EVLRX-4

well seeing judge ito teaching his daughters how to port made me think at 15 what the hell am i sitting around for.

so i grabbed my old 13b block and took the front side housing off and went at it.

took me about 1 hour 40 minutes to do isnt perfect but its just practicing so i dont think it needs to be.

i just did it free hand as i dont have a template to use but tried to make it a street port.

ok ok less talk more pics hehehe.







tell me what you think.

Lynn E. Hanover

Well OK, I think its great that we can accomplish what is "in effect" a cam regrind with just s die grinder or similar tool.



First, read and memorize, all of the tech articals on Paul Yaws web site www.yawpower.com to help establish what it is you are after, and what effect each change you make in the ports, will make on performance.



Play with the bernoulli web site and note that when a tube increases in diameter that the flow velocity decreases.



Determine what closing point you want to establish and make your own template up keyed on the dowel holes, so that you can transfer that markup to all of the irons.



use Prussian blue to mark the irons, or Dyechem, or just a Majic marker, to make a background to mark up the port location.



after you have the port marked off the way you want it, lay down several layers of duct tape just outboard of the porting lines, so you will not hose the irons when the grinder hops out of the hole. And it will.



I keep a shallow angle while porting. Here you want to change port timing with as little increase in bowl volume as is possible.



I would build one of Mr. Hanover's flow benches, and become a near genius in just a few hours, but it is not manditory for success.



Remember that the engine with the widest power band, will outperform anything with a short peaky power band. Old saws such as "HP sells engines while torque wins races" may have been encountered. The stock trans has wide spaced gears for easy driving, and building an engine that falls off of the tune between gears, will be slower than stock and a misery to drive. Not what you were looking for is my guess.



For two reasons, I would not move the outer line at all. That soon unsupports the leading end of the side seal and leads to poor sealing, as the square tip of the seal gets rounded off. Also, should you want to Bridgeport later on, the bridge will be more narrow than is good practice.



So the upper line (the closing line) is determined by what you want from the engine. Here is what I do. This may not be universal, so others may want to jump in with their thoughts. I do the big degree wheel thing and scribe a light line along the rotor, to indicate the closing line I want.



I then remove the rotor and alter that scribed line up a bit at the outer end, and down a bit at the inner end.

That way the trailing end of the side seal will not meet the edge of the closing line all at the same time, but come back aboard the iron from the inner end to the outer end, with no drama, no bounce or chatter, and no wear at all. It is not uncommon to reuse the side seals at year end, so long as end play is below .002".



The closing line is polished to a chrome like finish to reduce side seal wear, and improve flow.





I start the side seals off at zero clearance. So long as the side seal and corner seals pop back up from spring pressure when depressed, that is all it needs to run and get a near perfect seal.



I could get a zero hot leakdown on my piston engines, and very low ring drag.



For street use, you may want to run some measurable amount of clearance, but the more you start with the sooner you will need a rebuild.



The inner edge of the port is determined by the track of the outer oil scraper lip, path. In some irons there is metal available to be reduced. Just chamfer the edge of the bowl along here. Put in a tiny radius and polish it. There is nearly nothing to be gained by increasing bowl volume, as it is too large in stock trim already.



Where rules permit it, some builders fill in some bowl volume. The velocity in the runners is lost when flow reaches the increased volume of the bowl. (Bernoulli) So I just smooth and polish the outter walls where the flow tends to want to go anyway, and smooth but do not polish the inner walls where you are attempting to trip the boundry layer (a bit) and add energy to the flow in an effort to hold some of the flow against the inner part of the turn into the bowl. (Google vortex generators)



Only gross discontinuities are removed from the runners. Here, the highest possible velocity is what you are after, and increasing the diameter, slows velocity. So just a cleanup here.



Match the intake runner to the manifold. If there is a mismatch, at all make the runner bigger to avoid a sharp ledge facing the flow. An exact match is ideal. I still use a stock gasket and once the gasket fits the manifold I glue it on. Never needs to come off. If I need a new iron, I match it to that gasket, and all is well.



A broad power band is what you want. An engine with 240 HP from 6,500 to 9,600 with beat the snot out of an engine with 260 HP from 8,900 to 9,200 RPM and little else. If he cannot cover his gear spreads between shifts, your Mother can drive around him.





