Hey Guys,



I was looking at the rotary engine illustrated site and they have a nice pic of the various 13b port timing specs, ( click here for the link to the pic etc ) This got me wondering how i could figure out the port timing of some old extend port housings i have sitting in the shed. Looking at the pic i thought if i could work out where BDC is on the iron then i could get a protractor and work out the degrees of the timing, though if i was slightly out with where i thought BDC was then it would throw out all the measurements, so i am now asking the experts out there how they figure out the opening and closing degrees using a degree wheel or whatever they use https://www.nopistons.com/forums/pub...IR#>/smile.png thanks in advance



cheers



Lance

This is the rig I made up for that job. I use a cut off case bolt as the pivot.

The aluminum angle stock could be anything stiff. Could be bent up sheet stock. Could be angle iron, whatever. Align the edge of the angle stock with the water "O" ring marks on the front cast iron. Make up a trsnsfer punch for one of the case bolt holes.



A transfer punch is just a piece of the threaded end of a case bolt, or anything with that thread on it. Turn one end to a shallow point. On each side of the point, grind a pair of flats, so you can screw the thing in and out of the case bolt hole with a little Cresent wrench. Screw it into the hole you want to be the pivot hole, (should be roughly in line with the rotor bearing throw at TDC) leaving just a bit of the point sticking up above the local surface. Align the angle stock with the "O" ring marks, and gently tap the angle piece right over the transfer punch. It will mark the angle piece in the dead center location for that case bolt hole. Drill out the angle piece through the mark to fit the piece of case bolt. Remove the transfer punch. Some day you will find that thing in a drawer and wonder what the hell it is???



I added a spring to hold the angle piece tight against the crank throw but you could leave that off. Now you need a dial indicater with a magnetic base.

Mount it as in the picture.



Cut through an old flywheel nut and drill and tap it for a socket head cap screw.

This so you can thread it onto the crank and when in the position you want, tighten the screw so that the degree wheel cannot move.



I used two 10-32 screws to attach a large degree wheel to the nut, being sure to center it perfectly. If you work off of an engine stand you can attach the pointer to the stand, or to the frot iron using a manifold stud. It makes no difference where the pointer is attached to the front iron. Just be sure it is at the level of the degree wheel, and is adjustable. A bigger hole than is required for the stud and then washers on each side will do just fine.



Assemble the crank and rotor and stationary gear. Install the shortend case bolt pivot. Install tha angle piece over the case bolt. Install the dial indicater as shown.

Install the degree wheel but leave the jam screw loose.



Watch the dial indicater and move the crank back and forth over TDC. Turn the outer ring of the indicater so the zero on the indicater is TDC. Being carefull not to move the crank, turn the degree wheel so that the TDC mark is adjacent to the pointer. Tighten the pointer down. Check it all again. Tighten the screw in the flywheel nut down so that it cannot turn on the crank. Check it all again. Tighten everything again.



Now you have a TDC location that can only be reproduced by doing all of the above over again some other time. You could now install the front cover and front pulley to be sure that those TDC marks and the other marks on that particular pulley are where they should be. Some pulleys do not have all of the marks you need. Plus the pulley diameter is so small that it cannot be used for much of anything but ignition timing. You can resolve TDC inside of one degree with some practice.



Now if you can get your mind around the two TDC positions and two BDC positions in the rotary, you can ink up ports you have read about, or would like to try. Or, look at tables of opening and closing data from other engines, and draw those ports on your iron or rotor housings.



The picture is the rig as above.



Lynn E. Hanover

In this picture the rotor is at BDC intake stroke. Notice that the intake port is still open. In this case it loses at about 80 degrees after BDC.



The 90 on the degree wheel indicates BDC. You have to count off the additional degrees from 90 to get the number of degrees to the closing point.



alternatively, if you are going to spend the day working on closing points, you could identify BDC as in the picture (it is at 90 on the wheel) and being careful not to turn the crank, loosen the jam screw on the flywheel nut, and turn the degree wheel back to zero at the pointer. That way all readings to the closing point would be starting at zero and would read right off of the wheel with no addition.



Probably more than you wanted to hear.



