ported air horn

[LGAFF]

Did a plenum for someone.....they went to 63mm TB so they asked me to open up the Plenum to TB and Air Horn.......

Besides moving to 63MM I went in and smoothed out the all the trasitions some ported and unported pics:

Unported
http://i134.photobucket.com/albums/q115/lgaff/Picture068.jpg

Ported
http://i134.photobucket.com/albums/q115/lgaff/Picture069-1.jpg

Unported

http://i134.photobucket.com/albums/q115/lgaff/Picture067.jpg

Ported

http://i134.photobucket.com/albums/q115/lgaff/Picture070.jpg

[Blue Flame Restorations]

LOTS OF WORK!

[pantera1683]

Nice work Lee. How much does that run?

[LGAFF]

I threw it in with the port job....

[tomtom72]

uoooooh smooooooth !:p

nice flow ya got there mister!:-D

[Jim Nolan]

Was that increase to 63mm just for the porting. I know Aaron Scott stopped putting 63m throttle bodies on his portings because the HP gain was near zero. Did I miss something here?

[LGAFF]

This person needed a rebuild due to an issue so he upgraded through someone......I just followed up on the request...its worth a few HP...smoothing should help...I was a skeptic, but a Mercury smoothing the airhorn actually showed a modst increase. They apparently had an engine on the dyno and did step by step mods for HP

[mike100]

I kind of wonder at what hp level the 63mm throttle body is beneficial. I guess you might get a couple of hp from smoothing the sharp edges on a stocker- maybe, but I'd have to think you might benefit on a 500 hp engine more.

Has anybody done much testing on different combos?

[Kevin]

i remember reading, maybe incorrectly, that the pirate car didn't have any gains from a 63mm tb

[Paul Workman]

Transitioning the edges won't hurt, for sure. But, it seems to be quite abrupt still.

A topic for an FBI pizza night: I've been pondering something with a smoother and less abrupt transition; more in keeping with the 4% guideline (some use) for port transitioning. What I envision is more along the lines of a pair of internal funnel-like tubes. They would extend from the "big" ports and merge along a knife edge and morph to fill the shape of the horn at the inlet oval. Borrowing a term from another discipline, "impedance matching" is the goal: The less abrupt the change, the better for flow.

OK, it isn't an original idea. If you get a chance to look into the rectangle inlet of a supersonic fighter e.g., an F-15 or the like, and you'll see what I'm talking about. My point is, "bumps" in the air stream, like rocks on the bottom of a shallow stream of water, cause pressure waves that extend way beyond the shape of the intrusion.

Concept:

http://i185.photobucket.com/albums/x220/6PPC_bucket/LT5airhornconcept11-12-11.jpg

I have no idea if it would be worth the trouble to build, but it might be something to experiment with. Just a thought.

P.

[LGAFF]

Increasing the velocity would be a good thing, I think ultimately the ideal setup would be to separate the plenum in 2 and add a balance tube to the front of the plenum to promote "filling" of 1/8 cylinders.......bell shaped entries to the plenum runner would also be good to have