUR CAMS MANUFACTURER and ask for their input & suggestions

Precision Industries wrote:The formula for STR is EXACT OUTPUT TORQUE ÷ EXACT INPUT TORQUE = STR.

This requires a known power source and a data recovery system. STR is just what the name implies. The ratio of torque multiplication at stall. As soon as the turbine rotates (car moves) the ratio starts dropping rapidly until enough RPM has been reached for the ratio to drop to 1:1. The RPM that the ratio reaches 1:1 varies depending on other factors in and out of the torque converter such as impeller exit angle, stator design, impeller to turbine clearance, input torque (engine), etc.the stock torque converter you took out of your car has a STR of 1.9-1.94. In our tests we have never seen an STR over 2.55.
http://converter.com/truth.htm



read the linked info below or you'll miss a good deal of useful information

Image

viewtopic.php?f=71&t=2400&p=19038&hilit=converter+mounting#p19038

Image

Image
OEM flex plates are far thinner and more flexible than the SFI certified flex-plates , so they are far more likely to crack and split over time
instructions

http://www.autoshop101.com/forms/AT02.pdf
1

Examine your car's engine specifications (get the cars engine dyno tested or at leash have a good idea of the engines power curve,) or take it to a shop with a chassis dynamometer to have it measured. Note the engine's peak torque and the rpm that it occurs at youll want the stall speed to be just a bit lower on a street car to increase drive-ability and just a bit higher than peak torque on a race application to maximize useful power.
remember your converter slips a good deal more and produces a good deal more heat in the trans fluid below the stall speed, so you don,t want the engine spending a great deal of time below the stall speed in its intended application.
consult with at least three different converter manufacturers, about the best converter stall speed for your particular application, before making a choice and ask LOTS OF questions
2

Add about 15 percent to your engine's peak torque figure if you used a chassis dyno instead of factory horsepower ratings, and your looking at a race application,. The engine, transmission and wheel require a certain amount of horsepower to turn, meaning that such "wheel horsepower" will register lower than the flywheel horsepower you need.
keep in mind your car will be able to drive and move well below the cars stall speed with a high stall converter but your converter slips a good deal more and produces a good deal more heat in the trans fluid below the stall speed, so you don,t want the engine spending a great deal of time driving the car below the stall speed in its intended application, and adding a trans cooler with a higher stall converter is just about mandatory

viewtopic.php?f=57&t=176&p=3652#p3652

viewtopic.php?f=71&t=662&p=12989&hilit=trans+cooler#p12989

3

Order a torque converter that matches your engine's peak torque output and peak torque rpm as closely as possible. If you can't find one that matches it precisely, error on the side of caution by choosing one with a slightly lower stall or higher torque rating . You'll lose a little performance with a stall that's too low, but you'll lose performance, fuel economy and drive-ability with one that's too high.



EXAMPLE, HERES MY CORVETTES POWER CURVE

viewtopic.php?f=32&t=430

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it should be obvious why a 3000rpm-3200 stall converter stall speed was selected to maximize the power curves and why the ignition rev limiter is set at 6300 rpm
Image

Image

http://www.highperformancepontiac.com/tech/hppp_0805_precision_vigilante_torque_converter_install/index.html

