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Old 01-05-2013, 10:56 PM   #26
BlazeRex
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Originally Posted by ProfessWRX View Post
Seems like you haven't done a lot of things.

Why don't manual guys slip the clutch on dynos?

How does a dyno calculate torque? Does it use rpm? What happens if the Rpms are not directly connected to the drivetrain rotation?
Lol and you know everything I understand what you are saying, and it applies 100% if you are using a road dyno software. If you're measuring RPM accel vs. time NOT roll speed accel vs. time, slipping the clutch would net big numbers. Usually, like Airboy says, without a rpm pickup, you use a function called "calculate from roll speed" to estimate RPMs. If you're simply measuring torque output without a direct RPM signal to the dyno, slipping the clutch would just drop power, and kill your clutch. I'm not really sure where you're going with this.

I can tell you though, the auto has much more torque in the stall speed range than a manual does, whether you want to beleive it or not.
Quote:
Originally Posted by Airboy View Post
The Torque curve, as plotted against engine RPM, is not accurate in the sense that the engine is not actually at the RPM indicated on the chart but I wouldn't go as far as "artificially inflating..." That RPM scale is calculated from the roller speed. As soon as you step on the gas, the engine will speed up to the stall speed and the wheels has to "catch up". The calculated RPM will be less than the actual engine speed.

That being said, the torque curve, as shown, does give an indication of the acceleration that you would feel. Imagine if you were blindfolded and didn't know the car had an automatic, would it feel like a lot of "low end" torque?

I made some plots and stuff that covers this:
http://tinyurl.com/b28nyx6
More or less this is what I was trying to get at. You're just much better at articulating it. I would like to see torque output plotted vs. time, taking RPM out of the equation, and see if it would change the shape of the graph.
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Old 01-05-2013, 11:20 PM   #27
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Originally Posted by BlazeRex View Post
Lol and you know everything I understand what you are saying, and it applies 100% if you are using a road dyno software. If you're measuring RPM accel vs. time NOT roll speed accel vs. time, slipping the clutch would net big numbers. Usually, like Airboy says, without a rpm pickup, you use a function called "calculate from roll speed" to estimate RPMs. If you're simply measuring torque output without a direct RPM signal to the dyno, slipping the clutch would just drop power, and kill your clutch. I'm not really sure where you're going with this.

I can tell you though, the auto has much more torque in the stall speed range than a manual does, whether you want to beleive it or not.

More or less this is what I was trying to get at. You're just much better at articulating it. I would like to see torque output plotted vs. time, taking RPM out of the equation, and see if it would change the shape of the graph.
Torque multiplication from a stall does NOT increase torque output. There are many things that will ARTIFICIALLY increase output. A stall is one.

This community is so ignorant.

I can tell you've never owned a stalled automatic. Guess who has?
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Old 01-05-2013, 11:29 PM   #28
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Originally Posted by rexworx View Post

Not to start a pissing match but this car was locked into 2nd gear during the pull.
"Locked" into a gear and torque converter clutch lockup are two separate things.
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Old 01-05-2013, 11:38 PM   #29
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Originally Posted by Airboy View Post
The Torque curve, as plotted against engine RPM, is not accurate in the sense that the engine is not actually at the RPM indicated on the chart but I wouldn't go as far as "artificially inflating..." That RPM scale is calculated from the roller speed. As soon as you step on the gas, the engine will speed up to the stall speed and the wheels has to "catch up". The calculated RPM will be less than the actual engine speed.

That being said, the torque curve, as shown, does give an indication of the acceleration that you would feel. Imagine if you were blindfolded and didn't know the car had an automatic, would it feel like a lot of "low end" torque?

I made some plots and stuff that covers this:
http://tinyurl.com/b28nyx6
When going from slipping (under stall speed) to gripping (after stall speed) the torque is multiplied not due to an increase in torque output but it catching up and applying it all in a shorter amount of time. SEEMINGLY increasing torque output and greatly increasing a more immediate power output.

The dyno will show it in a torque spike. The driver feels it in a stronger launch. The torque output in actuality is not any higher.

The true reason a stall drops ET is due to getting you into your powerband immediately

...just like a clutch drop.
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Old 01-06-2013, 09:40 AM   #30
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Wow, got alot more responses then I thought it would.

No need to argue over every thing, I know the auto in 2nd will skew the numbers ever so slightly, but regardless, the car is running perfect and on the highway this thing is a blast.

Going to be getting a FMIC this upcoming week and a bigger turbo later on down the road.
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Old 01-06-2013, 01:30 PM   #31
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Originally Posted by ProfessWRX View Post
Torque multiplication from a stall does NOT increase torque output. There are many things that will ARTIFICIALLY increase output. A stall is one.

This community is so ignorant.

