3900 inatke

[rx191]

the vanes are varable but would work very well if they just opened at a certain vacumm point. but we where both wrong on the mounting i pulled one off at work last night. and they have 8 bolts total that hold the upper tot he lower and the lower is different. but the lower looks like it mite fit a 3400 i'm going to see if i can find a way to pull the lower off of one and try it witha set of gaskets i have.

[Guest]

the vanes are varable but would work very well if they just opened at a certain vacumm point.

Yeah, that's why I suggested the change to a vacuum actuator.

I might build a new upper for mine with the variable runner idea in the futire, to see if it's worth it.

[rx191]

i don't know if a vacuum unit would work i think the vane is made to servo motor. i haven't had a power steering pump off one of these yet so i haveb't been able to pull the varible unit out.

[v6h.o.]

Yeah sorry, You were right there is 8 of them

Intake Manifold Tuning Valve System Description

The intake manifold tuning (IMT) valve system uses variable air induction tuning in order to achieve maximum performance and efficiency over the entire operating range of the engine. The characteristic torque curve of a normally aspirated engine depends mainly on how the engines average pressure changes over the engine speed range. The average pressure is proportional to the volume of the air mass present in the cylinder when the inlet valve is closed. The design of the inlet system determines how large an air mass can be drawn into a cylinder at a given engine speed. An IMT valve is used to change the intake manifold plenum configuration. When the IMT valve is open, the intake manifold is configured to one large plenum. When the IMT valve is closed, the intake manifold is configured to two smaller plenums. The two intake manifold plenum sizes result in different torque curves, which improves performance at low and high engine speeds. During low speed, high load conditions the IMT valve is closed creating a longer runner path inside the plenum, which increases torque. During higher engine speeds and loads, the IMT valve opens creating a shorter runner path inside the plenum, which increases horsepower.

The IMT Valve assembly consists of the following:
• A tuning valve
• A micro-processor
• An electric motor
• A hall-effect switch
• An ignition voltage circuit
• A ground circuit
• A variable tuning signal circuit
• An IMT fan position signal circuit

Ignition Voltage Circuit

An ignition voltage is supplied directly to the IMT valve assembly through a 10-amp fuse. The ignition voltage provides power to a microprocessor and to a motor that rotates the IMT valve within the intake Manifold.

Ground Circuit

The ground circuit is supplied directly to the IMT valve assembly. This circuit provides a ground for the micro-processor and the motor.

Variable Tuning Signal Circuit

During operation the control module applies ground to the variable tuning signal circuit which indicates to the microprocessor within the IMT valve to turn the motor ON which rotates the IMT valve within the intake manifold plenum.

IMT Fan Position Signal Circuit

When the IMT valve is rotated the hall-effect switch detects the movement and provides a signal to the micro-processor which provides a feedback signal to the control module. The control module uses this feedback signal to determine the position of the IMT valve.

It sounds like all you would need to do is provide a ground signal to the circuit to have it opperate. Which could be done by having a switch mounted on the t/b to either close and provide a signal for the circuit to opperate the valve at a desired throttle input %. Such as maybe 80- 100% throttle angle if you wanted to do such a thing.

Again I plan on taking mine apart, just sometime when the woman isn't driving it or around for me to get in shit for tearing our new car apart :P
LOL.

[SappySE107]

So its not a true 2 stage but more like what nissan has been doing with the plenum split/combined. That is something I have thought about for a custom intake as well. To operate it, you could just use RPM based with TPS as a 2nd lookup. That way when you close the throttle it also splits the plenum again. Just a thought:P

[EspanolaGuitarista]

Some European car makers....

use variable length runners that actaully elongate. Like a velocity stack with a trombone feature. I have always liked that idea but it seems rather tricky to make something like that. That way the runner length can be tuned with a stepper motor. Say if you go from 800-6200 in increments of 50 rpms you would need 32 inches for peak torque and 16 inches for peak horsepower. So a variable runner length of 16 inches. It just so happens that if you increment in steps of 50 rpms you come out around 16. So if we could could build trumpets that can elongate 1 inch for every 50 rpms we could cover the entire range of a performance v6. Just an idea. With a stepper it would take gearing to multiply the motors movement. What about a plenum? Well a plenum could be attached to each side like a cross-ram type, but personally I would go with the velocity stack design and put small open element filters on each trumpet and then have a system of valves for each side. Three inline valves per side conected to one linkage. It would have a crazy sound. Like six vacuum cleaners going off at once. I would love to build that intake. Anyways that is my approach to it all.

[AaronGTR]

Anyone know if the 3500 and 3900 heads are the same? I seem to remember Brad saying that the 3500 heads have a bigger intake valve and the intake ports are moved slight compared to 3400 heads. That would mean if you wanted to put a 3900 UIM on an older 3100/3400 car, if it requires using a 3900 LIM then you would also need 3500/3900 cylinder heads. You'd be talking about swapping the entire top of the motor. And besides getting the flap in the UIM to work, you'd also have to see if the older fuel rail will fit the newer LIM since they changed the fuel rails. Probably wouldn't be room for the FPR there either so I think you'd end up having to customize a fuel rail and mount the FPR somewhere else. The 3900 UIM is also a lot taller so you'd need to check hood clearance.

Maybe it's just me but that sounds like an awful lot of work for minimal gains. Unless you have to money to buy all those new parts and really want to build an all out crazy motor, I'd just port the stock 3400 stuff and use the 3500 UIM on it like some are doing.

[bszopi]

I was wrong on the valve sizes. They are the same as the 3400, just lighter. I knew something was different about them, I just got confused. I blame it on old age...

As far as the heads being the same, I HIGHLY doubt it. If you read the description of the 3900, they talk about shifting the cylinder bores to allow for the increased bore size. This would mean that the location of the combustion chambers between the 2 heads would have to be different, as well as possibly the bolt locations. So yeah, highly doubtful any of it would even work on an older block.

[kprofthestrs]

yah. but what about using the the short block assm. and bolting a 3400 lower and upper intake on it. i don't know about the 3900 timing cover set up yet but the 3500 is similiar.

[torq455]

hey, hey, hey!!!! Blame nothing on age buddy!! You're not that old!!

[Fiero11]

There are two 3.5L engines. One is based on the 3.4L with small valves. the other is based on the 3.9L with big valves, and is in the 2006 Impala.