READ THE SUB LINKS, they contain a wealth of additional info

http://www.superchevy.com/how-to/transm ... selection/

http://www.carcraft.com/techarticles/se ... index.html

http://www.chevyhiperformance.com/techa ... index.html

http://www.chevyhiperformance.com/tech/ ... index.html

viewtopic.php?f=71&t=2400

http://www.protorque.com/FAQ.html#6

http://www.protorque.com/techi/ti_faq.htm

viewtopic.php?f=71&t=741

viewtopic.php?f=71&t=435

viewtopic.php?f=71&t=386

viewtopic.php?f=71&t=435&p=1910#p1910
"
STALL SPEED
Torque converter stall is a commonly used term and is commonly misunderstood. Stall is the speed at which the converter will hold the engine speed and not allow further gain (i.e., the engine "stalls"). The key word here is engine. The speed at which stall occurs with a given converter is a function of engine peak torque. It is clear that the stall speed on a given converter will not be the same coupled to a tame small block engine when compared to a big block with all of the muscle features added. When comparing stall speeds it is important to account for the engine that drives it. True converter stall can best be determined when a Transbrake is used. Testing for stall value by locking the wheel brakes generally does not produce a true stall value because the engine power can often cause wheel turn by overpowering the brakes. Stall speed determined by this method should be identified as such when discussing stall speed determination. Flash stall is determined by launching at full throttle and observing the peak speed attained at launch. Selection of the right stall speed for your vehicle should be matched to the engine peak torque, engine torque curve shape and vehicle weight. In general, the stall speed selected for your converter would be 500 to 700 rpm below the peak torque. This speed allows the margin for application of the torque reserve on takeoff. When selecting stall speed without having prior experience to go by, it is better to conservatively estimate the engine torque than it is to over estimate it. If you over estimate the torque output you will have a converter with a stall speed too low, making your car slow off the line and have slow ET. A properly selected stall speed will give you better launch and better ET. You can see why it is important to consult with professionals prior to making a stall speed selection. Within the converter, stall speed is balanced off against inefficiency after launch. Getting desired stall at the expense of performance after launch is just as costly as improper stall speed to begin. The optimum converter has careful selection and design of changes to the impeller, turbine and stator.
"HOW CAN I DETERMINE THE STALL SPEED OF MY CONVERTER?
Stall speed is very difficult to determine unless your car is equipped with a Transbrake to lock your drive train. Testing stall speed by holding the wheel brakes and running the engine against the locked brakes will usually result in wheel rotation before true stall speed is reached. The engine simply overpowers the ability of the brakes to hold the car. When rotation starts you are no longer at stall. For this reason people talk about brake stall which is not a true stall at all. An alternative method of measurement is to launch at wide open throttle and observe engine RPM reached at launch. This is flash stall.
"

For most hot street cars, that weight between about 3300lbs and 3700lbs (WHICH IS MOST MUSCLE CARS) with a reasonable street/strip compromise cam in the 225-235 duration range designed to run on pump gas and having a 3.73-4.11 rear gear with tires in the 25"-28" range,a 3000-3200rpm rpm stall should be fine in a combo like you describe, I'm running a 3000stall converter in my car, theres a common mis-understanding that installing a 3000rpm stall converter means the car won,t move until you hit 3000rpm, that's a fallacy, theres a bit more slippage but it drives just fine at lower rpms at part throttle if your just cruising, but the slippage make HEAT so don,t forget to add a decent trans cooler

Image

as an example on this 500hp 350sbc above,designed for the drag strip, a 4500 stall would be almost ideal.
Image
on this 400hp 350 designed for the street a 3000rpm stalls fine, but if you installed a 5000rpm stall you'll be loosing a great deal of the engines power curve

Advertized stall speed is "indicative" or only an average result usually based on a common stock engine displacement and torque level such as with a 350hp 350 sbc
The more torque your engine produces ,the higher rpm a torque converter will stall at.
A converter will stall higher on a hot 383 or 427 sbc than on a stock 350 despite what it's rated stall speed is.

The better manufacturers have a chart telling what speed a certain converter will stall at with what torque level but even then its just an educated guess, as each converter will be a bit different from its clones.
and remember you get what you pay for,if you find a new converter costs significantly less than similar advertised converters theres a REASON
and you can bet that they left out some feature you need like anti ballooning plates of brazing the internal fins, or they used thinner/weaker components

Example
a 9" converter stall is advertized as a 3000 stall
but gives your approximately

3000rpm @ 400 ft/lb
3185rpm @ 450 ft/lb
3300rpm @ 550 ft/lb
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: selecting a torque converter stall speed

Postby grumpyvette » June 14th, 2009, 5:47 pm

For street use,
I generally try to keep the cruising rpm at or below 2800rpm at 70 mph with the trans in its 1:1 gear,
if you have an overdrive transmission, that drops it down into a comfortable rpm range when matching the rear gears to tires, diam. in that top overdrive gearing [b]BE VERY SURE to get a LOCK-UP converter for OD use that allows you to operate the engine in locked up mode with the torque converter in top overdrive gear at lower than the stall speed,in that top gear, and a EFFICIENT TRANS COOLER so your not building excessive trans fluid heat cruising on long trips, obviously having an overdrive top gear, and a lock-up converter will be a big plus on engine life
naturally you'll need to select a cam, displacement and gearing etc that will cruise efficiently at that lower rpm range if your goal is BOTH performance and the ability to cruise along at 70mph, and yes its perfectly acceptable at times to keep the car in a gear other than over drive under some conditions
for common street strip combos this might help, remember your goal is to get into the effective part of the torque curve quickly without blasting thru to the upper rpms wasting much of your combos mid rpm torque
example on most TPI combos running a nearly stock intake and heads, and a stock rear gear ratio and a cam with 220-225 duration @.050 lift a 2600-2800rpm stall is plenty, because the rest of the combo won,t support power much above about 4500rpm, add a nice set of aftermarket heads, low restriction exhaust a killer intake and a 3.73:1 rear gear and a 2600-3000rpm stall still works on the street
before buying any converter discuss the combo with the converters manufacturer, AND YOUR CAMS MANUFACTURER and ask for their input & suggestions

