Not in the UK anymore unfortunately, a half decent Mk2 Escort rally car will cost you £12000-£20000. Even a good standard RS car will be £5000+
But the rules limited them to 8500rpm, if they were able to rev to 11500rpm wouldn't that equate to around 400bhp?
Yes, that "gobbledegook" takes everything into account as it is theoretical.
It is derived directly from the optimal, theoretical cycle -supposes there are no pumping losses, that volumetric efficiency is 100%, etc- and as such that theoretical efficiency is the maximum that can be obtained for that cycle.
It's a bit like climbing a mountain: you can buy the best gear there is, be the best climber ever existed, but you can't climb higher than the top. Tom De Moor
Power = Torque x 2 x pi x RPM /60
pi= 3.1415...
Just watch out that torque is in Nm, Power will be in W(att)
1 Hp = 736 WTDM
No... According to my own dyno software which displays either its 0.7456999 w
But its not! With tuned length intake and exhaust tracts better than 100 percent is easily possible. The japs have been fitting tuned length exhausts and tuned volume and length intakes and airboxes for years to achieve exactly that. Thats why they have power curves that look like a ship in a storm. It helps prop up peak power if its done correctly, and a few other places (various harmonics) along the way at other rpm points. And it makes other points worse hence the introduction of various intake and exhaust pressure wave (and for noise in some cases) valves etc.
You could with harmonic induction and exhaust tuning! It makes the mountain bigger.
Are you there again with those f*$cking Imperial conversions?
For automotif purposes that's the same because there are NO dyno's=20 (none, not even the F1-teams dynometers) which is and stays that=20 accurate. Best turn around 2.5% error margine and in order to maintain=20 that error margins need fairly regular calibrations.
Changes in the engine-output -over long dynoruns, read 10 minutes on=20 specified powerlevel) varie around 5%.
The tolerance on your dyno will be around 5%.
That also the reason why mentioning 412 Hp is selling air and=20 reminiscent of an -now defunt- Italian motorbike-maker stating his=20 engines at 67.32 Hp. I received one for free and couldn't get more than=20
42 HP =B12 HP out out it. Gave it away too and it seized like all the=20 others did...Tom De Moor
And now to prove that it's not so simple...
My wagon generates 2100 NM of torque at 1000RPM. What power is the engine developing?
Nope...ends up around 10% out for my truck.
2100 x 2 x pi x 1400/60 does not equal 440HP.
300 Hp
Tom De Moor
Around 420 Hp
I suspect that the real power of your truck is lower than the 440 HP@
1400 RPM or that your RPM-meter has an error or (most likely) both of the stated errorsFYI: on commercial vehicules powervariations on identical engines around 5% are considered normal.
Why do you think that manufactureres like Aston Martin, Ferrari and the big bucks Mercedes assemble the engine by hand? Tom De Moor
Are you there again with those f*$cking Imperial conversions?
All the americans did was steal our measurements and screw that up at the same time! They stole town names, gallons (and got it wrong) inches, miles etc. How can they get HP and KW wrong???
For automotif purposes that's the same because there are NO dyno's (none, not even the F1-teams dynometers) which is and stays that accurate. Best turn around 2.5% error margine and in order to maintain that error margins need fairly regular calibrations.
Completely wrong. My OWN design dyno system is used in many countries and each one is about as accurate and repeatable even between different sites as is digitally possible!
We machine the SOLID en1a steel drum to 402mm diameter and 562mm long and machine a spigot on each end to accurate dimensions. The density of en1a is a known quantity. The rotational inertia is calculated. The software knows the value. There IS NO POSSIBLE calibration. And it is neither tequired ever or wanted. The only way calibration could ever be wrong is if the drum was manufactured out of spec. They are + - 0.25mm dimensionally so as a percentage the biggest ever error between the smallest possible drum and the biggest is massively less 1 percent! It is for all intents and purposes permenantly absolutely accurate and can only remain so! There is not only never any need to "calibrate" it, its not even possible on purpose to prevent dodgy owners giving "better" figures. I could of course because I can alter the code in the source and recompile it. The drum sensor is of course digital and cannot ever miss a rotation because the handshake protocol would fail and the data would be screwed up!
Changes in the engine-output -over long dynoruns, read 10 minutes on specified powerlevel) varie around 5%.
That does not make the dyno innacurate!
The tolerance on your dyno will be around 5%.
I can run almost any healthy bike on different days and overlay ten different power runs and under controlled conditions all the curves look so similar that it just looks like one slightly thicker multicoloured line. If not then something changed. Like temp/pressure/tyre pressure or whatever. Massively more accurate than your 5 percent! I can clearly see the effects of putting the lights on! Repeatedly. The only thing that CAN change is the vehicle.
