why has typhoon got more torque that ls2 ??

[hsvLS1255]

am curious what determine the torque output of a motor.

for example the phoon has more torque than the clubbie, but has less kilowatts, so i guess you cannot relate more kw = more nm.

also for eg you would think the new m5 motor putting out 370kw would have a bucket load of torque, yet both the clubbie and phoon with less kilowatt have more torque ( i think).

never really understood how it works. is it capacity, number cylinders, aspiration that determine this, or is it too complex to descride ???

[Kirium]

Have you read all thru this (http://www.ls1.com.au/forum/showthread.php?t=25904) thread?? I've only skimmed it quickly while at work, so not sure if it covers it...

[Dacious]

Torque is twisting force, HP = torque x revs. It's more complicated than saying a motor which revs twice as hard with the same peak torque puts out twice the HP, but it is not too much more complicated. That usually means the higher-revving motor is much more gutless down low, but not always!

The F6 puts out more torque from a smaller motor because it has charge forced into it by a turbocharger (more air/fuel mix so bigger bang).

If you turbo- or supercharge the LS2, it will leapfrog the F6 for torque and HP. Single cam and two valves/cylinder are not as efficient breathing as quad cams and 4 valve heads, but get bigger gains from blowers as the advantage of more valves is better breathing - forcing it in makes that less important.

Like anything, you get nothing for nothing - working a small motor harder will mean more heat. The engine will likely, all other things being equal, last a shorter time and cost more while it does. Components need to be stronger/better made which increases cost etc.

There are a number of other things which affect how a motor revs and power characterisitcs - irrespective of torque and HP, an undersquare or long stroke motor can have high reciprocating weight. i.e. the crankshaft/rod assembly is larger and heavier, with bigger rod-ends and mains than an equivalent capacity oversquare/shortstroke motor. It's rods go through more angularity as the engine revs, the piston and rotating components travel further and reverse direction faster and harder - it is subject to far more lower-end stresses due to the longer rods swinging off it at greater angles.

The pistons have to be longer in relation to bore size, which induces drag at the skirts. This increase in weight causes the crankshaft assembly to actually suffer from increased inertia which holds back acceleration. One reason why racecars have lightened cranks and performance motors tend to bu shortstroke. For example, the Ford 5.4 motor with a 6,000rpm redline is right on the limit of the old 11.4 m/s average piston speed where oil stops lubricating the cylinder because the piston outruns it. The 6.0 Ls2 motor, due to a much shorter stroke, can rev to 7,500 rpm without getting there.....

Shorter-stroke motors usually produce more top-end (rev harder) but less torque. Multivalve engines usually get better flow at all rpm due to smaller port sizes which increase volumetric efficiency (cylinder filling) and can also get more valve area into a given cylinder size (again more fuel/air=bigger bang). You need fresh gasses flowing in and spent gasses out fast for efficiency and HP.

That's how the Ford V8 with sophisticated heads even stays on the same page as the LS1 and LS2. 4-valve DOHC heads allow better port shapes, central sparkplugs, flatter piston top and combustion chamber and lighter valve springs which only have to control smaller, lighter valves and less weight in the valve train - not having to slam a heavy valve shut while pushing the rocker and pushrod back.

The M5 likely has bigger ports/valves/more cam lift which all sacrifice bottom-end torque, but gets the HP through better hi-rpm breathing and increased redline. More, smaller cylinders can rev harder - V10 vs. V8.

Working example: F1 car motors are massively oversquare, all multi-valves, quad cams, and rev to 16,000rpm to produce HP, even though there's bugger all torque until 10K.

[mmciau]

Dacious,

Congratulations for a well developed explanation.

This should help people who may have difficulty understanding the output of engines.



Mike :)

[spiv]

Because boost at low rpm = big torque increase......

[flappist]

Two other points.

Power = torque * rpm. The F6 demonstrates 550Nm from 2000 to 4250 rpm and then is electronicly limited (probably so as not to embarass the GT by too much). If it were not limited it would produce about 347kw @ 6000rpm.
Ford tend to lie a lot when it comes to engine ratings. An ordinary boring 290(alleged)kw GT will produce a rwkw of 235-245. A Y series GTS (300kw) will produce 225 to 235.