http://www.coanracing.com/PDFS/InstallI ... nsConv.pdf

http://www.tcsproducts.com/file_library ... verter.pdf

http://www.hardtail.com/techtips/select ... erter.html

http://www.summitracing.com/expertadvic ... d43f224310

http://www.converter.com/vigilante.htm


http://www.highperformancepontiac.com/tech/hppp_0805_precision_vigilante_torque_converter_install/index.html

http://www.dragzine.com/tech-stories/dr ... al-chance/

viewtopic.php?f=71&t=662

viewtopic.php?f=71&t=741

http://www.ls1tech.com/forums/automatic ... ation.html

viewtopic.php?f=71&t=555

viewtopic.php?f=71&t=488

viewtopic.php?f=71&t=344

viewtopic.php?f=55&t=6546&p=20829#p20829

viewtopic.php?f=71&t=2400

viewtopic.php?f=71&t=435

viewtopic.php?f=71&t=580


practice launching and get the tire pressure adjusted so you get an equally dark, full tire width patch of black rubber on the pavement,too little air pressure usually makes the outer edges darker, to much air pressure usually tends to make the center of the tire marks darker

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VIN codes on some G.M. CONVERTERS
Codes:
B=2025
C=2075 and brazed impeller
E=1654
F=1611
G=1397
H=1397 and brazed impeller
K=1211 and brazed impeller
L=1654 and brazed impeller

http://www.vinguard.org/vin.htm

http://en.wikibooks.org/wiki/Vehicle_Id ... /VIN_Codes

http://www.decodethis.com/

http://www.nastyz28.com/decode.php

http://www.goodoil4u.com/vehicle_identi ... umber.html

http://www.vehicleidentificationnumber. ... etail.html

http://clubs.hemmings.com/clubsites/che ... rn_vin.htm

http://www.ehow.com/how_4855705_read-ch ... mbers.html
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: selecting a torque converter stall speed

Postby grumpyvette » March 21st, 2010, 11:33 am

its hard to over stress the importance of matching the cars rear gear ratio and stall speed on your converter, if youve got an automatic transmission ,to your engines peak torque curve and power band. Its just as important to realize you tend to get what you pay for in stall converters and the less expensive converters tend to fail far more frequently, making them a bad value, especially if they trash your transmission during their failure process.
but remember ALL high stall converters generate a good deal more transmission fluid heat ,making use of a good aux transmission cooler with a separate electric cooling fan, almost 100% mandatory

viewtopic.php?f=57&t=176

youll notice a few brands missing, in the list below, some were simply left off,some were left off because of recent problems with service or warranty issues reported by friends, these brands generally have good reviews among my friends



http://www.edgeracingconverters.com/

http://www.protorque.com/

http://www.converter.com/

http://www.ctconverters.com/

http://www.coanracing.com/

http://www.bteracing.com/Products.asp?c ... =981919515

http://www.gmtuners.com/gmtransinfo.htm

http://www.dragzine.com/tech-stories/dr ... al-chance/

Rear-Wheel Drive Transmissions

4L60-E

* RWD 4-speed automatic with overdrive
* 159-176 lbs transmission weight filled
* Gear Ratios:
* 1st -- 3.059
* 2nd -- 1.625
* 3rd -- 1.000
* 4th -- 0.696
* Rev -- 2.294
* Max Gearbox Torque: 670 ft-lbs



4L80-E

* RWD 4-speed automatic with overdrive
* 260 lbs transmission weight filled
* Gear Ratios:
* 1st -- 2.482
* 2nd -- 1.482
* 3rd -- 1.000
* 4th -- 0.750
* Rev -- 2.077
* Max Gearbox Torque: 885 ft-lbs



5L40-E

* RWD 5-speed automatic with overdrive
* 186 lbs transmission weight filled
* Gear Ratios:
* 1st -- 3.42
* 2nd -- 2.21
* 3rd -- 1.60
* 4th -- 1.00
* 5th -- 0.75
* Rev -- 3.02
* Max Gearbox Torque: 494 ft-lbs



GM RWD Torque Converters

Starting 1980-up, GM used a 4-digit ID sticker located on the converter body to help identify it. Below is a guide to help decipher it's meaning.

1st Digit (application trans)

* B -- THM250C, THM350C
* C -- 200C, 2004R, Pre-1984 1/2: 325-4L & 700r4
* D -- 1984 1/2-up 700r4, 4L60, 4L60-E

2nd Digit (approx stall, depends on engine)

* B -- 2025 rpm
* C -- 2075 rpm
* E -- 1654 rpm
* F -- 1611 rpm
* G -- 1397 rpm
* H -- 1397 rpm
* K -- 1211 rpm
* L -- 1654 rpm

3rd Digit (Clutch Assembly)

* 3 -- Poppet Valve
* 7 -- Poppet Valve
* 9 -- Poppet Valve
* A -- Red (pre-96)
* A -- Carbon (96-up)
* B -- Static Open
* G -- Carbon Fiber
* H -- Red (pre-96)
* H -- Carbon (96-97)
* H -- Woven Graphite (98-up)
* L -- Carbon Fiber
* N -- Woven Graphite
* P -- Woven Graphite

4th Digit (Body Mounting)

* C -- 3 round lugs, gas engine
* D -- 3 round lugs, diesel engine
* E -- 6 round lugs, gas or diesel
* F -- 3 square pads, gas or diesel
* G -- 3 square pads, gas or diesel

If there is no ID tag, there might be a number or letter stamped between the dimples of the impeller on the converter body.