That also the reason why mentioning 412 Hp is selling air and reminiscent of an -now defunt- Italian motorbike-maker stating his engines at 67.32 Hp. I received one for free and couldn't get more than
42 HP ±2 HP out out it. Gave it away too and it seized like all the others did...Tom De Moor
Are you there again with those f*$cking Imperial conversions?
Dynos use either ps in europe or hp or brake hp. Which means I am correct.
see link above and choose plain old hp and convert to watts. You will get my
745xxxxx with a minor rounding error.
Its not a uk "conversion" its the plain old hp dyno manufacturers use. Not the oddball ps that some europeans use.
Download my dyno software as written by myself and andrew judd (freind)
1992. Check it out. You may see that I was doing this for a long time. Remember that this was DOS days windows didnt exist yet it looks and works like windows and drag drop and drag draw and right clicks are all present and working on graph screens way before windows did so.and the EU power-definition (736 W) is 1.21%.
The eu power definition of 1 hp arrived long after the dynamometer was already using the original simple hp definition...
Forgot the link
Only 30 odd percent out.
How do you think engines are built at Ford etc?
Clue: The built by hand means not a lot.
At Ford plants the most important things are done properly. By robot rather than by wine-reeking communists. I'm always very puzzled by people who buy Ferraris and the like. They seem to not think about the place where their car is assembled and the British-Leyland like mentality that rules the places where they are assembled.
Same reply as with the other example.
Sorry: the relation between power and torque is known. There is neither a magical beast producing or eating power away from it. Any engineer is giving a soft question on his exam if he has to prove this formula.
What does an dyno measure? Torque and RPM. It doesn't measure power, power is calculated using the stated formula.
Tom De Moor
Please stop kidding yourself.
First concerning the thickness of the line: all power is a calculated value from measurement of RPM (1/s) and torque (Nm). The power figure is divised by 736 or 745 (choose what you like) in order to give the rating in HP.
A good exercise would be to calculate how much W(att) the thickness of the line represents. Hint : the smaller the graph the more Watt (or HP) the thickness wil represent.
Secondely -and especially of a rolling road- there are the errors due to heattransfer in the tires, which in turn changes the pressure in the tires, which in turn changes the contact area, which will influence the reading of the dyno.
I am not even starting to take into account the difference in contact area on a tire at low RPM or high RPM, the changes under load in the engine, meterological conditions (atmospheric pressure, temperature, remember?)etc etc etc
Yett you claim your dyno is massively better than 5% error, same results on differt days: sure,that is your claim, backed up by you. There are also people who sell oil in bottles of 10 cl which will eliminated all friction in the engine or anodised alu parts in wierd colors (vernier wheels for instance) which raise the sex factor of the engine by ten points but are weaker than the dull OEM parts.
Fact is that no rolling road gets a better fault margin than 3% , 5% is still very good. Nowerdays however there is a computer printout and then of course it is 100% correct, some give 3 figures after the decimal point.
Be certain: if the rolling road was accurate to the degree you claim, no decent tuner would invest in an engine dynamometer. Yett every tuner craves for an enginedyno. Rolling road has its uses as it has its limitations. Where a rolling road is really good , is in putting sand in people's eyes. An engine supposed to give 200 HP (160 at the wheels) and it gives but 140 at the wheels. A smart operator pushes in a greater transmission loss and the client goes happily home with an engine producing 220 HP at the crank... but that not how races are won.
We raced and build *standard* engines, read "standard" as blueprinted. The original engine gave only 26Hp cfr constructor notes. 5 years of searching later a carefull assembled engine with the right "stock" parts, blueprinted gave 42 Hp. Those extra 16 Hp all came in little bits: wall clearance between piston and bore for instance. Such things are just not visible on a rolling road however a lot of little bits add up to a not so litte bit and the difference between winning an second.
It has to be said: the last engine was scrutineerd after complaints about 25 times (in 32 races). Nothing out of the rules was found. During the next winter we had a meeting with the factory team: join them or stay away.
Tom De Moor
Wrong. On inertial dynos we know how much power and its all digital. We know the power because we know the enertia. We know the speed. We can produce a graph of power v roadspeed. We do NOT know the torque of the engine yet because we dont know the rpms. Later as the graph is displayed we use the rpm data that was captured at the same time to decide how high (we know the torque at the drum) to put the torque curve...
