Mister V

Hi folks,

I found out web site than tell you the Optimum Shift Point
(see http://www.bgsoflex.com/shifter.html)

To get the optimum shift point I need the following information;

- what are the Transmission gear ratios of the 2004 TL - 6MT from 1st to 6th
- and what are the Measured Horsepower and Associated RPM.

I am still trying to find any horsepower curve of the 2004 TL, the only think I know
is the motor deliver 270 hp at 5000 RPM, but this is not enough.

Is there anybody who knows where I can get more information.

Serge

P.S. I know that there is a website that give you the effeicient torque at the wheel for each car. I just can not find it anymore.

caball88

238lbs of torque

spidey07

placeholder

wanna see what the calculator comes up with and what I shift at (6200-6300)

Aegir

http://www.acura.com/models/model_sp....asp?module=tl

1st
3.933

2nd
2.478

3rd
1.700

4th
1.250

5th
0.975

6th
0.770

Final Drive
3.285




Have fun!

caball88

i punched the numbers in and it said that the best shift point for under the HP is at 6499RPM which doesn't surprise me because honda engines are high revving and most of the HP is in the upper part of the band.

Mister V

Hi,

I found gear ratio but still need hp curves.
(see at http://motortrend.com/oftheyear/car/...yw/index3.html)

Serge

Mister V

Thanks Aegir ...
Man that was quick.

Serge

Aegir

Like this one?
http://www.acura-tl.com/forums/showp...44&postcount=4

Mister V

Sorry I picked the wrong page, it should be
http://www.maximum-cars.com/Cars/Car...03&randomcar=1

Notice: I sent the previous one before I noticed you gave me the gear ratio

Presently I tried to enter those value into the Optimum Shift Calculator but it seems
not to work properly... However, why the value of the hp curves are lower than the Acura specification.

Serge

Aegir

My numbers were from a DynoJet (chassis dynomometer), so they don't include drivetrain and other 'road' losses.

Mister V

I give me that;

--------------------------------------------------------------------------------
Computation Results
Using the Criterion for Maintaining the Same Horsepower Before and After Shift:
Finding Best Shift Placement Points For Ratio 3.93 to 2.45: Error: Search outside range - need more RPM range in HP table! Finding Best Shift Placement Points For Ratio 2.45 to 1.70: Error: Search outside range - need more RPM range in HP table! Finding Best Shift Placement Points For Ratio 1.70 to 1.25: Error: Search outside range - need more RPM range in HP table!

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

Maximizing the Area Under the Horsepower Curve:
Finding Best Shift Placement Points For Ratio 3.93 to 2.45:

Found optimum shift RPM at 5999, which achieves maximum area under horsepower curve, and lowers the RPM to 3740 after shift
Finding Best Shift Placement Points For Ratio 2.45 to 1.70:

Found optimum shift RPM at 5995, which achieves maximum area under horsepower curve, and lowers the RPM to 4160 after shift
Finding Best Shift Placement Points For Ratio 1.70 to 1.25:

Found optimum shift RPM at 5998, which achieves maximum area under horsepower curve, and lowers the RPM to 4410 after shift

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

However the first part is not working

Serge

PeterUbers

iTrader: (1)

Um -- everyone who got the best results in the 1/4-mile w/ their CL-S 6MT or Accord 6MT just shifted at redline .. i think the TL should be no different.

Aegir

Huh? Power builds to redline. Why would you shift at 6000?

spidey07

not on this motor...it decreases.

When driving you can feel the power lay off around 6000.

There are rumors it is the ECU and we can squeeze more - rumors though.

Shifting at redline isn't always the fastest time.

Aegir

The dyno was from my TL. Horsepower builds to the limiter.

Mister V

Hi folks,

As the torque brings acceleration of the car, we should try to keep it as big as possible.
In fact with the TL... it is really easy to keep it around 200 ft.lbs. In fact the sweet spot is around 5000 RPM as 208 ft.lbs is the peak torque.