* 4 -- 1211 stall
* 5 -- Medium or high stall (depends on stator)
* 6 -- 1397 stall
* 7 -- 1654 stall
* C -- 2075 stall
* H -- 1397 stall
* K -- 1211 stall
* L -- 1654 stall



GM FWD Torque Converters

GM uses the same type 4-digit ID method of identifying FWD torque converters as with the RWD units, however the digits have different meanings. All 125-C, 440-T4, 4T60, and 4T60-E transmissions use the same style torque converter, and they are interchangeable before 1996. 1996-up converters are built to be compatible with GM's PWM TCC apply strategy which means that you can use the newer converter on the older trans, but not the older converter on the newer trans.

1st Digit (application trans)

* F -- 125C, 440-T4, 4T60, 4T60-E (245mm)
* J -- 4T65-E HD (258mm)

2nd Digit (approx stall (depends on engine)

* A -- 2795 rpm
* B -- 2560 rpm
* C -- 2385 rpm
* D -- 2095 rpm
* E -- 1865 rpm
* G -- 1630 rpm
* H -- 1515 rpm
* J -- 2060 rpm
* K -- 2760 rpm
* L -- 1895 rpm
* M -- 1525 rpm
* Y -- 1420 rpm
* Z -- 2375 rpm

3rd Digit (TCC clutch material)

* 0 -- Clutch omitted by factory
* 5 -- Clutch contains poppet valves

All other digits (pre 1996):

* Red Fiber material

1996-97

* C, E, H, K, P -- Carbon filled clutch

1998-up

* F, H, K, Q -- Woven graphite clutch

4th Digit (Clutch Type)

* B -- standard
* C -- viscous



Pertaining to the TCC Clutch material: starting in 1996, GM implemented a new TCC apply strategy. The 1996-97 trannys (exc 3T40), used a soft-apply (PWM) TCC strategy which was designed to soften the TCC apply so the "customer" would not feel it come on. This means that the PCM is actually making the TCC slip during apply. Only Carbon clutch torque converters should be used in 1996-97 trannys. You can use the carbon clutch TC's in earlier trannys that did not have PWM technology, however the lockup feel will not be the same. However, I have heard that these carbon clutches rarely burn-up or go bad. I have personally used the carbon filled clutch TC's on earlier trannys and the only experience I have witnessed with them is they apply firmer.

Starting in 1998, GM revised the lock-up strategy once again only this time the TCC may never completely lock up and may always slip about 20-60 rpm, depending on the vehicle. This means that even the carbon clutch units would not work well for these applications thus GM started using woven-graphite TC clutch material. I have heard that the woven graphite TC's should not be used in any earlier transmissions because the lockup will not work correctly.



This information should be used as a reference guide only.


listed stall speeds are always APPROXIMATE AT BEST, simply because the more torque the engine produces the higher the effective stall, a converter that stalls at 2600rpm on an 8:1 cpr 350 would more than likely stall at 3100 or higher on a 12:1 cpr 496 big block in the same car with the same transmission

viewtopic.php?f=71&t=2400&p=19038&hilit=installing+torque+converter#p19038


viewtopic.php?f=71&t=2794&p=7238&hilit=converter+stall#p7238

viewtopic.php?f=71&t=435&p=1911&hilit=converter+stall#p1911

viewtopic.php?f=71&t=488&p=602&hilit=converter+stall#p602
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
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Re: selecting a torque converter stall speed

Postby grumpyvette » September 15th, 2010, 12:05 pm

https://summitracing.custhelp.com/app/a ... dTNW1fNGFr
What You Need To Know About Torque Converters
What do I need to know about torque converters before ordering one?

