BHP- V -Torque

[Whittakerr]

Ray
It’s actually a BMW 520d with the optional 8 speed automatic sports gear box with a torque convertor (whatever one of those are).
Thanks for the info guys.

 

[seth1]

I agree with most things posted here,but there is a little bit more to engine characteristics than fitting a larger turbo in what ever form weather it be vnt or vgt and then electronically limiting its boost pressure.Turbo sizing at the beginning is very important and contrary to believe turbos have actually got smaller with the introduction of vgt,s and two stage turbocharging.But carrying far more importance in diesel engine development is the fuel system.No matter how large or small a turbocharger is fitted without decent fueling there is nothing,an exhaust impellor with no gas passing through it leads nowhere.As regards to flat torque curves,engine makers have strived for years to find these instead of progressive torque curves again this is dictated by camshaft profiles.In yester years these demands were hard to meet due to poor fuel injection systems,high combustion temperatures-not many makers fitted charge coolers,poor cooling etc.Its a comprimise,our company regulary deals with engines in automotive use producing 235hp but in marine application their rated at 800hp,the same engine with a water to water heat exchanger fitted instead.

 

[Dustydog]

I agree with most things posted here,but there is a little bit more to engine characteristics than fitting a larger turbo in what ever form weather it be vnt or vgt and then electronically limiting its boost pressure.Turbo sizing at the beginning is very important and contrary to believe turbos have actually got smaller with the introduction of vgt,s and two stage turbocharging.But carrying far more importance in diesel engine development is the fuel system.No matter how large or small a turbocharger is fitted without decent fueling there is nothing,an exhaust impellor with no gas passing through it leads nowhere.As regards to flat torque curves,engine makers have strived for years to find these instead of progressive torque curves again this is dictated by camshaft profiles.In yester years these demands were hard to meet due to poor fuel injection systems,high combustion temperatures-not many makers fitted charge coolers,poor cooling etc.Its a comprimise,our company regulary deals with engines in automotive use producing 235hp but in marine application their rated at 800hp,the same engine with a water to water heat exchanger fitted instead.

Seth
I'm fascinated that 1960's technology was producing motorway coaches capable of continuous 80mph plus speeds with such low BHP but high torque.
Has something got lost over the years??

 

[xtrailman]

Yes emission's have been reduced.
Remember the stinking exhaust fumes?
I was reminded of them recently, returning from a pleasant rural walk, a old chap in a old sports car, set off leaving a cloud of toxic waste behind it, you know, those cars that don't require road tax.
Andrew Marr runs one to avoid the congestion charge , i believe.
What a joke.
My neighbours over the road both run similar gas guzzling, road tax free second cars!
While my relatively low emission xtrail costs me £235 a year, or something like that.
It must make sense to someone, but not me, i just find it confusing, we are rewarding people who pollute!!

 

[seth1]

Dusty Dog,1960,s technology is were it all began and maybe slightly earlier.
We seen the introduction of Cummins engines in road vehicles.This maker with out any doubt is to answer for todays technology.Cummins invented a system known as "Pressure Time" or Mechanical unit injection as its better known today.It involved a low pressure gear transfere pump feeding fuel to a gallery in the cylinder heads which constantly kept the injectures charged up of fuel at a constant pressure through out the engine speed range.The injection pressure was typically 2500bar,thats roughly 900bar more than todays common rail.These units were and still are the bench leader and are extremly clean.VW,Landdrover,Audi all adopted this fuel system.
We then seen Foden with their FD series of Supercharged two stroke 4cylinder and 6cylinder engines.(3.8,4.6 litre)These were extremely effiecent as all two strokes are,and not all are piston ported either.
These utilised a turbocharger and supercharger developing in the region of 280hp back in the day and for such a small engine this was amazing.(4.6)
In the late 60,s two 6cylinders were paired together and won the world power boat race,this engine is still used today and is favoured by various Navys around the world as their choosen engine for pumps and gensets abord vessels as its non magnetic due to its aluminum mass.

 

[RogerL]

I'm fascinated that 1960's technology was producing motorway coaches capable of continuous 80mph plus speeds with such low BHP but high torque.
Has something got lost over the years??

Yes - flat, empty motorways - in the 1960s there were no motorway gradients of any note and they were virtually empty - so once up to speed they simply had to hold that power output.
Diesels (and the VW Beetle) had engines designed to be driven flat out all day.
In any case the BMMO CM5 coach which was the motorway version had a claimed top speed of 76mph and was fitted with a turbocharged version of the engine.