Knowing that I think that the best shift are;

1st -> 2nd at 5500 RPM -> 3465 RPM
2nd -> 3th at 5500 RPM -> 3773 RPM
3th -> 4th at 5500 RPM -> 4125 RPM
4th -> 5th at 5500 RPM -> 4206 RPM
5th -> 6th at 5400 RPM -> 4264 RPM (if someone try this one... he might fly!)

It is simple, if the driver always swift at 5500 RPM, the torque will always remain over 200 ft.lbs and acceleration should be great.

Note: they is a cool website where there is a 6MT TL on a dynometer (movies)

(see at http://www.vtec.net/articles/view-ar...icle_id=193388)

So thanks to all of you... just need to try it now!

Serge

Aegir

Try that out at the strip. Let us know how it turns out.

Mathematics and programs aside, think about it. Does it make sense to shift at 5500? I'm not doubting what you entered and what the program returned, but I think that calculator needs new batteries...

Mister V

Don't tell me you bought a TL and that you shift below 3000 RPM

This car has its maximal acceleration around 5000 RPM.. so it makes sense to get as close as possible to 5000 RPM. So shifting at 5500 RPM, kept you in a range of 3500-5500 where the torque is high. Shifting before that will means you never use that extras HP and that is boring.

Nevertheless, I have done it... You just need to take care from 0 to 1st because the front wheel might over spin, but the other shifts are really easy.

Notice I got more success without the stupid VSA (for Vehicle Sucks Acceleration). The VSA cut almost all the power when it 'senses' a front wheel slip. This is nice for normal driving but not for performance in a dry road condition.

As a remove the VSA, I've heard the front wheel slip during 2nd-3th shifting for a fraction of second.

VVVVVVVVVVVrrrrrrrrrrrrrrrrrrrrooooooooooooooooouu uuuuuuuuuuuuuuummmmmmmmmmmmmm Yeah!

PoochaKannInc

I think Aegir meant that the shift point might need to be higher than 5500 not lower than 5500. I have not been on any documented track so I can't comment on which is better, but it makes sense to me to shift around 6200-6500 rpms looking at the dynos provided by Acura (where hp and torque is measured at the crank).

Looking at that dyno, it looks like power decreases after the peak at 6200 rpm. However some will argue (I think correctly) that shifting at redline brings the rpms to the meat of the powerband in the next gear. Personally, I would shift between 6200 & redline.

Someone correct me if I'm wrong since I don't have any "hard" data to base this on. Thanks.

NightRider

Horsepower does steadily build to redline, if you were looking for the fastest, why would you shift before then? I belive like some others, that our redline is ECU limited, meaning that if we could have an 8000 redline like the RSX, we could pull more than 270 at the crank. HP does keep building to redline, I think the "drop" Caball said he felt was because TORQUE is decreasing, not HP. The optimum shift is 6800. Look at it this way - even if you DID lose power past 6200 (MAX HP), you would get more power keeping it all the way to 6800 than downshifting to like 4000 from 6200. The optimum is definitely redline as you notice if shifting around 6000 it puts you right around 4000 in next gear, as where if you shift at 6800 it puts you at around 4500, then VTEC kicks in and your off!

Aegir

Shift point calculators are useful for applications where peak power occurs before redline. As an example, a stock 5.0 mustang makes peak power at around 4500 but has a 6250 redline. The optimum shift point is at some point between the two. For the TL, peak power is at or close to redline so it makes sense to use as much of that powerband as you can if you are trying to go fast. The TL would likely go even faster if only we could expand the existing powerband into higher RPMs - as long as the engine holds together that is.

Road Rage

Almost always, the best acceleration in gears is achieved when the next gear selected puts you the fattest part of the torque curve.

Xpditor

Look at the torque curve on the chart.

Torque is the twisting power at the wheels. You see it drops off after 5500.

The only questions is: when shifting, will you have the same or more torque in the next gear as you would have if you stayed longer in this gear.

