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BEC donor of the future?
James - 10/12/11 at 06:48 PM

BEC donor of the future?

I went to the NEC bike show a couple of weeks ago.

Spent some time looking at the BMWs and sitting on the 1000rr. In terms of a BEC: 200ish bhp out of 1lt is great... but not if it's only at 13000rpm or whatever!

What did stick in my mind for potential BEC donorage was the 1600gtl. It's a 1600, straight 6. It's 'only' 160bhp but it makes it at 5000rpm (according to the blurb next to the bike) and more notably it's got 170Nm of torque. How does this compare with the Fireblades, R1's etc. etc. that we use?


http://www.topspeed.com/motorcycles/motorcycle-reviews/bmw/2012-bmw-k-1600-gt-and-k-1600-gtl-ar97581.html


So looks like it's got a lot of advantages- ie. lightweight engine and box of a bike, but decent torque levels and will have a nice 6-pot soundtrack. Guessing it's shaft drive too to presumably easy to connect to a diff.

Realise it'll not be the most common donor around and no wonder what sort of price they'll break at.

Thoughts?

Cheers,
James

matt_gsxr - 10/12/11 at 07:18 PM

From the marketing bumf.....


>Supreme in-line 6-cylinder engine with a high level of pulling power, especially in the lower and medium engine speed range.

>Engine output 118 kW (160 bhp) at 7 750 rpm and maximum torque 175 Nm at 5 250 rpm.

>Over 70 per cent of the maximum torque is already available from 1 500 rpm.

>The lightest and most compact 6-cylinder in-line engine in serial motorcycle production > 1000 cc weighing just 102.6 kg and measuring 555 mm in width.

With a rev limit of 8k this is more comparable with a mr2 engine or k-series.

So, it sits in that compromise between all out lightweight bec and lightweight car engine.

Interesting

clairetoo - 10/12/11 at 07:31 PM

Not too sure how you would go about fitting this into a BEC ?


Dangle_kt - 10/12/11 at 08:27 PM

I dont see the point, personally the high reving nature of becs is what makes them what they are.

More torque wouldn't be a bad thing - but a 8k rpm ceiling would mean I'd rather have a s2000 lump or something.

adithorp - 10/12/11 at 08:31 PM

quote:
Originally posted by James
200ish bhp out of 1lt is great... but not if it's only at 13000rpm or whatever!

James


Why?

The problem I've been told would be getting around all the traction control, security, etc in the bike loom. I talked to someone earlier this year who'd been to spain for a bike track day and him and his mates couldn't get anywhere near to 2 1000rr that were there on thier ex-race bikes.

matt_gsxr - 10/12/11 at 10:30 PM

quote:
Originally posted by adithorp

The problem I've been told would be getting around all the traction control, security, etc in the bike loom.


You could just fit aftermarket ECU (megasquirt for example). Cost would is no greater than the cost of a power commander.

There do seem to be tools out there for hacking the BMW ecu's but they seem to be pretty expensive compared to the free knowledge on some of the japanese kit.

I bet one of these engines would work nicely in a reverse trike

blakep82 - 11/12/11 at 12:13 AM

quote:
Originally posted by clairetoo
Not too sure how you would go about fitting this into a BEC ?




mid engine perhaps?
bit like a car engine with a transaxle maybe?

yeah, just seems like a car engine in a bike though... quite like the idea of a 1.6 staight 6 though. sounds like fun

scootz - 11/12/11 at 11:49 AM

I'd still rather sacrifice 12 of those ft/lbs to have the 40 extra ponies of the ZZR1400!

scootz - 11/12/11 at 11:50 AM

As for positioning... middy - hooked straight up to a reverse box which is hooked straight up to a diff!

ffrgtm - 14/12/11 at 06:26 AM

quote:
Originally posted by scootz
I'd still rather sacrifice 12 of those ft/lbs to have the 40 extra ponies of the ZZR1400!



HP is just a calculation derived from torque and speed.... it basically doesn't exist. Power = work (which is torque) * time (rpm... or radians/sec in metric). If you geared the bmw engine to "see" the same wheel speed that the saki' saw then you'd have more power with the bmw.

phelpsa - 14/12/11 at 07:59 AM

quote:
Originally posted by ffrgtm
quote:
Originally posted by scootz
I'd still rather sacrifice 12 of those ft/lbs to have the 40 extra ponies of the ZZR1400!



HP is just a calculation derived from torque and speed.... it basically doesn't exist. Power = work (which is torque) * time (rpm... or radians/sec in metric). If you geared the bmw engine to "see" the same wheel speed that the saki' saw then you'd have more power with the bmw.