Lynn E. Hanover

http://www.ch-ignitions.com/timing.html



This is what i used, blow it up so it just fits on a sheet of paper, keeping it in the same aspect ratio of course. This give you very good resolution. If you use the front of the crank and the front pully bolt, the hole is almost exactly the right size as printed, and you can use the keyway to index the wheel to TDC of the shaft. I made my pointer out of two pieces of coat hangers, each wraped around an exhaust stud, then one tightly wraped around the other longer one to provide stability and ajustability, it worked great. Aligning the pointer is a bitch if you dont have the tools to do it Lynns way. I ended up guessing, then checking it against the stock ports many times to get it right. this method is probably not 100% but it will get you within a degree or two.

The degree wheel is a "Mr. Gasket" 11 inch diameter, part number 6120. The larger the diameter the better.



Most major cam manufacturers have them. Or you can make on yourself. Use a large drafting protractor to lay out the degree lines.



If anyone has problems understanding the port timing stuff, I will be happy to try to explain it all. If I don't know an answer, I will make one up for you.





We need 18 GPM at 100 PSI so two filters are used. These are the best. K&N 450 pound burst strength spin on cans.



We had a strange failure in the last race. The distributor rotor broke a flat spring inside that keeps it tight on the shaft. On a 2/3 shift, the engine shut off and the trans jumped out of 3rd. I was thinking rotor bearing. We played the video over and over. There was no overrev at all. It just shut down. I took off the distributor and it sounded like it was full of pea gravel. The rotor was shredded. It got a little out of line when the spring broke and got tangled up with the fixed contactors.



the engine is fine.



This is your rotor. This is your rotor on crack. I should take a picture.



Lynn E. Hanover

Lance, the first thing you need to figure out is that the engine has a top dead center and bottom dead center for the intake cycle. It also has a top dead center and BDC for the compression side.

Understanding top and bottom for a rotary is very unique. In a piston engine TDC and BDC for a piston is very easy to visualize(basically if the piston is up and close to the top of the short block,that's TDC, and if the piston is all the way down like a water well, thats BDC) on a rotary is on it's side of the intake cycle for TDC and rotor tip to tip north on the rotor housing for BDC. The picture Lynn has shows a perfect example of BDC for the intake cycle.

Once you understand that, then you could move on to figuring at what intake degree the modified port starts to open in relation to TDC and closing the port in relation to BDC.. a good street port opens anywhere in the 20 to 25 degrees ATDC and closes anywhere in 60 to 70 degrees ABDC..



Lynn on that picture of your bridgeport, at what degree your intake port opens???thats a decent size intake port.

IO....110 degrees BTDC



IC.....85 degrees ABDC



EO.....80 degrees BBDC



EC.....75 degrees ATDC







Lynn E. Hanover

Do you know the cubic inch displacement for a 13b turbo oil pump? If not, how did you come up with 18gpm?

Thanks

Cam

I have been exposed to some data on that I can share with you. I was feeding ideas to a Swiss outfit that is trying to Certify a 86 single turbo sized rotary with some interchangable parts to the (real Mazda) engine.



They were having runaway oil temps. The coolers had been sized to calculated loads and as is often the case, the ideal is not achievable. So the coolers were too small, or the flow rate was too low, or there was air entrained, or what ever.



The engineers calculated the (40 MM 86 style) pump flow at 6,000 RPM to be 20 GPM. They could never get that much. The story goes on for some time with many more tests, and finally a test stand is assembled from new 86 iron and pump and pickup tube. A laboratory flow meter is installed and even a system to heat the oil to operating temperature.



I now cut to the chase.



They were using a multigrade aircraft oil. 15W50. First problem solved. It foams quickly because it is full of plastic. polymers that make the crummy 15 weight oil act like 50 weight oil when it is hot. A straight 40 weight synthetic is now in the engine. Less foaming right away.



The stock pump is just not very good, as a pump. The two compartments are shaded in timing to limit noise. The front half of the pump has to pull its oil through the rear half. Then pressurize it and force it back through the rear half.