 

[JTQ]

Dusty Dog,1960,s technology is were it all began and maybe slightly earlier.
.Cummins invented a system known as "Pressure Time" or Mechanical unit injection as its better known today.I

Cummins only adopted and developed a version of the "unit injector"; that honour went way back to a Brit in about 1910
In fact it was well used in the States even before Cummings took an interest in it.
Also whilst not sure but I seem to recall Maybach [Zepplin] were among the earlier adopters.
Come on play fair, credit where credit is due, you sound like the Beeb conveniently forgetting what we did

 

[seth1]

Cummins are from the states,they used unit injection from the 1930,s perhaps not with internal fuel gallerys but instead outside pipe work.They certainly developed the system into everyday use for multi cylinder engines.The system was developed by cummins into what we have today.
Dusty Dog asked a question he got an answer to the question he asked.
So what else should i have mentioned that "we done" and deserves credit?
Besides Foden and Hugey Gardener who was a brillant engineer and had many brillant ideas with his engines(gardiner).Stuff like shrouded inlet valves,piston rings which worked on one stroke and one direction,but then sadly dismissed turbocharging.Who does it leave in britain that made a huge impact to diesel engine design.And please dont say British Leyland.

 

[Dustydog]

Seth
Thanks for an excellent reply. I always thought VW were plagiarists

.
Is it the case that a HGV designed engine with a large CC kicks out more torque than BHP? The case I referred to seems to show that the ratio of torque is 4 times greater than BHP than compared to your average car say?
Roger
According to Steve Richards , an authority on the Midland Red Motorway Express Coaches, they regularly touched 90mph. Some of the engineers became concerned about the stresses being imposed on the tyres so RPM governors were fitted limiting them to 1900RPM rather than the 2,200 RPM regularly attained. On paper at least this limited the overall top speed to 76mph although there were some variances depending which ratio diff was fitted.

 

[RogerL]

According to Steve Richards , an authority on the Midland Red Motorway Express Coaches, they regularly touched 90mph. Some of the engineers became concerned about the stresses being imposed on the tyres so RPM governors were fitted limiting them to 1900RPM rather than the 2,200 RPM regularly attained. On paper at least this limited the overall top speed to 76mph although there were some variances depending which ratio diff was fitted.

If 76mph was the true top speed, ie properly timed not from speedo, on a level road with no wind then it's very likely they could see over 90mph on the speedo with a tail wind.
The average UK windspeed is 10mph - a coach driver doing say, 2 round trips a day from Birmingham-London will soon get a high enough tail wind to go a lot faster than rated speed.
I'll confess I've had several company cars on the limiter in overdrive when it's downhill, tailwind and light traffic - the speedos were showing about 20mph faster than the manufacturer's or Autocar's published top speed - I don't do it nowadays !!!

 

[colin-yorkshire1]

hi all.
interesting question posed by the OP and for those not disposed to all the techincal jargon very baffling looking at power outputs alone will not tell the whole story, for instance the power delivery of two engines ie 1petrol verses 1diesel would seem at first glance to be equal but that is far from the truth, the 1.9dti megane had the same power output as my old petrol 2.6 straight 6 VW. camper @ 66kw
max torque was delivered at almost the same rev scale @ 1800 to 1900rpm ok so the camper had 3 times the torque but weighed 3x as much, on paper both vehicles SHOULD have performed equally, however the phrase chalk and cheese springs to mind.

conversly before I bought the megane I posted on several forums inc this one as to the suitability of it as a tow car given the weight of the van, all the advice was at best neutral, most negative what car describing it as mediocre, however I liked the car it's cheap tax and insurance low running costs was a definite plus having just deciding to retire, in practice it was a relevation it towed the van without any problems anywhere we went from the biggest hills to the longest motorways despite all the all the negative info it was ideal for our use.
my advice to anyone requesting infomation about which car to buy for towing is, yes by all means absorb the techicalities but in the end go with the gut instincs maybe yes a mondeo or sorrie could have been a better tow car choice but what about the other 10months running costs when the van was not on the back.
colin

 

[Guest]

Who does it leave in britain that made a huge impact to diesel engine design.And please dont say British Leyland.

Err? actually Richard Hornsby Esq!

 

[RogerL]

According to Wikipedia http://en.wikipedia.org/wiki/Richard_Hornsby the firm Richard Hornsby & Sons built the first working (experimental) diesel engine in 1892 and invented the caterpillar track in 1905. Richard Hornsby himself had died earlier in 1864.