A torque converter reacts to engine torque--the more torque you feed a converter the better it will perform. For a converter to operate properly, the engine needs to make as much low and mid-range torque as possible in the same rpm range the converter is rated for. For street engines, this means limiting camshafts to 230° duration at .050" lift, advancing the cam no more than 2°-4°, and using a small cfm carburetor when possible. If the cam is rated at less than 216° duration at .050" lift, you don’t need a performance torque converter. Nothing about torque converters is more misunderstood than stall speed. Stall speed is directly related to the amount of torque the engine produces--the more torque, the higher the stall speed. For example, a converter with a 2,800-3,200 rpm rating might provide approximately 2,800 rpm of stall speed behind a mild small block V8, but about 5,000 rpm behind a big block making 800 ft.-lbs. of torque. Without knowing how much torque an engine makes, you cannot know how much stall speed a converter is capable of. While most converter manufacturers list stall speed ranges, those numbers are very general. True stall speed is impossible to measure due to many different variables. These variables include:
• Low vehicle weight
• Engine displacement
• Low compression ratio
• Intake manifold type
• Carburetor throttle bore diameter
• Carburetor secondary linkages
• Multiple carburetion
• Long duration camshafts
• Retarded cam timing
Many people return a torque converter because they believe it doesn’t fit their transmission’s input shaft. However, since performance converters are built to much closer tolerances than OEM units, the hub-to-input shaft fit is tighter. This often leads people to think the new converter’s hub is too small because they are used to slipping the stock converter on without any resistance. Heat is the biggest enemy of a torque converter and transmission. A higher stall torque converter imposes greater loads on the transmission and creates more heat. Thus, a high capacity transmission cooler designed to protect your converter and transmission from heat damage is a wise investment. Finally, nothing beats professional advice when choosing a torque converter. A phone call to one of the converter manufacturers or to experts like Summit Racing Equipment will help you pick the right converter for your vehicle.


one of the very common misconceptions I hear repeated endlessly is that a higher stall speed converter will make the car used on the street a P.I.T.A. to drive and that if you select something like a 2800rpm stall converter the car won,t move until, the engine rpms hit near that rated stall speed.
the truth is that if you select the correct stall speed for the gearing and application your car will be far easier to drive on the street.
that of course mandates you know a bit about how to select a converter stall speed and match it to your cars power curve.even thought I have a 3200 stall converter the car pulls fine at 1900rpm-2200rpm at part throttle, but no longer wants to jump the car forward and stall the engine when its put into gear like it did with the stock converter stall speed, or bog and not move untill the rpms build
heres my current corvettes 383, its most efficient power is produced in the 3100rpm-6300rpm power band , I selected a 3200 rpm stall and 3.73:1 rear gear ratio, with 25" tire height and the trans shifts at near 6400rpm under wide open throttle
Image
the 383 sbc has 11:1 compression, and this cam, installed 4 degrees retarded and runs a extensively ported stealthram with 36lb injectors and a 58mm throttle body and long tube headers, with ported trick flow heads
Image
notice the power band in theory should be from about 2100rpm-thru about 6100rpm, but the tunnel-ram type intake and extensively ported heads and intake runners and retarding the cam timing move it up to near 2800rpm-thru-about 6400rpm, usiong a 3200rpm stall means I,m nearly instantly in the power when the throttles held firmly on the floor, and the 25" tires and 3.73:1 rear gear helps
Image
Image
Image

taved wrote:Folks,

I thought that this would be of interest to some.

I have a mild 383 sbc with GMPP Bowtie Vortech 185cc heads (25534421) and a GMPP Hotcam in a 1972 Chevelle (TH350).

Static compression is calculated at 9.6:1. Cranking compression is 185 psi.

The dyno plots in blue- old exhaust system and stock convertor
stock iron exhaust manifolds, 2.5" true-dual pipes, Summit Turbo mufflers, tips to bumper

The dyno plots in red- new exhaust system and 2400 stall converter
Hooker sbc headers, 2.5" Pypes X-over pipe, 2.5: pipes, Pypes Race Pro MVR30 18" case mufflers, tips to bumper

I wish that I could take the converter off the comparison but it's too late.


Dave

video:

http://youtu.be/sJyWJCNl6Bk

Image


IF YOU LOOK CLOSELY THE VORTEC HEADS AND HOT CAM ON THAT 383 < OBVIOUSLY PEAKED IN THE 4000rpm-4500rpm RANGE, AS THE TORQUE CURVE DROPS NOTICABLY AFTER THAT RPM, WHICH WOULD BE EXPECTED WITH THOSE HEADS RESTRICTING A 383 , MUCH OVER 4500RPM








READ THESE THREAD
S

viewtopic.php?f=71&t=741

viewtopic.php?f=71&t=555

viewtopic.php?f=32&t=430
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: selecting a torque converter stall speed

Postby grumpyvette » September 23rd, 2010, 2:55 pm

http://www.makcotransmissionparts.com/C ... ookup.html

http://www.makcotransmissionparts.com/C ... t-GMC.html

Original article from Summit Racing's website.
http://summitracing.com/landing/must...Type=5#FeatTop
Torque converters are way up there on the list of Dark and Mysterious Things along with sorcery, corporate accounting practices, and figuring out dial-ins. Because there are so many factors involved in choosing the right converter, many people end up getting the wrong one for their application, resulting in poor vehicle performance and broken transmissions.

