bhp v torque

[seth1]

At last the pennys dropped.Thats the point im making Lutz,you,ve just said it yourself.So without torque were down to thraping the guts out of the vehicle to climb the hill on hp.I must admit i dont fancy climbing telegraph hill at 6000rpm.This is crazy to even surgest it.Perfect example-A lorry.Low hp in relation to high torque output.

 

[Lutz]

For the first 5 years of my caravanning career I towed a 1300kg caravan with a 1.8l petrol Vectra developing only 90hp. In order to keep up with the traffic flow on relative steep sections of the motorway the rev counter would be redlining in second gear, but as it didn't happen too often I put up with it and the car never grumbled.

 

[JonnyG]

For the first 5 years of my caravanning career I towed a 1300kg caravan with a 1.8l petrol Vectra developing only 90hp. In order to keep up with the traffic flow on relative steep sections of the motorway the rev counter would be redlining in second gear, but as it didn't happen too often I put up with it and the car never grumbled.

brilliant example Lutz thats the piont in those days it was all about BHP ,, and yet had you had a vectra 1.7 tds 82 bhp which is less bhp than you had but about 30 ft/lb more than you had, then you wouldnt have needed secound gear as often nor need to rev so highly to keep to the exact same speed as your 90bhp vectra....TORQUE.........

 

[JonnyG]

http://auto.howstuffworks.com/fuel-efficiency/hybrid-technology/fisker-karma2.htm
elecric motors ..TORQUE..TORQUE..TORQUE

 

[otherclive]

For the first 5 years of my caravanning career I towed a 1300kg caravan with a 1.8l petrol Vectra developing only 90hp. In order to keep up with the traffic flow on relative steep sections of the motorway the rev counter would be redlining in second gear, but as it didn't happen too often I put up with it and the car never grumbled.

Similarly to Lutz one of my cars was a Mondeo 2.0 auto with 130bhp towing 1350kg. It didnt have a problem and as the engine was smooth (unlike early TDs) it would drop down a gear and revs would rise but never redlined and it never felt stressed. The next car was a Mondeo 1.8TD a real dog of an engine. Rough, dropped off the turbo and noisy as hell when revving. It had far more torque than the 2.0litre petrol but was far less enjoyable to drive. So what does that say? Well comparing different cars with different power chains on just one parameter is a useless pastime. Having owned a 04 Sorento for 7 years it was a cracking car tow car, but given the chance of the Lexus I know which one I would opt for. After all driving is more than just towing isnt it?

 

[Lutz]

I think we're saying the same thing, but from a different perspective. Bhp is what gets you up the hill. As Bhp is basically torque times revs, either you need torque if the engine isn't going to have to rev or you need the revs if it's lacking torque. The result will be the same, either way.

 

[Surfer]

So is the car scrap after 10 years?
Who would buy a 10 year old car that may need new batteries at high cost, i stand to be corrected.
The other thing i've read with these hybrids is the relatively poor economy.
I would be interested in a full electric car once they can travel longer distances, and the batteries become cheaper.

Good question and it seems there is no answer!

 

[JonnyG]

So is the car scrap after 10 years?
Who would buy a 10 year old car that may need new batteries at high cost, i stand to be corrected.
The other thing i've read with these hybrids is the relatively poor economy.
I would be interested in a full electric car once they can travel longer distances, and the batteries become cheaper.

Good question and it seems there is no answer!

umm, who'd buy a 10 year old car with 150 or 180k on the clock given the engine maywell also need replacing soon at a very high cost. same applies to these hybrids many more of them are still running on 10 years on without replacement batteries than have needed to buy batteries and the prices of replacement are coming down too......poor economy? well that is subjective to how the vehicles is used and indeed a decade or more on there getting better and better....

 

[Dustydog]

From my own investigations the Lexus is the cheapest to tax, low emissions, circa £120.00 PA. And you can drive it through central London with no penalty because it is clean.
I've had a go in one and must say the whole experience is so different from my Sorie I'm going for one. Incidentally the overall economy is still best in class and as far as I can glean reliability is excellent. Honest John of the DT speaks very highly of it. What is interesting is the price variance between the Lexus and the BMW X5. About £8k per year BUT the X5's are all at least twice the mileage . Why is that???

 

[JonnyG]

From my own investigations the Lexus is the cheapest to tax, low emissions, circa £120.00 PA. And you can drive it through central London with no penalty because it is clean.
I've had a go in one and must say the whole experience is so different from my Sorie I'm going for one. Incidentally the overall economy is still best in class and as far as I can glean reliability is excellent. Honest John of the DT speaks very highly of it. What is interesting is the price variance between the Lexus and the BMW X5. About £8k per year BUT the X5's are all at least twice the mileage . Why is that???

dont really follow the secondhand value market these days but BMW products did/do tend to hold their value better than even the glossy guide quotes..it seems its all about market forces. BM's are BM's, which is actually good if you dont want one.

