Mr. Midas

Alright, ok, you all win. I'll tell I'll tell!



I am going to use the filler to DECREASE the size of my port runners in such a way to promote more even flow and a better charging effect caused by the INCREASE in velocity. Simple, right?





Now, could you guys with the experience please suggest a suitable filler? The pro's have stuff that is tried and true. What is it?





Thanks.

rotarygod

There's nothing new about that. The key is how much and where you do it. JB Weld, Devcon and other materials can work just fine. If you have it fail, you didn't prep the area good enough. The key is in really good cleaning of the surface that you are applying the epoxy to. You need to also rough up the surface quite a bit. Not only with sandpaper but also cut small grooves into the surface. This will help hold the epoxy on. I've used Devcon for years and never had a single issue.



As far as the smaller are goes, check out mototuneusa. It may be primarily a motorcycle website but the info applies to all engines. http://mototuneusa.com/thanx.htm There are alot of great articles there. Check out #17 for the proper way to prep a surface for epoxy. You'll need to experiment with how to do this on a rotary. You never know what could happen. It might work or it might not.

Mr. Midas

I know its not something new, although it is quite different from what the majority of porters are doing.

This isn't the only thing happening to my engine.(The other stuff is what really involves the most risk) I just wanted to have a clean thread on the best filler for the rotary. I'm sure most people have realized how much "dead space" there is in the ports. It is really evident when you use some modeling clay and a flow bench...



So, which Devcon do you use, how hard is it to sand, and can it blend/feather well?



Thanks.





Oh yeah, I almost forgot... MotoMan is one cool dude!!!

rotarygod

You need to be careful sanding it as you can easily go too far. Especially with a sanding drum on a Dremel. Use the Dremel to get close and then do it but hand. You can do the final roughing up with the Dremel but be VERY careful and steady or you'll have to go back and add more.



I don't know about type 1 or 2. I do know that my local home improvement store sells 2 kinds. One is a putty stick that you squish together (2 internal putty parts) in your hands and then apply and shape until it hardens. I don't use this stuff. I use the 2 part epoxy that comes in tubes and needs to be mixed like JB Weld. It even looks like JB Weld. I've never had any problems with it.



I do have a flowbench that I built btw! Haven't used it in a while. Need to pull it out again and play around with some different things.

banzaitoyota

I already posted which DEVCON to use, Liquid Steel 'B'

Lynn E. Hanover

This is a natural path of development on the intake side. The big problem with going faster is the port opening into the chamber.



The NA rotary has two RPM where it is more than 100% efficient. Or, volumetric efficiency exceeds 100%.



It ingests more than its displacement. Free turbocharging without the turbo.



So it isn't all that bad right out of the box.



I love fooling with this stuff. The fact that its been done is of no value to me. I want to see it on the flow bench.



The ideal runner is a very large diameter round tube. The one that works in a real engine is a quite small diameter round tube.



The higher velocity of the small tube adds inertia to the charge and aids in the over boost.



The two flow problems you see are that a round runner goes to hell in a 90 degree turn. And Bournulli kills off that velocity at the port opening shape that takes advantage of more favourable timing.



The ultimate answer is of course, the Periphery port. Ideal shape. no velocity change at the port face, and so on.....



As runner diameter is reduced, velocity for a fixed depression goes up. Until.....surface...or parasite drag begins upsetting the boundry layer, and drag increases at the square of velocity.



This is seen on both the dyno and the flow bench as sort of a wall where the next change in the same direction, seems to have little affect on the outcome. Total flow or power.



There is improvement to be had at the transition between the runner and the port opening. The "bowl" as it were. The combination of a turn of close to 90 degrees and a velocity drop from the drastically increased diameter (shape of the port opening) is a big problem.



The ideal shape for a turn is the flattened "D" shape. This is with the vertical back of the "D" shape on the inside of the turn. This is done without increasing cross sectional area, so as to maintain velocity.



The port face opening shape in the rotary is dictated by the various tracks of the seals. Not ideal. And the need to adjust closing timing to alter peak torque RPM.



Without redesigning the engine from scratch, there is a lot of room for improvement. The runners are cast as is the bowl shape.



Be sure to have your little weather station going to correct all tests to a standard day.





Lynn E. Hanover

ReactionEffect

Lynn just for trivia what are the RPMS that a N/A rotary excedes 100% VE?

Mr. Midas

From what I've been able to find so far, it does seem to be the best epoxy. The only thing that bothers me a little is that its max temp is 120 C = 248 F.

http://www.bsc.com.au/devcon/devcon.pdf





Great stuff Mr. Hanover! I do have a homemade flow bench, and was able to see how the port flow was affected in various areas. I do need to start factoring in the wearther like you said. The barometric pressure is always changing, as well as the ambient temperature.(can't forget altitude either, right?)



Ahg! Now I've got to go dig those equations up...





An S5 exceeds 100% VE when the VDI activates, right?(My best guess is 6000rpm).



What about the other rpm?





Nopistons Rocks!!! Thanks Guys!

banzaitoyota

no if they only still made BELZONA super-moleculiar

Lynn E. Hanover

One is real close to peak torque as you would expect, and the other (if I remember correctly) is well below that, so as to be good for economy but useless for racing.



Note that the three runner systems of the new engine is to take full advantage of the two peaks a total of 6 times, to maintain a fairly flat torque output. Very busy, but effective.





Lynn E. Hanover