Variable Port Size/Timing
 

Does anyone have any ideas aobut variable Port sizing when the engine is running. Picture it: a port that is continuosly variable according to the engine's rpm. This would allow for massive ports single, bridge, of peripheral and not kill the low end. If the port could get "small" enough, maybe idle could be considerably dropped. If I am correct, Lower rpms like less overlap because more compression is needed and Higher rpms like overlap so the air can travel through with ease. I know a 6 port is an attempt, but its harer to modify 6 port steel housings, and this is only 2 different stages. If I understand correctly, a 6port engine is kinda like a 2 stage Vtech system on a Honda. Except my parents CRV has i-VTEC, (triple stage- oooh!) There has got to be a better way to attempt at obtaining better low end than a 6 port engine (Hint: continuosly variable)

How do you seal the variable port area with the rotor sweeping over it???


-Ted

i was thinking if an external or arm was stuck into the port that rotated up or down would not need to make a seal to still be quite effective. I have no idea how to make a perfect seal and have it be continuosly variable at the same time. The sixport engine seals its different stages well, however, there are stages

mazda thought about stuff like that...that's how we ended up with 6-port induction ;)

I'm not worried about the seal.
I worry about the small lip left when you make your sliding "door".
This is going to eat up the apex seal or side seal.
Trust me - I've been thinking about this a looooong time now. :)
You're never going to have a perfect seal, cause there is always going to have a gap somewhere in the system due to the sliding "door".
If there was some way to make the surface with no gap that has a variable opening / aperture, I would've tried it by now. :(

I even thought of doing a bladed type aperture like a camera shutter, but that just makes things worse. :P


-Ted

Computer controlled solenoid actuated valves on piston engines..........

timing on valves is much easier to be changable. I was thinking computer controlled, but u cant use valves like on a poston engine

i dont know if you thought of this, but:

think of the rotating 6- port sleve. make it square, so it will be nearly flush to surface of the plate. then slide it back and forth on a track/rail with some sort of actuator.

put as big of a port as you feel like in the aux port area (so long as the side seal wont fall into the full port, obviosly), then machine out a recess for sleve/valve to slide back into when fully open.

this probly wont work becase the "recess" needed would probobly cut into water and/or oil passeges. but then again, this would require a completely redsigned side-plate.

just an idea.

but seriously, compared to most (especialy v-tec) small displacement high reving engines, n/a rotarys heve pretty respectable low end (not great, but decent when in proper tune) with a very linear powerband as is, in my opion.

How about a sleeve ,like the ones used in the two stroke bike`s exhaust ports?That should be able to stand the heat? Might only work for the exhaust though?

Karis

No matter what, you'll still end up with blow-by.

If you're going to do a variable side port, then you're very limited to the port area.
I was thinking about doing a variable peripheral port.
Small PP allows for high intake velocities which might be able to induce a tame idle at a decent RPM speed.

Thus, the variable "door" is going to see the apex seal (edge) and not just a side seal.


-Ted

i think a variable p port would be the most worth doing, and the easiest to design and fabricate. If the pport was rectangular, it could have rounded edges, but mostly rectangular, u could have a valve thant went up and downinside the sleeve for the port that would let it go to very low idles. When valve is down, then there would be no overlap between intake and compression cycle. but at high rpms a pport flows the best!

yeah Ted, it would be hard to eliminate the blow-by factor

I wouldnt consider on going through the trouble,on anything but a PP.

Ok,so who is going to do this for us?

how about stockports in the irons and variable periphial ports in the rotor housings, except not one solid port. imagine a large periphial port, but seperated into sections, each one like a long sliver, say 4-10 sections. each section is its own seperate port all the way to the inside surface of the housing. each section has a solenoid actuated rubber tipped blocker - all of which are outside the housings hidden inside the intake manifold. at low rpms, all the periphial sections are blocked off, the stock sideports provide adequate low end torque. as the rpms increase, the periphial sections are sequentially opened at increasingly higher engine speeds. you could have a similar setup with the exhaust ports.

