High Reving Engine vs torquy

[rstringer]

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

[Numb3rs]

Originally Posted by rstringer

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.

[rstringer]

Originally Posted by Numb3rs

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

[gmund1948]

Originally Posted by rstringer

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

[home7271]

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....

[gmund1948]

[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.

[footie]

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.

[e36jakeo]

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).

[rstringer]

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

[Numb3rs]

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!

[mkoesel]

Originally Posted by e36jakeo

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?

[mkoesel]

Originally Posted by rstringer

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.

[Epacy]

Originally Posted by mkoesel

even though the 335i has more low end torque.

5 ft/lbs? That is pretty much a wash.

[Hotan Braskey]

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).

[spearfisher]

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

[gmund1948]

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.

[mkoesel]

Originally Posted by Epacy

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.

[lucid]

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.

[mrgold]

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

[Epacy]

Originally Posted by lucid

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.

[Numb3rs]

Originally Posted by lucid

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!