I thought it would be interesting and informative to investigate the affect that different lockup stategies would have on the durability of torque converter lockup clutches of differing designs. Stock, multi-disc, small diameter, etc. This would be of particular interest to people thinking of installing a modified computer chip, but are still running the stock converter. Is this a topic that would be of interest to anyone?
Lockup strategies and their affect on clutch durability.
- Thread starter Alky V6
- Start date
It is a good topic and I played quite a bit wit hthis issue on my turbocharged 99 GT. I found that when I locked the converter at the beginning of 3rd gear, I picked up almost 26 mph in the 2nd 1/8th vs 22.
The durability becomes an issue because single disc(most) were not designed for full throttle lock-up before high speed. I killed a 10.5 Protorque HD lock-up clutch in 6 months. The Precision Industries 9 1/2 has an even smaller disc so I'm sure I would have killed that also.
So I sold my single disc and bought a multi disc which is designed for this purpose. I called all of the major Torque converter companies and only 1 or 2 recommended locking the converter in 2nd or 3rd under full throttle.
I plan to try the Extreme Duty Power Raptor Lock-up. 9 1/2 inch converter with 12" carbon fiber clutch rated for 700 hp and lock it at 70-80 mph.
Sounds like a story heard over and over. Trying to force more torque through a single disc L/U clutch to decrease ET by changing when the L/U command occurs. You get away with it for awhile, but sooner or later it catches up to you if you haven't properly matched the torque converter lockup clutch design to the new L/U strategy of the chip. Everyone is familiar with the term lockup at wide open throttle or WOT lockup. It has come to my attention, some of it through testing of a customers car, that lockup strategies can be modified in a manner that lockup is not commanded at the max throttle position sensor voltages that occur at WOT, but can be commanded at TPS voltages less than or just below WOT or more simply, between what would be the OEM programming and WOT. Maybe one of the chip wizards can chime in and confirm whether this is possible or not. Can the torque converter L/U or unlock command be modified as far as TPS voltages are concerned?
There are a multitude of aspects that involve this subject. Much of it is very technical. A vast majority if it involving engine management control, and mainly, different load sensing strategies used by any given EMS (engine management system). Some of you may get lost in the discussion of it, so I'll try to keep it as simple as possible. There will be information discussed that some transmission mechanics or even chip reprogrammers did not fully realize. Everyone needs to understand this so they can make an educated decision when it comes to modifying their car or modifying someone elses car.
I'm going to pinpoint one aspect at a time so that it can be thoroughly covered. This discussion may take several postings on my part, so please bare with me. This is very important stuff. Especially to the novice.
The first discussion will involve load sensing methods or more importantly the combination of different load sensing methods used by different engine management systems, their inherent strengths and short comings and how they are used to control different engine and transmission functions.
I have to run to work now. I'll get back to this tonight to start discussion 1a.
I'm going to pinpoint one aspect at a time so that it can be thoroughly covered. This discussion may take several postings on my part, so please bare with me. This is very important stuff. Especially to the novice.
The first discussion will involve load sensing methods or more importantly the combination of different load sensing methods used by different engine management systems, their inherent strengths and short comings and how they are used to control different engine and transmission functions.
I have to run to work now. I'll get back to this tonight to start discussion 1a.
Discussion 1a. Identifying the different engine load sensing methods used in various engine management systems.
For the EMS to properly operate some of the various functions of the engine and the transmission, it must have an input that can be used to calculate engine load. The most commonly known methods are listed below:
MAF = Mass Airflow Meter.
Speed Density = The use of MAP (Manifold Absolute Pressure), or TPS (Throttle Position Sensor), or sometimes a combination of both.
Alpha-N = The use of TPS signal and engine speed.
We'll look at the MAF system first and try to identify its strengths and weaknesses.
The MAF system is the most accurate at determining airflow into the engine. This sensor takes into acoount the temperature, density, and humidity of the incoming air. This sensors electrical current change is directly proportional to the weight or mass of the air entering the engine. There have been a variety of different designs of this type sensor. We won't go into depth on that subject. That is about it for this systems strengths. There are a few problems that come with this system.
The MAF sensor itself can present an airflow restriction to the engine when engine power modifications get past a point.
It is critical that air moving through the sensor is non-turbulent in order to get an accurate sampling. This makes modifications to the air intake before the sensor very important. Remember the screen that many people elect to remove?
