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Chaparral 2D Gears Confusion


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#61 TvO - guest

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Posted Nov 22 2010 - 07:05 PM

I can only think of two transmission manufacterers in 1967: Hewland and ZF. Perhaps one of the two allowed skipping gears?

:wave: Tommie.

Edited by TvO, Nov 22 2010 - 07:05 PM.


#62 zoic

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Posted Nov 23 2010 - 02:34 AM

View PostTvO, on Nov 22 2010 - 07:05 PM, said:

I can only think of two transmission manufacterers in 1967: Hewland and ZF. Perhaps one of the two allowed skipping gears?

:wave: Tommie.

Exactly the case, I remember reading in an article or from a documentary talk about some of the cars requiring to go thru each gear, while some others did not. But I can't for the life of me remember which of the cars were being talked about. I do remember Clark being talked about, so mayby it was Lotus vs other cars or the other way around.

Mayby somebody can find information which cars had the crash gearboxes?


PS. Looked around and the 5 speed ZF in the Lotus was synchronized, and the Hewlands were crash gearboxes(dog boxes).

Edited by zoic, Nov 23 2010 - 02:43 AM.


#63 Dark - guest

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Posted Nov 23 2010 - 03:15 AM

View PostTvO, on Nov 22 2010 - 05:08 PM, said:

I tried H shifting again just the other day after a long while using the stick in sequential mode. I figured since I now have a drivers license that might help, but then again I drive an automatic in real life so perhaps not :rolleyes: . Anyway I'd like to use heel and toe to change back gears, and also apply the clutch on all shifts, not on races online but just for some fun offline on my own. How do you guys do it? Personally I'm having trouble with people H shifting without clutch and/or throttle blips on downshifts, it just looks much nicer if they use it. The problem with the G25 pedals I have is that the brake and throttle are too far apart so I can't heel and toe at the moment. How did you guys solve that problem? Did you attach something to your pedal or did you put your foot another way or something. I saw some guy turned his pedals upside down, very clever as real cars are setup this way and conveniently the clutch pedal, now used as throttle, has about the same resistance built in and is closer to the brake pedal as well.

:wave: Tommie.

Heres a video i put on youtube a while ago showing heel and toe using G25 pedals Tommie



I don't really use my heel. I'm really using the side of my foot. Remco had a name for this style but i can't for the life of me remember what :)

#64 FloP

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Posted Nov 23 2010 - 04:46 AM

Well actually, if the best racing drivers in the world of 1967 didn't skip gears, they must have had very good reasons for this. It doesn't really matter whether they didn't do it because they simply couldn't or whether it was in order to save their transmission, avoid missed shifts, whatever. If it was the way to go for them, it'll have to be the way to go for me!

This is indeed a very interesting thread which makes me reconsider some aspects of my driving technique which haven't changed since I started driving with three pedals and an H-shifter. One of them is the pedal spacing. My setup is still just like BRD delivered it, which means that the throttle and brake pedals are more than 3 cm apart. This makes proper heel & toeing practically impossible, I assume - I'm no longer really blipping the throttle in any case.
Something else I noticed is that whenever I miss a gear under braking, I will almost inevitably run wide. This seems to indicate that I rely way too much on engine braking and may not be making proper use of the actual brakes as it should be.

Keep this discussion going, please! :)

#65 Paddy the Irishman

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Posted Nov 23 2010 - 04:55 AM

View PostDark, on Nov 23 2010 - 03:15 AM, said:

View PostTvO, on Nov 22 2010 - 05:08 PM, said:

I tried H shifting again just the other day after a long while using the stick in sequential mode. I figured since I now have a drivers license that might help, but then again I drive an automatic in real life so perhaps not :rolleyes: . Anyway I'd like to use heel and toe to change back gears, and also apply the clutch on all shifts, not on races online but just for some fun offline on my own. How do you guys do it? Personally I'm having trouble with people H shifting without clutch and/or throttle blips on downshifts, it just looks much nicer if they use it. The problem with the G25 pedals I have is that the brake and throttle are too far apart so I can't heel and toe at the moment. How did you guys solve that problem? Did you attach something to your pedal or did you put your foot another way or something. I saw some guy turned his pedals upside down, very clever as real cars are setup this way and conveniently the clutch pedal, now used as throttle, has about the same resistance built in and is closer to the brake pedal as well.