A close look at the partition between the front and back shows 4 sharp corners for the oil to cross. Two on the suction side and two on the pressure side. This is bad mojo. Mother nature does not like sharp corners. All of this adds up to foaming the oil. Oil with air in it cools poorly since air is an insulator. Five percent air in the oil means 5 percent less oil for lubricating.



But the biggest improvement in the above system was the removal of the bug screen on the pickup tube.



Cheap, easy.



The 95 twin turbo engine uses a 50 MM pump with separate oil supplies for the front and rear halfs of the pump. Much better, but they still have that bug screen in place.



Also the sharp ended pickup tube is a flow disaster. That you can change.



At the end of the project, the stock pump body is gone. A custom body with two pickups, but no bug screens. Over 26 GPM from the stock pump internals. They are dumping excess oil to stay below 90 PSI.



They will have a plate between the engine and the sump to help remove air from the oil, and it will have a large screen area in the center to keep debris out of the pump.

Lynn: Cool i will check out a couple of the performance shops in my area if i can't get one i will make one up https://www.nopistons.com/forums/pub...IR#>/smile.png which would probably work out a lot cheaper lol. Thats some very interesting info regarding the oil pump etc https://www.nopistons.com/forums/pub...DIR#>/wink.png



Ito: thanks for the reply, yeah i understand what you are saying, i had a really good look at the pic from the rotary illustrated site and rigged up half an engine and compared the rotor location to the pic etc and it all seemed to make sence https://www.nopistons.com/forums/pub...IR#>/smile.png Now i just got to get myself a dial indicator and make up a degree wheel https://www.nopistons.com/forums/pub...IR#>/smile.png



cheers



Lance

Looking at the two gears I have here (pump gear 36 teeth and e-shaft gear 24theeth) the pump spins at 2/3's the speed the e-shaft spins. When you say 6000rpm do you mean engine speed or pump speed?



I'm trying to figure out why so much oil flow is needed? Do the engine bearings leak that much by and need 20gpm to sustain the pressure need? It would be intresting to see how much oil the rear relief lets by at 20gpm. At 20gpm the velocity is way too high through the pressure lines (32.6feet/second) and the oil pump pickup (14.5feet/second!). There has to be a lot of pressure drop. In the hydraulic field we don't like to see more than 16'/sec in the pressure lines and 4'/sec in the suction. Not to mention the reservoir (oil pan) is WAY too small for that flow.

BUT I suppose the pump has to be sized pretty large to sustain pressure at engine idle speed. It would be neat to see a automotive company make a variable displacement oil pump https://www.nopistons.com/forums/pub...IR#>/smile.png

I do like the oil pump pickup tube modification. The addition of radius edges are great and the o-ring seal is all the better.

The 6,000 RPM is crankshaft speed.



The Swiss operation had calculated the pump output from its displacement. They had needed 16 GPM to get the rated rejection from the coolers they had.



The engine builders use different schemes to increase bearing clearance. Some hone out the bore of the rotor and bolt the bearing in place with little crush fit. Some just bore out the standard bearing down to the copper liner and run on that.

Some just run the factory race bearing that has only .0005" of additional clearance over stock clearance.



The bearing area in the rotors is very large and considerable clearance is run. In addition, a rather large pair of leaks in the nozzles that spray cooling oil into the rotors must be supplied and if racing, about .200MM each. The normal oil pressure would be 100 PSI or as close to that as you can get.



The quick way to improve the whole picture is working on the suction side. The Swiss found the best improvement from removing the bug screen from the bottom of the pickup. They also found good improvement from removing sharp corners from the pressureized lines and galleries.



My pressure lines are dash 12 and my suction line to the scavenge tank is a piece of 1 1/4" steel tubing. What would the speed be through a -12 line for 20 GPM and 16 GPM?



I have adjusted the pressure control on the pump to maintain 100 PSI. at 2,000 idle, oil pressure is 82 PSI.

I don't know that, but it should be puting out 16 GPM at 6,000 crankshaft RPM.



It will not do this in the stock installation, but it should have, based on volume testing at low RPM.



We use a Peterson 3 stage dry sump pump.





Lynn E. Hanover

Hey Mr. Hanover, I've been thinking about that TDC finder setup you have and I think I found a way to refine it further, to make it even more precise and repeatable. The issue I'm addressing is that as you near TDC the amount of motion seen at the lever arm gets smaller and smaller, so the difference between TDC and a couple degree before or after is very small.



