how do I improve torque?

[klammer]

To get back on topic a bit I have gears on my 3.45 and the simulations and arguments put forth by swamp a few years back are what led me to the gears. I already had the only real bolt on that matters (exhaust+tune) and wanted a bit of in gear snappiness for city driving. The ability to wind the engine up quicker in city conditions has great appeal for me as you rarely if ever need to change gears. This same principle came into play as I started to track the car more as well as allowing me to stay in the higher gear as I got faster (but this is specific to certain tracks and wouldn't be universally applied). On the track, and in the city, I want the "quicker", not necessarily "faster" car, one that is more responsive. This is where I find "value" in the FD mod as well as add that personal touch to MY car that others don't. I'll never argue the math as that's the point of it (not really debate able) just giving my personal take. I've spent way too much money and time in this car to be considered rational on the subject but as I've said before and I'll say it again, it's all relative. One mans trash is another mans treasure

[advans]

Torque? get an AMG. those things have nothing but torque.

[pbonsalb]

Originally Posted by klammer

To get back on topic a bit I have gears on my 3.45 and the simulations and arguments put forth by swamp a few years back are what led me to the gears. I already had the only real bolt on that matters (exhaust+tune) and wanted a bit of in gear snappiness for city driving. The ability to wind the engine up quicker in city conditions has great appeal for me as you rarely if ever need to change gears. This same principle came into play as I started to track the car more as well as allowing me to stay in the higher gear as I got faster (but this is specific to certain tracks and wouldn't be universally applied). On the track, and in the city, I want the "quicker", not necessarily "faster" car, one that is more responsive. This is where I find "value" in the FD mod as well as add that personal touch to MY car that others don't. I'll never argue the math as that's the point of it (not really debate able) just giving my personal take. I've spent way too much money and time in this car to be considered rational on the subject but as I've said before and I'll say it again, it's all relative. One mans trash is another mans treasure

Yes, there is a simulation for the DCT with final drive ratio changes of 3.15 to 3.45 and 3.15 to 3.62. I read it but do not have a link handy. Maybe someone will repost it. My recollection is that even the simulator agreed the 3.62 helped though not the 3.45, and this was for the very limited speed or rpm ranges that he considers important. The real world daily driving results are even more positive for the gear changes. I have probably done about 100 drag strip quarter miles in my life, but thousands and thousands of 30-50, 50-70 and even 60-130 runs, starting in all gears from all rims. I regularly wind a gear out to redline at full throttle, for example. Lining up for the perfect drag strip launch is not something I do often.

[BMRLVR]

Hello All, I have to post here again because these threads relating to the M3's S65 and it's lack of torque really irritate me. Let me explain why:

For a "Naturally Aspirated" engine with 4.0 liters of displacement the M3's S65 does indeed have good low end torque. The S65 is making 80% of peak torque from 2000 RPM to 8000 RPM and 85% of peak torque from 2000 RPM to 6500 RPM. The flat torque curve and correspondingly broad powerband of the S65 is what makes it seem so torqueless on the bottom....... The 295 Lb/Ft peak is in fact quite good and makes for 73.75 Lb/Ft per liter, which makes it above average for torque density for naturally aspirated engines!

Let's look at torque density of other Naturally Aspirated engines in performance cars.

Dodge viper (8.4 liter): 66.6 Lb/Ft / liter
C6 ZO6: 67.15 Lb/Ft / Liter
C63 AMG: 73.6 Lb/Ft / Liter
E90/92/93 M3: 73.75 Lb/Ft Liter
Lexus IS-F: 74.2 Lb/Ft / Liter
Audi RS4/5/R8: 76.5 Lb/Ft / Liter
E46 M3: 80.8 Lb/Ft / Liter
E46 M3 CSL: 84.1 Lb/Ft / Liter


So as you all can see, even some of the engines that most people consider torquey, actually put down low numbers for torque density. These engines just have large displacement on their side. No engine on the list with the exception of the RS4/5/R8 and engines come anywhere close to having a torque curve that is as broad and usable as the M3's V8 and. Even the S54's torque curve while having the highest torque density of the bunch (and one of the highest NA torque densities in the world, second only to the 4.5 V8 in the ferrari 458 Italia: 89.96 Lb/Ft / Liter) is as broad and flat as the V8 in our M3's.

