figures, i gots lots of stuff laying around, got tools, might as well and do a 'free' mod and try a spacer

 

Try it and let us know how it works!!!

 

All you need is some longer studs then stack a few spacers. I've got an extra or two laying around if you want them.

 

Would elevating your carb up 2 inches be so high that the hood would smash it?

 

out of all the diferent stuff i seen come through this forum that is one of the best ideas i heard in a long time,

i have been wondering the same thing myself,
but i was thinking of a 1" spacer

or take out the vacum plate and use a 2" spacer in its place

 

Okay, I can tell you several things to watch out for if you try it...

- Carb studs will need to be longer
- OMP rod will need to be lengthened
- The hood WILL PROBABLY NOT clear the air cleaner. There is about 1" of clearance stock, and the stock spacer is 1/2" thick. Plus you need to allow room for engine movement (I have blue marks on the bottom of my hood despite the 1" of clearance!)
- DO NOT make it an open spacer. What I mean is, #1 and #2 rotors need to be separate from each other. If you make it a big open spacer you screw up the vacuum signal and the carb will run extremely lean at the top end. I speak from experience here not theory

 

#1 yea figured that, looking for studs
#2 OMP whats that , its long gone
#3 Air cleaner whats that just like omp, long gone...(im ghetto), i might put it back on and run no hood, I am in Tx after all, no one would notice
#4 yea, figured as much IIRC your website had a thing on it about that, or something similar

so just the rotors need to be seperated? or all barrels

 

Just the rotors. It is beneficial for the primary and secondary runners to have a passage betwen them.

You really need to run an air cleaner! Rotaries die quickly unless their air is microscopically clean.

 

Just like my Baja Bug. It quickly lost compression and started buring oil like mad. While I was redoing the engine, I found that my spiffy chrome air cleaner did not have an element in it, so the carb was sucking down all the dirt/mud/sand that I was subjecting the car to.

 

GTU teams used to not run air cleaners on their race rotaries... what they were discovering was that after a few HOURS the engines would noticeably lose compression! I mean, OUCH!

 

10-4 on the air cleaner

 

peejay,
Why is it beneficial for the primary and secondary runners to have a passage between them?

 

prolly same reason siamese runners are good

(always heard good, but no idea why )

 

What exactly would a spacer accomplish? I mean, why do it?

~T.J.

 

It's beneficial because, I've discovered, the primary runner is rather small - it doesn't flow as much as the primary barrels of the carb. You need to have the passage so the primary barrel can flow its maximum, otherwise the secondaries won't open fully.

I had all four holes individual and ran a best of 15.6. No other changes to the car except for milling the primary-secondary channels open netted me 15.1. I think the channels are necessary

 

I still dont understand...Anyone care to try and explain? Im willing to learn...Maybe you could try explaining what a "runner" is and what this and that is. I understand what the intake and carb look like, but I dont know the terms for anything...Thanks

~T.J.

 

Runner - the port itself

 

Ok, why make the space between the carb and intake manifold larger? What bennifit could this possibly have? I mean, I thought you would want it as short and precise as you could get it? Why add 2" in there? And what are the channels? Im assuming you have 4 channels...Two for each rotor, one primary and one secondary. And your saying that you should, in essence, make only two channels? So you have one for both primary and secondary per rotor?

~T.J.

 

I'd like to know myself what benefits it has I'd do it just for the sake of experimentation.

 

From my "Stockels Auto Mechanic Fundamentals" book, I understand that lengthening the intake brings the powerband down in the RPM range.

Conversly, legnthening the exhaust RAISES the power bband in the RPM range.

I got no idea why. Well, some - but I'm unqualified to explain it. It only marginally makes any sense to me.
However, Paul Yaws site has a good tech artical on why this works, I think. I know for certain he explains why the exhaust length thing works.

 

Heres what I learned from college about basic flow on V8 piston engines. Closed plemonum with spacer(all four barrels seperated): better lowend torque.

Open plemonum shorter spacer(all four barrels all exposed to the same void): better highend power

Please note: this info is for V8 small block engines as a guide. I am sure its slightly different with rotaries. Like PeeJay mentioned with keeping the two rotors flows seperate?

 

always heard this was due to scavenging,

when people place cutouts on thir cars down here, most try and do it as far back as possible cuz 'it makes mo powa'

again no hard evidence, just what i hear.

 

From Paul Yaws site without permission...



Pressure Wave Tuning

"Since most rotary applications utilize a stock, or off the shelf aftermarket manifold, manipulating the pressure waves by changing the length of the induction tract is not as practical as with the exhaust system. For this reason I will not cover this in great detail.

The pressure wave theories that I discussed in the exhaust article apply to the intake system as well, but there are a few differences between the two. 1. The pressure waves will be much weaker, and so their effect will not be as great. 2. Since the intake manifold is typically much shorter than the exhaust system, the pressure waves will be reflected back and forth several times before they arrive at the intake port at the appropriate time in the cycle. Each time they reflect, they will lose some energy which reduces their usefulness. 3. In the case of the induction system, it is the positive, or high pressure waves, rather than the negative, or low pressure waves that are useful for increasing horsepower.

By timing the positive return wave to arrive at the intake port right before it closes, the pressure differential between the port, and the chamber will be increased. This will increase the flow into the chamber at the end of the cycle when it is typically at it lowest.

There are a few basic rules that apply to pressure wave tuning the induction system. A longer manifold will delay the waves for a greater period of time, and so tune the manifold for a lower rpm range, just as with the exhaust system. A longer manifold will also increase the peak torque output of the engine, in addition to the above mentioned effects. This is the result of the manifold containing a greater mass of air. (Remember, energy = mass times velocity squared.) At the end of the intake cycle, when the chamber pressure is increasing, this greater mass (Which is travelling at a high velocity) will better overcome the rising chamber pressure, resulting in greater airflow during that critical period. Additionally, a greater pressure drop will be created at the beginning of the cycle when the chamber begins to expand, because the engine will have to "pull" harder to get this greater mass of air moving. It is this initial low pressure condition which starts the pressure wave cycle, and the result is a pressure wave of greater intensity which if timed correctly, will increase volumetric efficiency"

Gueezus- Brutal tryan ta read that ****, yeah?