The MAF sensor is susceptible to contamination that can change the reading it gives to the EMS. A fine coating of fine dust, dirt and/or oil from some aftermarket filters are the most common types of contamination.
Air leaks anywhere in the intake system after the MAF sensor make the sensor reading inaccurate.
Being able to find a practical mounting for the sensor in a custom application can be time consuming. Although, the terms custom application and time consuming go hand in hand anyway.
In discussion 1b, we'll look at the Alpha-N system. Most assuredly the worst system to use in a turbo application.
If anyone feels they have anything to add or have corrections to some of the information given, please feel free to participate. Much of this information I've obtained from various books. As the discussion moves further there will be some of my own thoughts added in that will be food for thought for most of you.
Until next time.
For the EMS to properly operate some of the various functions of the engine and the transmission, it must have an input that can be used to calculate engine load. The most commonly known methods are listed below:
MAF = Mass Airflow Meter.
Speed Density = The use of MAP (Manifold Absolute Pressure), or TPS (Throttle Position Sensor), or sometimes a combination of both.
Alpha-N = The use of TPS signal and engine speed.
We'll look at the MAF system first and try to identify its strengths and weaknesses.
The MAF system is the most accurate at determining airflow into the engine. This sensor takes into acoount the temperature, density, and humidity of the incoming air. This sensors electrical current change is directly proportional to the weight or mass of the air entering the engine. There have been a variety of different designs of this type sensor. We won't go into depth on that subject. That is about it for this systems strengths. There are a few problems that come with this system.
The MAF sensor itself can present an airflow restriction to the engine when engine power modifications get past a point.
It is critical that air moving through the sensor is non-turbulent in order to get an accurate sampling. This makes modifications to the air intake before the sensor very important. Remember the screen that many people elect to remove?
The MAF sensor is susceptible to contamination that can change the reading it gives to the EMS. A fine coating of fine dust, dirt and/or oil from some aftermarket filters are the most common types of contamination.
Air leaks anywhere in the intake system after the MAF sensor make the sensor reading inaccurate.
Being able to find a practical mounting for the sensor in a custom application can be time consuming. Although, the terms custom application and time consuming go hand in hand anyway.
In discussion 1b, we'll look at the Alpha-N system. Most assuredly the worst system to use in a turbo application.
If anyone feels they have anything to add or have corrections to some of the information given, please feel free to participate. Much of this information I've obtained from various books. As the discussion moves further there will be some of my own thoughts added in that will be food for thought for most of you.
Until next time.
A great general start, Don. I'm going to jump in with a couple of specifics, though - hope I'm not earlier than you wanted 
. The stock 7148 ecm uses tables of %tps values versus vehicle speed in 3rd and 4th gears as the primary test whether to lock up if unlocked or to unlock if locked, along with separate minimum speeds for each gear to allow lockup in the first place, or to unlock, along with a delta-tps test to unlock on quick throttle movement. That is the stock system, and with the stock values the tcc is pretty much unlocked past about 50% tps. For racing, the most common chip mod is to force lockup at speeds greater than about 83 mph in 3rd and 4th gears. Most racers don't use 4th at the track but for completeness chipmakers usually set it too. That's harsh, though, because now the tcc stays locked at the 3-4 shift which is a real shock to the trans, so I know at least one popular chipmaker that only locks the tcc in 3rd so it unlocks at the upshift to 4th. Also, up in the rom where it can't be changed is a test that unlocks the tcc at speeds of 124 mph or greater no matter what, so for those real top end runs you need a manual switch to force lockup . Finally, the way Buick set up the 4th gear unlock tables the tcc usually won't ever unlock until you have mashed down far enough on the gas pedal to go ahead and cause a 4-3 downshift (and simultaneous unlock). Several chipmakers are now tweaking the 4th gear table to let the tcc unlock at lower %tps values to effectively get a "passing gear" while still in 4th - the tcc unlocks without the downshift and with the extra rpms you get very quick spoolup so you can get a few pounds of boost for a pass without the violence of a full 4-3 downshift. Makes a real nice improvement in driveability. No one has really discussed it but the assumption is that this unlocking and subsequent relocking when you let back off the gas is not going to significantly reduce clutch life. Since the relock is at light throttle I think this is reasonable but please, comment.