:wave: Tommie.

Heres a video i put on youtube a while ago showing heel and toe using G25 pedals Tommie



I don't really use my heel. I'm really using the side of my foot. Remco had a name for this style but i can't for the life of me remember what :)
I think that using brake and throttle with the right foot while changing down has generally been refered to as 'heel and toe', since that is what it was originally when the throttle pedal was in the centre, below the line of brake and clutch.
  
Then the toe (or ball of the foot really, but I do not think that 'ball and toe' would have caught on !) would be applied to the brake and the heel would  be naturally angled on to the throttle pedal.  I think that this arrangement continued into some of the 250F Maseratis among other cars, which stopped them being shifted around among drivers who were used to an opposite placement.

The practice is rather more difficult to achieve with the modern positioning of pedals because it does require the angling of the foot in the opposite direction - but that is the way it is....

#66 Dark - guest

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Posted Nov 23 2010 - 05:23 AM

Thanks Paddy. I'll stick to calling it heel and toe then.

FloP, i think i too am guilty of using the gears to slow down and under utilising the brakes. I find it crucial to get my down shifting spot on when i'm really tanking on otherwise running wide is the least of my troubles!

After driving with all three pedals for a while i realised i can control how much engine braking i have to deal with. I use different sized throttle blips in different situations. A smaller blip allows the back to come round a bit on corner entry if i need but a nice big blip keeps things in line nicely. I wonder if the drivers of the day did this too

#67 Remco Hitman - guest

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Posted Nov 23 2010 - 05:26 AM

LOL @ Ball and Toe :P

What Stewart is referring to is "sideflipping" which is what Dutch racing schools call it.
I figured it does indeed pretty much cover how most of us heel and toe.
Even Depailler used a sort of hybrid in the Tyrrell 008 (see attachment, repost).

The most important thing to configure is to get the brake pedal lined up with the throttle when it's fully depressed.
If you can build in more pressure in the process, that'd be great.
For those who've got G25/G27 and are considering better footwork, take a look at the G25 load cell mod: http://www.apelectrix.com/index.html
His site says he's closed up shop but there are plans to start taking orders again in Q4 2010 which is roundabout now.

Attached Files


Edited by Remco Hitman, Nov 23 2010 - 05:32 AM.


#68 Border Reiver - guest

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Posted Nov 23 2010 - 06:02 AM

View PostPaddy the Irishman, on Nov 23 2010 - 04:55 AM, said:

I think that using brake and throttle with the right foot while changing down has generally been refered to as 'heel and toe', since that is what it was originally when the throttle pedal was in the centre, below the line of brake and clutch.
  
Then the toe (or ball of the foot really, but I do not think that 'ball and toe' would have caught on !) would be applied to the brake and the heel would  be naturally angled on to the throttle pedal.  I think that this arrangement continued into some of the 250F Maseratis among other cars, which stopped them being shifted around among drivers who were used to an opposite placement.

The practice is rather more difficult to achieve with the modern positioning of pedals because it does require the angling of the foot in the opposite direction - but that is the way it is....

As a side note, in Taruffi's excellent book on the technique of motor racing ( http://www.amazon.co...90513515&sr=8-1 ) he does note that when getting into an unfamiliar car you should check which pedal configuration is in use. :) He also talks about getting out of an F1 car in one configuration and into a sportscar with the opposite configuration and the risks of getting into a panic and stepping on the wrong pedal! The book also talks about heel and toe and has some diagrams showing ways to achieve this for different pedal configurations. Well worth a read if you don't already have it.

