I think everybody missed the true intention of this post - In my opinion it was just posted to say: "my dad has a l337 carzor thats wickeder than an XRT :P"

Edit: note to Tommy - It is an interesting topic that you have brought forward, but you would have got a much better response if you had posted posted your statement as a question for debate, rather than using such a strong "THIS IS WRONG" tone. But anyway, my input into the discussion:

My bike weighs 180kg, and pushes approx 130bhp and 110nm at the wheel. I would not be able to get below 10 seconds on it, despite the high torque and power to weight ratio, unless I had a specific drag setup. The best I have ever managed over a quarter mile was 10.5x, I hit the sweet spot on that run - fast pull-away, smooth gearchanges and the front wheel was hovering about 2 inches of the ground for the first 200m. If I had tried to go any faster, I would have flipped the bike. Power is not everything, setup has a lot to do with it, as well as the vehicle's ability to use the power that it has effectively.

130bhp atw on a tl1000s? must be tuned to fook

Aye, TL standard is 113bhp and 108nm of torque (probably flywheel quoted figs too)

new gixer 1000, r1's and fireblades are around 135bhp atw and there quoted from the factory as having over 160bhp

Quote from evans :

This kind of argument has a name that I can't recall, but it's the same as saying this to your mother:

"A bird has wings. A bird is alive. You don't have wings, therefore you are not alive."

And come on Tommy, could you please just consider, next time you want to post, that there are a million + 1 variables in physics, and so building your argument on only two of those will not always be true?

You mean "Erasmus Montanus"

"A stone cannot fly - You cannot fly - Therefore YOU are a stone, dear mother"

Some of you people are proper harsh bastards...

And for 'theirishnoob'

Stop doing what any child does and try and reword what everyone else has written, to just look as if you're really intelligent and know what's cooking.

You're only adding insult to the whole thing and its taking the piss, everyone's moaning on these boards how its going down the drain but feel all chummy when you gun down someone in some sort of geek posse.


Edit: Danowat your comment has only confirmed what I thought to begin with so thanks, I mean what good is life if we're not being crapped on, right?

Quote from Rooble :

Some of you people are proper harsh bastards...

That's life baby, it's a harsh world

Quote from evans :

This kind of argument has a name that I can't recall, but it's the same as saying this to your mother:

"A bird has wings. A bird is alive. You don't have wings, therefore you are not alive."

And come on Tommy, could you please just consider, next time you want to post, that there are a million + 1 variables in physics, and so building your argument on only two of those will not always be true?

A false syllogism (thanks to QI ).

ahhhhh amps reach the point of drunkeness that he now sounds inteligent

Quote from andybarsblade :

ahhhhh amps reach the point of drunkeness that he now sounds inteligent

Oi! I resemble that remark, I'll have you know

Quote from alland44 :

You mean "Erasmus Montanus"

"A stone cannot fly - You cannot fly - Therefore YOU are a stone, dear mother"

Præcis! - Exactly the one I had in mind when I wrote my post, I just couldn't remember the exact words of Erasmus.

And amp, it is indeed a false syllogism

Quote from tommy10101 :

basicaly, the turbo demo car (cant remember whats its called) has 220bhp per tonne or somthing like that yet it can run 13.6 at 108 mph 1/4 mile times. My dad has a kit car with 260bhp and it weighs less than a tonne (876kg) and that runs 13.8 at 101mph. Therefore, they have got it wrong. I just thought i would let everyone know

That's dreadfully slow for that power to weight ratio. Running 260hp with an 876kg car through my drag racing simulation, Straightline Acceleration Simulator, reveals wildly varying times depending on tire traction, wheelbase, and center of gravity height.

With driven tires having a constant friction coefficient of 1, cg height of 22 inches, 106 inch wheelbase, 260hp @ 5000rpm and 340ft-lb @ 2940 rpm, Mucie M21 4 speed manual, gets this 12.84 sec @ 112.0mph (assuming 82% drivetrain efficiency and a 0.4 second gear change time).

That's with a drag coefficient of 0.42 and frontal area of 24 ft^2, which is more along the lines of a big, boxy, American sedan from days of old than what your Dad probably is running. Just to give an idea of how much the aerodynamics alone effect the picture, if the drag coefficient is changed to 0.36 it gets 12.78 @ 113.6mph (much less of a difference than I expected, actually).

It's traction limited all the way up to 60 mph, btw.. Drop the tire friction coefficient to 0.9 and we get 13.33 @ 111.1 mph. Reduce it to 0.85 and we get 13.63 @ 110.5 mph. The point is, just a tiny change in grip here produces a massive change in time.

If we give it as much traction as it wants (1.19 friction coefficient), the time plummets to only 12.29 @ 112.7mph. With better gearing and more grip, it'd go even quicker.

You sure your dad's car is really making 260bhp? I'm only using a 2.73:1 differential here and the Muncie's first gear ratio is only 2.2:1, so rather tall gears. He ought to be spinning the tires like crazy up to 60+mph if he wants too. Am I right? If not, the 260bhp number is probably just some bench racing fantasy.

I wouldn't say anything is wrong with LFS on this one. The LFS car, especially the particular tires it uses, are different enough from your dad's to account for the time and speed difference quite easily. Power to weight ratio is, as others pointed out, only part of the picture. Most important is traction in this case, it appears.

Yes, from 1/4 mile speed and vehicle mass you can calculate bhp, even bad launch does not make it too different, naturally it is not whole truth, but mostly close at enough.