 

[seth1]

Not being disrespectfull,both are lovely cars,but drive a pretty late X5 diesel,say a middle of the road X40d.What a machine,what an engine,miles apart from anything.

 

[xtrailman]

Whatcar have run a couple of hybrids long term, at present a Volvo V60 is on the fleet, 4 month in the reports are worth reading.
I have noticed that the cost of the electricity appears to be ignored which is odd considering i pay around 3 times more per unit for electricity on my tariff than i do for gas.
http://www.whatcar.com/car-news/january/1226697

 

[MichaelE]

To start with the Beemer is about 5-6k more expensive than the Lexus, plus the Lexus has all the kit already whereas the Beeemer doesnt like electric heated seats which will bump its list price up a bit.
I run a X5 4.0 too , really like it but the lease is up so have extended it for the time being as the new one isnt very nice in my opinion and carries a list price of 55K then add £1200 for upgraded alloys and £300 for folding mirrors, same for heated seats before you know it your adding another 5k to its price whereas this is all standard on the RX.
I have done quite a few car studies for Lexus and i have found they market their cars at city folk.

 

[Lutz]

Whatcar have run a couple of hybrids long term, at present a Volvo V60 is on the fleet, 4 month in the reports are worth reading.
I have noticed that the cost of the electricity appears to be ignored which is odd considering i pay around 3 times more per unit for electricity on my tariff than i do for gas.
http://www.whatcar.com/car-news/january/1226697

The Lexus produces its own electricity nad has no facility for hooking up to mains supply so the cost of electricity is not an issue.

 

[MichaelE]

So is the car scrap after 10 years?
Who would buy a 10 year old car that may need new batteries at high cost, i stand to be corrected.
The other thing i've read with these hybrids is the relatively poor economy.
I would be interested in a full electric car once they can travel longer distances, and the batteries become cheaper.

Good question and it seems there is no answer!

Done a quick search on the lexusownersclub website and for those interested in such things a complete replacement Battery pack for a 400H (previous model 5 yr warranty) is £ 3,199.00 inc vat, with a labour cost of £ 1,056 inc. vat.
In their defence no one knows the life of them and they havent had any failures
When a car gets to that age its value will be adjusted accordingly.
That may sound very expensive, but alot of cars parts will be expensive especially now as the mot test requires all air bags to be functional, couple of price examples, VW xenon light unit £1000 and a BMW 5 series seat wiring loom as the air bag warning light was on £1476 plus labour.

 

[xtrailman]

Whatcar have run a couple of hybrids long term, at present a Volvo V60 is on the fleet, 4 month in the reports are worth reading.
I have noticed that the cost of the electricity appears to be ignored which is odd considering i pay around 3 times more per unit for electricity on my tariff than i do for gas.
http://www.whatcar.com/car-news/january/1226697

The Lexus produces its own electricity nad has no facility for hooking up to mains supply so the cost of electricity is not an issue.

I didn't know that, interesting.

 

[Gafferbill]

Will the hybrid Lexus tug my ta wyoming. Mtplm 1697kg as well as the soento?
I'm finding it hard to differentiate bhp from torque converted to realistic tugging.

...... the best answer can be obtained from observing the well researched, tried and tested Road Transport Industry. They almost exclusively use diesel engines with a gear box that keeps the engine operating where the bhp output graph crosses the torque graph or within a margin either side. Find a tow car that does this and is heavy enough and you have cracked it in my opinion.

 

[Lutz]

...... the best answer can be obtained from observing the well researched, tried and tested Road Transport Industry. They almost exclusively use diesel engines with a gear box that keeps the engine operating where the bhp output graph crosses the torque graph or within a margin either side. Find a tow car that does this and is heavy enough and you have cracked it in my opinion.

In order to have a comparison that is fair, one would have to look at hybrid HGV's, but there aren't too many of those about. I only know of hybrid buses.

When you've got two propulsion systems, one an internal combustion engine and the other electric driving the same wheels, the bhp/torque curves will appear very different to what one is accustomed to. Above all, unlike a petrol or diesel engine, the curves will change dynamically as the electric motors, which have inherently ideal torque curves, cut in and out.

 

[Gafferbill]

I understand the engineering excellence of the Lexus. I am just not convinced by the whole life vehicle cost of such a system versus the diesel. It is not just HGV's....... light vans and other delivery vehicles are mostly diesel and makers of such vehicles would be the first to adopt the Lexus system if they saw it as the cost effective future. This is just my opinion.....the choice of a vehicle to purchase is very personal.