I can tell you've never owned a stalled automatic. Guess who has?
What is the point you are trying to make anyways with this 'artificial vs. "real" torque' business? I think we are on different pages by what you mean by "artifially inflating" numbers.

Now tell me, how does the dyno measure torque?
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Old 01-06-2013, 01:31 PM   #32
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Wow, got alot more responses then I thought it would.

No need to argue over every thing, I know the auto in 2nd will skew the numbers ever so slightly, but regardless, the car is running perfect and on the highway this thing is a blast.

Going to be getting a FMIC this upcoming week and a bigger turbo later on down the road.
Enjoy it man They are fun!
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Old 01-06-2013, 02:51 PM   #33
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Originally Posted by BlazeRex View Post
What is the point you are trying to make anyways with this 'artificial vs. "real" torque' business? I think we are on different pages by what you mean by "artifially inflating" numbers.

Now tell me, how does the dyno measure torque?
The dyno doesn't measure torque. All it really measures is acceleration of the drums. It then calculates the power required to achieve that acceleration and finally calculated engine torque using RPM data.

Load bearing dynos also measure the load being applie by the eddy brakes and add that back into the calculated power.

-- Ed
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Old 01-06-2013, 04:51 PM   #34
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People bash on the auto til they ride in it. Nothing feels better than leaving the line at full boost and holding it thru every shift. low rpm lag is helped greatly with a 3800 rpm stall. Stock is 3000
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Old 01-06-2013, 05:31 PM   #35
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Originally Posted by davhul View Post
People bash on the auto til they ride in it. Nothing feels better than leaving the line at full boost and holding it thru every shift. low rpm lag is helped greatly with a 3800 rpm stall. Stock is 3000
Just curious, who makes high stall converters for the 4EAT?
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Old 01-06-2013, 05:35 PM   #36
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Originally Posted by silvercookie View Post
Wow, got alot more responses then I thought it would.

No need to argue over every thing, I know the auto in 2nd will skew the numbers ever so slightly, but regardless, the car is running perfect and on the highway this thing is a blast.

Going to be getting a FMIC this upcoming week and a bigger turbo later on down the road.
Ya I've never been in an auto wrx if love to take a ride in one with the tq this car has and see what it feels like compared to a manual. It prob picks up and goes better than a manual when there is that stall before the down ****. If also like to see what it runs at the track with the 4 speed
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Old 01-06-2013, 07:07 PM   #37
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Originally Posted by Equilibrium Tuning View Post
The dyno doesn't measure torque. All it really measures is acceleration of the drums. It then calculates the power required to achieve that acceleration and finally calculated engine torque using RPM data.

Load bearing dynos also measure the load being applie by the eddy brakes and add that back into the calculated power.

-- Ed
Thanks Ed for clearing this up I was pretty sure that's how the dyno measured power output, by measuring torque applied to the rollers and how quickly it can accelerate them.

Also, I looked through Airboy's posts on his website, they are very informative. It makes sense now seeing it like he put it. The torque bump occurs due to the non-linear function of the rpm vs. road speed curve in an automatic, and how the dyno goes about calculating at what engine rpm a certain torque is made when using the "calculate from road speed" function.
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Old 01-06-2013, 10:45 PM   #38
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I don't see what everyone's pissing about. The proper TC makes a huge difference at the track. What's not real about this? Of course it would show up on a graph.
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Old 01-06-2013, 11:15 PM   #39
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Muahaha! 390wtq will be a blast to drive in the highway.
Beep.Beep.Beep... Other guy will be like wtf?
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Old 01-07-2013, 12:08 AM   #40
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The gains from a good high stall TC are very real at the wheels, which is what the dyno is measuring. It doesn't mean that the engine is actually making that torque at that RPM, but the real world performance gains are definately real and accurately displayed by the dyno. As long as people understand what the graph is displaying and the tuner isn't taking credit for magic torque tuning, there's nothing wrong with it.

-- Ed
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Old 01-07-2013, 12:10 AM   #41
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I'll have to look it up, but I had a crazy Chevy nova drag car on the dyno a while back. It was a high comp NA V8 with a high stall TC. The resulting power curve looked like a turbo car with a very flat WHP curve because the TC was keeping the engine in the powerband through the majority of the pull. That's how those cars can run some crazy ET's without a ton of peak HP.

-- Ed
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Old 01-07-2013, 06:40 PM   #42
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Originally Posted by Ysidro View Post
Muahaha! 390wtq will be a blast to drive in the highway.
Beep.Beep.Beep... Other guy will be like wtf?
This is what's wrong with the dyno.

He doesn't have 390wtq. From a highway roll the stall helps very little. It'll be a slouch from a roll in comparison to a launch.