But it doesn’t have to be this way. You too can learn how to choose the right torque converter, and this little primer will help you get started. We’re going to highlight the basics on things like stall speed, matching a converter to cam size and rear axle ratio, special considerations for nitrous and blowers, and more.

What a Converter Does
Without going into a bookful of theory, a torque converter is a hydraulic coupler between the engine and the transmission. It changes mechanical torque (engine torque) into hydraulic pressure before sending it back to the transmission. The converter also multiplies the torque at low speed or during periods of high engine load.


Inside a converter are an impeller, a stator, and a turbine, all surrounded by transmission fluid. The impeller rotates at engine crank speed, acting as a fluid pump. The turbine is the output member hooked to the transmission input shaft. The stator sits between the two, acting as a torque multiplier when impeller speed exceeds turbine speed. When the converter reaches its stall or lockup speed, the stator stops multiplying torque and the converter essentially acts as a fluid coupling. When the vehicle is coasting (no load), the converter directs torque back towards the engine, acting as a brake.

What is Stall Speed, Anyway?
The one thing people misunderstand the most about torque converters is stall speed. Many think that if they have a converter rated at 2,500 rpm, the car will rev up to that rpm and then take off. That’s not how it works. Stall speed is a function of engine rpm—the more torque your engine makes, the higher the rpm the converter will stall, or lock up at, and transfer that torque to the transmission.


There are two types of stall speed—foot brake stall and flash stall. Foot brake stall (also called true stall) is the maximum rpm that can be achieved with the transmission in gear, the brakes locked, and the engine at full throttle. The rpm reached before the vehicle moves is the true stall speed of the converter.

The problem with foot brake stall is that you will end up overpowering the brakes and suspension before you reach the converter’s stall speed. The only way to really measure true stall is by using a trans-brake. This will keep the vehicle from moving, allowing the converter to absorb 100 percent of the engine’s torque.

Race classes that do not allow trans-brakes are often called foot-brake classes. In this type of racing, the rpm obtained when the brakes are applied and the vehicle is not moving is considered to be foot brake stall. When the brakes are released, the engine goes to full throttle and “flashes” the converter.

That leads us to flash stall. It is the maximum engine rpm reached when you launch a vehicle at full throttle from a dead stop with no brakes applied. Flash stall is always lower than true stall because there is less load on the converter. It is dependent on many factors including vehicle weight, rear-axle gear ratios, and tire height. Anything that decreases the load on a converter (numerically higher gears, less engine torque, low vehicle weight) will cause the flash stall speed to be lower. Conversely, increasing torque, going to a numerically lower gear, or building a heavy car will increase flash stall speed.

Another factor that gets confusing is converter slip. Slip is basically a measure of converter efficiency. Due to the difference in rotating speeds between the impeller and the turbine, there is usually a five to 10 percent efficiency loss at cruising speeds for non-lockup converters. Because a converter gradually slips, or creeps up, to full stall/lockup rpm, the higher the stall speed, the more slippage you get. On a street-driven vehicle, that can lead to poor idle and low end performance, worse gas mileage, and most importantly, greater heat buildup—the number one killer of converters and transmissions. If you do run a high stall converter, a good transmission cooler is a must.

What Kind of Engine Are You Building?
Before you even crack open a torque converter catalog, you need to be realistic about the type of engine you are building. You need to match low and mid-range engine torque to the converter’s stall speed. For example, if you are building a street small block that makes most of its torque around 2,500 to 3,000 rpm, don’t get a converter that stalls at 4,000. Not only will the car be hard to drive, the converter will constantly slip and will eventually be destroyed due to overheating. If you build a big block that makes its torque at 4,500 rpm or so, don’t expect it to be much fun on the street because of the high stall converter and big rear axle gear required to get the converter to lock up.

Camshaft selection is also critical to torque converter selection. On the street, many people will choose a cam that will put an engine’s rpm range 1,500 to 2,000 rpm higher than stock. Not only does that reduce bottom end torque, but a higher stall converter will be required to match the new torque peak. Many people will get the recommended converter, but neglect to upgrade the rear axle gear to compliment the higher stall speed (more on gear ratios and tire sizes in a minute).

Say you built a small block V8 with a 235 degree (at .050)/.488 inch lift cam and added a converter rated at 3,000 to 3,500 rpm. To make the combination work properly with a minimum of converter slippage, you will need a 4.10 or higher rear axle gear with 26 to 27 inch tall tires. Illustration One shows you approximate stall speeds based on engine type, cam duration, and rear axle gear ratio.

Nitrous or supercharging also affect converter selection. An engine with one of these power adders produces more torque than it would if it was normally aspirated. That means a nitrous or blown engine needs a converter with a lower stall speed range. Otherwise, the converter will stall too high, causing it to slip and eventually self-destruct due to the extra heat generated.