Basically what all of this means is even if you had the same torque density of the CSL's S54 we would still have only have 336.6 Lb/Ft out of the S65.

Anyone who thinks the S65 is lacking torque never did their homework very well when buying their car. 4 Liters is 4 Liters no matter how how you slice it. People need to realize the achievement that was made with the S65 and how it makes so much torque and horsepower out of such a small package.

Really if you compare it, the Dodge Viper and ZO6 Vette engines lower than average torque density however due to their size they have lots of torque. Personally, I will take a high revving low displacement engine over a large displacement lazy one anyway of the week, shifting at 8400 is something I love!!!

[GIdriver]

Originally Posted by BMRLVR

Hello All, I have to post here again because these threads relating to the M3's S65 and it's lack of torque really irritate me. Let me explain why:

For a "Naturally Aspirated" engine with 4.0 liters of displacement the M3's S65 does indeed have good low end torque. The S65 is making 80% of peak torque from 2000 RPM to 8000 RPM and 85% of peak torque from 2000 RPM to 6500 RPM. The flat torque curve and correspondingly broad powerband of the S65 is what makes it seem so torqueless on the bottom....... The 295 Lb/Ft peak is in fact quite good and makes for 73.75 Lb/Ft per liter, which makes it above average for torque density for naturally aspirated engines!

Let's look at torque density of other Naturally Aspirated engines in performance cars.

Dodge viper (8.4 liter): 66.6 Lb/Ft / liter
C6 ZO6: 67.15 Lb/Ft / Liter
C63 AMG: 73.6 Lb/Ft / Liter
E90/92/93 M3: 73.75 Lb/Ft Liter
Lexus IS-F: 74.2 Lb/Ft / Liter
Audi RS4/5/R8: 76.5 Lb/Ft / Liter
E46 M3: 80.8 Lb/Ft / Liter
E46 M3 CSL: 84.1 Lb/Ft / Liter


So as you all can see, even some of the engines that most people consider torquey, actually put down low numbers for torque density. These engines just have large displacement on their side. No engine on the list with the exception of the RS4/5/R8 and engines come anywhere close to having a torque curve that is as broad and usable as the M3's V8 and. Even the S54's torque curve while having the highest torque density of the bunch (and one of the highest NA torque densities in the world, second only to the 4.5 V8 in the ferrari 458 Italia: 89.96 Lb/Ft / Liter) is as broad and flat as the V8 in our M3's.

Basically what all of this means is even if you had the same torque density of the CSL's S54 we would still have only have 336.6 Lb/Ft out of the S65.

Anyone who thinks the S65 is lacking torque never did their homework very well when buying their car. 4 Liters is 4 Liters no matter how how you slice it. People need to realize the achievement that was made with the S65 and how it makes so much torque and horsepower out of such a small package.

Really if you compare it, the Dodge Viper and ZO6 Vette engines lower than average torque density however due to their size they have lots of torque. Personally, I will take a high revving low displacement engine over a large displacement lazy one anyway of the week, shifting at 8400 is something I love!!!

Than you for providing such an illustrative post. Very intresting.

[pbonsalb]

After reading that, the car still feels like it does not have much torque.

[kyleb350]

The complaint is lack or torque, not torque density How I wish we got the GTS motor option here in the states.

[PaneristiDriver]

Originally Posted by BMRLVR

Hello All, I have to post here again because these threads relating to the M3's S65 and it's lack of torque really irritate me. Let me explain why:

For a "Naturally Aspirated" engine with 4.0 liters of displacement the M3's S65 does indeed have good low end torque. The S65 is making 80% of peak torque from 2000 RPM to 8000 RPM and 85% of peak torque from 2000 RPM to 6500 RPM. The flat torque curve and correspondingly broad powerband of the S65 is what makes it seem so torqueless on the bottom....... The 295 Lb/Ft peak is in fact quite good and makes for 73.75 Lb/Ft per liter, which makes it above average for torque density for naturally aspirated engines!

Let's look at torque density of other Naturally Aspirated engines in performance cars.

Dodge viper (8.4 liter): 66.6 Lb/Ft / liter
C6 ZO6: 67.15 Lb/Ft / Liter
C63 AMG: 73.6 Lb/Ft / Liter
E90/92/93 M3: 73.75 Lb/Ft Liter
Lexus IS-F: 74.2 Lb/Ft / Liter
Audi RS4/5/R8: 76.5 Lb/Ft / Liter
E46 M3: 80.8 Lb/Ft / Liter
E46 M3 CSL: 84.1 Lb/Ft / Liter


So as you all can see, even some of the engines that most people consider torquey, actually put down low numbers for torque density. These engines just have large displacement on their side. No engine on the list with the exception of the RS4/5/R8 and engines come anywhere close to having a torque curve that is as broad and usable as the M3's V8 and. Even the S54's torque curve while having the highest torque density of the bunch (and one of the highest NA torque densities in the world, second only to the 4.5 V8 in the ferrari 458 Italia: 89.96 Lb/Ft / Liter) is as broad and flat as the V8 in our M3's.

Basically what all of this means is even if you had the same torque density of the CSL's S54 we would still have only have 336.6 Lb/Ft out of the S65.

Anyone who thinks the S65 is lacking torque never did their homework very well when buying their car. 4 Liters is 4 Liters no matter how how you slice it. People need to realize the achievement that was made with the S65 and how it makes so much torque and horsepower out of such a small package.

Really if you compare it, the Dodge Viper and ZO6 Vette engines lower than average torque density however due to their size they have lots of torque. Personally, I will take a high revving low displacement engine over a large displacement lazy one anyway of the week, shifting at 8400 is something I love!!!

Very good point, although the S54 isnt second. The GT3 RS 4.0, and Carrera and Carrera S (991) have better torque density. Just keeping facts in check.

991 Carrera 84.70 lb/ft per liter
RS 4.0 84.75 lb/ft per liter
991 Carrera S 85.52 lb/ft per liter

But also dont forget that gearing still plays a huge role in torque as it is applied through each gear and the final gear ratio, which, is far more important than looking at only the tq the engine produces.

[BMRLVR]

Originally Posted by PaneristiDriver

Very good point, although the S54 isnt second. The GT3 RS 4.0 and even the new Carrera S (991) have better torque density. Just keeping facts in check.

RS 4.0 84.75 lb/ft per liter
991 Carrera S 85.52 lb/ft per liter

But also dont forget that gearing still plays a huge role in torque as it is applied through each gear and the final gear ratio, which, is far more important than looking at only the tq the engine produces.

Thanks for the correction!!! How did I ever leave out the venerable Porsche Flat 6...... A truly amazing engine even after over 40 years in production!

[m3an]

it's where the torque is made, irrelevant of "density".. Think about it, a 4.6 liter mustang makes torque under 3k, .. Every M car is about high HP at the cost of not making lots of low end torque. It is what it is, but you cannot compare an M car torque to anything else. torque gets you moving and HP wins races. It is the torque though that makes the car feel a little sluggish at times unless it's revved out.
If that's the case, I had a 2.0 liter that made 300 lb ft of torque at 3200, and it was much faster than my m

[CanAutM3]

Originally Posted by pbonsalb

The torque multiplication will not be reflected in any gear on the dyno. Otherwise, you would get something like maybe 1000 lbs torque in 2nd gear and 250 lbs torque in 5th gear. The dyno chart will reflect engine torque, not transmission and differential multiplied torque, but the dyno chart will show that engine torque reduced by the drivetrain drag losses.

You can dyno in any gear you want. I have dynoed in 3rd, 4th and 5th, without seeing any dramatic differences. The 1:1 gear is often chosen because it should be the most efficient gear since there is no step up or step down that consumes a little power.

The flywheel torque value produced by wheel dynos is a number that does not really exist anywhere on the car. It should only be used a reference to evaluate the "shape" of the torque curve. A wheel dyno calculates power at the wheel then calculates a torque value at the flywheel based on power at the wheel and engine RPM.

The reason it is best to use a 1:1 ratio, is that on most gearboxes, this ratio is a direct drive (doesn't go through gears), so there is less drivtrain loss due to loaded gear meshing.

