700 nm of torque out of a vt ss

[farnzie97]

hey everyone,
well today was the big day i picked up my Vt ss series 2 m6.
it had an ls1 edit done, i didn't really no what to expect but what i got was
awesome, the boys down at aps in frankston really no whatthere doing, i ended up with 701 nm of torque, and with 231.9 rwkw. i nearly fell over when i read my dyno sheet.
i would recommend aps to anyone that is going to get this done.
cheers.

[planetdavo]

Unless you have a big blower hanging off the engine, I'd take 701Nm with a (cough) grain of salt.
There's no way an "edit" alone could come remotely near that figure.

[SICK SS]

i think your confused with tractive effort. Unless your runing some type of FI you dont hav that much torque

[JimmyXR6T04]

i agree with the other blokes.. although you never know. In saying that, my XR6T has some where around 700-850Nm and 304rwkw. But it's impossible to tell when they use tractive effort.

Post up your dyno sheet mate, and i'm sure you'll get all the help ya need here :thumbsup:

[stig]

Have a look at my Dyno sheet from APS has similar figures of 770+nm. But as said above this is not a correct reflection of what your cars torque reading is.

Dyno Sheet (http://www.ls1.com.au/forum/showpost.php?p=850627&postcount=7)

Mine's more like 650nm in relation to the figures you'll see on Holdens website. So your's would be closer to say 550-600, at a guess?

stig

[HeathLS2]

From what i belive, as a rule of thumb you actualy lose 1/3 kw at the rear wheels but you actually gain about 1/3 Nm at the rear wheels because of your extra mechanical drive eg. gearbox and diff

[chevypower]

From what i belive, as a rule of thumb you actualy lose 1/3 kw at the rear wheels but you actually gain about 1/3 Nm at the rear wheels because of your extra mechanical drive eg. gearbox and diff

Torque at the wheels varies depending what gear you are in, obviously in first gear, there is a crap load more torque at the wheels than in 6th gear

[planetdavo]

Torque at the wheels varies depending what gear you are in, obviously in first gear, there is a crap load more torque at the wheels than in 6th gear
Possibly a good example here for all the people that like to "brag" about their power outputs.
A chassis dyno should be used to compare before/after outputs when modifying/tuning, not as a means of comparing their cars to a factory Holden/HSV's FLYWHEEL kW's or to other people that say they have 2 million rwhp or whatever....

[LSX-438]

I wish someone could adequately explain (in simple language) the wild variance we see in torque numbers across different dynos . Yeah sure dynos are for tuning etc. etc. etc., but horsepower seems at least remotely comparable.... as for torque, some of the numbers i see are rather huge.

Is that supposed to be 700Nm at the treads? that would make it like 850Nm at the engine right?

[Plan B]

I wish someone could adequately explain (in simple language) the wild variance we see in torque numbers across different dynos . Yeah sure dynos are for tuning etc. etc. etc., but horsepower seems at least remotely comparable.... as for torque, some of the numbers i see are rather huge.

Is that supposed to be 700Nm at the treads? that would make it like 850Nm at the engine right?


It's geared.... So when measuring torque; 1st gear to 6th gear would be just as different as a final drive ratio or tyre size... But the HP should always be the same. That's my simple take on it but Todd from Mainline would know the exact science. :)

[Oztrack Tuning]

Dyno operators can on a Mainline Dyno use Derived Torque which levels out the playing field. But most choose to use wheel torque which is a result of gearing, tyre size and roller size.

To compare torque you need to stay on the same dyno and use the same tyres and do the run in the same gear. Even then most of the time the plot is kph vs Nm.

[ExAreSix]

Best way to figure out torque is to calculate it yourself.

BUT, there's a bit of guesstimation to begin with...

231kw atw is 309HP. So, I guesstimate a flywheel figure of 310kw, or thereabouts.
Now, where was this peak power made? Not real sure of a typical LS1's peak power rpm, but a guess at around 5000rpm??

So, using these figures of 310Kw/415HP @ 5000rpm.
We can calculate the figure (use google to find the equation, I'm not doing everything for you guys) we get a figure of 435 foot pounds of torque. Which equals 590Nm.

Standard car 220kw/446Nm
Edited Car 310kw/590Nm

I'll let you guys calculate the percentage increase, but it should add up...

[farnzie97]

hey
sorry about this post people, when i started it i wasn't trying to compare anything i was just posting my results from my dyno cause i couldn't believe them myself,
ill put my dyno sheet up tomorrow,
cheers.
sorry about the **** up my mistake.

