BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > M3 (E90 / E92 / E93) > General M3 Forum (E90 + E92 + E93)
 
BPM
Post Reply
 
Thread Tools Search this Thread
      02-12-2008, 11:46 PM   #1
rstringer
Enlisted Member
13
Rep
43
Posts

Drives: audi
Join Date: Jan 2008
Location: vancouver

iTrader: (0)

High Reving Engine vs torquy

Hello,

My technical knowledge about cars is rather limited therefore I don't quite understand the advantage of a high reving engine vs a torqy one.

In my mind if one can produce a lot of torque at lower rpms that seems to be more useful than reving the engine really high to achieve the same output.

Now It seems that BMW traditionaly always goes with the high reving concept (except the E39 M5) and I like to think that there is a very good technical reason behind this which I unfortunately do not understand.

I would appreciate it if someone could shed some light on the subject.

Cheers,
Rob
Appreciate 0
      02-13-2008, 12:20 AM   #2
Numb3rs
Banned
12
Rep
610
Posts

Drives: Looking
Join Date: Feb 2008
Location: Terra Ferma

iTrader: (0)

Quote:
Originally Posted by rstringer View Post
Hello,

My technical knowledge about cars is rather limited therefore I don't quite understand the advantage of a high reving engine vs a torqy one.

In my mind if one can produce a lot of torque at lower rpms that seems to be more useful than reving the engine really high to achieve the same output.

Now It seems that BMW traditionaly always goes with the high reving concept (except the E39 M5) and I like to think that there is a very good technical reason behind this which I unfortunately do not understand.

I would appreciate it if someone could shed some light on the subject.

Cheers,
Rob

Hello Rob, I pretty new here, but I have driven many types of cars and tracked/auto-x'd on and off over the last 10 years. Let me take a stab at your question.

On a track, if you have a higher revving engine, it almost undoubtedly has a larger/longer rev band, meaning you can keep up the rpms and as you accelerate out of a turn, you have more inertia within the engine. (rotating mass). You also don't have to shift as much because the engine has a broader range. Now, this is not necessarily true for all tracks and conditions, but high-revving engines do have the advantage on certain tracks.

You have to work alot harder to extract all the performance out of the car. In my experience this is a double-edged sword, because it makes driving the car more fun and intimate, but in daily driving there are days where you don't want to be bothered.


Torque'y engines have low end grunt, are more drivable and typically get better gas mileage. The Corvette does pretty well in auto-x or track conditions and can power out of corners. Some would suggest that you do not have as much throttle control with a slower revving engine such as the LS2.

In the end, I guess it comes down to what you really prefer or like. I hope this helps and I am sure other, more knowledgeable people will chime in. But if it is any consolation, I am shopping a new car and I have yet to make a decision of what engine type I want.
Appreciate 0
      02-13-2008, 12:28 AM   #3
rstringer
Enlisted Member
13
Rep
43
Posts

Drives: audi
Join Date: Jan 2008
Location: vancouver

iTrader: (0)

Quote:
Originally Posted by Numb3rs View Post

Torque'y engines have low end grunt, are more drivable and typically get better gas mileage. The Corvette does pretty well in auto-x or track conditions and can power out of corners. Some would suggest that you do not have as much throttle control with a slower revving engine such as the
So are torqey engines always slower reving than high reving engines?

Rob
Appreciate 0
      02-13-2008, 02:35 AM   #4
gmund1948
Second Lieutenant
Germany
14
Rep
253
Posts

Drives: 335 cab,C-6 08, 73 911E 59 D,
Join Date: Apr 2007
Location: American in Germany

iTrader: (0)

Quote:
Originally Posted by rstringer View Post
So are torqey engines always slower reving than high reving engines?