Rob

#69 Remco Hitman - guest

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Posted Nov 23 2010 - 06:05 AM

View PostBorder Reiver, on Nov 23 2010 - 06:02 AM, said:

As a side note, in Taruffi's excellent book on the technique of motor racing ( http://www.amazon.co...90513515&sr=8-1 ) he does note that when getting into an unfamiliar car you should check which pedal configuration is in use. :) He also talks about getting out of an F1 car in one configuration and into a sportscar with the opposite configuration and the risks of getting into a panic and stepping on the wrong pedal! The book also talks about heel and toe and has some diagrams showing ways to achieve this for different pedal configurations. Well worth a read if you don't already have it.

Rob


Fantastic little book! Recommended  :thumbup:


Also get the Skip Barber handbook: LINK

Edited by Remco Hitman, Nov 23 2010 - 06:08 AM.


#70 Lee200

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Posted Nov 23 2010 - 08:28 AM

I've got Skip Barber's book, "Going Faster", and reread the chapter on shifting.

He says that during downshifts, you can either select each gear in order OR skip a gear.  There are pros and cons to each method.

Skipping gears allows for more constant pressure on the brake pedal, but the downside is that it can throw off your timing for blipping the throttle to match the engine and transmission speeds.  In some race cars, it is sometimes impossible to downshift quickly enough through each gear as the car can decelerate so quickly using the brakes.

Skip is talking about modern race car transmissions that don't have synchronizers which probably are the same or similar to what they used in the '60s.

As Paddy mentioned, he also says that years ago, some race cars had the throttle pedal in the middle hence Taruffi's warning to figure out the pedals.  The clutch was on the left and the brake was on the right and were located higher than the throttle pedal.  To brake and downshift at the same time, you had to blip the throttle with your heel while braking with the toe/ball of the right foot.  This is where heel and toe came from.

With today's pedal arrangement, the heel and toe method is more like brake with the ball of the right foot and blip the throttle with the side of the foot.  So today the technique is more like ball and side.

Edited by Lee200, Nov 23 2010 - 08:51 AM.


#71 Akseli - guest

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Posted Nov 23 2010 - 10:40 AM

View Postzoic, on Nov 23 2010 - 02:34 AM, said:

View PostTvO, on Nov 22 2010 - 07:05 PM, said:

I can only think of two transmission manufacterers in 1967: Hewland and ZF. Perhaps one of the two allowed skipping gears?

:wave: Tommie.

Exactly the case, I remember reading in an article or from a documentary talk about some of the cars requiring to go thru each gear, while some others did not. But I can't for the life of me remember which of the cars were being talked about. I do remember Clark being talked about, so mayby it was Lotus vs other cars or the other way around.

Mayby somebody can find information which cars had the crash gearboxes?


PS. Looked around and the 5 speed ZF in the Lotus was synchronized, and the Hewlands were crash gearboxes(dog boxes).

The Internets said that Eagle and Brabham had Hewland DG 300 gearbox which I think is a dogbox. Ferrari had it's own gearbox and so did BRM. Cooper had ZF.

So it's not unrealistic not to use clutch in some of the cars ;)

#72 M Needforspeed

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Posted Dec 05 2010 - 04:21 PM

Lee

    I checked infos on the Chaparral gearbox, and crossed technical books and mags,thinking rather twice before posting this.


     Beginning by the end, for those who had doubt, the 2F selector wasn 't sequential.It was only a clutchless gear change system.

    Initially, the automatic transmission was a creation of Jerry Mrlik and Joe Kurleto of Chevrolet R & D.Under the control of Frank Winchell.This unit was installed in the Corvette GSII sport car GM project.The car had then been tested at the Midland rattlesnake track by Chaparral crew.
     Beside, it's clear that the Chaparral used the same half shaft than the GSIIB Chevrolet.Half shafts connected to differential by constant universal joints.At a time were cars fitted with high torque engines rather used Giubo joints, best suited for sudden torque changes.

  http://www.facebook....132382650133227

  
  Chaparral 2 A : Jim Hall " originally, the transmission that we used was a one speed with a hydraulic torque converter.The original unit had been mounted in the Chevrolet experimental GSIIb sport racing car that R D sent to midland for testing and evaluation in early 1964 and that was the transmission that we installed and that I used in the Chaparral 2 at Laguna Seca.By the fall of 1964, a two speed transmission was in use."
  
