Hey all, I am designing an intake manifold for my N/A, hey I need all the power benifits that I can get
I am doing the math to get the proper intake runners, but I have some quesitons abou thow you derive runner diameter and wave tuning.
I have been looking at the 787B intake set-up (no I am not making on anything like that). and I noticed that the extensions were all after the throttle bodies, does this have anything to do with the wave tuning in the manifold or just the so-called "Ram Effect" of the airhorns on the throttle's.
And also on the wave tuning aspect can the intake be tuned very well if it funnels down into one large throttle, or would the be more gains with the giving the runner there own smaller throttle.

These are all the quesitons that I can think of right now, but I am sure that I will come up with more at a later time.

-Justin

 

https://www.rx7club.com/forum/showth...5&pagenumber=3

The r26b doesnt move the throttle because it would be impossible to use as a throttle then, in short it doesnt matter as long as its not restrictive.

That depends, most PP's ive seen have no plenum, but i think building a properly designed one, with one large throttle body would be fine aswell.

 

The R26B tuned based on the pipe organ resonance principle. A different length tunes to a different frequency or rpm. It doesn't really matter where the throttleplates are for this to happen. At wide open throttle they effectively aren't there anyways and this leaves the intake to tune as it sees fit. The only possble downside is that the throttleplates even in their open position still have a small degree of turbulence that would disrupt airflow into the intake port. that obvioulsy wasn't a problem though for Mazda.

Before you use a new intake manifold, I hope you bought a computer. You will see little gain from the stock ecu and probaly some losses in spots.

 

Yeah, I will be using a standalone with this intake., cuz I am also going to switch to webber style throttle bodies.

 

Another question, do you include the throttles and air horns in the length of the runners?

 

Yes that leangth should be included as well. For the pp it should be about 6-7 inches long from the rotor housing wall to your butterfly on a standard weber 48 ida with stock velocity stacks. I would not try use a tunnel ram technique on a pp, it would be too much volume and kill velocity. Which engine is this for?

 

I am making it for a bridged aux port, and street ported primary/secondarys. I pretty much have the layout all drawn up, just need to find lengths, and what not.

 

So your going to construct it out of aluminum tube? I would just go shorter that the stock one. Which carb are you using? I have a 48 IDA mani for a 13b that is very short. Its the shortest side port mani i have seen.

CJG

 

Yes I will constrcut it out of Aluminum tube, and I am going to set it up a lot like most IDA manifolds, but I am going to give the aux ports there own TB and runners, to take advantage of the extreme port timing that the bridged Aux ports will have, and not sacrafice drivability.
It will somewhat resemble the RX8 intake, but they are using a plenum style intake with one large TB.

 

You are the first person I have seen who actually knows how to do it properly! Seperate runners for seperate ports people!!!

 

I think there was a custom intake like what your saying up for sale on parts trader about 5 months ago. It had about 8 inch long tubes that came off each port, streight out, that bent about 80 degrees up, then each had a TB. I cant really remember, but it wouldent bee that hard to set it up. Figure the linkage out, so that it only runs off the center ports at low rpm, then at higher rpm just mash your foot to the floor to open the other 2 ports. Or you could whimp out and use a vacume system to open the ports at the "proper" time. you could also program into your ecu to only turn the injectors on in the aux. port at a certain rpm. Just throwing ideas.

CJG

 

I am thinking of using something like a throttle stop that would be under the TB's, this might take a while to do since I am only 20 and have NO engineering education.