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Old 12-20-2012, 05:00 PM
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F-BIRD'88 F-BIRD'88 is offline
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Its real simple. The dynamic compression ratio is based on simplictic intake valve closing point.
When for 1 is very hard to accuratily establish.

2. the RUNNING engine's real in cylinder pressure has nothing to do with the cranking compression.
when its running at speed.

Highest pressure is right at the peak torque output.

Engines do not run a 500 rpm.

In the real world, engines do not operate in a tightly controled environment.
Gas quality changes, operating temps change, air inlet temp changes widely.
The knock tolerance of a engines varies widely based on the actual operating conditions at any one time.

As a general statement engines that operate in the real world with more than 10.5:1cr that are not computer electronic controled will be knock sensitive on even good pump gas reguardless of the cam used.
When things get hot they get hot.

if you build and engine with excessive compression ratio for the fuel and conditions your luck will run out sooner
or later.

rutching a engine by over camming it does not work and builds a crap engine at best.

For every internet guru that claims that you can do this and that there are 4 guy who found out how the real world really works.
You don;t pick a cam based on simple dynamic compression ( theory).

You cannot predict the cranking compression based on published cam specs.
These are not the true running open close specs of a RUNNING engine.

Here is some cold hard truth, based on 40 some years of doing this kind of stuff.

11:1 is real diecy on pump gas in any real world engine operating in the real world on pump gas.
and caming it up more will not change that. ( without real power loss)

You cannot establish or correct an engines fuel octane requirement
by fugging the cam.
Your cam picks are always lame and wrong fo both power and .....

Your power estimate are always wrong and lame based on over simplistic $20 computer programs and wrong inputs.
Your technical advise is either very generic, inaccurate, based on inaccurate popular internet theory and definately not from real experience.

There is a very good but old saying:

Believe none of what you hear, only half of what you read, (especially on the internet) and all of what you can PROVE.

In short you are full of BS,,,, SIR. have a nice day.


Hey F bird tell us what your really think

Last edited by F-BIRD'88; 12-20-2012 at 05:19 PM.
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