N.B. This is not supposed to be a flame magnet, these numbers have been seen by many many GT & GTS owners.

Although FPV do have more powerful engines they limit their output in lower gears to protect the driveline. This one of the major reasons why HSVs are generally quicker over the 400m.

[M&Ms]

Although FPV do have more powerful engines they limit their output in lower gears to protect the driveline. This one of the major reasons why HSVs are generally quicker over the 400m.

Something Ford will hopefully fix in their next upgrade. Now back on topic (and slightly off topic too)...

As has been said before, car engines make torque, and power is a function of this torque. A car that is able to make a high (or consistant) amount of torque at higher revs will see a great rise in it's peak power figure. Torque is what actually accelerates a car faster. Anyone with basic physics knowledge should remember Newtons second law: Acceleration is directly proportional to Force, and Inversly proportional to mass - high School stuff -. In this case, Torque represents the force (albiet Torque is a twisting force) and mass is, well, the mass of the car. Now there is also other considerations when talking about cars, such as gearing, the shape of the torque curve etc, but generally speaking, a car with more torque and similar power should be faster than one with less torque and similar power. Furthermore, if you compare the acceleration curve with the torque curve, you can actually see similarities, and will find that the greatest acceleration is experienced at the point of max torque.
Car manufacturers of late have been picking up on these and now we see a greater emphasis, with car makers' claims, on torque or the torque range, with claims of XXX Nm @ X000 - Y000 RPM (e.g, F6/XR6T, RS4/RS6, AMG etc) rather than max power figures.
Then new M5 is an example of a car with a lot of power (373KW) and not as much torque (520NM). Closer inspection shows that the M5 makes it's max torque at 6100 RPM and max power at 7750 Rpm, clearly showing that the high power figure is achieved through the higher RPM's rather than through the high torque figure.
So in conclusion, car's make torque, and power is calculated from this torque. Car's that can a) make higher torque in the upper rev range or b) rev much higher with a constant amount of torque, will end up making more max power. It should be noted though, that it is difficult to maintain a constant torque in most engines after about 5000 Rpms, as friction and other factors reduce the torque output significantly, and thus we usually see a dip in the torque curve in (high CC) engines anyway.
hope this rambling helps answer some questions, and someone correct me if anything I've said is wrong or doesn't make sense.
Thanks

[MIC33R]

The M5 likely has bigger ports/valves/more cam lift which all sacrifice bottom-end torque, but gets the HP through better hi-rpm breathing and increased redline. More, smaller cylinders can rev harder - V10 vs. V8.

The M5 probably still has quite a good bottom end I'd say. It's got double VANOS for variable valve timing on both inlet and exhaust cams, which really helps the breathing. If it had Valvetronic for lift control adjustment it'd be even better.

[CarlFST60L]

I love this > http://science.howstuffworks.com/fpte4.htm

the typhoon's the truck, the LS1/2 is the Mustang > http://science.howstuffworks.com/fpte5.htm

Tyhoon's are great down low, they dont have to knock it back to 2nd @ 60 like a LS1/LS2 to be quick. I race a typoon quite often (he has unichip, works accross the road, i have edit, exhaust and diff), he definatly pulls harder than me at low revs, no question, but i always win, why? because i dont let my rev's fall below 5000rpm while racing ;)

Guess thats why i want that GenT so bad, i dont wanna drop it back to 2nd at 60, roll on in fourth ;)

[COUPE]

Two other points.

Power = torque * rpm. The F6 demonstrates 550Nm from 2000 to 4250 rpm and then is electronicly limited (probably so as not to embarass the GT by too much). If it were not limited it would produce about 347kw @ 6000rpm.
Ford tend to lie a lot when it comes to engine ratings. An ordinary boring 290(alleged)kw GT will produce a rwkw of 235-245. A Y series GTS (300kw) will produce 225 to 235.

N.B. This is not supposed to be a flame magnet, these numbers have been seen by many many GT & GTS owners.

Although FPV do have more powerful engines they limit their output in lower gears to protect the driveline. This one of the major reasons why HSVs are generally quicker over the 400m.


Great explination Dacious ... Well Done!!!