[chevypower]

I wish someone could adequately explain (in simple language) the wild variance we see in torque numbers across different dynos . Yeah sure dynos are for tuning etc. etc. etc., but horsepower seems at least remotely comparable.... as for torque, some of the numbers i see are rather huge.

Is that supposed to be 700Nm at the treads? that would make it like 850Nm at the engine right?

incorrect. Simple analogy, when your turning a nut with a spanner, lets say the spanner length is 1 metre, and you apply 1 Newton of force (which is similar to weight), you will have 1Nm of torque to undo the nut. If you extend the handle length to 2 metres, but still only apply 1 Newton of force, you have 2Nm of torque. Think of that on the engine now, the engine putting out the same torque, regardless of the gear the car is in. But in 1st gear, the engine will have greater leverage on the axle, which means more torque at the wheels. 1st will give the engine the advantage over the wheels, and there is more torque at the wheels than at the engine, 6th gear there will be less at the wheels than at the engine. Think of gear ratios, as torque ratios.

[Plan B]

hey
sorry about this post people, when i started it i wasn't trying to compare anything i was just posting my results from my dyno cause i couldn't believe them myself,
ill put my dyno sheet up tomorrow,
cheers.
sorry about the **** up my mistake.

Mate, you have put a good question forward..... Everyone needs to understand stuff....

Good question I say! Let's hear the answers from people in the know. :)

[SICK SS]

hey everyone,
well today was the big day i picked up my Vt ss series 2 m6.
it had an ls1 edit done, i didn't really no what to expect but what i got was
awesome, the boys down at aps in frankston really no whatthere doing, i ended up with 701 nm of torque, and with 231.9 rwkw. i nearly fell over when i read my dyno sheet.
i would recommend aps to anyone that is going to get this done.
cheers.

it was stated 231.9rwkw and 701Nm i myself was asuming the torque was im rear wheel torque as was the 231.9 rwkw was.

[awddynotodd]

Dyno Torque Figures – the truth.

I’ll go over this once more, as previously I have explained it on several occasions, but here it goes. (Maybe the Mods might make it a sticky)

On the styles of Chassis Dyno’s we see here in Australia, for example a Mainline Dynolog or a Dyno Dynamics, both of these dyno’s, calculate power at the roller in the same fashion. That is, we measure Roller RPM and Roller Torque and these 2 variables are used in the traditional Power calculation formula, either metric or imperial, you get the same result:

HP (@ roller) = (roller torque ft/lbs x roller rpm)/5252

Or

kW (@ roller) = (roller torque Nm x roller rpm)/9543

When the term Roller Torque is used, this means we are measuring Torque from a Load Cell that is attached in some fashion to the Retarder (Eddy Current Retarder/PAU) that is coupled to the Drive Rollers (the knurled rollers). The Retarder applies a braking force to the Rollers, and since the Retarder Frame is restrained from turning by the Load Cell, the force is transferred into the Load Cell which measures force in typically Kg or Pounds force. The length of the arm the Load Cell is attached to is precisely known, so with force over a given length we can determine Nm or Ft/lbs.

Roller RPM is usually measured by an Inductive speed sensor of some type, or a Shaft Encoder, or in the old days on a Vane Dyno, a Tacho generator.

These 2 inputs are used by the Dynamometer Control System to calculate the Power.

Now, because we measure Torque down in the Dyno bed from a device that is coupled to the Roller, ANY gear multiplication, or gear reduction, will influence the Torque measured at the Roller. So some variances that come into the equation are:

Torque Converter slip ratio
Transmission ratio
Differential ratio
Tyre size
Roller size

These variables all influence the Torque as measured at the roller.

Some people will then initially think, the lower the gear, the more Torque, so the more Power we will make, THIS IS NOT TRUE.

Remember the formula for calculating Power, we have Torque AND RPM, so if we use a lower gear ratio, the corresponding RPM will be reduced by the same factor as the Torque is increased, so we end up with the same power. This is a purely mathematical explanation.
The reason some of the confusion happens in regards to Torque (roller torque) on a Chassis Dyno, is there are 2 common sizes of rollers used on dyno’s here in Australia, those being 219mm or 273mm (these are raw, unmachined sizes).

The larger diameter roller will have a higher Torque reading at a given Road Speed, but have a corresponding lower RPM, the torque value increase will be the difference in Roller Diameter, I’ve done the maths for you, the 273mm roller will have 24.6% more torque. What this means is, a particular car may have 200RWKW, but it may have 500Nm on a 219mm roller, but 623Nm on a 273mm roller.