If your gear ratios are not matching to engine's powerband, even that can make such difference which topic starter represented.

Surely there can still be imperfections in model too, engine powercurve for example is not like it is in real car and many other stuff is not simulated yet, surely there can be some issues.

Quote from andybarsblade :

130bhp atw on a tl1000s? must be tuned to fook

It is quite far from standard, - every time I crash it I improve something on it

next step is to replace the horrible rotary damper...but the ohlins aftermarket replacement shock is ridiculously overpriced.

when I first got it (second hand) it was pushing 124bhp, and 106nm (on the same dino as the latest figures). The major performance increase since then is due to the having the heads gas flowed and the valve seats cut.

Quote from ajp71 :

No I'm talking about why the calculator thing is inaccurate.

Calculator is perhaps inaccurate, but you should be able to calculate good estimates from Bhp. http://www.streetrodstuff.com/ ... Horsepower_Calculator.php

There you can see formulas used too.

Rolling road is inaccurate too, still some people think it reveals how much bhp car has

If you really like to find out how much bhp engine has, you need to take out it from car and put into proper engine dynamo meter, expensive, takes lot of time, etc.

That earlier calculator was quite bit off for my car, over 19secs 1/4 even it runs around 17,4 secs when stock, now bit faster, so at least for me that first linked calculator did not worked at all.

1/4 speed is good indication of what kind of power level car might have as launch does not affect it a lot.

Car has 130bhp (well, that is again estimate, but 109whp is measured from rear wheels, again rolling road value, just one estimate less here), 1075kg weight and it has run:
0-100kph 9,2secs
0-400m 16,6secs and 140kph
0-1000m 30,3secs and 171kph

Not a rocket at all, but it is not meant to be, yet Maybe you can test and find working calculator for those numbers

Quote from ev0 :

It is quite far from standard, - every time I crash it I improve something on it

next step is to replace the horrible rotary damper...but the ohlins aftermarket replacement shock is ridiculously overpriced.

when I first got it (second hand) it was pushing 124bhp, and 106nm (on the same dino as the latest figures). The major performance increase since then is due to the having the heads gas flowed and the valve seats cut.

Wheel or flywheel figures?

If the dyno says 124, then it's probably more like 116. If it's wheel horsepower, then you have around 105hp at the flywheel.

All commerical dynos over-read.

Quote from tristancliffe :

Wheel or flywheel figures?

If the dyno says 124, then it's probably more like 116. If it's wheel horsepower, then you have around 105hp at the flywheel.

All commerical dynos over-read.

Tristan, what is wildest misleading dyno reading you have seen?

I have seen how some chip seller took classic before and after graphs, gain was something like 150hp with chip and in other dyno it was more like 10hp and we are talking less than 300hp level here. It is dead easy to fool someone with dyno curves, you can get almost that power to paper what you like, no matter what car has.

One thing we laugh here is how at Sweden their dynos seem to show at least 100hp more as when same car is tested here after it is bough, it gets that much less in dyno

But Tristan, if dyno shows 124hp from wheels, how you end up to 105hp at flywheel. Lot bigger change than 124 -> 116 and there should be bigger margin of error because of faulty drivetrain loss estimates dyno/operator uses?

Quote from tristancliffe :

All commerical dynos over-read.

Why is that?

Must have been quite busy there JTbo, checking all those Swedish dyno's out...

Thomas

its very easy to fool dyno readouts by changing the abient temp settings, putting the temp sensor in a cup of tea while doing the power runs ive heard of before lol.

24% losses through the drive train is what is normally quoted for lancer evos 4wd, dunno about bikes but i would guess its alot less around 10-13%

Quote from Thomas H :

Must have been quite busy there JTbo, checking all those Swedish dyno's out...

Thomas

You probably misread, I was talking about cars that are on sale in Sweden and then shipped to here, mostly rally cars etc. I'm sure same thing happens everywhere, seller gets big figures in dyno by fooling it to help selling car

Quote from JTbo :

Tristan, what is wildest misleading dyno reading you have seen?

Hard to say, because we don't really know what the accurate power figure is. But we had a car measured that we reckoned was probably about 350hp, but the dyno said 415!!!! No way on earth was it 415!

Quote from JTbo :

But Tristan, if dyno shows 124hp from wheels, how you end up to 105hp at flywheel. Lot bigger change than 124 -> 116 and there should be bigger margin of error because of faulty drivetrain loss estimates dyno/operator uses?

Well, I worked on the basis that a dyno reading of 124 really means 116ish. And then there are efficiencies, which mean that (assuming the 124 was a wheel power figure) you're looking at arounf 105 - 109hp at the flywheel (again, ish).

Quote from Bob Smith :

Why is that?

Because people go home thinking "wow, it's way better than I thought. I'll use that Rolling Road again". If they under-read people wouldn't use their service. So everyone's over-reads by quite a margin to keep the customers happy, and generate return custom. When telling a customer figures, never tell him a figure below what is real, always over-quote. This applies to work cost estimates as well...

You were generalizing a bit there JTbo, that's all. Had to make a comment...

Thomas

Quote from tristancliffe :

I worked on the basis that a dyno reading of 124 really means 116ish. And then there are efficiencies, which mean that (assuming the 124 was a wheel power figure) you're looking at arounf 105 - 109hp at the flywheel (again, ish).

But wouldn't wheel power be less than flywheel, I think you got it wrong way there?
Flywheel 116ish and wheels 105-109ish, right?

Was just about to write the very same thing