Different theory on turbo cams

[Ted B]

For the sake of clarity, let's talk about VE so I don't confuse anyone.

VE is essentially the ratio of the volume equivalent of air mass actually drawn into cylinder / actual volume of the cylinder, both corrected for pressure.

If we measure volume at the air intake (ambient presure), a turbo or SC increases increases the air mass AND volume flowing through that point. When the ECU makes VE calculations, it is actually calculating mass, not volume. When we see a title of "200" on a cell in the load table, it means the engine is flowing the equivalent of 200% air mass of the theoretical normally aspirated max, but the volume of air flowing through the ports (and all pressurized areas) at any given rpm is roughly the same as if it were normally aspirated.

If we measure volume at the throttle body (or any other pressurized area), the turbo is not increasing the volume of air. In other words, the turbo is not making the engine mechanically more efficient. Things that directly affect mechanical efficiency are intake manifold/runner dimensions, cams and timing thereof, exhaust manifold runners, intake and exhaust ports, etc.

For those who were under the impression that the turbo is making the engine mechanically more efficient because it is 'forcing' air into the engine, that is incorrect.

[Henson]

Here’s a law for ya. The Henson’s law of… get a book. Try a search on thermodynamics 101. Please stop calling it Volume. To what pressure are you referring to? You should use V-dot or ‘volume flow rate’. I prefer, ‘mass flow rate’ or m-dot.

M-dot can increase in two ways, in a small integral of time. One, a change in cylinder size (volume). Not happening yet. Or two increase in density aka “m”.

You can only stuff so much popcorn in your mouth unless you brake the popcorn down (chew) 'More Dense' or, expand your mouth wider, and that’s just rude. So the question is how fast can you eat you popcorn? It would be easer if it was denser (uncooked).

Increased density, increase the oxygen thus increases power with increase fuel. Increase power increases exhaust pressure.

m = mass
m-dot = mass flow rate

V = volume
V-dot = volume flow rate

L = length
L-dot = v =Velocity
L- dot ,dot = v-dot = a= Acceleration

Confused?

Mmm. Popcorn sounds good.

[85ttops]

damb you henson now im really confused

[under pressure]

I didn't miss any part of your Theory. I don't acept it for anything other than your theory. But if it works for you then go with it! Rick

[Ted B]

I do, and it works not only for me, but for all of my peers making considerable power (i.e. 400+whp) with turbo fours.

If overlap was so unnecessary to turbo motors, then turbo cams wouldn't have *any*, and that's pure B.S. In fact, the only cam sets proven to be capable of 800-1000whp in 2.0L EVOs all have considerable overlap.

Cheers!

[Pat_in_L.A.]

Here’s a law for ya. The Henson’s law of… get a book.

You can only stuff so much popcorn in your mouth unless you brake the popcorn down. ....

Mmm. Popcorn sounds good.

Sometimes the simplest approach is the best. I really like Henson's response. I'll go melt some butter.