now that is a bloody good point tinkerbell..
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now that is a bloody good point tinkerbell..
not at all tinker, its good that u brought it up. I hve thought about it like that, but im looking at it from an engineering point of view in the sense of the forces involved with the piston weight and counter movement.
I agree that suffocation occurs wihtout the extra lift and duration of the vtec cam, but these engineers are talking about the piston speed issue associated with the long stroke. The piston speed and the angle of the crank required to get this long stroke creates a vibration in the inside of the engine, add to thsi friction, head constraints and you can really see why its such a good engine that honda come out with.
good to hvae ur input tho as always
I think BMEP is the way to go for some part of the argument, you can compare a wide variety of engines using this claculation. Although BMEP is an actual pressure figure, so some of the values you guys have been getting are a bit weird. For the prelude (2.2L, 200Hp, 7200rpm) I get 1.1MPa or around 160 PSI. s2000 (2L, 240Hp, 9000 rpm) gives 1.2Mpa or 170PSI. Current honda F1 engine (3L, 960Hp, 18000rpm) gives about 1.6MPa, or 230PSI. So there definatly higher cylinder pressures in an F1 machine.
Another argument would be the weight of the engine rotating parts, basically the more weight the higher the engine loading from rotation speeds. So light pistons would really help out in lowering the engine loads at speed, giving the ability to develop more power and still remain with parts that are not over stressed.
Other things would include fuel type, CR, bore/stroke, etc
J_Mech
everyone go back to basics. torque is a turning force, measured by a force multiplied by the diameter. so torque is how hard the explosion pushes down on the piston which turns the crank. ok.
power is defined as the rate of doing work. so work done / time taken. To the layman, "how quickly we can do a certain amount of work"
one last thing that must be defined is work. work is force multiplied by distance moved.
Now this is quite simple, because we can graph the "power curve" we can derive it and find any value at any point in time. so we end up with:Quote:
Originally Posted by pornstar
P = dW/dt
Where P is power, W is work and t is time.
And the units for power are kW = kJ/s and hp = 550 ft·lbf/s
Power is just a timed rate of work.
The reference Andy was making was in relation to the power made at a particular RPM or the relationship between power, rpm and how it is spread out throughout the rev range.
Good stuff maximus. But i think you will find its illusive in the fact that honda engines make big power in fact arent making big "power". Why cant your average honda civic or integra tow another car? cos the truth is, torque as the measurement of force turning the wheels is much lower than the hp/kw figure that hondas make.
The illusive factor is that time factor. Ie hp is one foot pound moved by a horse in a given amount of time. If you look at it this way, its illusive because it really is just how many times the engine is doing it over a given amount of time that is giving the honda engines big hp/kws.
Thats why i dont like that measurement of power.
Well the most common honda engines are in the sub 2.5L category (hence not the best suited for towing) but I know what you're getting at. The fact that they have bad low end torque, and I take it that this is the discussion.
So.....does someone wanna post the torque stats for a 1.8L honda vs say a 1.8L Nissan?
But will that be enough?
umm... yea, i think i said that.Quote:
Originally Posted by wynode
Andy, what is this thread about? you started it off talking about NA and FI and both their advantages and now you have moved on to talking about how little torque honda engines have. Everyone has posted something up totally unrelated, i think, because no one really knows what you want here. Give us another quick run down.
Low torque in a honda engine. Either a lower force (bang) or shorter turning diameter. It would be rediculous to shorten the diameter so i'm guessing the force is decreased. This could be due to their economy factor. Put in less fuel, less bang, but lots of little bangs (8k rpm) makes the car move pretty quickly.
:thumbsup:Quote:
Originally Posted by Savant
i told you he sounded stoned when he stated these threads
-2ds
Maybe everyone needs to get into a similar mind state as andy to understand the question?
Well my idea of the honda engine is that it is a compromise.
Honda seems to have taken the ideals which they wish to fulfill, and incorporated it into there engines.
The element of torque lacking from there engines is a direct trade off of fuel economy. And all a turbo is doing to the engine is acting much like an artificial capacity increase to fill this gap, but it then reintroduces the higher use of petrol along with its increased performance.
I currently dont see any engine that features fuel efficiency, linear power production across the rev range, aswell as high levels of torque across the rev range.
Even just power and fuel economy, as even the honda engines when using vtec are not highly fuel ecomonical.
The only real solution to this problem i think, is increasing the efficiency in which an engine uses its fuel, the maximisation of its combustion and resultant energy use.
Also alternate fuels could be an issue, as the increases in torque that diesel produces is well known.
Another thing that honda's do well is have low emissions ;)