Power is power. It doesn't change with gearing. If the BMW produces less power than the zzr then it can't suddenly make more at the wheels!

Torque is the mystical figure that means nothing until it reaches the road. Power is the useful one.

[Edited on 14-12-11 by phelpsa]

ffrgtm - 14/12/11 at 11:25 AM

HP = [ 2*PI*n(rpm)*T(ft-lbs) ] / 33,000 which is roughly = [ n * T / 5250 ]

Ever notice how on every dyno plot the torque crosses hp at exactly 5250? It's not magic... it's a byproduct of the completely calculated figure of HP.

You can see by this equation that if an engine has more torque at a lower rpm you can simply keep cranking up rpm to get more power... this torque that's actually going into accelerating the vehicle runs through gear ratios which are a very simple ratio.

I can agree that I was more than fuzzy with the whole "sees" thing, but I will say that the relationship between inertia is more complex when you try to translate it through gear ratios.... Inertia or Impedance = (dest/source)^2

So while I'm claiming you can just trade torque for more HP by changing gearing... it doesn't always work out that way in real life.

I still disagree with the sentiment that torque is the made up figure though.... the rate at which the engine is producing the torque can always be changed... but the actual mechanical advantage the pistons have on the crank shaft isn't going change.





More than likely I have something backwards in my understanding though

bobinspain - 14/12/11 at 01:49 PM

quote:
Originally posted by ffrgtm
HP = [ 2*PI*n(rpm)*T(ft-lbs) ] / 33,000 which is roughly = [ n * T / 5250 ]

Ever notice how on every dyno plot the torque crosses hp at exactly 5250? It's not magic... it's a byproduct of the completely calculated figure of HP.

You can see by this equation that if an engine has more torque at a lower rpm you can simply keep cranking up rpm to get more power... this torque that's actually going into accelerating the vehicle runs through gear ratios which are a very simple ratio.

I can agree that I was more than fuzzy with the whole "sees" thing, but I will say that the relationship between inertia is more complex when you try to translate it through gear ratios.... Inertia or Impedance = (dest/source)^2

So while I'm claiming you can just trade torque for more HP by changing gearing... it doesn't always work out that way in real life.

I still disagree with the sentiment that torque is the made up figure though.... the rate at which the engine is producing the torque can always be changed... but the actual mechanical advantage the pistons have on the crank shaft isn't going change.





More than likely I have something backwards in my understanding though







The 5250 number prompted me to look at "How Stuff Works" online.
It's pretty interesting (but heavy) stuff.
Turns out 33,000ft.lbs of work/min = 1 HP.
33,000/2Pi = 5252.
HP=Torque x RPM divided by 5252.
So to generate more horse power for a given torque, increase the RPM. (shorter stroke, smaller bore etc).
I didn't venture into the inertia stuff. (After all, as Clint Eastwood's creation Harry Callahan would say, "A man's gotta know his limitations."

phelpsa - 14/12/11 at 07:00 PM

quote:
Originally posted by ffrgtm
HP = [ 2*PI*n(rpm)*T(ft-lbs) ] / 33,000 which is roughly = [ n * T / 5250 ]

Ever notice how on every dyno plot the torque crosses hp at exactly 5250? It's not magic... it's a byproduct of the completely calculated figure of HP.

You can see by this equation that if an engine has more torque at a lower rpm you can simply keep cranking up rpm to get more power... this torque that's actually going into accelerating the vehicle runs through gear ratios which are a very simple ratio.

I can agree that I was more than fuzzy with the whole "sees" thing, but I will say that the relationship between inertia is more complex when you try to translate it through gear ratios.... Inertia or Impedance = (dest/source)^2

So while I'm claiming you can just trade torque for more HP by changing gearing... it doesn't always work out that way in real life.

I still disagree with the sentiment that torque is the made up figure though.... the rate at which the engine is producing the torque can always be changed... but the actual mechanical advantage the pistons have on the crank shaft isn't going change.





More than likely I have something backwards in my understanding though


Take it back to very basics, ie what energy goes in must come out. Assuming time is constant (dangerous these days!) what power goes in must come out. You can't create energy.

Torque curves etc are just a method of measuring how well an ICE is able to convert the energy stored in the fuel into useful mechanical energy at a given engine speed. As you have worked out, it is just a power curve (what the dyno measures, useful power) with the power divided by the RPM/5250 (if its bhp and lb/ft).

Torque, inertia etc etc are just methods of transferring energy, it can't create it.