I am thinking about an intake manifold for the Fury. I want to try some tomfoolery, I plan on having port injection right at the flange but I'm thinking about making a variable length intake manifold. The idea would be to build the intake from a flange cut to the shape of the gasket. Then extend it into pipes and nesting runners that would be actuated while driving, extended runners at idle for low end grunt and have them shorten up as RPM increases. How would I be able to seal the runners what kind of slipping seal could be used on the runners or could I use tubing with compatible ID and OD to fit what kind of clearance would be needed for it to be effective?

Any thoughts?

Thanks.

_________________
It is easier to REACT,
than it is to THINK!

Middy.

Have you ever looked at the runner set-up on a *cough* Ford Taurus SHO engine? Quite a slick unit Yamaha put on that 3.0.

Recently I read a 'layman's' book on Intakes, Fuel Injection, and all that other stuff. The Taurus SHO and some late models of Jag actually use two runners per intake port, a short one and a longer one. Depending on the mode of operation (warmup,full throttle, etc...) a solenoid will switch between the two at a certain rpm and computer sensed 'load' requirement.
They also attach the runners to the flange with rubber hoses and OEM hose clamps...

One that reals in and out like an accordion would be interesting.

Good luck on your research,

-D.Idiot

I had heard mention of a variable runner intake but I was not sure how it would be done I'm thinking here that an infinitely variable sliding runner design would be the optimum setup and might be done inexpensively I just found this site on Ram effect tuning it has some theory on it good whistle wetter.

http://www.chrysler300club.com/uniq/all ... theory.htm

I didn't realize the SHO had variable runner technology that's pretty neat.

What kind of seal would I need to use on the runners? An accordion style hose would probably cost as much in turbulence as it would gain in adjustability.

_________________
It is easier to REACT,
than it is to THINK!

Middy.

If I remember correctly, when the SHO engine switches the runners (full throttle, etc), it has both the long and the short runners open at the same time. Makes quite the sound...

Middy,

My grandfather was kind of a 'tinkerer' and did some weird backyard fix-its in my day....

His approach to your solution would be to think of how the slide on a trombone works or how the large tube and slightly smaller tube on a shock absorber can lengthen and shrink, couple that to a control mechanism, and come up with a rubber sealer for the tubes (bushings, rubber panty hose over the outside...????) to keep the air in, and you're in
good shape...I think.

this will be a fun topic...

good luck, brainfood breakfast of backyard mechanics...

-D.Idiot

I think Volvo also has a variable runner length system, their manifold has some sort of "flapper valve" the switches the flow between two sets of runners with-in the same manifold.

I wonder if we could weld some new longer tubes onto a Clifford type 4 bbl manifold an mount another carb further outboard.
DD

Does it have to be variable in length, or could variable flow capacity work just as well? What I mean is, rather than vary the length of the runners, could you have something like a runner that is separated lengthwise internally by a rib. The internal rib would divide the runner into two separate long chambers. The chambers would open up at each end to a common junction chamber. At the carburetor end, a baffle plate would pivot at the beginning of the rib separating the two longitudinal chambers. The baffle plate would be controlled manually or by sensor, and would slowly close off access to one longitudinal chamber, leaving the remaining chamber open as the only intake. At the manifold end, of course, you would detect flow from both chambers entering the common chamber, but as the baffle closes, the detected flow would be coming fully from one chamber, and gradually no flow from the other chamber.

Just a thought....

OOPS!!! Didn't finish reading Doc's remark about Volvo. My mind was wandering. Yeah, Doc, kind of like that. From the outside, it would appear as though you have the typical six intake runners, but actually, you would have them split into twelve "runners".

_________________
There's a difference between ignorance and stupidity.
Ignorance is not knowing any better.
Stupidity is knowing, yet doing it anyway.

I think if you were to just split the runner but leave both sides of the runner the same length you would not have the same benefit as the variable length runner. The Idea is to make the best use of the runner length to produce a tuned runner that would give a volumetric effeciency of greater than 100% because of the pressure waves that travel within the runner. The above link explains it quite well with regards to the runner length in the Long Ram manifolds that were on many of the 60's 300 cars.

_________________
It is easier to REACT,
than it is to THINK!

Middy.

Offenhauser had a split port intake in the 70s. Called the 'Dual Port', the smaller port was fed by the primary side of a 4 barrel, and the larger port delivered the secondary flow. The idea was to keep velocity up at part throttle and when only running on the primaries. This was during the oil embargo, fuel supply was a concern and all kinds of ideas and products were being produced to increace MPGs. I don't remember one for a slant, most were for the V-8s and the Vega/Pinto four bangers.

Cecil

Geez, now my wheels are turning...

Last night I kept thinking of a dual runner setup for the /6 based on Yamaha's SHO design...

For the six longer runners, how much would a u-turn affect flow?

How about sticking the moving part of the runners inside the plenum? That way, any leakage will draw air in from the plenum, which won't throw the mixture off.

_________________
"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

I like that idea Matt the plenum might get to be a little large. I' haven't had a moment to sit down and do the math yet but for some reason I doubt that the movement will have to be that far like maybe slightly more than an inch. I'm also curious if anyone has looked at the above page I wonder where they take the runner length measurement I assume that on the one end the measurement would start at the back of the valve but do you stop measuring at the plenum? would having a large er plenum have an effect on the reflection or bounce of the pressure wave?

Can anyone tell me what the intake duration should be on my Stock, 1966 225 ci slant? so I can start doing the math to work out the lengths needed.

Keep the brainstorming going, this is one of the more interesting threads I have been involved in.

_________________
It is easier to REACT,
than it is to THINK!

Middy.

Hey Matt it occurs to me you have just solved the problem of mounting a carb and kickdown linkage on this manifold without having to go the Lokar cable route!

Very good idea.

_________________
It is easier to REACT,
than it is to THINK!

Middy.

Variable runner lengths is interesting, pretty hard to engineer though. Two sets of tubes with a butterfly valve to close one or the other tube is what I've seen used before.

You might achieve a broad power band with supercharging and a much simpler manifold.