. The stock 7148 ecm uses tables of %tps values versus vehicle speed in 3rd and 4th gears as the primary test whether to lock up if unlocked or to unlock if locked, along with separate minimum speeds for each gear to allow lockup in the first place, or to unlock, along with a delta-tps test to unlock on quick throttle movement. That is the stock system, and with the stock values the tcc is pretty much unlocked past about 50% tps. For racing, the most common chip mod is to force lockup at speeds greater than about 83 mph in 3rd and 4th gears. Most racers don't use 4th at the track but for completeness chipmakers usually set it too. That's harsh, though, because now the tcc stays locked at the 3-4 shift which is a real shock to the trans, so I know at least one popular chipmaker that only locks the tcc in 3rd so it unlocks at the upshift to 4th. Also, up in the rom where it can't be changed is a test that unlocks the tcc at speeds of 124 mph or greater no matter what, so for those real top end runs you need a manual switch to force lockup . Finally, the way Buick set up the 4th gear unlock tables the tcc usually won't ever unlock until you have mashed down far enough on the gas pedal to go ahead and cause a 4-3 downshift (and simultaneous unlock). Several chipmakers are now tweaking the 4th gear table to let the tcc unlock at lower %tps values to effectively get a "passing gear" while still in 4th - the tcc unlocks without the downshift and with the extra rpms you get very quick spoolup so you can get a few pounds of boost for a pass without the violence of a full 4-3 downshift. Makes a real nice improvement in driveability. No one has really discussed it but the assumption is that this unlocking and subsequent relocking when you let back off the gas is not going to significantly reduce clutch life. Since the relock is at light throttle I think this is reasonable but please, comment.First, a correction to my last posting.
Speed Density systems measure TPS and/or MAP, and engine rpm to calculate the theoretical intake of air for a given engine displacement.
Thanks for the help ijames. Valuable info indeed. I plan on getting into the ranges of adjustability for all the different parameters you mention, but your right, it is too early for that. The object of this discussion is to lay down a foundation of knowledge for everyone concerning this topic first, then we can start discussing the theoretical affects of changing this or that parameter in the chip. More people armed with the basics of understanding can then participate in the theoretical affects discussions.
Discussion 1b. The Alpha-N system.
This is a type of Speed Density system. It is the simplest system and merely uses throttle position angle and engine rpm to calculate the theoretical intake of air for a given engine displacement. The assumptions for this system are as follows:
Very simply, for any given throttle angle and any given engine rpm the engine will ingest a determined amount of air. With a determined amount of air, we know we will need a determined amount of fuel in order to get our target air/fuel ratio. The flaw with this system is its inability to compensate for variations in engine volumetric efficiency or VE that may occur at any one given TPS angle and engine rpm combination. A complete disaster in a turbocharged application. Depending on drivers style and modifications done to the engine, you could have boost at 1/3 throttle and 3000 rpm, or not.
The Alpha-N system is too primitive for our turbo applications so we won't waste too much time here. The important thing to keep in mind is its strict use of TPS to determine, or more importantly, not be able to properly determine the engine's volumetric efficiency or torque load output at any given engine rpm.
In discussion 1c, we will talk about another speed density system. One that has the ability to compensate for changes in engine VE. I think we'll also cover VE for those out there who may be wondering what it is.
Speed Density systems measure TPS and/or MAP, and engine rpm to calculate the theoretical intake of air for a given engine displacement.
Thanks for the help ijames. Valuable info indeed. I plan on getting into the ranges of adjustability for all the different parameters you mention, but your right, it is too early for that. The object of this discussion is to lay down a foundation of knowledge for everyone concerning this topic first, then we can start discussing the theoretical affects of changing this or that parameter in the chip. More people armed with the basics of understanding can then participate in the theoretical affects discussions.
Discussion 1b. The Alpha-N system.
This is a type of Speed Density system. It is the simplest system and merely uses throttle position angle and engine rpm to calculate the theoretical intake of air for a given engine displacement. The assumptions for this system are as follows:
Very simply, for any given throttle angle and any given engine rpm the engine will ingest a determined amount of air. With a determined amount of air, we know we will need a determined amount of fuel in order to get our target air/fuel ratio. The flaw with this system is its inability to compensate for variations in engine volumetric efficiency or VE that may occur at any one given TPS angle and engine rpm combination. A complete disaster in a turbocharged application. Depending on drivers style and modifications done to the engine, you could have boost at 1/3 throttle and 3000 rpm, or not.
The Alpha-N system is too primitive for our turbo applications so we won't waste too much time here. The important thing to keep in mind is its strict use of TPS to determine, or more importantly, not be able to properly determine the engine's volumetric efficiency or torque load output at any given engine rpm.