   It is stated that the system was itself inspired by the 1948 automatic transmission patent Dynaflow used by Buick.Inside the torque converter, this system incorporated two turbines but only a single stator, which resulted in a higher level of performance and greater efficiency of transmitted energy to the main drive shaft. Buick also incorporated variable-pitch stators in 1955 for improved flexibility.
    
    I have no infos if Chaparral used those variable-pitch stators.

    The Chaparral gearboxes didn't use a planetary gearset.Why ?

  
    In the sixties,planetary gearsets and bands were commonly used for automatic transmissions.But planetary gear trains had three disadvantages :
  
    - With a traditional epicyclic gearing ( one sun gear  + x planets + one ring gear fixed to the output shaft), you can only get two speeds + reverse speed.Getting 3 speeds on the Chaparral 2F wld have needed using more complex epicyclic gearing boxes, like Ravigneaux or Simpson systems.Ravigneaux compound planetary gear wld have lengthened the casing + adding some weight again.With the side effect to adding clutches and brakes.

Ravigneaux simplified mechanism :

Simpson simplifed mechanism :
  
    
    -The ring gear diameter length, that increase the dimension/weight of the casing.

    -Planetary gearsets systems use bands actionned by hydraulic pistons.Those bands acts as brakes, locking the ring gear, to ease gears change.With a high torque engine such the Chevrolet 427, bands or any other clutches system  wld have coped with high friction stresses.

    Instead, Chaparral 2D/2F gearboxes were simple devices without any planetary gearsets or bands.

     How the system was set to work ?

       Speeds were engaged by small diameter dog clutches, each with three bold dogs, designed to stay engaged until the throttle was released.The driver was told to get always the RPM over 5000 rpm, so the Torque converter could lock up rigidly to prevent further slip and power loss.This has certainly a relationship with the torque converter stator/turbines shape designed for the engine torque curve.(see the two Chevrolet 427 engine graphs below)
    
       So we can think, drivers selected gears change in the 5000 rpm range.
    
      But when changing gear, the driver had to ease the throttle to unload the dog and snatching the gearlever as quickly as he could.No planetary gearsets here, so gears change needed apprenticeship !


       Phil Hill : " I found the automatic transmission easy to adapt to break the habit of taking shifting for granted.Shifting the Chaparral automatics had to be well tuned.Get off the throttle, shift carefully, get back on the throttle.Any carelessness- remember there was no clutch- would result in eventually knocking the corners off the dog clutches, so that in long distance races the transmission would begin jumping out of gear and create a situation that would worsen until the car became undrivable "

       It therefore wasn 't really an "automatic" transmission,it was a fluid-clutch transmission.  

  
      So the Chaparral gear selector did not engage or disengage the actual gear teeth which were permanently meshed. Rather, the action of the gear selector was to lock one of the freely spinning gears to the shaft that runs through its hub. The shaft then spinned together with that gear. The output shaft's speed relative to the countershaft was determined by the ratio of the two gears: the one permanently attached to the countershaft, and that gear's mate which was now locked to the output shaft.
   Greater the engine torque was, the more was a chance sliding effects wld increase.The advantage of dog clutches is in the absence of sliding effects.
   Gear teeth were simple straight-cut spurs.those teeth shape ease the meshing and was largely used on non synchromesh sports cars.
  
     In the 2D two speed transaxle, the transmission's spur gears  were small in diameter and fine- pitched.Let 's suppose They were enlarged when going to the 2F / 3 gears.Looking at the differences in  the size of the gearboxes casing between 2D and 2F give some arguments...  
     Anyway,diameter are smaller than with friction clutches and no need to changes the clutches because of the friction wear.So both volume and weight of the transmission block casing can be lowered.