Assuming that the oil pan rail is 90 degrees to the rotor housing shape, one could chuck the plate upright onto a known level surface, attach a straight piece of angle iron to the surface of the housing, exactly vertical, in such a way that the e-shaft cannot rotate a full 360 degrees. Turn it until it stops, note the degree wheel numbers, turn it the other way until it stops, note the numbers, then split the difference, re-align the degree wheel to suit, and re-check it. No judgment calls with the dial indicator required, since the side to side motion of the eccentric is much greater per degree of rotation when it's not close to TDC (or BDC for that matter).



Maybe I'm just turd-polishing here. In any event, a jig could easily be produced out of flat stock and angle iron that locates off of the dowel pins, so it takes almost zero set-up time, just set the jig on the housing, pop the pins in, knock the e-shaft back and forth, recenter the degree wheel, recheck it, and done.



I make it sound so easy, I think I'll go and do it tomorrow.

The formula for velocity in a line is .3208 x V ÷ A = Velocity in feet per second. V= volume in GPM and A= area in square inches.



General rules for oil line velocity:



Suction, 2-4 feet per second (depending on how thick the oil is). If this can't be achieved then try to keep pump inlet vacuum lower than 4"Hg (the radius on the oil pump pickup works great like the swiss proved in the above example)



Pressure, this is a little more open. In a low pressure system like cars oiling system I'd like to keep it lower than 10-15ft/sec because of pressure drop. In high pressure (3000-5000psi), like some hydraulic systems up to 30ft/sec can be used if pressure drop isn't a major concern but space is.



Return, 10-15ft/sec (not really used in a cars oiling system, it's just dumped back via engine bearings).



Soo... if you say by the Swiss calculations the pump should put out 16gpm@6000rpm (engine speed) then that would mean the oil pump would have a CID (cubic inch displacement) of .924

My two outstanding traits are that I am cheap, and I am lazy. Your idea will work, I think, but it sounds like more than I want to be involved in.



It is similar the piston stop method of finding TDC in a piston engine.



The rig I built has the fulcrum at one end, the crank throw in the center and the dial indicater at the other end.



The dial indicater moves twice as far as the crank throw. And you can use a version of the positive stop method with a dial indicator.



You set the indicator by rocking back and forth over the position that you suspect to be TDC and set the indicator at zero. Now set the degree wheel to the zero position and lock it down.



Move the crank in one direction until you get substantial movement on the indicator. For example .030". Mark the degree wheel next to the pointer with a sharpie. Then move back across TDC to the .030" position again and mark the degree wheel with a sharpie.



True TDC is between the two marks on the degree wheel. If the zero on the degree wheel is still the point between those two marks, your TDC indication is dead on, and you lock down the degree wheel on the crank and carry on.



If the zero on the degree wheel is not the point between the two marks, put that point in front of the pointer, and without moving the crank, loosen the degree wheel, and move the wheel only until the zero on the wheel is in front of the pointer.



Lock down the degree wheel onto the crank and repeat the procedure until the point half way between the marks is the zero on the degree wheel. Time and time again I find no difference between the raw selection of TDC based only on the first dial indicator setting, and a check of the TDC position based on the above.



Even the error based on the obvious parallax generated by this setup is inside of one degree. (moving the crank lobe toward the fulcrum generates slightly more motion than moving it away from the fulcrum).



I can resolve inside of one degree with just the indicator. I have seen no port timing data reported in less than full degree callouts. So, accuracy inside of one degree is close enough.



This sounds dreadfully complex, until you walk through it one time. Totally repeatable. Cheap and easy.



Lynn E. Hanover

I'm sorry.



I skipped right over part of your question. The displacement I did not know.



THe 18 GPM at 100 PSI, actual from a flow meter on the dyno for 9,600 RPM.



The Calculated 16 GPM at 85 PSI from the engineers for 6,000 RPM are the figures I have seen on paper.



The 18 GPM is available from an aftermarket external pump.