We now need to understand the Torque that gets to the roller, and why it is normally higher than at the Crank. Remember I listed all the things that will influence the Torque at the Roller, Gearbox Ratio, Diff Ratio, Tyre size etc. If I simplify it somewhat, we’ll use a gearbox ratio of 1:1 in the following example, I also am not accounting for driveline loss in this example.

Take a traditional LS1, a torque figure of 530Nm is quoted at the crank. If the Gearbox Ratio is 1:1, so we have 530Nm going into the diff, now if we have a diff ratio of 3.46:1 (this is a gear multiplication), we then have 1833Nm at the axles. (Those that have had their cars dyno’d on a Dyna Pack Hub Dyno will be accustomed to these numbers). The next step in the Torque journey is the Tyre to Roller ratio.
This is where the Dyno Roller size will affect this value. If we transfer the 1833 axle Nm thru a 650mm tyre to a 219mm roller (this is now a Gear Reduction), this ratio is 1:2.968, so we divide our 1833 by 2.968, gives us 617.58Nm on a 219mm Roller.
In the case of a 273mm Roller, our ratio is 650/273 = 2.3809, so we divide the 1833 axle Nm by 2.3809 giving us 769.87Nm roller Torque on our 273mm roller.
Remember the larger roller will be doing less rpm at a given road speed, so the same power will be present.

To simplify this somewhat, both Dyno manufacturers have a term that makes the differences in Roller sizes a non issue, this term is Motive Force on a Mainline Dynolog, or Tractive effort on a Dyno Dynamics. Motive Force/Tractive Effort is a Calculation (this is where some dyno operators get it wrong, they believe the dyno measures Tractive effort).
Motive Force/Tractive Effort is calculated as such, Roller Torque/Roller Radius, so in our example above, we have 617.58Nm/0.1095metres (radius or 219mm roller) giving us 5640 Newtons (not Newton Metres, Newtons are a linear force, Newton Metres are a twisting Force). On our large roller, we have 769.87Nm/0.1365 giving us 5640 Newtons.

Putting this into context for this thread, APS Service Centre’s dyno has 273mm rollers, so their Roller Torque figures will be approx 24.6% higher than say Sonny’s dyno, because Sonny has 219mm Rollers in his dyno, but both dyno’s would show the same Power and Motive Force.

In order to simplfy the Torque values even further, both Dyno Manufactures have what we term “Derived Torque”, which is a calculated value based of RWKW and Engine RPM, this calculated “Derived Torque” takes any gear multiplication out of the equation, so one very good way of using Derived Torque is, if you have a particular car that had 3.46 diff gears, and has now been changed to 3.7, the Derived Torque value will not be affected, whereas the Roller Torque will, due to the fact the overall gearing of the car has changed.

Derived Torque numbers will be basically your Engine Torque minus Driveline Torque loss, so owners of cars who get a Dyno Printout can more easily come to terms with Derived torque, as they accept that Torque at the wheels will be lower than at the engine, (Derived Torque is a bit of window dressing, or dumbing it down).

On a Mainline Dynolog, the user has 3 available RPM signals available to the software for it to Calculate the Derived Torque, Tacho RPM (ie HT lead, injector trigger etc), OBDII Tacho RPM, or lastly Derived RPM from the Roller Speed. The first 2 options will provide very accurate Derived Torque values, whereas using Derived RPM (which is based on a ratio of vehicle dashboard tacho against roller speed), will not be very accurate on a Automatic car due to the varying slip ratio of a torque convertor, but will be accurate at whatever point the Derived RPM figure was set. Dyno Dynamics also have a version of Derived Torque, I believe it is just called RWNm or just Torque Nm on a Graph when printed, I’m also led to believe that the DD version also only uses a derived RPM number for the Derived Torque, not an actual true Engine RPM value, but I could be wrong, and if someone can clarify this, I’m happy to be corrected.

While I suggest to users of our system to use Derived Torque on Reports given to customers, they can do as they please, and a lot just use Roller Torque. It only takes a few seconds to choose to display Derived Torque. All of our reports do report Motive Force though, so for a comparative point of view to a Dyno Dynamics Graph, compare the Tractive Effort to Motive Force on a Mainline Dynolog.

Now a something to remember, the Motive Force or Torque, has the exact same shape curve when compared on a similar Graph Scale.