In discussion 1c, we will talk about another speed density system. One that has the ability to compensate for changes in engine VE. I think we'll also cover VE for those out there who may be wondering what it is.
there are few set rules here.the engines ability to gain rpm against road resistance ,final drive,the automatic transmission and vehicle weight vary greatly even in similar situations with different torque convertors,operating climates and fuels.obviously ,it should be understood that the faster the engine can gain rpm against applied resistances the faster the turbo will respond to exhaust gasses energy which is recycled to drive the turbo,compress air and create positive manifold pressure to force it into the engine to raise volumetric efficiency and multiply usable power.it should also be noted that high vaccuum periods in the intake manifold increase the amount of time it takes the engine to burn fuel from start to finish thus introducing timing concerns verses coupling bias.a turbo convertor must be loose enough to build boost when the vehicle is stationary and create a hydraulic coupling to efficiently accellerate the vehicle BEFORE the lockup phase of the torque convertor cycle is introduced.some vehicles will adversely change induction patterns with the 1 to 1phasing of the flywheel and input shaft at the wrong moment.contrary to popular belief or educated guesses we have found that most 9 second and mid 10 second cars will run faster with a unlocked convertor (non locker)at 90%percent hydraulic coupling than one which is locked.however ,anything in the mid tens and slower will usually run harder locked up at the top of 3rd gear.this also reduces ingestion disruptions because the rpm drop from a higher point in the usable rpm range makes the engine less sensitive to this .i think a dash mounted toggle installed in the aldl should be used to find the best point to lock the convertor in relation to various modes of operation ,and then generate a chip based on facts extracted during testing.
One thing that happens when cars get into the mid 10second range typically they have larger cams, better breathing heads, larger turbo's needed to sustain power. What happens is the power band is moved up in the motor, thus keeping the rpm's higher yielding greater power through increased airflow and results. Locking a converter prematurely cuases a huge drop in RPM's and thus moves the motor out of its sweet spot hence the drop. So the cam plays a big part to where this power band is.
Now it is possible in the GM ecm to command whatever you want with the TCC by writing code. So what the stock chip does, and what can be done.. two different sets of variables.
Small cams benefit more from locking.. true??
Now it is possible in the GM ecm to command whatever you want with the TCC by writing code. So what the stock chip does, and what can be done.. two different sets of variables.
Small cams benefit more from locking.. true??
750H.P.V6
Brutal 6 Racing
- Joined
- Sep 4, 2001
Don,
I'm not sure what you're fishing for but I'm sure you're hoping to entangle me in you net so I'll give you my thoughts. My first thought is why it took so long for this issue to come up? It seems to me that even the newest turbo intercooled Buicks are close to 18 years old. Secondly is that 98% of all turbo cars have been modified with an aftermarket chip. Since you have been in business for yourself for over 10 year why is it just recently that you have been experiencing torque convertor failures and why must it be a fault of the chip programming?
As I stated previously in a deleted post TCC lock up is a function of TPS and VSS (vehicle speed) on a Turbo Buick. There are no other inputs. Carl Ijames restated that above. BTW, Carl is about the sharpest guy in the country when it comes to this stuff. As I stated once before, of the STREET chips I have seen the TCC lock/unlock tables for both 3rd and 4th gear are stock with only the. 3rd and 4th TCC lock minimum lock and unlock MPH values being changed. Locking the convertor at a higher MPH at light throttle can actually be beneficial from driveability standpoint especially when dealing with a car with a large turbo, heads, cam etc.
This should in no way impact torque clutch wear and may actually help in a high stall type convertor. In a high stall application, with the higher stall speed comes slippage. The slippage is most evident at light throttle. When the convertor is locked up at lower MPH the car will be at a lower RPM also which is in turn more in the slippage range of a high stall convertor. During this phase of the convertors operation it is largely inefficient and there is a greater difference between impeller and turbine speed. If the TCC lock up point is moved up to a higher MPH there will be less differential RPM between the impeller and turbine and less TCC clutch wear will take place.
Neal
I'm not sure what you're fishing for but I'm sure you're hoping to entangle me in you net so I'll give you my thoughts. My first thought is why it took so long for this issue to come up? It seems to me that even the newest turbo intercooled Buicks are close to 18 years old. Secondly is that 98% of all turbo cars have been modified with an aftermarket chip. Since you have been in business for yourself for over 10 year why is it just recently that you have been experiencing torque convertor failures and why must it be a fault of the chip programming?