 

[Dustydog]

According to Steve Richards , an authority on the Midland Red Motorway Express Coaches, they regularly touched 90mph. Some of the engineers became concerned about the stresses being imposed on the tyres so RPM governors were fitted limiting them to 1900RPM rather than the 2,200 RPM regularly attained. On paper at least this limited the overall top speed to 76mph although there were some variances depending which ratio diff was fitted.

If 76mph was the true top speed, ie properly timed not from speedo, on a level road with no wind then it's very likely they could see over 90mph on the speedo with a tail wind.
The average UK windspeed is 10mph - a coach driver doing say, 2 round trips a day from Birmingham-London will soon get a high enough tail wind to go a lot faster than rated speed.
I'll confess I've had several company cars on the limiter in overdrive when it's downhill, tailwind and light traffic - the speedos were showing about 20mph faster than the manufacturer's or Autocar's published top speed - I don't do it nowadays !!!

Roger
Your knowledge astounds me. I wish I knew so much

 

[seth1]

Rodger awfully sorry but that is a BIG no no admitting something like that on here.Get ready for the riot act.LOL

 

[Gafferbill]

…….interesting to note that a 1960's Midland Red coach would not now make it to London from Birmingham.

It would not now be able to enter the London Emissions zone.
It could I suppose have a complient engine fitted or pay the £200.00 daily charge.

 

[seth1]

Or fit a particulate trap in place of the exhaust silencer.

 

[emmitdb]

Greetings Again,
Good to see that this thread has got so much attention.
Sorry if I seem to "No Understandee!!" but could I give an example and see what you lot come up with.
Assume my car (Audi A6 Avant was fitted with a diesel turbo but instead of 163bhp, it had say 140bhp BUT instead of 226 ft lbs of Torque it had say 280ft lbs.
What would I notice when towing my caravan? (Its a modern 4 berth lunar with a MTPLM of 1460kgs.)
All replies gratefully received

 

[seth1]

Hello using your example,if both vehicles were travelling up the same hill with the same weight,the vehicle with the most torque would out pull the lesser torqued vehicle if both vehicles were left in the same gear and gear for gear and to not confuse matters if engine speeds were identical all the way up the hill.It would make for a far nicer journey,far less tiring simply because of less gear changing,increasing fuel ecomomy and less wear on components.But as other people will tell you you could drive the lesser torqued car on engine speed in other words rev the guts out of it and make up for it that way.As you are you have a nice set up 160 odd hp and 230 odd lbs ft i am a bit suprised really.

 

[MichaelE]

Sorry i have to disagree with RogerL.
A very simple explanation torque helps with acceration and bhp will carry it to the top speeds.(Power is the rate at which work is done)

Well you'd better apply for a Nobel prize - you're trying to rewrite the laws of physics.
Power is indeed the rate at which work is done - and the more work done in a given time the faster the acceleration and hill-climbing.

Hey RogerL my son is looking at buying a Fiat Punto Abarth and the reviews are:

"In Sport mode the Abarth is great fun - the engine produces more low down torque and the steering becomes heavier. This makes the car better at overtaking as improves acceleration and improves steering feedback in corners"

The car review mag seems to think torque is good for acceleration

 

[Lutz]

"In Sport mode the Abarth is great fun - the engine produces more low down torque and the steering becomes heavier. This makes the car better at overtaking as improves acceleration and improves steering feedback in corners"

The above statement doesn't make sense unless the author was notoriously lazy in changing gears. Power is what determines acceleration and power is torque times engine speed.

 

[MichaelE]

I am confused, everyone seems to to have different answers for Torque vs BHP either on here or written.

 

[Lutz]

It's easy. It's not a matter of torque VERSUS bhp, but torque AND bhp. One without the other is not of much use to anyone. Comparing the two maxima at their respective engine speeds only describes the characteristic of the engine, not necessarily its ability to tow.

 

[JohnGriffiths]

To add to what Lutz has said, some like their power delivered HOT! like a Ferrari engine screaming at 8000rpm. Some like me prefer a slow chugging diesel at 1500 rpm. With the same BHP they will pull up the same hill but one does it with less fuss, one does it with less spirit, just depends on your view.

 

[Whittakerr]

Worlds smallest working V12.
I must confess to pinching this link from another forum, but thought you guys would enjoy it.
Shame its not British.
http://www.youtube.com/watch?v=m3KdpzL3Hkk