Rob
Actually the throttle response (reving ) with a torqey engine will seem a bit slower (I own an 08 corvette) and peak earlier, than the M3 V8 I drove both back to back for about 40 minutes on Sunday here in Germany on the same route.( I also drove the wifes 335 convertable)

Torque is often discussed as Pull as in powering out of a corner. a Corvette has massve torque low in the RPM range so if you make a mistake and slow too much going into a corner, the car with more downlow torque will "Pull"
you back to speed quicker than a car that has to rev higher to access its power band. THe Corvette will grunt its way out of a corner taken too slowly sometimes with a rough Oversteer (rear-end out reaction, the M3 pulls well too (torque surprised me) but you must rev the engine to a higher RPM level. The BMW seems to rev more quickly than the Vette in my opinion. the snorting "pull" and related oversteer is a bit less but much more controllable in the M-3 than the Corvette. THe Corvette does not easuily get the power to the pavement (suspension and gearing in the Corvettes design) but is a bit faster although you must have more balls to drive it faster than an M3

Now I am rambling but if you take an M3 too deep into a corner and try and accelerate out, you will likely not catch up as quickly as in a corvette.
You therefore have to be more careful on turn entry and hold the engine RPMs at a higher level in the M3 (not a lot however) through the corner to be able to accelerate out as quickly.

The best examples are Honda S-2000s and Mazda Miatas, both cars have very little low-end torques so they are great for drivers training in that you must learn proper technique in cornering to drive the car compettitively or else you will be waiting forever for the car to get up to speed if you slowed too much

Gearing, supension, and tires also play important roles

The M-3 has MORE than enough torque, and is very smooth all the way to redline. I was really amazed that it will torque steer MUCH more easily than my wifes 335 out of a corner.

Done rambling, hope it helps
__________________
TELL me what real drivers training do you have besides your State Drivers License ?
Appreciate 0
      02-13-2008, 03:18 AM   #5
home7271
New Member
2
Rep
22
Posts

Drives: E90
Join Date: Apr 2006
Location: Bellevue WA

iTrader: (0)

torque x rpm x numeric constant = hp

Torque is the pull/force or the acceleration you feel. So an engine with good low end torque drives very well around town.

On a track however, engines need to perform through out the entire rev band since the car is constantly looking to gain speed (or revs). Therefore for good lap times, you generally want engines that have higher hp (or higher redline) with all other factors being equal.

Remember, the gearbox is a torque multiplier as well. If you can rev higher, you can have a lower gear ratio to increase the torque at the wheels without sacrificing the top end speed.

Hope this makes sense....
Appreciate 0
      02-13-2008, 03:59 AM   #6
gmund1948
Second Lieutenant
Germany
14
Rep
253
Posts

Drives: 335 cab,C-6 08, 73 911E 59 D,
Join Date: Apr 2007
Location: American in Germany

iTrader: (0)

Well Said

__________________
TELL me what real drivers training do you have besides your State Drivers License ?
Appreciate 0
      02-13-2008, 04:16 AM   #7
OzStriker
Captain
OzStriker's Avatar
Australia
48
Rep
923
Posts

Drives: Ford Falcon Ute, Ducati 1198S
Join Date: Sep 2007
Location: Melbourne

iTrader: (1)

Garage List
Send a message via MSN to OzStriker
On a track the M3 pulls anywhere above 3k rpm, leave it anywhere between 4k and 8k and you have massive pull.

I can see this is oh so much better than say a 530NM 6 liter American V8 that will produce that over a 2.5k range.
Appreciate 0
      02-13-2008, 04:18 AM   #8
footie
Major General
footie's Avatar
No_Country
370
Rep
7,576
Posts

Drives: F90 M5 Comp
Join Date: Oct 2007
Location: No where fast

iTrader: (0)

Garage List
2008 E92 M3  [0.00]
I think you are generalising thing a little too much into saying that N/A high revving engine are always better because with regards to proper track cars you are changing the gearing to suit the track in every occasion.

In rallying almost all engines are turbocharged and don't rev anywhere near as high as a proper racing N/A engine so in a way that knock the theory that one is better than the other. It's gearing as much as anything which determines how well a car performs on a given road/track.

One thing I will say is that a high-revving engine usually has a more progressive torque band which builds to a peak in much the same way as the horsepower does and this makes for a more adjustable car.
Appreciate 0
      02-13-2008, 04:32 AM   #9
e36jakeo
Captain
United_States
31
Rep
625
Posts

Drives: 2008 M3 6 Speed MT!
Join Date: Oct 2006
Location: Northern CA

iTrader: (0)

A reason to use a low-torque, high revving, high HP design is to allow for a lighter drivetrain. Torque from the engine requires beefier parts to be able to handle it. If you use a high revving smaller engine to make the same HP then you can usually make the car lighter.

