Power under the curve

[Vette73]

I often hear this phrase when it comes to the LT-5.....Kind of have an idea of what it is.......Can anyone elaborate further?

[mike100]

lets say a a small block chevy pulls really hard from 3500-5500 rpm. or an LS V8 from 3500 to 6000. But then we are talking about 4 valve per cylinder engines like an LT5 or Coyote Ford 5 liter..maybe those pull great from 3500-6500...which is a lot of good power over a wider range of engine speeds. So the curve part is the graph of Hp vs rpm if you plot it out. The multi-valve engines just do more over a wider range of rpm.

[XfireZ51]

I often hear this phrase when it comes to the LT-5.....Kind of have an idea of what it is.......Can anyone elaborate further?

An OHV valve motor drops off quicker, while the LT-5 maintains a flatter power curve. So the area under that curve, and therefore the average power is greater.

[BigJohn]

Funny thing my LT-5 has overhead valves!

[XfireZ51]

https://en.m.wikipedia.org/wiki/Overhead_valve_engine

[Paul Workman]

I call it the "Ah! Huh? You aren't catchin' him!" effect!:dancing


An analogy from electronics is considering the HEATING (RMS) voltage of a sinewave vs. a squarewave...if that helps?

Both waveforms may have the same PEAK value, but the SQUAREWAVE has an RMS value equal to the PEAK, whereas the RMS of a SINEWAVE is .707 of the peak value.

The PEAK of the SINEWAVE could even be higher than that of the SQUAREWAVE, but up to the point where the RMS value of the SINEWAVE reaches the RMS value of the SQUAREWAVE, the heating effect of the SQUAREWAVE is greater than that of the SINEWAVE, in spite of the higher PEAK voltage level of the SINEWAVE. (Clear as mud??)

Newton's 2nd law of motion:

Force = Mass x Acceleration
or put another way: Acceleration = Force (read: rear wheel TORQUE)/Mass

This is why we often see our ZR-1s victorious in a drag race (especially in a 1/2+ mile contest) even when the opposing (pushrod LS motored) car has greater PEAK horsepower (within limits). Or, to put it another way, the LT5 is still making usable torque (force) in a lower gear while the opponent has to shift into a higher gear - thus resulting significantly less rear wheel force.

This video shows what happens very clearly every time the C5 shifts while the LT5 is still winding out in the lower gear...

ZR-1 vs. C5 video (https://www.youtube.com/watch?v=PzPPEK9Qf3M)

In it you can see the result of peak hp/torque of the (C5) coming on quickly (that and a slightly lighter weight of the C5 [negated some(?) by the passenger's weight]). See the C5 jump to the lead out of the hole. (I love the initial "HA!" commentary by the passenger)

Then as the LS runs out of steam and is shifted into 2nd, we see the LT5 is still pulling; winding out - still in first gear - the Z first matches speeds before it starts pulling away. (The moment is marked by the "Huh?" from the unsuspecting C5 passenger) ))

Notice the lurch between the two cars after every shift of the C5. The fact that the Z is winning misses the point: that is the effect of having more "power under the curve" has on the Zs performance vs. comparable (PEAK hp, street driven) pushrod motors.

And, finally the realization sets in: "You aren't catchin' him!" :o That's power under the curve!

[Dynomite]

I call it the "Ah! Huh? You aren't catchin' him!" effect!:dancing


I call it Caught him and now you guys are having us read a book rather than admit it :D


Newton's 2nd law of motion:
Force = Mass x Acceleration
or put another way: Acceleration = Force (read: rear wheel TORQUE)/Mass


I am not so sure about Acceleration = Force (read: rear wheel TORQUE)/mass either :sign10:
Especially the Force is rear wheel TORQUE part :D

[BigJohn]

Very Funny: the valves are still in the heads above the pistons in overhead cam engines.
They don't open and close in the block like a flathead engine.
Wikipedia is really not a good source! They are very famous for their inaccuracies.

[Paul Workman]

Very Funny: the valves are still in the heads above the pistons in overhead cam engines.
They don't open and close in the block like a flathead engine.
Wikipedia is really not a good source! They are very famous for their inaccuracies.

Yeah, we "get it." :D But, truth is where you find it, and finding an occasional worm in an apple doesn't mean the rest of the barrel is bad.

OHV: "That depends on what your definition of the word "IS" is...":razz:

[Dynomite]

OHV (Over Head Valve) ;)
Valves in Head.

Now......lets talk Torque and Force :D

Or if you prefer to talk about Bill and Hilliary sayings......I am out lol lol lol

Sent from my iPhone using ZR-1 Net Registry (https://siteowners.tapatalk.com/byo/displayAndDownloadByoApp?rid=90383)

[BigJohn]

I am all for big big torque!!!!!!!

[XfireZ51]

Very Funny: the valves are still in the heads above the pistons in overhead cam engines.
They don't open and close in the block like a flathead engine.
Wikipedia is really not a good source! They are very famous for their inaccuracies.

The colloquial usage of OHV v OHC is as it was described in Wikipedia. Technically of course the valves are over the pistons in both architectures. On a daily basis however, OHV is generally used to describe a motor w a valvetrain actuated through pushrod and rockers from an in block camshaft.

Here's just one other source.

http://www.samarins.com/glossary/dohc.html

[BigJohn]

Cool beans!

[XfireZ51]

:handshak:Cool beans!