The bearings are very large for the amount of stress involved and that tends to cover up the often poor performance of the stock pump. When trying to fathom what path the development my have taken, especially when the Japanese have been at it, one can only surmise that they have different divisions working on each

piece of the pie. No one is ever told that their idea just flat sucks, lest they "loose face" so they work for years on a piece that could have been completed here in an hour. Honda sends people here to work, so American supervisors "round eyes" can tell them when they are full of ****, and make them do the proper research and modeling before submitting proposals. Worse, the ones who have family connections cannot be told anything in Japan, and often arrive with one hell of a chip on their shoulders. They leave here as much better engineers, and are able to think on their own, rather than as a part of a big committee.



But once again I digress.



So if you take off the screen from the stock (86 style 13B pump at 40MM diameter)

the pump starts working pretty well. If you add a thick washer as in the drawing, so as to eliminate the vena contracta, it works even better. If you change the body, so that both sections of the pump have their own oil supply, it puts out 26 GPM at 6,000 RPM at 85 PSI.



Damn fine pump, and it was in the engine all along.



So then comes the 93-95 pump, and it is bigger (50MM) and has suction oil supplied to both ends of the pump, and it works great. But admit that the bug screen was a problem? Never. Admit that the shaded rotors were a problem? Never. Admit that pulling suction oil through the rear section and then forcing pressurized oil back through the same section was a problem? Never.



Why spend millions to change the pump if the old one could put out 26 GPM with a few common sense changes?



So none of the engineers that worked on it loose face.



This is a new pump, with all new design people.



If we loose 7,000 engines to foamed oil, it was us who were racing around operating outside the limits of the design, not the fault of the engineers in Japan.



I have yet to see an RX-8 pump. But the design probably sucks.



There you are. More than you wanted to know about oil pumps.





Lynn E. Hanover



The picture is the dash 12 pressure line into the engine. Note the oil pressure gage line in dash 4 and the oil temp bulb. The bellhousing is Chevy S-10 pickup truck.

Lyn, would you recoomend removing the bug screen for a daily driver? I dont really see what good it is unless you drop a tiny nut into your oil pan or something..

Hey Lynn, I like the adapter you made for your rear plate. It looks a lot like the one I made https://www.nopistons.com/forums/pub...IR#>/smile.png

I thank you for all the info you've shared and I'll try to store it in my head for future. BUT, I have one question, the oil pump is a positive displacement pump. How can it put out more flow at a set rpm with one inlet and another amount of flow with a different inlet? I'm guessing tolerances between the gerotor ring and housing?

I think it has to do with the inefficiencies of trying to supply both pump rotors off of one inlet vs. each rotor off of its own inlet. Im sure lynn will correct me if Im wrong though.

Re-read the notes about aeration for one clue.



As for the rest, pump cavitation would be my best educated guess. At some point, with ANY kind of pump, it takes less energy to create a vacuum on the backside of the rotors/blades/whathaveyou than it does to draw the fluid being pumped. Enhance the passages to require less energy to get the fluid into the pump, and you will reduce cavitation at a given pump speed, netting more flow.



And of course, if the fluid is aerated in the first place, the cavitation process is greatly facilitated, since air is compressible and expandible, and it's far easier to expand a gas than it is to create a vacuum. Vacuum being used here in its truest sense, a space with no or next to no matter in it.

Not enough data, and it is a kind of personal thing. If you have the experience and the facilities to snatch an engine out every now and then just to look inside, I think you should take it off and mod the end of the pickup. Because, the above would indicate that you use the engine well above the 6,000 RPM where this problem starts to restrict flow and add foam to the oil.



If you don't spend much time above 6,000 RPM, I wouldn't do it. Just no point to it.

In the airplane engine they will be very close to a 100% duty cycle. You jump in and go to WOT, and sit on it for three hours. So wide open right in the RPM range where this problem lives.



On the street you pass through this for just a second or two with each gear change. So it just is not going to hurt you unless another set of factors is in play.

