You need torque!

[2strokespirit]

I read alot of Banshee owners is talking of HP figures. You need torque as well, a good combination between torque and horsepower and that is were the Banshee struggles on lower rpm, with the torque. With a lot torque you can get bigger wheels-more traction-better acceleration.

I am working on some Banshees, not an expert, but trying to get more torque at lower rpm, currently getting 59nM on stock bore and stroke and 60HP, with 14 front sprocket and 38 rear with razr 20-11-9 we do 150+km/h on a GPS. I wil smoke a 70-75HP Banshee that have 50nm or less with the 70-75 HP combination.

I am a RZ350 tunner, but like the banshees.

 

First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car or bike, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a bike will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. Torque is the only thing that a driver feels, and horsepower is just sort of an esoteric measurement in that context. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm. Therefore, horsepower isn't particularly meaningful from a driver's perspective, and the two numbers only get friendly at 5252 rpm, where horsepower and torque always come out the same.

 

In contrast to a torque curve (and the matching pushback into your seat or handlebars), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.

 

OK. If torque is so all-fired important, why do we care about horsepower?

Because (to quote a friend), "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.

 

For an extreme example of this, I'll describe a waterwheel I got to watch awhile ago. This was a pretty massive wheel (built a couple of hundred years ago), rotating lazily on a shaft which was connected to the works inside a flour mill. Working some things out from what the people in the mill said, I was able to determine that the wheel typically generated about 2600(!) foot pounds of torque. I had clocked its speed, and determined that it was rotating at about 12 rpm. If we hooked that wheel to, say, the drivewheels of a car, that car would go from zero to twelve rpm in a flash, and the waterwheel would hardly notice :-).

 

On the other hand, twelve rpm of the drivewheels is around one mph for the average car, and, in order to go faster, we'd need to gear it up. To get to 60 mph would require gearing the wheel up enough so that it would be effectively making a little over 43 foot pounds of torque at the output, which is not only a relatively small amount, it's less than what the average car would need in order to actually get to 60. Applying the conversion formula gives us the facts on this. Twelve times twenty six hundred, over five thousand two hundred fifty two gives us:

 

6 HP.

 

Like I said, you need a good combination between the 2. If you let your bike dyno, ask the torque figures, not just the Hp.

Just my opinion and experience

Edited October 25, 2006 by 2strokespirit

[rocketboy]

i agree to some extent but theres alot more factors to accleration and winning races than torque of a given engine .4 pokes make excellent lowend torque with a much wider usable curve over your typical banshee engine (rz has powervalves to help it in that dept) but it makes up for it by design of a parallel twin that reaches high rpm very quickly and its ability to generate pure power strokes unlike a 4 stroke having to wait for 4 revoultions .I totally see your point on the feeling we get when it comes on the pipe and pull is the torque but the egines speed at which it reaches its powerband at a given rpm is just as critcial . this is why a banshee does so well at drag racing regardless of the fact it makes poor lowend torque and performance ,loo kat a harley davison tons of torque but slower than snails because its lacks the ability to rev and reach high rpms ....you forgot to add in the roost factor lol....good informative post BTW

[blak banshee]

Thats the exact reason they make diesel ferraris!

[dawarriorman]

I didn't read your whole post, but I skimmed it. And yes your right to a point. But torque means nothing by itself. Torque alone will not move anything. The ability to apply that torque over time is what moves the car/bike/atv, and that is horsepower. You can take your muscle car with 600 ft lbs of torque, and I'll take an F1 car that probably doesn't have half that. I'll be waiting for you at the end of the 1/4 mile.

 

The measure of torque at the crank is meaningless, because it doesn't drive the vehicle. Torque at the wheels is what provides the force, and that is run through a transmission. The reason that vehicles with broad powerband with torque down low do so good is they are easier to launch, and the gearing is more forgiving.

 

Take a 4 stroke for instance, all you have to do is rev, dump the clutch and go. So what if the engine bogs down when you launch, you still have nearly the same amount of torque as you would at the engine's peak, you don't lose much time. The 2 stroke on the other hand, you have a narrow torque band, and you have to have everything setup to launch right. The tires can't have too much grip or you'll bog down, but not enough grip and you spin hopelessly. You also have to work the clutch right so you don't over or under rev. Then you have to shift right on the dot.

 

Your argument is flawed. You CAN'T have any horsepower without torque, you can have torque without horsepower, and in that case you go nowhere. A proper balance makes you fast, and rideable, too much hp without torque makes for a fast vehicle, but not practical or rideable.

 

Torque is meaningless without horsepower.

[2strokespirit]

I agree with you, I dont mean that it wil be better if the basnhees torque was lower. But with more torque at lower rpm it would have had a wider powerband and be better, and we get it out of them, although the RZs have powervalve the Banshees makes much more torque than RZ if their powervalve system is disconnected, because the stock porting helps for the lower rpm power because there is no power valve. Like i said, you need a good combination between the 2. If you go and port a banshee like a RD/RZ350 raise the exhaust port the same hight, and do the transfers you can get almost 60 HP out of the motor with zotall bottem end, it goes like HELL on the topend, if you can spread the powerband wider it will rocks. Theres a local guy here, they still race Banshees in enduros, theyve won the Roof Of Africa with a Laegers 350. If you read the article they say that bike made more torque at lower rpm than the same guys racing YFZ450, I spoke to him, he said in 3rd gear at 4000RPM you can just snap the throtlle and the bike lifts its head up from the ground. I know them personally, like I said, they are known racers here, but again wont give any secrets out! More torque than a YFZ450 at low rpm., sounds almost lik s**!!