    We can remember than Chaparrals were rather lightweighted cars, and their gearboxes architecture played their part, here.


    A simplified cutaway drawing of the what can be Chaparral gearboxes show " the geared element of the transmission was a simple two-shaft all - indirect gearbox  with its speeds engaged by dog clutches on its input shaft.".but till today, Jim hall has never given any figures on the system.Secrecy is still the rule, 40 years after Chaparral final season.
    
    
    One of the reason is they became too much confident .When they designed spurs, seals and mainshaft, is they knew a well known effect of a fluid hydraulic  torque converter is absorbing vibrations and shock load from the engine.And for the 2D and 2F,compared with the 2A/2C the torque converter had evoluted in a stronger one. But the mainshaft and all the driveline components were lighter, because of the progress in metallurgy. But during 67 season, they couldn't handle the extra torque on longer races.
  Those stresses needed to put those parts on the Chevrolet R&D drawing board again, then machined and shipped to Germany.it is well what they did for Brands Hatch...and they won !

Troy Rogers about the Chaparral 2F : " there was little that could be done to make it more robust other than careful assembly and particuliar attention to the relevant seals and oil cooling" Apparently, the team that was based in Germany for the WSC season,couldn't do much more than using the same gears components, changing only seals and oil."
  
Troy Rogers " The only problem with the 2F was that with putting that big engine in,the gearbox couldn 't take it.We had troubles with seals, we had trouble with mainshafts- any numbers of problems.The gearbox was not designed for that much torque.There were new mainshafts, a new type of seals for the Brands Hatch race "

  Jim Hall about the 2F " we had known about the gearbox problem early in the season.But it took time to redesign the components and get them machined "

  More generally, it is therefore logical that it was at racing tracks with chicanes, like the one they added at Monza,or after the banking connecting to the road course at Daytona, or Sebring hairpin that the car was more inclined to have gearboxes problems.


  Bruce Jennings at Sebring 1966 race: " the automatic transmission was fantastic.it was very easy to operate and it was a real plus factor, because you could concentrate on driving, not shifting "
    


  

   Hulme about the Can Am Chaparrals : " the best way to beat the Chaparral was always to beat it off the line, because its auto gearbox always gave us that little initial edge "


        2F DNF related to transmission problems :
  

        2 F at daytona 67 : First time that the automatic gearbox was dismantled in the pits, to everybody eyes.
        2 F : Monza 1967 : after less than an hour, a driveshaft coupling failed "
        2 F : Le Mans : " seals between the torque converter and gearbox had failed "

  I joined two graphics about some 427 ci V8 Chevrolet engine numbers.As we can see,the power curve got a sudden increase at 5000 Rpm.This wld cross the infos about the drivers gearing at that RPM.
  That' s well here that the engine torque decreased.So shifting at 5000 RPM wld give a double advantage :
  -decreasing the mechanical stresses on the input and output shafts, because of the lower torque
  -upshifting always with  the power on the increasing curve


  I will control now, if the GT mod Chaparrals AI's are really shifting around those 5000 rpm ! :P

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Edited by M Needforspeed, Dec 06 2010 - 06:28 AM.


#73 Paddy the Irishman

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Posted Dec 06 2010 - 04:20 AM

What an interesting post.  Thank you very much NeedforSpeed.

In addition to the direct knowledge about the Chapparal transmission you have enlightened me with the information that when I talk about the 'doughnuts' (Am. donuts) on various Lotus cars, I should really say "giubos".  

That'll fix the pundits  :D

Now to try upshifts on the Chapps at 5000rpm....

#74 M Needforspeed

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Posted Dec 06 2010 - 06:06 AM

thks Paddy .You are welcome..

I forgot  the animation for the Simpson system.It is only a Ravigneaux patent variant .Here one :


Edited by M Needforspeed, Dec 06 2010 - 06:31 AM.