F1 cars are the most extreme example of low torque, high HP. The 2.4L V8s in those things rev to 19,000(!!!) RPM and make something like 900 HP normally aspirated. But they only make around 250 to 300 lb ft of torque max. The way they achieve their incredible HP is through incredibly short gearing (torque multiplication to the extreme).
__________________
Driving sideways: It's not faster, but damn it's more fun!
Appreciate 0
      02-13-2008, 09:57 AM   #10
rstringer
Enlisted Member
13
Rep
43
Posts

Drives: audi
Join Date: Jan 2008
Location: vancouver

iTrader: (0)

Thanks everyone for your input.

What I conclude from all this is that for city driving a torquy engine is more advantagous since there is not enough time (denser traffic) to get the engine rev up to produce the same amount of hp.

Rob
Appreciate 0
      02-13-2008, 10:15 AM   #11
Numb3rs
Banned
12
Rep
610
Posts

Drives: Looking
Join Date: Feb 2008
Location: Terra Ferma

iTrader: (0)

Sorry, when I meant throttle response, I meant the modulating the speed of the car, ever so precisely, such as on the threshold of tyre spin and cutting an apex...etc. Ride on the edge of breaking it loose.

You have more precision with a high-revving engine, you have better connection with the throttle and your tyres.

Rob, yes. That is the general consensus, that torque'y engine's are less fatiguefull than the more attentive hi-revving engines. Though, if you get an new DSG manual w/ECU shifting.... none of that matter and my point becomes moot!
Appreciate 0
      02-13-2008, 11:15 AM   #12
mkoesel
Moderator
United_States
7162
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

Quote:
Originally Posted by e36jakeo View Post
The way they achieve their incredible HP is through incredibly short gearing (torque multiplication to the extreme).
Not sure what you were actually trying to say, but the engine will make the same power even it were sitting on an engine dyno. I.e gearing is not the reason for the power of the engine itself (but will effect power to the wheels, sure). The reason for the high HP is the high revving nature of the engine. Power will go toward infinity as RPM does, and that's true of any motor (or any rotating mass for that matter).

Also, as far as I remember reading F1 engins make much less than 100ft-lb/L (like every other N/A engine). I don't think its much over 200 ft-lb, right?
Appreciate 0
      02-13-2008, 11:30 AM   #13
mkoesel
Moderator
United_States
7162
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

Quote:
Originally Posted by rstringer View Post
Thanks everyone for your input.

What I conclude from all this is that for city driving a torquy engine is more advantagous since there is not enough time (denser traffic) to get the engine rev up to produce the same amount of hp.

Rob
"torquey engine is advantageous" - yes, definitely.
"not enough time to get the engine rev up" - not necessarily. M3 will accelerate roughly the same as a 335i for example, even though the 335i has more low end torque. The reason is the rear end gearing (higher ratio in M3), as that determines the torque at the wheels.
Appreciate 0
      02-13-2008, 11:38 AM   #14
Epacy
Reincarnated
Epacy's Avatar
206
Rep
4,227
Posts

Drives: 02 Maxima SE
Join Date: Mar 2007
Location: IL

iTrader: (0)

Garage List
2008 M3  [0.00]
Quote:
Originally Posted by mkoesel View Post
even though the 335i has more low end torque.
5 ft/lbs? That is pretty much a wash.
__________________
Appreciate 0
      02-13-2008, 12:15 PM   #15
Hotan Braskey
Private First Class
Hotan Braskey's Avatar
2
Rep
184
Posts

Drives: 1M on Order- VO please
Join Date: Jun 2005
Location: Maryland, USA

iTrader: (0)

But the 335i makes that torque at around 1500 rpm, whereas the M3 peaks higher up the rev range (I am not sure where it makes max torque).
__________________
If all the animals below the equator were capable of flattery, then Thanksgiving and Halloween would fall on the same day.
Appreciate 0
      02-13-2008, 12:28 PM   #16
spearfisher
Lieutenant
spearfisher's Avatar
10
Rep
409
Posts