As I stated previously in a deleted post TCC lock up is a function of TPS and VSS (vehicle speed) on a Turbo Buick. There are no other inputs. Carl Ijames restated that above. BTW, Carl is about the sharpest guy in the country when it comes to this stuff. As I stated once before, of the STREET chips I have seen the TCC lock/unlock tables for both 3rd and 4th gear are stock with only the. 3rd and 4th TCC lock minimum lock and unlock MPH values being changed. Locking the convertor at a higher MPH at light throttle can actually be beneficial from driveability standpoint especially when dealing with a car with a large turbo, heads, cam etc.
This should in no way impact torque clutch wear and may actually help in a high stall type convertor. In a high stall application, with the higher stall speed comes slippage. The slippage is most evident at light throttle. When the convertor is locked up at lower MPH the car will be at a lower RPM also which is in turn more in the slippage range of a high stall convertor. During this phase of the convertors operation it is largely inefficient and there is a greater difference between impeller and turbine speed. If the TCC lock up point is moved up to a higher MPH there will be less differential RPM between the impeller and turbine and less TCC clutch wear will take place.
Neal
lock up strategy should not be an issue with torque convertor clutch durability,however lock up strategy should be carefully plotted and then implemented in the form of chip programming to improve the performance of a vehicle and reduce the amount of fuel consumption during operation which in turn reduces pollution,engine noise,engine wear etcetera.it should not be stated that lock up strategy in itself can have an effect on convertor clutch lining or the torque convertors mechanical parts .when those of us responsible for using properly matched components and calibrations do our job correctly,the end result should always be that things work properly.we should always examine and reexamine applications before deciding on the parts to use.the saying a penny saved is a penny earned certainly doesnt apply when purchasing transmission components.all combinations will respond differently to applied loads in a given operating range therefore proper calibrations should be based on careful analysis of operating properties as stated before or,the use of knowledge gathered over time through trial and error in real world operating conditions,such as that gathered by those who are smart enough to burn chips,i certainly cant do that and must rely on the knowledge of those who have paid their dues to figure out what works best.ill still tell them where i want it locked during a wot run at the track however and if they tell me no ,i want to know why.there is a science to everything,including wiping your ass,so always do your research down to the smallest detail that is relevant and dont under any circumstance fill the cracks in your brain with "koutamares"ie nonsense that takes you away from the truth of the PRINCIPLES OF OPERATION".it should be stated that improper torque converor quality will reduce a vehicles performance
Chris is catching on. Properly matched components and calibrations.
Lets not get ahead of ourselves here. There are people out there that need the basic back ground knowledge first.
Remember the main purpose of this thread is to properly and completely educate the upcoming performance enthusiast so that he/she can make an informed decision.
Discussion 1c. Engine load sensing speed density systems.
In these types of systems a manifold absolute pressure sensor (MAP) is used to indicate the air pressure inside the intake manifold. When manifold absolute pressure is low, intake vacuum is high (idle). MAP is high when vacuum is low or in the case of a turbocharged engine under boost condition, the MAP is above atmospheric pressure. When the EMS is armed with the MAP sensor reading, throttle position, ambient air temperature, and the engine rpm, it can deduce how much air is entering the engine. Using this information to index into a VE table explicitly calibrated in detail for the particular engine type it is managing, the correct fuel and ignition timing can be provided to the engine.
Advantages of this system over a MAF system are few. No figuring out a place to mount the MAF and the airflow restriction in front of the turbo is eliminated.
The main disadvantage of the MAP system is its sensitivity to MAP problems. Its vacuum hose or pipe has to be secure with no leaks. If the MAP is defective or moves out of calibration, drivability and performance problems will surely occur. EM systems that use MAP only, are especially dependent on an accurate reading along with the afore mentioned parameters to calculate airflow into the engine.
The next discussion will cover VE (volumetric efficiency). What it is and how different engine components and even chip modifications can affect it.
Lets not get ahead of ourselves here. There are people out there that need the basic back ground knowledge first.
Remember the main purpose of this thread is to properly and completely educate the upcoming performance enthusiast so that he/she can make an informed decision.
Discussion 1c. Engine load sensing speed density systems.
