Originally posted by bnoon:
Originally posted by warmonger:
[b] I went through the same thing by driving it with the secondaries pinned open and then working normal. No apparent gain up high, but noticeable drop down low.
Those who ask why I didn't dyno this mod... I don't need to. I only dyno questionable mods that might only gain me a few HP. This mod did not qualify for that. 
The next mod, I probably will dyno though since I want to sell swap kits for it. Aluminum 3 liter UIM mated to the oval plastic lowers will be available as well. Why the aluminum uppers? They're portable where the plastic UIM is not.
Page 2 doodz! [/b]Brad, I understand the concept and yes I get it. There is nothing blocking the airflow when they are removed, so there is less restriction.
HOWEVER! It(pinning the secondaries) does suit to determine that there is a LOSS down low. This in itself was what I was after to determine. I wanted to find out if I was going to loose take-off torque, which I did. I also reported that I had no gain up top, which is to be expected (though I didn't print that).
In my case, I alread tried to compensate for the secondaries by widening the passages considerably. I have small gaps around my throttle blade plates, about 1-2mm on the sides where the shafts are. I leak a little air past each throttle plate even when they are closed.
As far as adjusting spark timing and fuel with them removed, what makes you think that is necessary? If there is a higher volume of air then the MAF will surely pick that up.
As far as spark timing: Picture driving a car up hill and lugging the engine in an older vehicle in high gear. What happens? You can make it up the hill at a constant speed at part throttle in that gear, but then you try to accelerate by opening the throttle more, and you get loss of power and possibly pinging. On a newer car you get no pinging but a loss of power because the air velocity goes down and the timing is pulled when pinging appears.
This is exactly what happens with the secondaries. Because our engines spin out 7000 rpm, there is a need for higher airflow at those higher engine speeds. At low rpm the airflow requirements are much lower.
By calculations, our engines would require 262 cfm of air at 5000rpm, but that jumps to 376 cfm
at 7000 rpm.
Therefore, I cannot see how you will get a comparable improvement in low rpm power that will equal what you loose with just spark timing adjustments.
The secondaries being removed may help high rpm flow a little, but they will NOT be a restriction for the low rpm air requirements that the engine has. Therefore all you have succeeded in doing is allowing the SAME amount of air to flow through two paths now instead of one. This means that the airflow velocity HAS to go down if the volume is constant. In the end you loose power because the velocity went down. If you keep the velocity up you get to take advantage of a small pressurization in the cylinder due to the momentum the column of air has.
OK, you can choose to remove the secondaries and improve flow above 5000 rpm, but you loose a bunch of power down low. How about keep the secondaries, but improve high rpm flow?
The shoshop (baastards that they are) had a good idea. They bored the secondary intake runners larger and installed larger throttle plates. No loss of low rpm torque and improved the flow at high rpm.
That is the proper way to solve this problem. The best of both worlds and what I did to my manifold reflects that a little bit.
*Sorry for the long post*
warmonger