Drives: C6 ZO6
Join Date: Oct 2007
Location: FL

iTrader: (0)

Dragsters have high HP & TQ
F1 cars high HP low TQ

high hp and a lower tq is easier to modulate through the corners, I prefer that, but I'm addicted to the kick in the pants that Tq gives you, hence I bought a C6
Appreciate 0
      02-13-2008, 01:05 PM   #17
gmund1948
Second Lieutenant
Germany
14
Rep
253
Posts

Drives: 335 cab,C-6 08, 73 911E 59 D,
Join Date: Apr 2007
Location: American in Germany

iTrader: (0)

The M3 May surprize you

The Torque is Much more than I expected, and because it revs so fast
its right there, almost corvette like, a heck of a lot more useable than the
335, unless you have time to rev it out.
__________________
TELL me what real drivers training do you have besides your State Drivers License ?
Appreciate 0
      02-13-2008, 01:17 PM   #18
mkoesel
Moderator
United_States
7162
Rep
19,370
Posts

Drives: No BMW for now
Join Date: Jun 2006
Location: Canton, MI

iTrader: (1)

Quote:
Originally Posted by Epacy View Post
5 ft/lbs? That is pretty much a wash.
You mean peak torque, E? By "down low" I am referring to the beginning of the rev band.

To be fair I don't have a dyno comparison handy, but I do recall the 335i having the advantage below 2000RPM or so.
Appreciate 0
      02-13-2008, 01:24 PM   #19
lucid
Major General
lucid's Avatar
United_States
329
Rep
8,034
Posts

Drives: E30 M3; Expedition
Join Date: Apr 2007
Location: USA

iTrader: (0)

You guys realize the low-end stock 335 vs. M3 torque comparison has been discussed, literally, to death on the thread that was eventually frozen, right? The relevant WOT steady-state data for the entire rpm range for both cars, including torque at wheels data superimposed in graphic form, is on that thread. And, I'd say let's leave it there to keep this thread on topic. I know you guys mean well, but if we go back to that discussion here, this thread will die for sure.
Appreciate 0
      02-13-2008, 01:41 PM   #20
mrgold
New Member
United_States
0
Rep
24
Posts

Drives: F82 M4, E82 135i, E92 M3 SOLD
Join Date: Feb 2008
Location: Los Angeles, CA

iTrader: (1)

Here's a link with some good info that will help you guys understand a little better about HP and Torque.

http://www.vettenet.org/torquehp.html
Appreciate 0
      02-13-2008, 01:43 PM   #21
Epacy
Reincarnated
Epacy's Avatar
206
Rep
4,227
Posts

Drives: 02 Maxima SE
Join Date: Mar 2007
Location: IL

iTrader: (0)

Garage List
2008 M3  [0.00]
Quote:
Originally Posted by lucid View Post
You guys realize the low-end stock 335 vs. M3 torque comparison has been discussed, literally, to death on the thread that was eventually frozen, right? The relevant WOT steady-state data for the entire rpm range for both cars, including torque at wheels data superimposed in graphic form, is on that thread. And, I'd say let's leave it there to keep this thread on topic. I know you guys mean well, but if we go back to that discussion here, this thread will die for sure.
We need it again!! Hash it over and over and over until every person is sick of the talk and doesn't buy either car because they don't want to be associated with people like that.
__________________
Appreciate 0
      02-13-2008, 01:55 PM   #22
Numb3rs
Banned
12
Rep
610
Posts

Drives: Looking
Join Date: Feb 2008
Location: Terra Ferma

iTrader: (0)

Quote:
Originally Posted by lucid View Post
You guys realize the low-end stock 335 vs. M torque comparison has been discussed, literally, to death on the thread that was eventually frozen, right? The relevant WOT steady-state data for the entire rpm range for both cars, including torque at wheels data superimposed in graphic form, is on that thread. And, I'd say let's leave it there to keep this thread on topic. I know you guys mean well, but if we go back to that discussion here, this thread will die for sure.
Sorry, new here. Can u link me to that thread. I completely understand this topic, but I feel I would find it a good reference as to the "general consensus" discussed thus far... thnx!
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 01:19 AM.




m3post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST