Correct air intake pipe size for 4x4 snorkel ?

[TMcRally]

On a Porsche Cayenne twin turbo, it makes around 500 flywheel horse power.4.8l V8 X 7,000rpm red line

I want to run 2 independent snorkels, each snorkel will be just under 2m from air box to open end.

I'd like to keep the ID to the smallest commonly available size but I don't want a restriction.

Is there a simple formula I can use ?

Thanks

 

[gruntguru]

Unwelcome is not an engineering term.
An additional intake pressure drop on a turbocharged engine is less detrimental to power than the same pressure drop on a NA engine.

je suis charlie

 

[Lou Scannon]

It depends what is limiting power...

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[gruntguru]

I believe my statement to be generally true but there may be specific examples for which your statement is true eg a turbocharger sized to operate at its choke limit or overspeed limit at maximum power (neither would be a sensible turbo match). In either of these cases the power loss will be about the same as NA.

Engine running at its EGT limit would be another example - again an extreme case where the operating point is at the edge of the envelope.

je suis charlie

 

[Lou Scannon]

In addition to the above,
Knock margin/limit
Maximum cylinder pressure limit
piston/top ring thermal limits
compressor surge margin
ignition system secondary voltage margin
fuel system margin

Any or several of these limits/margins may play a role in a highly optimized application. Adding intake or exhaust restriction will subtract from the margin or require a tuning compromise to respect the limit.


"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[romychaj]

what will influence air flow more than the exact size of the pipes is: air filter restriction, restrict. of an add-on offroad filter, sharp turns in the pipes, exact configuration of the openings (its easier to suck air out of a pipe than you might think), what else? unless you use something like a vacuum hose any effect will be within the measuring tolerance of a din/en dyno (2%) for sure.

you can also look at the size of the turbo entries, ad 30% of area for good measure and go from there. what you want to avoid is messing up the maf signal, leave at least 10" of original ducting before the maf.