Page 2 of 3
Posted: Sun Jan 28, 2007 9:39 pm
by khunjeng
spetz wrote:Torque at the wheels mean nothing
My friends 3L Magna with slight mods makes 600 something
Get bigger/heavier wheels and this goes up, too many issues
torque at the wheels means nothing. really. So when does it matter?
do u know how both hub or roller dynos work? tyres and width will make the biggest difference on a roller dyno. doubt its given +400nm though.
I would suggest they ran it up on 1st or 2nd gear lol that would give some big numbers or used some super thin typres on a roller dyno.
Use a hub dyno...more consistant and get rid of the tyre slip component.
In summary, Torque atw is useful. However if your setup is crap and your tuner has no idea, then yes, might be a waste of time.
I have seen heaps of roller dynos work fine and give expected results.
Posted: Sun Jan 28, 2007 9:39 pm
by khunjeng
double post.
Posted: Sun Jan 28, 2007 11:49 pm
by FTEvolution
khunjeng wrote:I'm getting close to 500....u tell me which one cains at the lights...
Exactly, I am still yet to Dyno mine, but as said above, I realy don't care for a power reading, I want to know the torque, once I know that I will begin to modify the car to broaden the torque range and of course increase it. I want a nice big power band to operate in.
Posted: Mon Jan 29, 2007 7:15 am
by khunjeng
FTEvolution wrote:khunjeng wrote:I'm getting close to 500....u tell me which one cains at the lights...
Exactly, I am still yet to Dyno mine, but as said above, I realy don't care for a power reading, I want to know the torque, once I know that I will begin to modify the car to broaden the torque range and of course increase it. I want a nice big power band to operate in.
go for it! as we know so well, more torque equals more fun...
Posted: Mon Jan 29, 2007 1:37 pm
by spetz
There are way too many variables that determine what nm at the wheels you get
And the inconsistency between dyno's when it comes to torque is much greater than when measuring kw
So basically because these numbers are so all over the place (from running different wheels, etc, and dyno differences) this doesn't mean much
With kw atw you could calculate within some reasonable figure the power at the engine you make, with torque there isn't really a way
In reality, you can get a higher torque at the wheels with a car that actually makes less torque due to so many variables
And besides, isn't torque at the wheels basically tractive effort or something?
Posted: Mon Jan 29, 2007 3:06 pm
by khunjeng
spetz wrote:There are way too many variables that determine what nm at the wheels you get
And the inconsistency between dyno's when it comes to torque is much greater than when measuring kw
So basically because these numbers are so all over the place (from running different wheels, etc, and dyno differences) this doesn't mean much
With kw atw you could calculate within some reasonable figure the power at the engine you make, with torque there isn't really a way
In reality, you can get a higher torque at the wheels with a car that actually makes less torque due to so many variables
And besides, isn't torque at the wheels basically tractive effort or something?
lol no comment see above.
Posted: Tue Jan 30, 2007 12:43 am
by spetz
Does this mean I win???

Posted: Tue Jan 30, 2007 8:30 pm
by khunjeng
spetz wrote:Does this mean I win???

no. Depends on the type of dyno and the scale used to measure.
Only torque and speed can be measured; Power must be calculated from the torque and speed figures according to the formula
KW = Torque x RPM / 9549
Most dynos work on the principle of measuring torque. However some do it though acceleration.
some dynos require you to make some assumptions about the relationship between speed and RPM. If you have a manual transmission it is possible to correlate these pretty well but if you are running an automatic the results will have errors since the convertor slip changes with load and RPM.
Chassis dyno have the issue of tractive effort at the wheels. hub dyno will eliminaites this inertia issues and measure torque "at the wheels" consistantly (to get Flywheel torque simply divide the figure by the final drive ratio, often a number close to 4)
The tractive effort is obtained by multiplying the torque by the total ratio of power train and dividing this some by the rolling radius of the driving tyres.
+/- 10% is a good factor when talking dyno inaccuracy not +/- 300nm.
As u can see, many different issues. One dyno run by your mate is by no means the whole story.
With a proper setup, u can get good figures useful for tuning.
Posted: Sun Feb 04, 2007 8:39 pm
by khunjeng
update on this, the formula above will calulate flywheel torque....however still applies.
Multiply this by the final drive and you will get your at the wheels torque.
This is why your mates maga will have big values. Say the final drive is 4.1 and the fly torque is roughly 200nm...then its gonna be like 800nm at the wheels....
Sorry didn't make that clear.
Some dynos will do thsi for u, all calculate the fly figure or give your tractive effort...all are related.
