Beyond Cyl.Pressure & V/P Index: What Next?

[Kevin Shasteen]

Calling all math junkies who eat, drink, sleep, walk & talk thermodynamics & fluid dynamics....come out-come out wherever you are!

 

Where do we go from here: from the Dynamic Comp.Ratio thread & the V/P Index site, which takes the following into consideration-the displacement of the engine, Duration of the Cam, Nominal (SCR) Compression, Effective (DCR) Compression, and ties them into the Atmospheric Pressure in order to calculate Cyl.Pressures: yea that data-where do we go from here?

 

So, mathematically...or logically speaking, what is the next dot to be connected in anyone's attempt at building a Hi.Perf. engine?

 

My question more specifically is this...how would you go about choosing your cyl.head's intake ports, your intake manifold & Carb (or TB) to meter that incoming air to compliment what you know once you obtained your Cyl.Pressure?

 

My question isnt so much geared toward fuel delivery nor spark intensity; rather now that we have cyl.pressure coupled to our Nominal & Effective Compressions, how would you go about using this data in properly metering that incoming air...such as an in choosing an Intake Manifold or Carb/TB system?

 

I have a clue but I wanna see what some of you think.

 

For the V/P Index site-go to: http://www.victorylibrary.com/mopar/cam-tech-c.htm

 

Remember that the VP Index Chart, scroll down the page to find it, gives a formula that leaves out a step. This formula is:

 

V/P = CP x VE x N x .003

 

The step they left off was after the .003, in that there should have also been a, "x 2". Making the corrected formula like so,

 

V/P = CP x VE x N x .003 x 2

 

As the site suggests, the V/P Index is just a number for comparison: however, what I like about it is that is ties in your Cyl.Pres w/your Nominal & Effective Compression Ratio's...and IMHO this is quite important. If you understand the V/P Index you will see how all three previous mentioned issues: Cyl.Press., DCR, & SCR are all effected by Atmospheric Press-so their trinitarian relationship is equally effected by a rise or fall in that Atmospheric Pressure.

 

So, the question is how do we go about utilizing this data in choosing our metering of the incoming air to compliment our Cyl.Press, DCR, & SCR?

 

Any takers....anyone?

 

Kevin,

(Yea,Still an Inliner)