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Notice all these designs share 1 basic similarity. a long and a short runner. While I understand the engineers are trying to acheive the best volumetric efficiency for each tuned length, it's a tradeoff at best. Long tubes work at peak efficiency say around 3000 rpm while the shorts at say 5000 rpm (hypothetical). The fact that both are being used at high rpms may cancel each other out in terms of intake pulses reaching their proper points on each set of runners. I don't know if this is a consideration at all.
The FSVT intake is on the right track to being a perfect design. Picture the pivoting part as having tubes that slide inside the stationary tubes. You now have the perfect intake! A variable runner intake that would be effective through the entire rpm range! Extended at low rpms and as the rpms increase, it retracts into the stationary runners. That design might actually work!
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I remember a few years back on SHOforum we had a discussion about the intake on the Yamahammer. Some did some research and dug up a patent by yamaha on, I believe, the dual runner intake manifold. Maybe all the similiar designs are because of that?
Ryan
Trollin!
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wow, this is a disturbingly good topic. I hate to sideline it with my question but I gotta know. what is the purpose for the 6 knobs [and the 2 tabs, that unfortunately are not in the photo]. 
yes... I am a cougar owner trolling on your board.
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Those "knobs" are the left over risers from the casting process. Risers are holes in the casting that allows air to escape when the molten Al is forced in.
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Originally posted by Stazi:
Those "knobs" are the left over risers from the casting process. Risers are holes in the casting that allows air to escape when the molten Al is forced in.
thats what I thought! So it would be "safe" to [carefully] grind them out?
[sorry when you spend that many hours grinding something, you have alot of time to question everything]
yes... I am a cougar owner trolling on your board.
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Originally posted by Auto-X Fil:
Tom-
My information comes from a pretty reliable source. A couple very bright kids at Penn State who just got their Mech Eng degrees did a senior project on the intake for our Forumula SAE car, and they have found that there is so little laminar flow in any intake that it's not worth designing around: and if there is ANY power to be found, the FSAE guys will design for it! They use two injectors per cylinder, and switch to the one further upstream to enhance atomization at high revs to get 2-3 hp!
Looking at a Catera and the Nissan VQ variable intake, I've wondered which is better. Modern designs have the switching system for the intake near the filter, which eliminates some of the issues we have - dirty butterflys, etc. But I am not enough of an expert to think about redesigning the system. However, there may be some gains in an aftermarket system. Whether it's better to simply rebuild the system like Mustang proposes, or move the secondary intake switching system, I don't know. There's probably not the aftermarket, however, and so we'll never see a $500 intake to get us 10hp. Too bad, because it might even look as cool as the stock one!
Okay, sounds like it really isn't as far off from what I was saying as it first may have sounded. I was pointing out that it was highly dependent upon velocity. Your points are well taken and I could be mistaken. Either way, any improvements to the manifold won't be worth the money I'd bet.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
See My Mods
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Originally posted by warmonger:
improvements to the manifold won't be worth the money I'd bet.
Yeah, I guess that's the place we're getting to. Whenever I mod my car, I ask "Why didn't Ford do it this way?". The answer for suspension bits is mostly ride quality. This means if you sacrifice ride quality, you can make your car handle MUCH better. Here it's just money. There's no other tradeoff to take advantage of. They did as well as they could with what they had to work with, and so there's no cheap way to improve it: if there was, they'd have done it.
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I think the designers had to deal more with trying to fit the intake in a tight spot in regards to hood clearance. They did very well at that. It definately wasn't a cheap design by any means though. Motorized butterfly valves come to mind. Now we're seeing plastic intakes which from a mass production standpoint is a hell of a lot cheaper than a cast aluminum intake. So it still is possible to see impovements based on the technology at hand.
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Oh yeah, I bet you'd see significant power from an intake that fit in a modified hood. Good point. You could duplicate the Focus intake (x2, of course), extrude hone it, and poke it up through. Maybe in carbon fiber? 
Crap, there goes the money thing again... 
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Originally posted by terry haines:
...the pics he posted are of a Porsche 'proto' 2.5
V6....and where did everyone get them?....they are ALL
mine as I have all the info on that engine.FWIW gas
velocity,plenum volume etc are far more important on a
multi-vale.A log intake will do little to improve
power.I'd suggest some of the masses look at current
and recent Formula 1 engine designs,also as a 3.0 and
later Duratecs do not have secondries but don't fall
flat at low RPM's....the Zetec has never had
secondries and is a 4 valve head etc....lets hope they
can work out 'why'...LOL...TH
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