You will see by the curve that, if you shift about 5500 RPM, you will have more torque in the next gear than you would if you road it up to redline.

Does that make sense? It does to me. I think I'll try it.

I wonder if that's what the 5At does if you just leave it in drive and punch it?

XP

Road Rage

No, it does not jibe with the laws of physics - even though you are correct that the torque drops off a tad above the RPM you stated, acceleration is a function of rate of work, and the higher RPM are doing more work than is being done at 5500, so your theory will predictably result in slower ET and terminal speed. The quality calculators take into consideration these principles, and as I said before, if you are shifting from, say, 2-3, you would want to get the 3rd gear in the fat part of the torque curve. Sometimes, in the upper gears of a car with tons of torque, short-shifting (shifting below redline) works out - that is true for my 2003 Cobra, which has over 400 ft/# just off idle! 2-3 is done at about 5750 RPM, well below redline. Hope this helps.

Aegir

Fortunately for us, the torque curve on the J32a3 is fat from about 2000 to 6800 - it's hard to go wrong. I submit that shifting at 5500 is equivalent to driving a car with 20 or 30 less horsepower. You're only utilizing 270 if you are getting up into the 6000+ rpm range. Clearly it would be counterproductive to be bouncing off the limiter, but shifts in the 6500 range seem in order.

Fun discusion!

Mister V

Hi folks,

I've done a compilation of the previous curve... which shows the torque at the wheel in respect of the gearbox position (1st, 2nd, 3th,...). I took the gearbox ratio given by Acura and verify if it matches with my car. And it does. The gear ratios are good.

So, please forget my first calculation attempt... because I forget to include the gearbox.
First rule: more horsepower implies more acceleration...
Second rule: if you use torque then do not forget gear ratio.

So I've done a new graph based on the dynometer result... But, I've tried to insert my graph as an image to this post.. but it does seems to work for me.
How do you do guys to insert and image? I have to figure that out later.

However I've put the image on a ftp site and you get easily download it from explorer typing ftp://ftp.ireq.ca/tmp/ and the filename is <Acura TL gear torque.zip>.

Basicly, it shows that the best shift

- 1st -> 2nd : 6850 -> 4300 RPM at 40 mph
- 2nd -> 3th : 6750 -> 4600 RPM at 62 mph
- 3th -> 4th : 6550 -> 4900 RPM at 88 mph
- 4th -> 5th : 6500 -> 5000 RPM at 117 mph
- 5th -> 6th : 6400 -> 5000 PRM at 150 mph

And interesting point, the car limit is near to 150 mph, so if you go for speed you may stay in 5th gear.

Personnally, I don't think that I will try this combinaison. I will limit myself to 6200 RPM so that will give me a little margin. Just can wait to try it.

Notice: If Acura have added a electronic cut off protection and they probably have their reasons. So shifting over 6200 RPM, implies the risk to enable this protection if you are too slow.

Serge

Aegir

This is awesome work. The shift points you plotted hit the fat part of the torque curve, just as Road Rage was saying. Thanks for taking the time to post this!

PoochaKannInc

Mister V...those numbers make more sense to me. Thank you for doing the legwork for us!

Time for me to go out and do some legwork myself...

cpurick

Unless peak power is waaay below redline -- or unless you have a close-ratio 10-speed -- you should almost always go to redline.

Even if the corresponding RPM for the next gear (at a given speed) is more powerful at the engine, the loss of mechanical advantage due to taller gearing will usually result in less torque at the wheels after shifting. (In most cases, redline in any gear still produces more power at the wheels than is available at any RPM in the next higher gear.)

If you have significantly more engine torque at a lower RPM (usually characterized by peak torque lb/ft value that's higher than peak power), then it may be possible to get more power at the wheels after shifting.

The selection criteria "Maintaining the Same Horsepower Before and After Shift" may be valid -- *if* it refers to the power at the wheels.

Some of those RPM values are so close to even thousands I can't help but wonder what their program thinks redline is.