Another benefit of displaying Derived Torque, if you are a Horsepower and Foot Pounds of Torque junky, instead of kW and Nm, the Derived Torque and Horsepower will cross at 5252rpm, (just like it does on an Engine Dyno).

Below are a couple of Graphs showing the differing ways in which Torque/Derived Torque/Motive is displayed on our system.

Power and Roller Torque:
http://users.tpg.com.au/adslmqf3/dyno_graphs/roller torque.jpg

Power and Derived Torque
http://users.tpg.com.au/adslmqf3/dyno_graphs/derived torque.jpg

HP and Ft/lbs
http://users.tpg.com.au/adslmqf3/dyno_graphs/hp tq.jpg

Torque Only
http://users.tpg.com.au/adslmqf3/dyno_graphs/torque only.jpg

Motive Force Only
http://users.tpg.com.au/adslmqf3/dyno_graphs/motive force only.jpg

Hope this helps.

[stig]

What he said! ^^^^^

[Holden Man]

I vote post #17 as the longest I have ever seen !

(very helpful though ;) )

[Snapper]

Where is the thank you button.

A lot of effort / time and great information in that.

[farnzie97]

hey people.
wow that was the longest post i have ever seen!!!
anyway, here is my dyno sheet if you wanna look at it,
cheershttp://i155.photobucket.com/albums/s312/farnzie97/bend.jpg

[Oztrack Tuning]

Todd
I recently saw a car (A4/3.07) on a Mainline Dyno do the following.
It made peak power at about 250kph and at 153kph and in both situations indicated similar rpm. BUT the power was higher in 2nd gear by about 15rwkw.

Is this because of efficiency losses in the A4 at that speed or wheel slip at the high speed required to rev it out in 3rd gear as opposed to 2nd.
The afrs were the same and so was the timing. But the ramp rate was higher in 2nd gear.

There has to be a heap more friction at 250kph than at 153kph.

[B-REX]

Accelerating a mass at a slower rate will draw less power from the car.
Accelerating the roller to 50 kmh in two seconds for example will give a higher final dyno reading than acceleration the roller to 120 kmh in two seconds.

[awddynotodd]

Todd
I recently saw a car (A4/3.07) on a Mainline Dyno do the following.
It made peak power at about 250kph and at 153kph and in both situations indicated similar rpm. BUT the power was higher in 2nd gear by about 15rwkw.

Is this because of efficiency losses in the A4 at that speed or wheel slip at the high speed required to rev it out in 3rd gear as opposed to 2nd.
The afrs were the same and so was the timing. But the ramp rate was higher in 2nd gear.

There has to be a heap more friction at 250kph than at 153kph.

It wouldn't of been 250kph Steve, probably 205, as our dyno's only go to 240KPH.

Something with that high gearing can suffer at lower power levels. There are things like windage losses to consider with higher road speed.
Being an auto, there is also the Torque Convertor to consider and how it will react to various gear ratios and load applied to it.
If you used a very slow ramp rate in 3rd, it would of made the same power, the inertial losses of the vehicle aren't as big a factor at slower acceleration rates. The more powerful the car, the less impact the inertial losses are.
If you get a chance, hold the car at WOT at 6000RPM in 2nd and then in 3rd @6000RPM and see if the 15KW difference is still there.

[ratter]

After reading Todds explanation and his willingness to sit down and type that sort of info, I'm glad I bought a mainline

[Oztrack Tuning]

The scan logs said 253kph but yes it would have been less than that on the rollers and a bit under 240kph. 6700rpm in a 3.07 in 3rd. Cammed LS1

[CV860L]

I was just about to post my own way of working it out but it seems Todd beat me to it.....my answer was going to be very similar :lmao: :lmao: yeah right.
Excellent explanation, no wonder quoted torque figures are all over the place.
Now I know why the explanations I have got in the past leave me scratching my head.
Thanks.

[Oztrack Tuning]

On the same dyno cars with the same gearing and in the same gear can be compared in Torque. But you need to assume the same amount of tyre slip.

[Plan B]

After reading Todds explanation and his willingness to sit down and type that sort of info, I'm glad I bought a mainline

I bet!

Isn't it funny how you'll see most of the well known tuners use this equipment.

[pagey]

To simplify this somewhat

Thank god you simplified it.. :idea:

[BlueVZSS]

Great post.

Let me see if I have this correct....drive car onto dyno...try to make car go very fast while going nowhere......a miracle occurs and a chart is printed.