variable length intake with ITB's

[hoov100]

anybody every think of using a ITB setup with with variable length intake horns?

[proxlamus©]

hmm.. good call..

 

doesnt BMW have variable air horns on their ITB setup?!

[hoov100]

i dont think any of the car manufactures are using a variable length intake system.

[olie05]

yamaha does. on the 2007 r1 but they are not infinitely variable

 

[bubbleguinea]

ever heard of an IMRCV?

intake manifold runner control valve????

 

i think its the 3.8 for windstar motor....mid 90's???

 

we sell the part to a lot of warehouses...

[BRAAP]

ever heard of an IMRCV?

intake manifold runner control valve????

 

i think its the 3.8 for windstar motor....mid 90's???

 

we sell the part to a lot of warehouses...

 

 

Hmm… This sounds interesting. Do any of your parts books etc have any more information on this intake runner control valve or possibly some pics? Curious if it operates like we are thinking? If so, do you think it could be used with an aftermarket EMS such as MS or Wolf controlling it on another engine? Is it an on/off device, 5 volt, 12 volt etc? If you can get us more info, that would be great.

 

I do recall the Taurus SHO with the Yamaha built 3.0L used two different length intake runners, long ones for low RPM, then some where in the 4k RPM range, a butterfly/valve would allow the shorter runners to feed the engine. I wonder if this system you mentioned is the same or similar?

[TheNeedForZ]

you mean ITB as in Independent TromBone?

 

http://en.wikipedia.org/wiki/Variable_Length_Intake_Manifold

 

IIRC there are systems that switch between two lengths of runners like Paul mentioned. There is also a type of system that connect/disconnect two plenums to create different amount of total plenum volume.

[NCchris]

IIRC there are systems that switch between two lengths of runners like Paul mentioned.

 

Honda did just that on the 94 Acura Integra. The B18c engine has an intake plenum with two sets of runners, one long (low speed) and one set shorter. A butterfly valve switched to the short runners at approx 5800 rpm. Not an ITB but different intake runners. System works well.

chris

[bubbleguinea]

isnt that what the 00's model sentra SE-R spec V had???

 

two sets of butterflies?

[award280]

Honda did just that on the 94 Acura Integra. The B18c engine has an intake plenum with two sets of runners, one long (low speed) and one set shorter. A butterfly valve switched to the short runners at approx 5800 rpm. Not an ITB but different intake runners. System works well.

chris

 

I have a '94 Acura Vigor. 2.5L inline 5 with the dual runners and the butterfly valve. I have also been trying to think of a way to incorporate this into a custom Z intake mani.

[76280z]

The mazda 787B had variable length runners (telescoping) this might one to look at. Many newer cars have a variable geometry intake (a big round thing) where the runners curve around inside and it uses a valve to vary it (newer chryslers, fords, BMW's, etc.)

[HowlerMonkey]

First may have been the 1986 pulsar SE with the 16 valve.

[Careless]

The mazda 787B had variable length runners (telescoping) this might one to look at. Many newer cars have a variable geometry intake (a big round thing) where the runners curve around inside and it uses a valve to vary it (newer chryslers, fords, BMW's, etc.)

 

so it's like a one motor that just turns the far intake runners into the closer intake runners along the same axis? That'd work!

 

but i think just having an IN/OUT would be easier for custom setups

[Careless]

question.... a lot of these systems are on hondas and pulsars and all those other cars that have had somewhat of a good aftermarket following... but didn't they make aftermarket intakes that "removed" those alternate intake runners?

[Nizm0Zed]

Yep, heres a pic of the 767B mazda engine.

Woooo, pretty. (this complete engine would make a kiiler conversion)

 

 

as for controlling it with an aftermarket ECU, i would imagine all you would need is a stepper control module, capable of controlling the motors, and a reference from the ECU telling it where it needs to be in relation to the RPM table.

Some ECU's may even have the load capability to control the motors directly

[Careless]

Yep, heres a pic of the 767B mazda engine.

Woooo, pretty. (this complete engine would make a kiiler conversion)

 

 

as for controlling it with an aftermarket ECU, i would imagine all you would need is a stepper control module, capable of controlling the motors, and a reference from the ECU telling it where it needs to be in relation to the RPM table.

Some ECU's may even have the load capability to control the motors directly

 

That's more like what i was talking about ! And I know a bit about using stepper motors! My dad is an AC/DC Motor electronics engineer and professor at George Brown College (or was, he's retired).

 

He'll be so happy to help me with this.

 

Would 12 volts be enough to actuate the stepper motor directions fast enough though? Stepper motors to move piece of aluminum long enough like that might need to be a tad bulky. It might be easier to use a stepper motor that is controlled by a screw drive mechanise, rather than a cable system.

 

I'll see what my dad says about running those with a servo attached to a hood flap, and some hysteresis control to keep the flap open until idle is reached again and the trumpets are fully retracted.

 

That way the hood flap isn't going up and down a million times a minute.

[Careless]

Inkjet printer motors. BINGO

 

http://www.aaroncake.net/circuits/stepper.asp

 

here's a cool circuit.

 

It uses PWM (pulse width modulation) to control speed. Every pulse is one turn. A lot of printer motors are 12 volts. Not sure if they have the gearing to move a "relatively" heavy piece of aluminum fast enough. SPST is the switcher.

 

so if you can take current RPM, and do some math with current distance and target distance, an EMS should be able to send a number of pulses very quickly. using a smaller duty cycle, the motor would count steps quicker (it's just a switch, not a voltage sensing input), or using larger widths on the switch would cause it to work slower.

 

Not sure how fast of a sensing circuit this is though.

 

It's also mentioned that a PICAXE circuit might work well too in comparison to the linked stepper control.

 

THE ONLY problem I can see happening with this, is the motor controller starting to lag behind compared to throttle input =/

 

anyone with input on this? experience using these motors?

[Careless]

ok guys, this is what we're looking for to control something like this:

 

http://www.active-robots.com/products/motorcon/easy-step.shtml

 

This motor controller can be programmed in a multitude of ways.

It is an 'intelligent controller'.

 

It can use voltage, degree calculation, pulse width modulation, clock positioning, and a bunch of other features.

 

It can work up to 35 volts, but if one can find a fast acting relay, we could use it to trigger a quad-block of common relays that would control all 4 sensor wires for the 3 motors one would need for a 6 cylinder (2 perhaps?) on PWM mode. (not on voltage reg mode, obviously)

 

SO FAR , this entire setup doesnt look too expensive. perhaps 150 or so dollars, or 200 with fabrication of brackets.

 

 

EDIT: forgot to mention, aftermarket ECU's come with PWM output for idle air valves.

 

perhaps if another input can be configured to do the same, it might be even easier

[KillerBjt]

http://www.autozine.org/technical_school/engine/tech_engine_2.htm#Variable-Intake

[capt_furious]

I'm wondering if there's a way to run something like this in a purely mechanical fashion, using engine vacuum as the governing factor. The first thing that came to mind when I was reading the thread was a sliding sleeve like the ones on the Mazda 767B shown above.

 

The sleeves would have to be pretty lightweight, it may be too much mass to move using engine vacuum. Fiberglass or cf tubes on a common plate(maybe CF with aluminum reinforcements), using a single-acting vacuum piston with a 'draw' stroke(vacuum being applied to the rod side of the piston), working against a return spring. As RPM increases, more vacuum is made, the piston extends further.

 

You wouldn't get the fine control of an electrically governed unit, but if it was done right, you might be able to achieve a similar level of effectiveness.

 

...sealing the sleeve to the walls of the intake to prevent a leak(which would reduce the effectiveness of the variable intake) might be a problem.