The Final Ratio
Rear axle gear ratio and tire diameter are very important to proper converter selection. You need to have enough of a final cruise rpm (rpm generated based on tire diameter and rear axle gear ratio) to allow the converter to function at full lockup at cruising speeds. If you don’t, the converter will constantly slip.


Illustration Two shows you the rpm generated at 60 miles per hour with various gear ratios and tire diameters. This will help you determine where your converter should stall. You can see how close your vehicle’s actual cruise rpm is to the chart by reading the tach at a steady 60 mph, find your gear ratio and tire diameter in the chart, then compare your rpm reading to the chart’s suggested rpm.

Size Does Matter
Torque converter size can also be confusing. Converters can range from 11 and 12 inches in diameter all the way down to 7 inches. Basically, the smaller the converter, the less fluid has to be pumped through it. Less fluid means less drag on the converter internals, which allows it to stall at higher speeds. That’s why you see 8, 9, and 10 inch converters listed for racing applications. In general, you want to avoid small converters on a typical street car due to the much higher stall speeds (usually 3,000 rpm and up).


If you are adding a lot of nitrous (over 200 horsepower), running high blower pressure (over 12 psi), or use a trans-brake, you will need a converter built to handle the extra stress. The extra torque generated can cause a converter to “balloon”, or expand in diameter. Look for a converter with a high quality stator assembly and an anti-ballooning plate to keep it from expanding.

The Fitting Room
A common complaint about aftermarket torque converters is fitment. Often, a new converter will not fit the transmission’s input shaft because it is built to much closer tolerances than OEM converters, so the hub-to-input shaft fit is tighter. Just because the new converter will not slip onto the input shaft doesn’t mean the converter is defective—just use a little extra effort.


A good way to check if a new converter will fit properly is to compare it to the stock converter you are taking out. Illustration Three shows the three critical dimensions: overall length (from engine mounting face to end of hub), hub slot depth, and hub slot inside diameter. Before you remove the old converter, check the dimension from the bellhousing to the front with the stock converter in place. This will help you position the new converter properly.

Other Considerations
A higher stall converter will place extra stress where it mates to the engine, so make sure you use quality converter bolts (like those made by ARP) and an SFI approved flexplate. SFI approved flexplates for Chevys are usually double drilled for small and large bolt patterns, eliminating the need to guess which bolt pattern you have.


Aftermarket torque converters are neutral balanced, designed for internally balanced engines. Most externally balanced engines have the balance weight on the flexplate, so this is no big deal. But on externally balanced Chryslers—340 and 360 small block and 440 big block—the factory put the balance weight on the torque converter. If you have one of these engines, make sure to get the appropriate flexplate counter weighted to match the engine balance. Most SFI approved Chrysler flexplates have this counterweight.

Don’t consider this to be the end-all and be-all on torque converters. The best way to get the perfect converter for your application is to talk with the tech guys at Summit or even better, directly with the companies that build the converters. Hopefully, this guide will help you ask your converter builder the right questions—and understand his answers.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: selecting a torque converter stall speed

Postby grumpyvette » September 28th, 2012, 12:44 pm

when you go to select a converter stall speed keep in mind that You can have a lot of mismatched parts, and your engine and drive train will still seem like it has few or no major performance issues, you can forget to use options like deep baffled oil pans, transmission coolers and larger radiators, windage trays etc, the engine may run fine for a while, but in the long run its going to cost you in both performance and engine durability, issues and increased parts failure rates.
even when component parts are significantly restricting power compared to what it could be producing, but if all the parts are better matched to the engines power band and the cars gearing and intended operational range, you'll get an even better bang for the buck. Build the engine for the 90% of the time your using the car and your driving style. A car that's normally driven on the street and highway doesn't need or work well with parts that belong on the race track, both durability and mileage will suffer and so will your average performance, its almost always a better idea to work toward increased durability, that for the last couple potential peak horse power, if getting them reduces the engines durability.
stop and think thru your options and get advice from both several different cam and several different torque converter manufacturers , both will try to help if asked because they want you to be happy with the results.

as a general rule stock converter stall speeds rarely exceed about 2300rpm and rear gear ratios rarely are higher numerically than about 3.33:1 so once you make changes the stock converter stall will rarely match or work correctly with longer duration cams required for increasing upper rpm power bands that those larger cams will require.
any converter with a stall speed above about 2600rpm will require a aux trans cooler if you regularly beat the car, demanding higher rpm performance and the higher the stall the more heat is produced in most cases.
I constantly get guys who have never used a high stall converter who think that having a 3500 stall converter installed will mean the car won,t move until the engine reaches 3500 rpm, thats not even close to true, what it means is that if you stand on the brakes and floor the engine the engine rpms will peak at near 3500rpm, allowing you to have instant access to the higher rpm power curve
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: selecting a torque converter stall speed