#75 richard cooke

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Posted Dec 06 2010 - 06:14 AM

View PostPaddy the Irishman, on Dec 06 2010 - 04:20 AM, said:

Now to try upshifts on the Chapps at 5000rpm....
I thought the info says stay above 5000rpm, not shift at 5000  :)

#76 M Needforspeed

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Posted Dec 06 2010 - 06:39 AM

all that 5000 Rpm affair explains why in pits, the Chaparral drivers kept the foot on the brake pedal.At 5000 RPM, the torque converter wld have blocked the turbine output firmly, and the car train would have moved.In order to keep simplicity at max, there was no way to stay in neutral gear.  
   With a planetary gearset,keeping the sliding shaft in neutral wld have been easier to put inside the system.

   But at the start of the race, competitors that could revs at 6500/7000 Rpm  got clearly an advantage over the Chaparrals car.That's what Denis Hulme says,in his own words.The 427 was also used by Jim Hall 2G  on the 1967 Can Am races.

Edited by M Needforspeed, Dec 06 2010 - 06:44 AM.


#77 Paddy the Irishman

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Posted Dec 06 2010 - 07:04 AM

View Postrichard cooke, on Dec 06 2010 - 06:14 AM, said:

View PostPaddy the Irishman, on Dec 06 2010 - 04:20 AM, said:

Now to try upshifts on the Chapps at 5000rpm....
I thought the info says stay above 5000rpm, not shift at 5000  :)
:oops: You're right Richard, and there was I thinking that I might have found an advantage  :idunno:  :unsure:

#78 Lee200

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Posted Dec 06 2010 - 08:26 AM

View PostM Needforspeed, on Dec 05 2010 - 04:21 PM, said:


    I checked infos on the Chaparral gearbox, and crossed technical books and mags,thinking rather twice before posting this.


     Beginning by the end, for those who had doubt, [u][b]the 2F selector wasn 't sequential.It was only a clutchless gear change system......


Hi Marcel and thanks for all this great information on the Chappie's "mystery transmission". :bigclap:

This agrees with the limited information we had at the time about the torque converter and how it worked.  So the sports cars are modeled pretty well IMHO.

The only area that I'm a little sceptical about are the torque and horsepower curve charts.  The 427 engine is shown producing about 580 horsepower which I believe is optimistic.  In 1966, Ford tested a single overhead cam version of their 427 engine that produced 575 horsepower, but they never used it and stuck with the familiar pushrod design which produced 500 to 525 horsepower depending on which source you read.  I suspect the Chappie's Chevrolet 427 engine was similar and AFAIK, it used pushrods too.  So that's why we used 525 horsepower as the base power for that engine.

Of course, to simulate a torque converter in GPL, the only way is to artificially use a lower power engine which is what we did.  On average, the Chappie 2D and 2F engine was tweaked to be about 80% efficient to account for the torque converter.

In one of your pictures, the torque converter is clearly shown.

FYI, here are my notes about how torque converters work.

--------------------------------------------------------------------

Here are some notes on torque converters and how to simulate them in GPL.

A torque converter is a fluid coupling designed so that it can also act as a torque multiplier.  The engine output shaft is connected directly to a rotor, called the impeller, and a second rotor, called the turbine, is connected directly to the transmission input shaft.  Normally the two rotors are not physically connected and transmission fluid/oil is used to transmit the force from the impeller to the turbine.

When the two rotors are not physically connected, they are free to rotate at different speeds.  The ratio of the turbine to impeller speeds is usually noted as V. V will vary from 0 when the turbine is not turning at all to 1.00 when the turbine and impeller speeds are the same.

The "stall speed" is defined as being V=0 and really has nothing to do with engine speed.  It is simply the point where the turbine is not turning.  Above the stall speed, the turbine turns and transmits torque to the gears.  Passenger car torque converters are designed so that the engine can idle and not produce car motion; especially with the brakes applied.  Racing torque converters are designed to have a stall speed that matches the engine's maximum torque rpm to produce maximum car acceleration.

