Hp displacement ratio

[Slicks]

you also stand the risk that some forum members consider bhp/liter as something irrelevant, used as they to the american adagium that there is no replacement for cubic inches, and will try to tell you so....

You still dont understand that saying? Theres no replacement for [adding] displacement, only alternatives. Going FI for example is an alternative, not a replacement, because there are more downfalls to it, than adding displacement (to an extent).

[hightower99]

Scaling engines really is something that doesn't work like you would expect. You must understand that 100kW of power is 100kW of power whether it is from a 1.4L racing engine or a 4L diesel.

As engines get smaller in size their potential effeciency goes down but the required specific power rating (kW/L) to achieve a suitable output increases.

As engines get bigger their potential effeciency increases but the required specific power output needed to produce a good output power is lower.

Example: two engines one is a 1L V12 and the other is a 4L inline 4.

If you need an output of 200kW then the 1L V12 needs to produce 200kW/L whereas the 4L I4 only needs to produce 50kW/L.

Note that the 4L engine has the potential to be as much as 12% more effecient!



Now it is cool to know that the S2000 makes almost 120hp/L but it's total power is still only 240hp...

the C6 Z06 corvette only manages to produce alittle over 72hp/L but it's total of 505hp stomps the S2000.


HP/L is only a rating of how much air and fuel can flow through the engine per displacement.

-It has nothing to do with effeciency
-the higher the specific output the more energy you are wasting
-having a higher specific output means nothing, only total power does.
-Increasing specific output is only necessary when you are stuck with a certain amount of displacement.

[hightower99]

You do realise that those numbers are the manufacturers claims and that those manufacturers have no set standard across their industry. Basically their just pulling numbers out of their asses.

1 kW is a set standard

it is 1kW anywhere...

If you are referring to a set test method than no they don't but thats because they use simple formulas that everybody in the ICE industry knows...

as in it doesn't need to be a set standard.

[Ferrer]

But also very high turbo lag.

The 4.7-litre supercharged engine in the Koenigsegg CCX isn't bad either. And it hasn't turbo lag...

[Bob]

How can any unit be more or less precise than another. Its all down to how many significant figures you quote it to.

True I was just saying that since HP and W are usually stated to the ones place, it the smaller unit hp is usually more precise. On the other hand, these things vary with things like weather etc. and it really doesn't matter. I was just defending horsepower because i like it

[derekthetree]

-having a higher specific output means nothing, only total power does.

weight?
real world fuel economy?

True I was just saying that since HP and W are usually stated to the ones place, it the smaller unit hp is usually more precise. On the other hand, these things vary with things like weather etc. and it really doesn't matter. I was just defending horsepower because i like it

i was on at drakkie. i like horsepower too

[NSXType-R]

The 4.7-litre supercharged engine in the Koenigsegg CCX isn't bad either. And it hasn't turbo lag...

But look at the amount of liters they have to work with.

More than double. A N/A V-8 can still produce a lot of power without a supercharger. The highest output I've seen on an I-4 was 240 for the S2000.

[ruim20]

You do realise that those numbers are the manufacturers claims and that those manufacturers have no set standard across their industry. Basically their just pulling numbers out of their asses.

Have you ever seen one of thoose things go? or even driven one? Mine is a measly 2.5cc and the thing sometimes looks likes it's going to run up the walls!

[jediali]

I do and I am not even American The value is measured in Watt or kiloWatts.... (b)hp is an old and outdated value and less precise as kW's

They just keep using those values for the older people that dont know any better

mathamatically bhp is as accurate as kW, and hightower is saying everything i want to say- what a genius he is

[Sweeney921]

You do realise that those numbers are the manufacturers claims and that those manufacturers have no set standard across their industry. Basically their just pulling numbers out of their asses.

I'm quite sure they dyno the engines at the crank. It's not made up.

Have you ever seen one of thoose things go? or even driven one? Mine is a measly 2.5cc and the thing sometimes looks likes it's going to run up the walls!

They manage to post such ridiculously quick times (0-60mph in ~1.5 seconds), but they never weigh more than 10 pounds and their wheels are 2-3 inches in diameter, which maximizes their torque. So saying that they post nasty fast times doesn't support any claim that they have powerful engines. Their quickness comes from a super low hp/lb.

I want a HPI Nitro RS4 Evo 3 for christmas

[Slicks]

weight?
real world fuel economy?

More weight and worse fuel economy?

[h00t_h00t]

But look at the amount of liters they have to work with.

More than double. A N/A V-8 can still produce a lot of power without a supercharger. The highest output I've seen on an I-4 was 240 for the S2000.

Power isn't everything, how its delivered is what makes the car fun/boring.

[Sweeney921]

Power isn't everything, how its delivered is what makes the car fun/boring.

that doesn't really have anything to do with this thread though.

[Mr.Tiv]

Didn't the Turbo 2.1 Cosworth out of the Group B race spec RS200 Evo put out like 600bhp? Perhaps, I am confusing my statistics, not that power matters with that car-it's fast by anyone's standards.

[NSXType-R]

Power isn't everything, how its delivered is what makes the car fun/boring.

I was replying to a post of Ferrer's.