[2strokespirit]

You missed the point, everyone always talk about HP, its meaningless without torque, just like you said torque is meaningless without HP. You need a GOOD combination between the 2. I dont want to start an argumant, but a Formula 1 car has loads of torque for the record. :-) On the banshees the art of tunning is getting a lot of torque over a wider powerband, without losing too much on topend and not any engine builder can do that, you cant have horsepower with no torque you are right, but getting more torque out of a engine wil always let you gain HP, dont missunderstand me, the art is to get the torque over a wider powerband amd get a good combination and you will not believe the differance. I have seen dynos of 75HP and 50nm and then again 61.5HP with 59 nm. The best engine builder is the one that can give you both. So it is possible to get HP without torque, otherwise this $64 102 dyno is full of shit! :-)

 

 

 

A Ferrari has loads of torque a very good combination :-)

Dont want to argue. Just an interresting fact!

[csrmel]

lets talk about torque for a moment. average male human can pull over 600ftlb of torque from their legs. and probably 300ftlb from their arms.

 

why cant a human on a bicycle win a drag race between himself and a banshee ? the human has 600ftlb's, theres no banshee in the world with over 200ftlb. answer is the human lacks horsepower. banshee has ample ammounts of hp.

 

torque is how hard you can twist something, like a crankshaft. i know i am capable of tightening 250ftlb torque headbolts on my car. hp is how hard you can twist something measured over time. i am slow compared to an engine. i have less than 1/3hp. humans have a very low rpm on a bicycle so the hp is low. if human could make 600ftlb at 5000 rpm then we would all be monsters.

[2strokespirit]

If you had read the last sentence, "a good combination between the 2".

 

For instance a 60 hp motor with 40nm of torque against a 60 HP motor with 55nm of torque, who will win a drag race on hill climbing????? I dont even have to answer that question if the power yo weight ratios are the same..

Its a true fact when it comes to the racing world. That is where I wil pass you on the hills, sand etc, torque aint meaningless.

[Mullet Man]

side not, if you are tightening heads to 250lb-ft, then you have broken bolts or studs everywhere LOL. ::

 

i think this argument started when the 1st internal combustion engine was produced

Edited October 24, 2006 by Mullet Man

[2strokespirit]

There is a lot of confusion when it comes to torque. Torque is pulling power, the more torque you have, the easier you wil be able to drag a lot of weight over hills, threw sand etc. Thats why they need high torque enjins for towing big loads or in fact any load. For instance, (horsepower gives good acceleration) but if you accelerate hard and reached a speed of say 60mph, torque is the factor wich is going to keep that bike running at 60mph, uphill, through thick sand, against strong head winds, not horsepower!!!!!!!

I dont want to start bragging but I am a Mechanical engineer, i dont just suck this out of my thumb.

Go search the internet if you dont believe me!!

 

LOL....

 

 

[i agree, so lets leave it there. lol

I just wanted to raise the torque factor :-), guess it wasnt a good idea.

[CadillacBanshee]

I dont think i finished reading one of the previous post. Sounded like a bs post to begin with. I skimmed through the whole thing and i agree, the combination of both is what you want...DUH. Thats why you regear when you modify your engines...is the spirit guy new here???

 

caddy

[2strokespirit]

Good point, thanks. LOL.

Yeah I am new here. Only Sooouth African i think. lol

[strokersquid]

hey good to see some rz tuners here. i actually dont own a banshee but several rzs and im eventually going to build a cub rz for canyons and track. this site has been great since these guys know their stuff and i get different opinions about stuff like reeds and engine mods. ive gotten downloads on engine teardowns and rebuilds. try finding that on an rz website !!!!!!!

[rocketboy]

thta sounds nice on paper but in the real world, a 700cc raptor with 40 pounds of torque doesnt have an ice cubes chance in hell chance against a ported 350 with the same amount of torque

[dawarriorman]

There is a lot of confusion when it comes to torque. Torque is pulling power, the more torque you have, the easier you wil be able to drag a lot of weight over hills, threw sand etc. Thats why they need high torque enjins for towing big loads or in fact any load. For instance, (horsepower gives good acceleration) but if you accelerate hard and reached a speed of say 60mph, torque is the factor wich is going to keep that bike running at 60mph, uphill, through thick sand, against strong head winds, not horsepower!!!!!!!

I dont want to start bragging but I am a Mechanical engineer, i dont just suck this out of my thumb.

Go search the internet if you dont believe me!!

 

LOL....

[i agree, so lets leave it there. lol

I just wanted to raise the torque factor :-), guess it wasnt a good idea.

But the amount of torque you are putting to the wheels is NOT the amount of torque you see on a dyno, the amount of torque you see at the wheels is that of the dyno run through the transmission.

Lets say one engine has a peak of 200 ft lbs of torque at 8000 rpm and another engine has 600 ft lbs of torque at 2000 rpm. The second engine should launch like a son of a bitch and pull the other hard as hell right? 304 horsepower for the first engine vs 228 hp for the second engine. Put a 4:1 reduction ratio on the first engine so the rpm is the same as the second. Now its putting out 800 ft lbs of torque at the same 2000 rpm. Its an engine that never can produce as much torque as the other at the crank, but once its run through the transmission and put to the ground, it will spank the other motor every time.

 

Point is torque is a number, nothing more. It is meaningless by itself. Horsepower is what gives torque meaning, its torque applied over time. I know what your trying to say, but your taking it too far. A motor with 75 hp and 50 ft lbs of torque will beat a motor with 60 hp and 60 ft lbs of torque every day, if the first motor is set up right. Even though you've seen high hp motors lose to lower hp motors with more torque, thats not because the motor with more torque was faster, thats because the setup of the high hp motor was wrong, and couldn't take advantage of the power.

Edited October 24, 2006 by dawarriorman