The power figure is
Well we will choose mine 745 since thats the one that relates to hp rather than some recent european invention...
Which I already know and the thickness of the line represents less than 2 hp over the worst case over say 10 runs on my 137bhp suzuki stock gsxr1100wp. In any case the variation which is much less than the 5 percent you are talking about is not due to the dynos inaccuracy since it cannot have any but changes to the temp and heat soak of the engine. Thats a real and accurate result. IT simply shows whats really happening.
Yes. Extremely marginally but I doubt you could detect that. If it was a measurable change then why and how could all ten runs look like a single trace? Plus I can plot run down losses from top speed with any bike in neutral. In both cases its such a small difference on a single drum of 402mm diameter that its WAY inside your crazy 5 percent! And unseen at all as far as I can measure!
But we are measuring rear wheel hp. All of what you just said is both meaningless and does not cause power reading changes.
And temp and pressure are corrected in real time during the runs. And we mean intake air temp. And a good dyno room is a controlled envioiroment anyway!
Yes but I can prove it! Easily.
Bull. Agood inertial dyno in a controlled envioroment with proper airflow is way more repeatable than 1 percent. The dyno iteslf which is what you WERE talking about is repeatable to many decimal places...
In a properly controlled envoiroment an engine is also very very repeatable. But even if not the dyno isnt lacking accuracy just showing the result of changes somewhere!!!
Nowerdays however there is a computer printout and then
Well inertial systems ARE correct. The only way to get an error is
a) machine a chunk off the drumm! b) use the wrong temp/pressure/humidity which I cant do as its automated. c) "calibrate" it wrong on purpose - with many systems that easy, but locked into the software before compiling on mine.
They do? Then since I sold the same software and sensors and interface card for both why do you suppose I sold 45 chassis dynos and no engine dyno systems ? Plus the chassis dyno produces rear wheel figures. I never attempted to show "engine figures" because thats not possible!
Achassis dyno can only measure rear wheel hp. Everything else is bullshit.
A smart operator pushes in a greater transmission loss and the
Where did I ever claim it was? My dynos can log transmission/tyre/windage losses and add it to the power curve. Its possible but meaningless bull so its locked out of the end users software. Its used only for logging windage and bearing run down losses so of the roller alone so it can be removed from the results. It is spun by electric motors to 250mph and allowed to naturally spin and stop whilst the computer logs a negative power curve. This is all invisible to the end users.
Trust me, if it makes 0.5 hp more after a bunch of pre and after runs I can measure it and see it. If you think otherwise then you have been to a) braked dyno b) a non experienced dyno operator that does not understand the controlled enviorement thing.
Inertial dynos really can be that accurate.
And that relates to dyno inaccuraccy how?
Yes, they want dynometers which can test power sustained over a longer period (mostly 1 minute), so that accelaration errors are omitted, flow is stabilised, modifications (ECU programming for instance) can be done while under power, in a situation which ressemble the car environnement, where noicelevels, cooling and oliepressure can be monitored etc, etc.
An inertia-dyno whether measuring the acceleration of a drum or the flywheel of the engine can not do that out of principe: it is impossible to measure at 1 predefined RPM.
A inertia rolling road is a "burst" tester: measured are Rpm's and acceleration ( more correct the time to get from one RPM to the next). Most do it in steps of 50 RPM.
We bought our first ineria-powertester way back in 1986 (Dr Schrick). It used the engine flywheel acceleration in order to calculated engine power.
It is impossible to measure power in a sustained way on an inertia dynometer. Secondly an engine dyno has the annoying fact that they drive the engine on the downrun. When the measured flywheel acceleration this is no problem but if they drive a steel drum , the energy in it is absorbed by the engine and it isn't designed for that. Yes : better ones have brakes on it: these get cooked over quite rapidely.
Finally the reasons why you sold chassis dyno and not engine dyno are simple:
- the level of technology (and maintenance and other equipement) for a inertia dyno is way below that of an dyno where power has to be consumed, cooling is most of the times on inertia tester not even adressed because of the very limited time the engine spends under power.
Our handheld inertie-tester from Dr Schrick was bought in 1986 for 1000 UKP, my rolling road with engine brake (Bosch) was bought in 1993 for 4 million BF (around 60 kUKP) without the cooling tower nor installation. Whereas the inertia meter claimed to measure up to 500 HP, the Bosch is limited to 200 Hp.
- the people who buy the inertiatesters are interested in selling powergraphs for about 100 UKP a piece. That is not something feasable if the engine has to be taken out of the car / bike or if the dyno's must dissapate the enginepower.
Tom De Moor.
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