Lynn E. Hanover

ChainSawOnSteroids

How about bridge porting?

vipernicus42

I find that interesting because on Paul Yaw's website he says that when he flow tested port-matched runners he found they absolutely killed flow.



http://www.yawpower.com/Flow%20Testing.html



Jon

ilia

Unfortunately, flow bench data is not everything when it comes to deciding if a certain design will make power or not. Sometimes, very counter-intuitive things happen that have to be overriden by experience in order to come to a useful conclusion.



With that being said, this is my first post here, and I know nothing of rotaries (yet).

Lynn E. Hanover

Yep,



I would go along with that. Once you pay Paul a billion dollars for an intake manifold, you would probably want to stay out of it with your die grinder. The stock manifold is very well done. Most aftermarket manifolds are even better. If he flows it and says (by shipping it to you) that it is good, then you match a gasket to it, and then leave it alone, and use the gasket to match your intake runners (in the irons) to his manifold.

And you do as little grinding as is possible to get that match. Anything you remove from a runner reduces flow velocity for a fixed depression (vacuum).



Building a flow bench is just not that hard to do. There is a web site for flow bench building and use. And I posted the plans for mine, which is very simple to build. If Paul would post the plans for his (personal design)

Or even sell the plans, I would build his design.



http://www.tractorsport.com/cgi-bin/forum/...n/ikonboard.cgi



Use a big degree wheel on the crank to determin what closing point you came up with freehand. Use your new flow bench to determin that you have gone in the right direction shape and velocity wise.



Use that data, and clay copies or cardstock profiles, of that port to attempt to replicate that port in the opposing iron. Flow each new port with the manifold attached to it, and the carb or throttle body propped open. Wired open would be good. Notice that all of the colored liquids in the flow bench accumulate on the cieling when the throttle plates slam shut accidentally.



Lynn E. Hanover

mazdaspeed7

Have you ever filled in some bowl volume on your engine? This is a recurring trend I keep seeing in high end head porting on piston engines by the guys who really know their stuff, as well as some of the things trickling down to more average people. And the bowl in rotaries is way worse than any of the stock piston heads.



My real question here is the practical aspects of getting the epoxy to stay in place and not risk damaging the engine. Any tips?

Lynn E. Hanover

I have never done anything in the bowl. It is not permited in SCCA rules. I have however used Devcon



Plastic Aluminum to fill in around the tube installed to make up a Periphery port housing, and to fill in a housing to form up a Monster bridge port. The Monster port is nearly a waste of time, as it only works at very high RPM, and has no bottom end at all. Worse even than the "J" bridge port.



Used where porting is free but Pports are not allowed. I rough up the areas where the epoxy will contact the aluminum with a course ball bit. The rougher the better. Scrub with dish soap and water, then after that dries, do again with Ketone.



If I were to do this in the bowl, I would drill a number of 1/8" holes over the area to be epoxied.



You might even drill and tap for 10-24 screws. I would not finish tap all the way through the hole so that the screw binds up in the bottom and locks up. Then trim off the screw short of the proposed finished surface.



The Aluminum Devcon has aluminum powder mixed into it, so it replicates the expansion rate of the base metal. The plastic steel has powdered iron mixed with it. It works for many repairs, and can be drilled and tapped. I would use the steel formula in the bowl.



Filling in the bowl would be for NA engines where low end torque needs to improve. Or in mildly ported street engines. All out racer put out power from above 7,000 RPM to 10,000 RPM and have no low end torque no matter what you do.



Use a flow bench to dial in the position and depth of epoxy. Use childrens modeling clay for filler on the flow bench. Then make paste board profiles of that surface, so you can replicate it in epoxy.



I have plans for a nearly no budget flow bench if you would like them. No charge of course.



http://home.earthlink.net/~mmc1919/venturi.html



Here is the hyperlink to the Bernoulli dynamic page. Note the affect on shapes on the graph at the bottom of the page. Move the yellow blocks up and down, and side to side to produce test shapes.



Look at these shapes in air horns. One of the least likely examples flows the best.





Lynn E. Hanover