What is the tube between the air box and plenum called?

[Steve Tinker]

Thanks for the link Topless - your SAE paper seems to confirm my findings.
Ricardo Engineering has an enviable reputation in Europe for their state of the art engineering going back to the 1920's, probably one of the best consultants in the world....
We all want to improve on the design or efficiency of our vehicles, but sometimes the factory engineers who have access to millions of dollars worth of equipment really know what they are doing - or at least should do....
Unfortunately, the bean counters have a bigger and bigger hand in the final product.

[ChrisZang]

OK,

you guys got me thinking. So I'll first source a used intake and then try the mod.
If anyone has one lying around let me know. I'll also post in the classifieds

[Boxtaboy]

Wait a second...from what I'm reading, people are saying you lose torque from doing this mod, and so you're gonna do it anyway?!

[ChrisZang]

Originally Posted by Boxtaboy

Wait a second...from what I'm reading, people are saying you lose torque from doing this mod, and so you're gonna do it anyway?!

Yeah, if I don't try I'll never know - won't I?
But by securing a spare pipe I can go back to OEM

makes sense?

And actually I don't think that torque will suffer

[Topless]

Chris, give it a try and let us know what you find. If you can measure your results you will know for sure if power improved. 30-70 mph times work pretty well for performance testing our cars.

For those interested in more information on induction tuning, intake acoustic resonance, helmholtz properties, and how standing waves affect engine torque, this may be useful:
http://dinamoto.it/DINAMOTO/8_on-line_papers/risuonatore/risuonatore.html

[manolo]

I would love to see some data on this. I've seen AFE's dyno chart but Im skeptical.

[Steve Tinker]

The engineering paper that Topless link shows us is only the input side of the internal combustion equation - even more complicated is the exhaust gas / muffler variations available. And one can definately affect the other.

Going back to the original question, it would have been so much easier for Porsche (or Mazda) to simply bolt on an inlet manifold sans Helmholtz resonator like Chris & Voilamettalic plan on doing BUT (as Topless says) a lot of clever engineers have done the calcs and come up with a resonator that fills the cylinder with a more efficient charge - and for very little money. How could the accountants complain. If the Helmholtz had cost $500 to produce, it may be a different matter.

Many years ago, we were trying to improve Manx Norton & AJS 7R motorcycle race engines to try & complete with the Japanese 2 strokes and it was quite common to replace the Amal GP carburettor inlet trumpet length to move the power band up or down the rev band. At the same time, we were changing the length and shape of the exhaust to prevent "megaphoneitis" a phenomenon where a hole appeared in the powerband and you went backwards so to speak. This was long before dyno's or ignition curves & power printouts.

I'm not saying don't try the mod - after all its not going to cost a lot and it can be reversed, but personally I must have spent hundreds of hours trying to "improve" basic physics concepts on motorcycles and cars, all designed by far cleverer engineers than me, and all I mostly got was blooded knuckles & negative results. Maybe I should have studies Mech Eng instead of Elec Eng.....

[Gary H]

I'm sorry, but can someone spell it out to me: I can find references to Helmholtz resonators relating to noise suppression...and that's it.
Having an expanded air reservoir POST MAF/Throttle body can make a huge difference to the available torque - I had this bulbous looking cross-over pipe on my old Miata and it made a huge difference...but this is um-metered air before it gets to the throttle body.

So the Helmholtz resonator on the snorkel is there for added torque?

And there was me thinking it was ll about noise reduction and passing certain EU noise levels...