V 2 torque

General Bike chat
jchesshyre
Posts: 590
Joined: Wed Jun 15, 2016 9:09 am
Location: Chester, Cheshire

Re: V 2 torque

Post by jchesshyre »

Yes - a torque figure is meaningless for these purposes without knowing at what revs this figure is produced.

Also, for the record, four-cylinder machines can and often do put out a higher torque figure than a similarly-sized twin, and at higher revs e.g.

2001 VTR1000F: 97 Nm @ 7000 rpm
2001 CBR929RR: 103 Nm @ 9000 rpm

2006 VTR1000 SP2: 105 Nm @ 8000 rpm
2006 CBR1000RR: 115 Nm @ 10000 rpm

2016 Panigale 959: 107.4 Nm @ 9000 rpm
2015 CBR1000RR : 114 Nm @ 10500 rpm

All depends how they're tuned.

And look at a different kind of bike, and compare with the Storm: the 2016 CB1100 (retro air-cooled four). The engine is 150 cc larger than the Storm's, the stroke is slightly longer, and it even has a marginally higher compression ratio, yet the torque figure is slightly lower (93 Nm) and at significantly lower revs (5000 rpm).

[figures taken from motorcyclespecs.co.za]
Last edited by jchesshyre on Tue Jan 29, 2019 12:08 pm, edited 1 time in total.
User avatar
Stephan
Posts: 983
Joined: Sun Apr 15, 2012 6:58 pm
Location: Prague, Czech

Re: V 2 torque

Post by Stephan »

I just repeat the most important is rev range where the torque is produced, that is why 929 is much faster than vtr.

Theoretically, If you have engine producing constant 60 nm in 6-13k rpm, or 110 nm in 4-7k rpm, bet which one will be faster :)
User avatar
KermitLeFrog
Posts: 1634
Joined: Sat Apr 11, 2015 6:44 pm
Location: Hexham

Re: V 2 torque

Post by KermitLeFrog »

Stephan wrote: Tue Jan 29, 2019 12:08 pm I just repeat the most important is rev range where the torque is produced, that is why 929 is much faster than vtr.

Theoretically, If you have engine producing constant 60 nm in 6-13k rpm, or 110 nm in 4-7k rpm, bet which one will be faster :)
Exactly! For a real world performance comparison you need to integrate (sum up) the power over a rev range and consider gearing. A racing bike making high power but over a narrow rev range will need a close ratio box to keep the engine speed within that small range.

Peak power is a lousy way to compare potential performance as an engine only produces peak power at one point in its rev range. If you are going for top speed it can be important but the engine (unless it has a CV transmission) needs to travel through a rev range and the power it makes before (and to a lesser extent after) peak power often has more effect on acceleration than peak power itself.
"I spent a lot of money on booze, birds and fast cars. The rest I squandered" (George Best, RIP)
User avatar
Beef
Posts: 288
Joined: Mon Jun 12, 2017 10:01 am
Location: Reading -ish

Re: V 2 torque

Post by Beef »

KermitLeFrog wrote: Tue Jan 29, 2019 11:37 am
Beef wrote: Tue Jan 29, 2019 11:00 am I like the tractive force link.
Personally I think torque is very important. It is, but on it's own it does nothing. It's a force. Torque x revs = power

With those graphs for tractive force, the acceleration dropped in each gear due to less torque available at the rear wheel(s), The higher the ratio, the more effort required to turn them. keeping those ratios the same, the vehicle weight the same, but add more power, the acceleration would increase.

Look at tractor/tank stats, whilst they may not be the fastest vehicles on the planet, they can reach their top speeds whilst ploughing or dragging loads the same as they can unloaded. Not relevant

Power enables you to change up before the redline and still pull hard.
2Xtorque x Yrevs = Zpower. Xtorque x 2Yrevs = Zpower (double the torque at the same revs produces the same power as the torque at double the revs)

Yeah OK, I knew that.

I sound like a broken record here but this misconception that torque is a thing that does work is simply wrong. It muddies the issue . I struggle with that comment - a Chieftain tank engine produced 650bhp, not a massive amount compared to some supercars/muscle cars but put a 650bhp car engine in a Chieftain and I bet it doesn't move, and IF it does, to nowhere near the same as the original engine :confused
jchesshyre
Posts: 590
Joined: Wed Jun 15, 2016 9:09 am
Location: Chester, Cheshire

Re: V 2 torque

Post by jchesshyre »

Beef wrote: Wed Jan 30, 2019 8:45 am
KermitLeFrog wrote: Tue Jan 29, 2019 11:37 am
Beef wrote: Tue Jan 29, 2019 11:00 am I like the tractive force link.
Personally I think torque is very important. It is, but on it's own it does nothing. It's a force. Torque x revs = power

With those graphs for tractive force, the acceleration dropped in each gear due to less torque available at the rear wheel(s), The higher the ratio, the more effort required to turn them. keeping those ratios the same, the vehicle weight the same, but add more power, the acceleration would increase.

Look at tractor/tank stats, whilst they may not be the fastest vehicles on the planet, they can reach their top speeds whilst ploughing or dragging loads the same as they can unloaded. Not relevant

Power enables you to change up before the redline and still pull hard.
2Xtorque x Yrevs = Zpower. Xtorque x 2Yrevs = Zpower (double the torque at the same revs produces the same power as the torque at double the revs)

Yeah OK, I knew that.