Posted: Tue Feb 06, 2007 2:14 am
by spetz
Yeah I know but you see because heavier wheels, wider tyres and all those things change this figure so much, that's why I don't see it being that relevant
Posted: Tue Feb 06, 2007 7:52 am
by khunjeng
spetz wrote:Yeah I know but you see because heavier wheels, wider tyres and all those things change this figure so much, that's why I don't see it being that relevant
depends on dyno mate as said before hub or inertia/roller. In reality if your using a heavy wheel/tyre then in the real world you are also. So its reflective of your real world scenario so whats your point? When you calculate back to Flywheel torque..the difference will be small.
tested numerous cars of which were in stock condition. the dyno produced numbers VERY close (within 2 kw) to stock specifications. They were setup properly on a roller with correct weight etc entered.
also might be good to understand what you are measuring or what the numbers on your graph are representing as this helps, its not obvious in many cases.
Finally you need to take a few runs and take the average. Many ppl have done it.
Posted: Tue Feb 06, 2007 10:33 am
by Delvance
I don't see why a GPX would have a problem against a stockish wrx ? The winner from that will depend on launch and shifting (well, driver i guess).
And i would happily take the 6a12 mivec over a turbo motor. Much nicer power delivery in terms of no sudden power/torque climb and still has enough torque for me to poodle around in 4th or 5th.
Posted: Tue Feb 06, 2007 11:03 am
by Bennoz
Delvance wrote:I don't see why a GPX would have a problem against a stockish wrx ?
I do. I eat GPXs for breakfast & WRXs eat me for breakfast.... an extra 75 odd N/m of torque is the difference.
Posted: Tue Feb 06, 2007 2:39 pm
by khunjeng
Delvance wrote:I don't see why a GPX would have a problem against a stockish wrx ? The winner from that will depend on launch and shifting (well, driver i guess).
And i would happily take the 6a12 mivec over a turbo motor. Much nicer power delivery in terms of no sudden power/torque climb and still has enough torque for me to poodle around in 4th or 5th.
LOL
race one and find out.
Posted: Tue Feb 06, 2007 4:22 pm
by Delvance
Lol, i wouldn't have commented if i hadn't done it before...more than once against the person that taught me manual. Although come to think of it, his is a wagon, has his tools for work in the back and he's a big tall fella while my manny gpx is empty with no spare or tools. 1st and 2nd gear, he pulled ahead by a panel or so, 3rd gear i cleared him.
The above was done in a safe proper place, and i do not condone street racing.
Posted: Tue Feb 06, 2007 4:29 pm
by khunjeng
Delvance wrote:Lol, i wouldn't have commented if i hadn't done it before...more than once against the person that taught me manual. Although come to think of it, his is a wagon, has his tools for work in the back and he's a big tall fella while my manny gpx is empty with no spare or tools. 1st and 2nd gear, he pulled ahead by a panel or so, 3rd gear i cleared him.
The above was done in a safe proper place, and i do not condone street racing.
RX maybe...not WRX. You ave no hope if he is driving normally or unless he totally misses a gear. Even with some tools in the back.
I have driven a few stock WRXs and they cain my GPX. And I probbaly have a bit more power than you.
Posted: Tue Feb 06, 2007 4:38 pm
by Delvance
02 WRX awd wagon. He's my bestmate, know exactly what car and mods he has. He didn't miss a gear/mishift.
They are around 1300kg...tools put it to 1400 at least, then driver...say 1500 kg on the wrx with only volt stabiliser earh kit, iridiums and a muffler.
Manny gpx...say 1170 (bearing in mind i have no tools or spare), with me in it. 1240kg. Has a hks mushroom, heatshield and insulated intake pipe.
Fair bit of difference in weight for around 10kw and 80nm to beat ?
Anyways, it was done more than once because we were like WTF and the result was the same.
Edit - but yeah, i believe that a stock wrx would pull ahead of a manual gpx slightly, not going to be shamed though ? *shrugs*
Posted: Tue Feb 06, 2007 5:32 pm
by khunjeng
Minus 100kg of tools in a comparision...
Its still a faster car by over 1s as 0-100 so that tells the story. So do the Qmile times. 4wd makes a big difference, FWD is kinda limted.
Most ppl have beat beaten hands down by most WRXs.
Spend 1k and he will be another 1s faster again...
Posted: Tue Feb 06, 2007 6:16 pm
by oodLes
Completely out of nowhere here, but I think the FTO has great power for its setup. You don't want much more than around 220hp through the fronts otherwise you're going to have a lot of fun launching the sucker and suddenly being in the left or right lanes, neither of which was your choice.
Its another reason I went with the FTO, its such a well rounded package of a car.
Posted: Tue Feb 06, 2007 8:01 pm
by Delvance
oodLes wrote:Completely out of nowhere here, but I think the FTO has great power for its setup. You don't want much more than around 220hp through the fronts otherwise you're going to have a lot of fun launching the sucker and suddenly being in the left or right lanes, neither of which was your choice.
Its another reason I went with the FTO, its such a well rounded package of a car.
+1
When i bought my FTO, i still had extra cash. Could've easily went for a turbo or more powerful car, but the FTO is such a well rounded package. Only downside is insuring it! It's great how so many people underestimate it as well. Older V8's have been put to shame, as well as some turbos. Put some twisties into the equation and suddenly cars with a lot more power begin to worry.
Desperately want to get an lsd for mine hehe.