[BMRLVR]

Originally Posted by talontid

it's where the torque is made, irrelevant of "density".. Think about it, a 4.6 liter mustang makes torque under 3k, .. Every M car is about high HP at the cost of not making lots of low end torque. It is what it is, but you cannot compare an M car torque to anything else. torque gets you moving and HP wins races. It is the torque though that makes the car feel a little sluggish at times unless it's revved out.
If that's the case, I had a 2.0 liter that made 300 lb ft of torque at 3200, and it was much faster than my m

Maybe you should re-read my post!

The S65 has 85% (251 Lb/Ft) of peak torque available at 2000 RPM.

The highest torque rating of any 4.6 liter mustang I could find was 325 Lb/Ft from the 2010 3V engine and that peak is at 4250. I doubt they make a boat load more torque below 3000 than the S65. I would welcome you to give me more info on the torque curve though!

P.S.: The whole torque gets you moving and horsepower wins races crap is just that.... CRAP! You can't have horsepower without torque. Horsepower is just math to express force (i.e.: TORQUE) delivered over time.

[CanAutM3]

Originally Posted by BMRLVR

Maybe you should re-read my post!

The S65 has 85% (251 Lb/Ft) of peak torque available at 2000 RPM.

P.S.: The whole torque gets you moving and horsepower wins races crap is just that.... CRAP! You can't have horsepower without torque. Horsepower is just math to express force (i.e.: TORQUE) delivered over time.

Bingo!! Agreed .

I had the same argument in a different thread.

PS. Although, to be more precise, power is force on a distance over time.

[CanAutM3]

This thread has been a very interesting read. I will fuel the fire by adding my 2 cents .

Professionally coming from an experimental test background, I would always tease the analytical guys by saying that their models were only good at predicting anything only after they were calibrated with real world data .

However Swamp is right in saying that there are a lot of variables to control in the real world. Experimental data needs to be statistically averaged to have any significant meaning. In other words, you cannot rely on a single run/test to prove or invalidate a theory.

Good calibrated models are extremely useful in developing almost any product. They have significantly reduced the cost and lead-time to develop products by reducing the required quantity of testing and trial and error aspect of it.

I also partially agree with Swamp that relatively small changes in gearing do not have significant impact on the total spectrum of the performance envelope. However, if one wants to improve performance in a specific range, gearing can have an important impact. Any racing team can attest to that, where they will pick optimal gearing for every single track. Most often, simulation models are used to figure out that optimal gearing (analytical models are useful )

If gear ratios would have no impact on performance, why would we even bother having multiple ratio gearboxes, we could simply go with a direct drive from engine to wheel and reduce drivetrain loss .

[swamp2]

Originally Posted by CanAutM3

This thread has been a very interesting read. I will fuel the fire by adding my 2 cents .

Professionally coming from an experimental test background, I would always tease the analytical guys by saying that that their models were only good at predicting anything only after they were calibrated with real world data .

However Swamp is right in saying that there are a lot of variables to control in the real world. Experimental data needs to be statistically averaged to have any significant meaning. In other words, you cannot rely on a single run/test to prove or invalidate a theory.

Good calibrated models are extremely useful in developing almost any product. They have significantly reduced the cost and lead-time to develop products by reducing the required quantity of testing and trial and error aspect of it.

I also partially agree with Swamp that relatively small changes in gearing do not have significant impact on the total spectrum of the performance envelope. However, if one wants to improve performance in a specific range, gearing can have an important impact. Any racing team can attest to that, where they will pick optimal gearing for every single track. Most often, simulation models are used to figure out that optimal gearing (analytical models are useful )

If gear ratios would have no impact on performance, why would we even bother having multiple ratio gearboxes, we could simply go with a direct drive from engine the wheel and reduce drivetrain loss .

Thanks, good post.

I do hope others with little or no such great testing background that you have understand some of the basics about variation and uncertainty in real world testing. One of my favorite expressions about test vs. simulation is, "No one believes the simulation except the guy who ran it but everyone believes the test except the guy who ran it". The veracity of that it certainly changing over the years but there is still truth in it because anyone who believes simulation is junk and testing is absolute simply understands neither.