Postby grumpyvette » February 14th, 2014, 6:48 pm

HOW DO YOU DETERMINE YOUR CURRENT CONVERTER STALL SPEED?
Image
the difference between a stock converter and shift points and the results you get with correctly matched components, can easily exceed 25% or more in the useable power transmitted to the rear tires
Image

READ THIS RELATED THREAD

viewtopic.php?f=71&t=741

version one
1. Position the car on a deserted street or parking lot so that as it moves no one will be in the way.
2. Raise the rpm to a fast idle in neutral to get maximum engine vacuum for the power brakes and press the brake pedal heavily and hold to get the maximum holding power.
3. Come off the throttle and shift into drive or manual low.
4. Still holding full brake pedal, go to WOT in less than 1/2 second and hold for a second or two noting the maximum rpm attained; and then return to idle.
Note: The car may move a few feet and then abruptly stop when returning to idle - this won't invalidate the results. Important: Don't hold WOT for more than 2 seconds as the trans fluid will heat rapidly in the stalled condition.

version two
http://www.freeasestudyguides.com/torqu ... -test.html
If the torque converter stators one way clutch is suspected of slipping or being seized a torque converter stall test should be performed before bench testing the converter. Always check with vehicle manufacturer before performing this test
Image
To perform this test install a tachometer, chock all four wheels, and set the parking brake. Make sure the tachometer is viewable from the drivers seat. Place your foot firmly on the brake pedal and place the transmissions shift selector in Drive. While holding the brake pedal press and hold the throttle pedal to the floor for 2 or 3 seconds. Always check with the manufacturers recommendations because this test places stress on the transmission. Never exceed 5 seconds. Compare the reading (stall speed) on the tachometer to the manufacturers specifications.

During a stall test the torque converters impeller is spinning at maximum speed while the turbine is being held stationary. Since everything from the turbine back is being held stationary a vibration like an out of balance drive shaft would not appear during a stall test.

Troubleshooting the Stall Test:

If this reading is below specifications the torque converters stator one way clutch is spinning freely or there is a restriction in the exhaust system. If the reading is above specifications the transmissions clutches and bands are slipping.

version THREE
Take the following precautions Check with your car or transmission manufacturer to make sure it's safe to run the test. Most newer transmissions, as well as some older ones, can actually be ruined by a stall-speed test. Don't run a stall-speed test for more than five seconds at a time. Don't run this test on vehicles that have traction control or anti-lock brake systems. On some electronically controlled transmissions, a stall-speed test will set off your check engine light.
Prepare your car Before testing your torque converter, make sure all your fluids are in good condition. Also, chock your wheels and set the parking brake. If your car doesn't have a tachometer, install one that can be seen from the driver's seat [source: ASE Test Prep].
Start your engine Press the brake pedal all the way to the floor and start your engine. Shift your transmission into drive. Don't let go of the brake.
Put the pedal to the metal While pressing on the brake pedal, press the accelerator to the floor for two to three seconds. Don't exceed five seconds, or you risk blowing out the transmission. The RPM the engine maxes out at is the stall speed.
Interpreting the stall-speed test result If the RPM reading is lower than the specifications for your particular torque converter and engine, it means the torque converter is failing and needs to be repaired or replaced. If the RPM reading is too high, then your transmission is slipping and you'll need to investigate the problem
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: selecting a torque converter stall speed

Postby 87vette81big » February 15th, 2014, 9:10 am

Your oldest posts from 2008- 2010 have been most informative to me last few weeks Grumpy reading on my own.
The torque capacity of the 4L60E is a bit optimistic. Rated 670 Ft/lbs.
I would rate it at 350-375 ft/lbs stock. The weakest link is the 3-4 clutch pack layout stock.
The rear reaction gearset is weak. The factory blueprint clearances are terrible. Loose as a Goose.
Blueprinted & built right with NOS MADE IN USA 4L65E Front & Rear 5-pinion 4L65E gplanet gearsets, special calibration valvebidy parts, you can push to 600 Ft/lbs Continous.
Last around 10,000 -50,000 miles.
The 4L80 E is rated 880 ft/lbs. A modern BBC Race engine exceedss that too.
Twin Turbo or a 500 Hp shot of Nitrous gives pver 2,000 Ft/lbs Flywheel Torque instant.
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Re: selecting a torque converter stall speed

Postby 87vette81big » February 15th, 2014, 9:15 am

A Vortech YSi blower at 28-40 psi gives over 2,000 ft/lbs instant in a race engine too.

So are modern overdrives all superior ?
I question that.
Turbo 400. Powerglide. 727 Torqueflite, C6 Ford still used in drag racing.
They hold up to heavy abuse.
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