At stall speed, the torque converter multiplies input torque by a factor of around 1.5 to 2.5 times.  This multiplication factor decreases in a linear fashion with V and can go below 1.0 when V=1.00.  Obviously, this is inefficient and passenger car torque converters have a mechanical clutch that activates around V=.90 which physically locks the impeller and turbine together so they rotate at the same speed.  This immediately causes V to be 1.00 and torque multiplication to remain constant at 1.0.

The efficiency of a torque converter is measured as the ratio of output to input torque taking into account the torque multiplier effect.  It is parabolically shaped, beginning at 0% at stall speed, rising to a maximum around 80% when V=.80 and decreasing as V increases to 1.00.  If a mechanical clutch is fitted and engaged, the efficiency increases linearly from that point until it reaches 97% to 100% when V=1.00.

My research has turned up very little information on maximum torque converter efficiency before clutch engagement, but the few data I've seen show maximum efficiency between 75% to 90%.  Close to maximum efficiency occurs over a fairly wide V range of .40 to .90.

The multiplier effect and efficiency probably vary depending on the input torque and impeller speed which are directly related to the engine.  However, the only data I've seen and this discussion are based on a constant input torque and impeller speed.

For GPL, we don't have code to create a torque converter so the only way to simulate it is to modify the engine BMEP/torque curve and/or the engine's capacity so that less torque gets to the gearbox. Assuming a racing engine is usually accelerating or decelerating, we could also assume that the torque converter's V will typically be somewhere around .50 where efficiency is only slighlty less than maximum due to the relatively level shape of the parabolic curve at that point.

For the Chapparal 7.0L engine, Richard used an average of about 81% efficiency in the high rpm range where a racing engine normally operates which seems reasonable.

The Chaparral had what was considered at the time to be a "mystery" transmission.  From my research today, it seems this was a torque converter coupled to a normal three speed manual transmission.  I've found no data on the torque converter's efficiency or whether Chaparral used a clutch to couple the impeller and turbine rotors.  I doubt they bothered with an impeller/turbine clutch as a racing torque converter is rarely at V=1.00 where the clutch could enhance efficiency.  Also, one source says that Chevrolet didn't introduce the lockup clutch on their torque converters until 1979 so it's doubtful that the Chaparral had one.

Although less efficient than a manual clutch, the torque converter allowed Chaparral to do away with the clutch pedal and thus gave the driver the ability to operate the movable wing with his left foot instead.  Obviously, Jim Hall thought the gain from the wing outweighed the loss from the torque converter.

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Edited by Lee200, Dec 06 2010 - 08:33 AM.


#79 sky

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Posted Dec 06 2010 - 08:52 AM

lee,

i was thinking the same about the engine power output, but it might be 525bhp at the wheels compared to idk 580 at the crank or wherever else they measure? one of those common misunderstandings... ?

#80 Lee200

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Posted Dec 06 2010 - 09:06 AM

View Postsky, on Dec 06 2010 - 08:52 AM, said:

lee,

i was thinking the same about the engine power output, but it might be 525bhp at the wheels compared to idk 580 at the crank or wherever else they measure? one of those common misunderstandings... ?

Yes, you could be right Roman.  There are all sorts of ways of measuring horsepower.  The horsepower curves we have for the Ford are engine horsepower though; not at the wheels.

Until the large 7.0L engines were banned for 1968, Ford was working on this monster which used two camshafts with pushrods and reportedly produced 630 horsepower:

http://srmz.net/inde...6254&qpid=56168

By pure coincidence, one of the Ford dyno technicians from the '60s lives near me and he told me the Calliope engine was worthless as the intake systems didn't allow the power to be modulated well.  It was pretty much 0 horsepower or 630 horsepower.  Try driving that   :o

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Edited by Lee200, Dec 06 2010 - 09:19 AM.





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