As to your last point I've never said gear ratios are unimportant. The combination of the ratios and the FD must be matched to the engines characteristics, primarily just torque and redline. Once that is done and done well, for many street cars, there is very little overall benefit to a FD modification. Some isolated benefits may happen and some contests may be harmed rather than helped.

[CanAutM3]

Originally Posted by swamp2

"No one believes the simulation except the guy who ran it but everyone believes the test except the guy who ran it".

Love this quote

[swamp2]

Originally Posted by BMRLVR

P.S.: The whole torque gets you moving and horsepower wins races crap is just that.... CRAP! You can't have horsepower without torque. Horsepower is just math to express force (i.e.: TORQUE) delivered over time.

Although I firmly believe that power (and specifically power to the wheels divided by weight) completely trumps torque as the relevant output to measure a car by, simply because torque is more or less meaningless without knowledge of the gearing, there is some empirical truth to the benefits of high crank torque engines benefits at lower speeds and lower rpms. There is also a benefit to such engines for lazy driving (i.e. wrong gear) performance contests. Whatever floats ones boat...

Crap expressions such as this typically contain a shred of truth but also serve to foster an incorrect/incomplete view of a technical/engineering/physics topic.

[swamp2]

Originally Posted by CanAutM3

Love this quote

Use it all the time in my profession (which by the way is in physics based simulation...)

[CanAutM3]

Originally Posted by swamp2

Use it all the time in my profession (which by the way is in physics based simulation...)

So our respective professional backgrounds are two parts of a whole

[BMRLVR]

Originally Posted by swamp2

Although I firmly believe that power (and specifically power to the wheels divided by weight) completely trumps torque as the relevant output to measure a car by, simply because torque is more or less meaningless without knowledge of the gearing, there is some empirical truth to the benefits of high crank torque engines benefits at lower speeds and lower rpms. There is also a benefit to such engines for lazy driving (i.e. wrong gear) performance contests. Whatever floats ones boat...

Crap expressions such as this typically contain a shred of truth but also serve to foster an incorrect/incomplete view of a technical/engineering/physics topic.

Exactly!

Swamp, you and I have had some good banter on here, and I respect your posts highly since you are one of the few that actually add value to the forums.

In the statement you make above saying that their is some benefit to high crank torque at lower speeds I totally agree. What we need to reinforce to the forums is that unless you have power (i.e. BHP, KW, PS, etc) torque is indeed meaningless. Torque (Force) can in-fact be exerted with no power developed but power can not be developed without torque (force).

Obviously gearing does play a big factor as you mentioned as well, although the gearing does not effect crank numbers what so ever. The reason FD gearing has little effect on the M3's performance is the fact that the torque curve is so broad and flat that it just makes you shift more with little benefit. On an engine with a narrower torque curve the FD makes more difference by allowing the engine to spend more time in the area where torque (and hence horsepower) is higher.

Please corroborate the message that I am trying to deliver by reiterating the statement of mine that horsepower can't exist without torque. They are one and the same, the only difference is that an engine that delivers more torque in the lower RPM is going to be making more horsepower earlier in the rev range. High low end torque is great however an engine with higher average torque will be desirable to the one that makes a more low end torque but falls off quickly as the revs climb. This exact reason is why Diesels feel so unsporting (And I do know a thing or two about Diesels). Boatloads of low end torque but the lack of torque as the revs climb makes them feel slow and boring to drive even though sometimes the numbers are more than the feel would lead you to believe.

[CanAutM3]

Originally Posted by BMRLVR

Torque (Force) can in-fact be exerted with no power developed but power can not be developed without torque (force).

Very well put.

[CanAutM3]

Originally Posted by SehrSchnell

Many great points and very informative. I stated plenty of times why I went with those gears (the feel - nobody can argue that away), but here is a quick question, why did BMW chose to equip the M3 GT4 with the 4:10 gears? We all know there is no free lunch, and that gearing has its disadvantages, yet they still went with. Any ideas?

My view on this is that the 4:10 gear is probably better suited for the "range" in which you are using the car. Same would hold true for the GT4. On a race track, you would rarely use the full range of the 6th gear with the taller gearing. Using the 4:10 gear allows maximizing torque at the wheel (the total area under the curve for all gears) in the desired speed "range" required at the track.