I like that idea. I think 4-10 sections would get the job done. It wouldn't be continuosly variable, however, it would be realistic. I like the idea of keeping small stock ports. I would mismatch steel housings, and get the smallest 4 port combination that can happen. That pport design would not be that complicated. Maybe hard to make though. Also, it would be smart to make a computer control the pport sections in steps with rpm being the input into the equation. The tacomneter has wires going to it right?, maybe one could splice into those wires for a rpm level signal. I am not good with programming computers, don't even know where to start with controlling this system. If someone tried to control it with some vaccum system, that would be such a waste of time and effort. I don't have funds to try this. Im spending all my money getting my car running. Were you guys hoping since i started the thread, that I had funds to try it?, sorry. Incentive to try this: Faster acceleration, sales, and praise from us. Man, I wish i could try staged pports

I think it would be an awesome motor, but it would take $$$. The rotor housings would be the hardest part, you would need a serious machine shop to do that kind of work i think. You would probably also need a custom intake manifold to fit the blocker assembly inside of it. Yes, you could do it in steps, with the signal for the tach. A certain voltage corresponds to a certain engine speed. You could have an electronic controller that would open each port section at a specified voltage, you could also make it adjustable so you could tune it yourself. Someday, when i have money.....

You could just cut horizontal slots into the housing, and make a new manifold that controlled all of this, maybe a manifold that could control the 4 side ports and the, hmmm..., lets say about 5 slots that are periferal. Also, make it so the side port tunnels are longer in the manifold, and so the pport tunnels are shorter, to tune it for the appropriate rpm. It would be much easier to use a 4 barrel carb. That would be sweet to have a carb that was more than a two stage like the Nikki or the Holley. That is why fuel injection is better, but its such a biatch. Blasted Wires!

What about this: The ventile is controlled by the engine's need for air and when the engine need more air at higher RPM, the engine will suck more and the ventile will open up more. The orange/red to the left is the pressure difference.

This idea does not help on the idea of variable side ports. it could work on controlling stages of a pport design. Except, the only thing i dont like is that it takes engine power to pull that spring loaded ventile open. If it was used, then stronger springs could be used on the higher ports. Remember, the amount of airflow is not the only factor, but where the airflow stops. This is because, at low rpms you want more compression, which is mostly determined by where the port opening ends on the intake to compression cycle. The biggest advantage to this is it's ability to contoll flow without using a computer.

Well just skip the spring then and replace it with a pneumatic piston which is controlled a computer, then you can close and open it at will. Problem solved?

And yes, this is for p-port only and its just something i drew on 10min and there for not the final product

I have though about this as well, way i thought might work would be to make a long PP port, so like a normal PP looks like a cirlcle this would be much longer, too long to actully work as a nomal PP, you would need to keep a strip in the middle of the PP for the apex to rest on as well.

then create a block to fill it with 3-4 inline valves which would need to be electronically controled as you pick up more RPM, the vlaves would open/close you could have an interesting combination with 3/4 vlaves and make the air intake much smoother.

you would also want something for the exhaust end, maybe like a camera aperature, that can chnage the exhust outlet size to provide better idle/low rpm stability.

hey, Eson, what CAD software did you use? Cuz I'm looking into getting SolidWorks (student ofcourse). Let me know how you like which ever program you used. And, yeah, good idea, and the problem is solved. Now all we need is funding to make this!

That is Solidworks and its one of my favourite programs. Sure its a bit tricky to learn new functions by yourself (no eduacation in SW), but there is just soo much you can do.

I dont know what the SW student version cost, but the real SW cost way too much for a private person and i could recommend Sketchup, not that ive tried it, but i like the look of it and its really cheap. But i dont know the accurate as they announce the program as a sketching program and not CAD software. If you are looking for a 3D, CAD simular program, try sketchup, otherwise i dont know.

I have used Sketchup. It is very very simple, every function can be learned in about an hour and half, REALLY. You can get a free trial, and use it for about 8 hours. Quite a bit of time since its so easy to learn. Try it. Yeah, SW is $80 student version, not bad for 2 years license. Anyways, that is off the topic. I was just reading about the Renesis engine on www.Rx8club.com. From what I understand, its a 3 stage induction. Its like a 6port engine, however the center housing's ports can be shut off aswell. I would say the best thing to do would be adding a small peripheral port that comes on at like 8000-8500 rpms, and raise the redline a little, to like 10,000.

What the Renesis does is alrady good enough, isn't it? You just 'stage' up the ports sizes and locations (the equivilant of differnt duration and lift on a camshft) and you open bigger, retarded parts (as far as the timing goes) as the rpms increase.

One thing I wonder is if the turbo 13B in the FD does that. Its 4 port, right?