 

[xtrailman]

Will the hybrid Lexus tug my ta wyoming. Mtplm 1697kg as well as the soento?
I'm finding it hard to differentiate bhp from torque converted to realistic tugging.

...... the best answer can be obtained from observing the well researched, tried and tested Road Transport Industry. They almost exclusively use diesel engines with a gear box that keeps the engine operating where the bhp output graph crosses the torque graph or within a margin either side. Find a tow car that does this and is heavy enough and you have cracked it in my opinion.

That would mean my diesel revving at 3600 rpm, with only 340 nm of torque, while in practise i rarely have to go above 2K revs, usually running at 1500 rpm.
I always thought that theory related to petrol engines?

 

[bertieboy1]

It's not a case of bhp V torque,bhp and torque are related by the fundamental formula bhp = 2 x pie x n x T/33000 ft/lbs
Where n = engine rpm and T = torque in ft/lbs and pie = 3.142.
Torque and engine speed are directly proportional to bhp. ie the higher the speed or the higher the torque the more power output from the engine.
Car manufacturers usually quote maximum engine power and torque at a specific rpm.
Of course the above is from my apprentice days and is perhaps too simplistic when applied to a motor car.
From the fugures given the Lexus seems to be running at a far higher rpm than the Kia.

 

[JonnyG]

It's not a case of bhp V torque,bhp and torque are related by the fundamental formula bhp = 2 x pie x n x T/33000 ft/lbs
Where n = engine rpm and T = torque in ft/lbs and pie = 3.142.
Torque and engine speed are directly proportional to bhp. ie the higher the speed or the higher the torque the more power output from the engine.
Car manufacturers usually quote maximum engine power and torque at a specific rpm.
Of course the above is from my apprentice days and is perhaps too simplistic when applied to a motor car.
From the fugures given the Lexus seems to be running at a far higher rpm than the Kia.

with the Lexus being hybrid and having elecric motors which normally generate there max torque almost straight off, it complicates matters as to knowing how much torque the vehicle has from really lowdown and not just the MAX it has.... also turbo diesel tend to play around with formuli ie "the more torque the more power from the engine".simply by setting max psi of turbo around max torque range and then slowly dropping off the turbo psi which kinda ruins the statement "the more torque a vehicle has the more power from the engine" as thats controlled more by the turbo and its psi settings...

 

[otherclive]

It's not a case of bhp V torque,bhp and torque are related by the fundamental formula bhp = 2 x pie x n x T/33000 ft/lbs
Where n = engine rpm and T = torque in ft/lbs and pie = 3.142.
Torque and engine speed are directly proportional to bhp. ie the higher the speed or the higher the torque the more power output from the engine.
Car manufacturers usually quote maximum engine power and torque at a specific rpm.
Of course the above is from my apprentice days and is perhaps too simplistic when applied to a motor car.
From the fugures given the Lexus seems to be running at a far higher rpm than the Kia.

with the Lexus being hybrid and having elecric motors which normally generate there max torque almost straight off, it complicates matters as to knowing how much torque the vehicle has from really lowdown and not just the MAX it has.... also turbo diesel tend to play around with formuli ie "the more torque the more power from the engine".simply by setting max psi of turbo around max torque range and then slowly dropping off the turbo psi which kinda ruins the statement "the more torque a vehicle has the more power from the engine" as thats controlled more by the turbo and its psi settings...

i think that you are confusing the turbo effect in your posts. All the turbo does is put more air into the cylinders so Bertie's analysis is correct. Engine torque and power are purely generated within the cylinder dependant on pressure, piston loading and revs. External factored such as turbos, supercharger, fuelling maps do nothing other than modify what goes on in the cylinder. In my earlier post I said that being petrol I would expect the Lexus to have a different characteristic to the Sorento and only by driving the two cars can one decide what your choice would be.

 

[Lutz]

Just to put some figures to the Lexus RX400h performance data: -
The petrol engine develops 211bhp at 5600rpm and 212ftlb torque at 4400rpm -
The electric motor at the front axle develops 167bhp at 4500rpm and 246ftlb torque at 0 to 1500rpm -
The rear electric motor develops 68bhp at 4610 to 5120rpm and 96ftlb torque at 0 to 610rpm -
However, because the respective values are achieved at different rpm, one cannot add all three sets of figures together to calculate the net overall performance. The actual maximum is 272bhp.

 

[seth1]

So please correct me if im reading this wrong,by your reckoning Clive if you took the two stage turbocharging of your D5 it would still produce the same torque?Is this what your saying?The formula Berties using is correct but nowadays it doesnt really stand up.Even going back to the late seventys Cummins were offereing engines called custom torque, were HP was kept low (225) but the torque output was very high to the level were it matched the offering of the same engine but with a lot higher HP.With the addition of EDC the game has completly changed.