Plenty of GT's producing under 230 rwkw ... so I wouldn’t take it as gospel that every GT is producing those numbers … Even in Motor the GT and Pursuit have exact same engines, but the difference was 240 rwkw for the GT and well under 230 rwkw for the Pursuit (maybe 220 or less? I can’t remember, mag is in the garage somewhere) ... Go figure!!! .....Just like the LS2 got 226 yet there are guys who are getting 240 rwkw (forum member vuster’s car), also I think F1 Performance posted a dyno sheet of 240 rwkw for a stock LS2. Even APS with the F6 only got 200 rwkw on their dyno, but I’m sure there would be other F6’s pushing more figures than that.

So claiming Ford motors push out more power isn’t that definite, and vice versa.

[COUPE]

For example, the Ford 5.4 motor with a 6,000rpm redline is right on the limit of the old 11.4 m/s average piston speed where oil stops lubricating the cylinder because the piston outruns it. The 6.0 Ls2 motor, due to a much shorter stroke, can rev to 7,500 rpm without getting there.....

Love this quote and how true. I've spoken to many GT owners at various performance workshops around Sydney, and they say the same thing. This engine can't be stroked and it's at its limits in terms of revs.

I know when I'm racing I want revs. A lot of people will differ but thats just my personal preference. This is why I like the LS2 so much, it's got enough down low and loves to rev for a big V8.

[Jag530G]

The key with Turbo/Supercharging is forcing more Air/Fuel mixture into the combustion chamber.

A Turbo 4.0L running at 0.5 Bar (so 1.5 times Atmo pressure) is essentially pumping in the same amount of Air/Fuel Mixture as a 6.0L HSV VZ with is an atmospheric engine running at 1 times Atmo pressure. Hence the similar peak torque figures.

A WRX 2.0 running 1 Bar (so 2 times Atmo pressure) is pumping the same amount of A/F Mixture as a Falcon Atmo 4.0L (running at 1 times atmo pressure) and consequently both have similar peak torque figures.

A Bentley Arnage Turbo 6.75L V8 running at 0.5 Bar is pumping 10.125 Litres of A/F mixture, hence peak torque of approx 900 Nm.

An interesting note about BMW, over recent years they seem to have a design standard of 100Nm per Litre of capacity for their atmo petrol engines, the new 3.0 litre engine is 190Kw/300Nm, compared to the HFV6 of 3.6L, 190Kw/340Nm. BMW certainly show the way with great specific power and torque figures.

Boost helps increase Brake Mean Effective Pressure (BMEP)

Torque = (Brake Mean Effective Pressure x Stroke / Piston Area) x Num of Cylinders

[Martin_D]

Easy...because its got a turbo on it, and turbos make torque....shitloads of it. :cool:

[Danv8]

Easy...because its got a turbo on it, and turbos make torque....shitloads of it. :cool:


Especially a few turbo's blowing a 18.1 V12 Diesel. :drool:
3276nm.

[2001 ITR]

Generally speaking I’d rather have torque than power. There is a turn up at Winton that doesn’t suit the gearing of my Honda Integra. 2nd seems to be too low and 3rd is too high for this turn (not enough torque coming on to the front straight), If I had more torque I could slot in to 3rd and let the torque pull me through.

An old quote is “Power may sell cars but torque will win races”.

In some cases you will be better of looking at an engine dyno readout to see the shape of a torque curve rather than just quoting a peak torque figure at X revs. Some of the Euro turbo motors (Audi RS6/RS4?) have a peak torque figure but the torque curve is very flat either side of the revs at which peak torque occurs.

P.S. Try typing in “BMEP Brake Means Effective Pressure” in to Google and see what influences revs and capacity make on engine outputs. Power = torque X revs so if you increase the revs you should increase the power output, but who wants to cane an engine to make it perform (and how long will it last).

P.P.S. Isn’t it strange that the number of gearbox ratios are climbing and CVTs are becoming more popular (these are great for low torque/rev-band engines) yet variable-valve timing, variable induction lengths, etc are making torque more accessible than ever (Mercedes Twin Turbo V-12 1000Nm of torque!).

[peber]

Just like the LS2 got 226 yet there are guys who are getting 240 rwkw (forum member vuster’s car)

remember too that figures vary between dynos, and theres always enviromental conditions. a mates vl turbo has had a number of dyno runs and has seen differences up to ~20rwkw between dynos, without any changes to the boost, etc to the car itself.