I came from the world of stalled automatics. This bench/dyno talk is funny because there's so much misinformation.
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Old 01-07-2013, 07:03 PM   #43
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I don't see what everyone's pissing about. The proper TC makes a huge difference at the track. What's not real about this? Of course it would show up on a graph.
The dyno is a tool. A tuning tool. When you throw a variable in the mix you've thrown out the ability to tune. Now you're looking for numbers for bragging rights only. Bragging rights for power never made. Do you understand that the stall is a variable and the driveline is not directly connected to an rpm? It is inaccurate. It can't calculate torque with that variable.

Nobody is arguing that the ET will show improvement. But guess what? ET is never proof of power made.

If he was swapping converters then sure there's a bit of things to look at, but there's no talk of it. The dyno is wrong.

That's all I'm getting at. You can all say otherwise but it's really fanboy leg humping ignorance.

Sorry.
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Old 01-07-2013, 07:19 PM   #44
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Originally Posted by ProfessWRX View Post
Nobody is arguing that the ET will show improvement. But guess what? ET is never proof of power made.
I see your point, but many here think that track numbers are the final word in measuring engine output. Would you say that efficiency is then improved by a good track TC? That lower ET has to come from somewhere, and is clearly not an illusion.

The graph at least indicates that.
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Old 01-07-2013, 07:32 PM   #45
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Originally Posted by Dave D. View Post

I see your point, but many here think that track numbers are the final word in measuring engine output. Would you say that efficiency is then improved by a good track TC? That lower ET has to come from somewhere, and is clearly not an illusion.

The graph at least indicates that.
A good torque converter will improve ET by getting you immediately to your powerband.

The power isn't changed. The time it took to get there did. There's the ET improvement.

Now, a GOOD TC can (CAN NOT does) also net a few mph due to its efficiency and lighter rotating mass. But this is usually minimal if at all.

A proper stalled auto will trounce a manual of equal modification in a drag race. Not due to power being more, but optimizing the amount of time spent at or around peak power.

Gearing is significant as well. Take two identical cars, gear one to run out of rpm at the 8th mile. It will destroy the other. Now run them down the quarter mile and watch the "faster" get obliterated. It didn't make more power, it just uses it better. It won't dyno any higher, but you can feel it too. Same thing going on.

ET is far from the total picture. Traps are far from the total picture. Dynos are far from the total picture.

There's way more to racing than numbers. And a dyno graph is the last thing I'd bench race with.

Random info:
My previous car at one point dynod a pitiful 325rwhp. It had a small 3200 stall and 3.42 gears (which were no longer right for the car) It ran 12.5@108 one night. With a proper stall getting the car to its powerband and the gearing it needed (4000 stall/4.33 gears) it would have dropped to around 11.8 with all else being equal. And still only 325 whp. The dyno wouldn't reflect any changes except for a possible slight efficiency shift.

I know this because I had it dynod and used the dyno for what it is. A tuning TOOL. I knew exactly where my shifts needed to be, I knew exactly where I needed to stall up to. Peak power was at 5950rpm. No reason to shift any higher than 6700 rpm in 2nd gear. It's only slower to go to any closer redline with where third gear started at wot. 4.33 gears would have topped me out of third gear at the 1/4 with 26" tires. I knew 28" tires would have gotten me about 10 mph more before I needed 4.10s.

That car would have run mid-low 11s this year had I not sold it. And mostly just in optimizing power already made. (And adding some for fun.)

Last edited by ProfessWRX; 01-07-2013 at 07:56 PM.
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Old 01-08-2013, 07:02 PM   #46
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Im so lost here as fast as torque converter messing with numbers etc etc.

Someone please explain how i would get the closest to "real" numbers.
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Old 01-08-2013, 07:06 PM   #47
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Im so lost here as fast as torque converter messing with numbers etc etc.

Someone please explain how i would get the closest to "real" numbers.
Have the dyno operator LOCK the torque converter clutch. The TCC has nothing to do with the gear the car is in. Unless that is an aftermarket stall with no clutch. That is the only way to get an accurate dyno.
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Old 01-08-2013, 07:14 PM   #48
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Well i was reading up on the TC lock switch things.

So basically right before the run he would lock it, do the pull, and then unlock before slowing down again correct?

And this is all done in 2nd gear.

Do you know of anyway to lock the trans into 3rd without it downshifting it self?
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Old 01-08-2013, 07:17 PM   #49
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Well i was reading up on the TC lock switch things.

So basically right before the run he would lock it, do the pull, and then unlock before slowing down again correct?

And this is all done in 2nd gear.

Do you know of anyway to lock the trans into 3rd without it downshifting it self?
If you have tuning software you can easily change the tables of the TCC and shift thresholds to maintain a gear and TCC lockup.
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Old 01-08-2013, 07:17 PM   #50
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If you have tuning software you can easily change the tables of the TCC and shift thresholds to maintain a gear and TCC lockup.
Some cars can lockup the TCC by just pulling a certain fuse. Don't know if the wrx has one that'll do that.
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