I sound like a broken record here but this misconception that torque is a thing that does work is simply wrong. It muddies the issue . I struggle with that comment - a Chieftain tank engine produced 650bhp, not a massive amount compared to some supercars/muscle cars but put a 650bhp car engine in a Chieftain and I bet it doesn't move, and IF it does, to nowhere near the same as the original engine :confused
Surely if it had the right gearing and transmission then it would move, it would just be a massive waste of petrol (and engineering) since the engine would need to be held at peak power (6500 rpm or whatever) to do so?
User avatar
KermitLeFrog
Posts: 1634
Joined: Sat Apr 11, 2015 6:44 pm
Location: Hexham

Re: V 2 torque

Post by KermitLeFrog »

Beef wrote: Wed Jan 30, 2019 8:45 am
KermitLeFrog wrote: Tue Jan 29, 2019 11:37 am I sound like a broken record here but this misconception that torque is a thing that does work is simply wrong. It muddies the issue . I struggle with that comment - a Chieftain tank engine produced 650bhp, not a massive amount compared to some supercars/muscle cars but put a 650bhp car engine in a Chieftain and I bet it doesn't move, and IF it does, to nowhere near the same as the original engine :confused
One engine is designed for a tank and one for a car. They will have different gearing. Also PEAK power is not what it's about.

Put a car engine into a tank and with the same spread of power, the correct gearing and gearbox, it will move the tank along just as well. Why wouldn't it?

Try a thought experiment. Consider a back box which contains an engine and gearbox. You have no idea of what the engine format and displacement is, you have no idea of how fast or slow it's running. All you have is a turning shaft coming out of the box. Now consider two black boxes, each with a shaft turning at, say, 100 rpm. You measure the torque applied by the shaft. The torque on the shaft is identical on both boxes. And, since both shafts are running at the same speed, the power is identical as well.

One might be a small highly geared multicyclinder engine running at high revs. The other may be a large capacity lower geared engine running at lower revs. The output, the power, is the same.
"I spent a lot of money on booze, birds and fast cars. The rest I squandered" (George Best, RIP)
User avatar
Beef
Posts: 288
Joined: Mon Jun 12, 2017 10:01 am
Location: Reading -ish

Re: V 2 torque

Post by Beef »

But we are talking about engine power/torque not what gearbox it is added to :confused

Yes with the correct gearbox (as wasteful as it may end up) you can get an engine to do pretty much anything. I am talking about an engine output at flywheel, no gearbox involvement.

I am not trying to start an online argument or troll, I am merely trying to understand :)
jchesshyre
Posts: 590
Joined: Wed Jun 15, 2016 9:09 am
Location: Chester, Cheshire

Re: V 2 torque

Post by jchesshyre »

Beef wrote: Wed Jan 30, 2019 10:54 am But we are talking about engine power/torque not what gearbox it is added to :confused

Yes with the correct gearbox (as wasteful as it may end up) you can get an engine to do pretty much anything. I am talking about an engine output at flywheel, no gearbox involvement.

I am not trying to start an online argument or troll, I am merely trying to understand :)
But you can't talk about whether an engine can move a particular vehicle (e.g. a Chieftain tank) without talking about the transmission. Without a transmission the engine won't be moving anything, so it's always a factor.

If we're only talking about engine outputs and excluding the transmission and gear ratios, then we can't start talking about whether or not these engines can propel certain vehicles.
User avatar
Beef
Posts: 288
Joined: Mon Jun 12, 2017 10:01 am
Location: Reading -ish

Re: V 2 torque

Post by Beef »

Yes I get that, I'm on about if you was to remove one engine and just drop in another!
User avatar
KermitLeFrog
Posts: 1634
Joined: Sat Apr 11, 2015 6:44 pm
Location: Hexham

Re: V 2 torque

Post by KermitLeFrog »

I suppose we've gone away from your original question. Sorry, probably my fault.

As to the torque produced by various engine configurations the answer is... it depends. It depends on much more than the configuration.

Your original question
"Does any one know if a v twin has the potential to produce more TORQUE than an inline 4 of same displacement."

The simple answer is it depends, as you say, on more factors than configuration. As someone said above, some 1000cc IL4s produce more torque that some 1000cc V-twin engines and vice versa.

One way to perhaps get it clearer in your head is to compare two V twin engines and the differences between them. An HD and a Duke perhaps.

Also, thinking in terms of bore and stroke confuses the issue as it's only one aspect as is configuration. You have to look at the whole design to understand how the power is made.
"I spent a lot of money on booze, birds and fast cars. The rest I squandered" (George Best, RIP)
jchesshyre
Posts: 590
Joined: Wed Jun 15, 2016 9:09 am
Location: Chester, Cheshire

Re: V 2 torque

Post by jchesshyre »

This seems like rather a good discussion of it all, even though it's about cars.

https://www.hotrod.com/articles/hrdp-04 ... wer-guide/

Regardless of number of cylinders, their distinction between 'grunters' and 'screamers' is along the same lines as our distinction between twins and fours (and remember these are general trends whenever we speak about engine configurations - you can get twins that rev much higher than some fours of a similar capacity, e.g. 1199 Panigale redlines at 11,750 rpm, CB1100 EX redlines at 9000 rpm).
Last edited by jchesshyre on Wed Jan 30, 2019 12:35 pm, edited 1 time in total.
User avatar
Beef
Posts: 288
Joined: Mon Jun 12, 2017 10:01 am
Location: Reading -ish

Re: V 2 torque

Post by Beef »

That's a good read. I had known most of that at some point but other new info must've pushed it aside or beer beat it up!!

Final line 'you can have torque without horsepower, it's called a dump truck!'
Post Reply