In these types of systems a manifold absolute pressure sensor (MAP) is used to indicate the air pressure inside the intake manifold. When manifold absolute pressure is low, intake vacuum is high (idle). MAP is high when vacuum is low or in the case of a turbocharged engine under boost condition, the MAP is above atmospheric pressure. When the EMS is armed with the MAP sensor reading, throttle position, ambient air temperature, and the engine rpm, it can deduce how much air is entering the engine. Using this information to index into a VE table explicitly calibrated in detail for the particular engine type it is managing, the correct fuel and ignition timing can be provided to the engine.
Advantages of this system over a MAF system are few. No figuring out a place to mount the MAF and the airflow restriction in front of the turbo is eliminated.
The main disadvantage of the MAP system is its sensitivity to MAP problems. Its vacuum hose or pipe has to be secure with no leaks. If the MAP is defective or moves out of calibration, drivability and performance problems will surely occur. EM systems that use MAP only, are especially dependent on an accurate reading along with the afore mentioned parameters to calculate airflow into the engine.
The next discussion will cover VE (volumetric efficiency). What it is and how different engine components and even chip modifications can affect it.
You asked for input, so I'll give a bit. I'm not baring anything though..
I know it's never well received to point out such things, and I'll put a bunch of smiley icons on it to make sure you see the humor..
but you may be eligible for a Pretension Award. Did I sign up for Elementary EFI somewhere and miss the syllabus? If you want to discuss engine management, fine..but drop the condescension, OK? Most of the preceding I will take as generic rehash from someone's book. In my experience, removing the screens in the MAF can screw up the idle fueling but not much beyond that, as inlet air quantity and velocity increases. Those screens are largely there to help with transition airflow at low speeds, i.e., tip-in.
Again, what the heck is this? I can't think of anyone, anywhere, who's ever run a GN set up with Alpha-N. Strangely enough, I know what VE is also.
Chris, I get a headache whenever I read your posts. Hit the "return" key once in a while, instead of the "submit post" twice.
I think your last sentence is valid and simple, though. Experiment with various RPM levels, see what makes the car fastest. I disagree with the first statement, agree with the second..I'm not sure I'd want that as a specialty, though. As Neal mentioned several posts ago, I think a generic conclusion would be that the greater the RPM drop when the converter is locked at WOT, the more clutch wear you'll experience. Racing and parts breakage being what they are, I doubt you'll find anyone with definitive data on clutch durability differences with various lockup strategies; we're mostly just trying to go faster.
I'm not sure you're going to get there from here. I am interested in this subject as well, as I am getting closer to getting my car, AKA the Heap That Will Never Be Finished, on the track. I currently have a 400 with an ATI N/L converter in it, but I would like to consider an eventual swap to a 4L80E and a lockup converter.
Does anyone have any info on the progressive lockup schemes used in some late model transmissions? Are they using a pulse-width control scheme? I wonder if that would increase or decrease the clutch wear? It would certainly seem to decrease the shock on driveline parts and the RPM drop at lockup.
Hi Kendall,
I'm sorry your bored with anything being discussed. I think I made it clear that much of this information is from what I've learned from books and the purpose of this particular thread is to educate the up coming performance enthusiast. I promise that the discussions will get more interesting, but I want to make sure everyone, including myself, have the basics down right. That's why I invite feedback. There might be fault in some of my assumptions and I'm looking for correction if there is.
Why did I bring up Alpha-N? Aren't some of the control functions of a stock chip similar to an Alpha-N strategy?
I'll get to the discussion of VE tomorrow.
Good night everyone.
I'm sorry your bored with anything being discussed. I think I made it clear that much of this information is from what I've learned from books and the purpose of this particular thread is to educate the up coming performance enthusiast. I promise that the discussions will get more interesting, but I want to make sure everyone, including myself, have the basics down right. That's why I invite feedback. There might be fault in some of my assumptions and I'm looking for correction if there is.
Why did I bring up Alpha-N? Aren't some of the control functions of a stock chip similar to an Alpha-N strategy?
I'll get to the discussion of VE tomorrow.
Good night everyone.
Someone say progressive
.. hummm... wonder if pulsing the lockup solenoid could control how hard the lockup hits. Like in the case of a 5 disc that hits really hard.. give it a controlled slippage? That way minimizing the rpm drop impact, at the same time keeping rpm's higher.I can see on a passenger vehicle how it could work for transitioning in the lockup. Dont know if slipping the clutch would be good on a WOT blast..
DonWG I guess the thread should have had a different heading. Its great to go over the basics as to how EFI works, just that the title of thread... dunno.. gives a different impression.
I dont mind talking bout lockup strategies and making hypothesis as to what works better.. I guess i'm having a hard time putting 2+2 together with what your doing. Not that its bad.. just dont see the connection. Most of this thread has very little revelance with fluid hitting a TQ and its clutches getting applied.
Truly sorry for the boring stuff. I just feel there are those out there that may need the back ground and I don't want to leave anyone behind. This thread is targeted towards the beginner. If anyone feels this topic is interesting enough and wants a more advanced discussion, there is nothing stopping them from starting their own thread. I incourage it.
Must run to work. Later.
Must run to work. Later.
Neal - about part throttle lockup speeds. It's true that the closer the engine rpm is to the stall speed (from below) the smaller the rpm drop on lockup. When people go to 3000+ stall converters the rpm drop at light throttle in 4th with the stock speed threshold can be 400-600 rpm (from memory here, and it depends on how hard you are mashing on the gas) compared to about 200 rpm with the stock D5 converter. This feels like a harsh shift, and most people want the speed threshold raised to reduce this rpm drop. I never thought about the clutch wear part, but I'm sure you are right that the smaller the drop the less wear. However, for around town driving with the threshold raised to 45 or 50 mph the converter will never lock, which means it is slipping more, making more heat, and hurting gas mileage. About a year and a half ago I went back to the stock 3rd and 4th gear thresholds with my 3200 stall 10" Yank converter, and after a day or so of driving I never noticed the lockup any more but I think I gained 1 mpg around town. I do probably putt around a little slower than most, but even driving pretty aggressively the lockup never seemed obtrusive. Also, I guess that I feel that this is under such light load conditions that the clutch life shouldn't be affected either way, especially if you are doing wot lockups with the same converter .
.
750H.P.V6
Brutal 6 Racing
- Joined
- Sep 4, 2001
Carl,
You're right about the decrease in gas mileage etc. that occurs when the part throttle lock up points are raised. Personally I set the 3rd gear lock somewhat high at around 40 MPH. Normally you won't see the lock up in 3rd gear unless the car is selected to drive. Typically the car will upshift into 4th if the selector is in OD prior to the convertor locking up in 3rd.
I also like to set the 4th gear lock up at 52 MPH for mildly modified cars and up to 60 in cars with really big turbos etc. The thought is that the convertor will be locked up at freeway speed and not much below that. I have actually made chips with no 3rd gear lock at all since I find it really quite annoying. As with most things the lock up points need to be selected to work in conjunction wiht the rest of the combo. In an all stock combo lower TCC lock up MPH will definately yield better gas mileage.
Neal
You're right about the decrease in gas mileage etc. that occurs when the part throttle lock up points are raised. Personally I set the 3rd gear lock somewhat high at around 40 MPH. Normally you won't see the lock up in 3rd gear unless the car is selected to drive. Typically the car will upshift into 4th if the selector is in OD prior to the convertor locking up in 3rd.
I also like to set the 4th gear lock up at 52 MPH for mildly modified cars and up to 60 in cars with really big turbos etc. The thought is that the convertor will be locked up at freeway speed and not much below that. I have actually made chips with no 3rd gear lock at all since I find it really quite annoying. As with most things the lock up points need to be selected to work in conjunction wiht the rest of the combo. In an all stock combo lower TCC lock up MPH will definately yield better gas mileage.
Neal
750H.P.V6
Brutal 6 Racing
- Joined
- Sep 4, 2001
Carl,
Sorry for another post but I couldn't go back to the previous one and add to it. I had a question about the programming in the ROM that won't allow for TCC lock up at speeds above 124 MPH. It sounds like that would be impossible to keep the TCC locked above 124 right? The reason I ask is that we have several guys including myself that typically run well over 130 MPH thru the traps and I haven't had the convertor try to unlock.
Neal
Sorry for another post but I couldn't go back to the previous one and add to it.
I had a question about the programming in the ROM that won't allow for TCC lock up at speeds above 124 MPH. It sounds like that would be impossible to keep the TCC locked above 124 right? The reason I ask is that we have several guys including myself that typically run well over 130 MPH thru the traps and I haven't had the convertor try to unlock.Neal
Eric Stage I
TurboTweak Guy
- Joined
- May 25, 2001
The part of the TCC ROM code that is referencing 124mph is actually capping the mph input to 124mph. So at any speed over 124mph, the last table value in the TCC tables will be used.
Eric
Eric