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Discussion Starter · #1 ·
OK. I've narrowed it down to either the PRM cold air or the Weapon R with the ram air kit. I've ruled out the CTA intake because of its too large diameter piping and the hot air it gets from under the hood.

My questions are(for anyone who has either of these or knows):

1. In pictures of the PRM intake installed on the 1.8, I dont see the VAF(MAF). Where is it?

2. What parts of the stock intake are best left alone? I hear removing the resonator box will sacrifice low end torque. Is this true?

3. Is the RX7 VAF worth it? Is it a direct bolt on?

thanks in advance
 

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1. can you show me the pics you're talkin about...cause the VAF should be right behind the filter.

2. Maybe it does, maybe it doesn't. I took both the resonator and the restrictor off mine and i seem to be fine on 2500 rpm launches.

3. I don't know. I'm buying one off Tito for 26 bucks, afterward I'll tell you.

Note: I'm going turbo later on, so I'm sure it'll help then. :D
 

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The car wont run without the VAF installed. The RX7 VAF is a direct "bolt in", in that it fits perfectly. Getting it to run well is a different story. It may take some tuning, and there are a lot of threads around regarding how to go about that. Some folks have an easier time with it than others.
Regarding the resonator box, I'll cut and paste my post from the ERDT message board on the subject and see if that answers any of your questions. Some folks arent registered at that website, so pasting a link wouldnt work for them. Here goes.....

Its called a Helmholtz Resonator. It has a legitemate purpose, however it isnt a necessary component. You can remove it and, theoretically, you should lose some low end torque. However, the amount of torque lost is negligible (Around 4 ft/lbs) for the stock 1.8 BP engine and only applies if the engine is still utilizing the stock intake tract and has no other modifications. I never realized any performance loss when I removed mine and the car certainly isnt any slower on the dragstrip, so I havent worried about it. I've also fabricated a completely new intake tract. Some people might notice the change, others may not. Give it a shot and see if it affects your car would be the best answer I could give you. The small hose that connects to it is simply the Idle Air Control Valve feed hose and is a needed part. Just re-insert that hose anywhere into the intake tract AFTER the VAF or MAF.

The technology behind the "box" is very complex and mathematical. The resonator is tuned to the intake tract and the engine itself, so, changes to the intake tract length and diameter and other engine modifications make the stock resonator ineffective.

The opening and closing of the throtte bore creates 2 negative induction pulses, per revolution, that travel down the intake tube untill they reach the end (The air filter). Once the pulses reach the end they invert to a positive pressure wave which travels back up the intake tube towards the throttle bore. The "box" helps time these waves so that they reach the plenum and boost pressure when its needed in order to maximize the efficiency of the intake tract.

The Helmholtz resonator is designed with a VERY specific volume that is determined more-so by the specifics of the intake tract than the engine displacement itself, so this is why the "box" no longer plays the same role when you make changes to the intake tract. If you change the intake tube; shorten it, make it longer, make it larger in diameter or smaller in diameter then the stock Helmholtz resonator is no longer a valid part of the tract. In some instances it may actually have adverse affects on the efficiency of the intake performance, so your best bet is to try it with the "box" removed. If you notice a difference then, by all means, re-install it.
Ideally, one would need to manufacture a new resonator based on the specifics of the modified intake tract but the performance gains most likely would not warrant the expense and in-depth engineering required to do so.

In short, there a lot of factors that determine the make-up of the resonator. One would have to know the engines volumetric efficiency at a desired RPM, the volume of the intake plenum and a desired intake velocity which, in itself, would require knowing what velocity the engine would perform best with at a given RPM range. That, also, will change with engine modifications. Knowing all of that and more, one could determine the ideal intake tract length and diameter for that application. Good luck.
 

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Discussion Starter · #4 ·
OK, just to be clear, which is the resonator box? The square thing behind the VAF, or the long skinny tube that runs above the radiator support? The PRM intake uses the stock intake tract, so I assume I can keep the resonator box on if its the thing behind the VAF.

here's the link to the pic of the PRM intake...no VAF?(scroll down)

[/img]http://www.corksport.com/main.php3?primNavIndex=0&mainURL=/store/index.php3?cat=227108
 

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Well, the intake in the picture shown isnt for a 91-96 EGT. They might have one for the 2nd gen, but that pic isnt a 2nd gen setup. It looks to me like there is a MAF inline where the plug connects.
The resonator is the square box behind the VAF on the 2nd gen. You can sure leave it on, but youll be modifying the intake and engine performance, so I doubt the resonator would perform the same anyway.
 
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