Using a straight weight oil will get rid of most of it. Just leave out the plastic. If the book says 5W40 or 10W30, the small number is the actual weight of the oil (a scale of flow resistance) and the big number is the weight it acts like when it is hot (operating temperature). So you have a very light oil for good start up lubrication and cold starts where that is a problem, and a 30 or 40 weight at temp. But you get there by adding plastic strings that link up when heated(polymers) that by themselves don't lubricate worth a damn. Also, if the metering pump is still in use you won't be feeding the apex seals that gummy plastic crap. Good old straight weight dino oil burns better than polymers.





This my opinion. Your results may vary. This information came to me after a nasty in line skating head strike.





Lynn E. Hanover



The picture is the inlet end of my Weber. Vena contracta? I don't think so!

Nobody bites on the "vena contracta" or a 12A bolted to a Chevy S-10 bellhousing,



but the group answers almost all of the pump questions on their own. You gotta like that.



A big centrifugal fire pump on an aircraft carrier can put out 5,000 GPM at 100 PSI.



The suction piping may be in the 24 inch area. This pump is kept full of sea water 100% of its life. It must be primed with water or it won't work when you need it.



There are 4 smaller pumps in front of this pump to provide the required "feed" so that the suction side of the big pump never drops below 50 PSI. These pumps are called booster pumps. The big pump will not start until there is 50 PSI in the inlet.

If it did start up Several 400 HP electric motors 440 volts 400 cycle three phase AC, The big pump would cavitated (instantly boil the inlet water) and damage itself.



As has been offered, the suction side of any pump can be pulled down well below sea level pressure. One bar (barometric) or 14.7 PSI at sea level. So if our pump spins up and pulls a perfect vacuum in the inlet, there will never be more than 14.7 pounds available to push oil into the pump. So, since Murphy lives, there will never be a suction side design that will deliver the full 14.7 pounds to the pump interior. So a predicted pump output must include the losses of available fluid in the suction side caused by design faults. The pumps are rated in their ability to pull close to a perfect vacuum as suction lift. You can see the pump struggling to lift a column of oil some 8 feet, or in our case 7 inches. In any case the farther away from perfect we get on the suction side, the poorer the pump performance as output speed increases.



A poorly designed pump and suction side piping may work very well at low RPM, and be a complete disaster at a higher RPM. Like the Mazda. In the Mazda case that point is high enough that in simple street use there is no problem.



The many ways to improve the suction side:



Add a pair of booster pumps. Very good outcome but too complex.



Remove bug screen. Cheap, works well. Must keep crap out of sump.



Mod pickup tube to look like a trumpet bell. Very big improvement. Easy for some folks. A good change.



Use a small ball bit in a die grinder, to streamline the junctions of drilled passages and cast in place kidney shaped ports below the stock pump land area. Very big improvement. Should practice on junk iron before ruining your good engine.



Bolt on a three stage dry sump pump, and forget most of your oiling problems.

Expensive but the most effective fix.



Lynn E. Hanover

Hey Lynn,



ok im going to bite https://www.nopistons.com/forums/pub...IR#>/smile.png please explain to us about the 'vena contracta' and the chev bellhousing https://www.nopistons.com/forums/pub...IR#>/smile.png some great knowlegde in this thread https://www.nopistons.com/forums/pub...IR#>/smile.png



cheers



Lance

Vena Contracta in our case is the apparent restriction caused by a dynamic in hydraulic flow caused by container shape or inlet or outlet shape in a system.



When you see a air horn on a carburetter instead of just the flat top of the carb, it seems natural to think that the carb with the air horn will work better, but why?



We live in a pressurized bubble. One bar, or 14.7 PSI at sea level. We can cause air or fluids to move to locations where we want them by lowering that local pressure in a device like a pump, a rotor housing or a cylinder. By enlarging a sealed chamber from a near zero volume to some larger volume, From TDC to BDC, in a rotary or a piston engine. One side of the piston or rotor has added a small amount of pressure to our world. So a slight pressure increase is apparent in the crank case. The pressure inside the sealed volume will go way below the local pressure (14.7 at sea level). If you then open a port that leads from the outside world to the inside of the low pressure in the test volume, the local pressure will flow into the volume and equalize the pressure.



Use your mouth to suck some air out of a pop bottle, then while holding that low pressure in the test volume (the inside of the bottle) stick your tongue over the hole to hold the vacuum in the bottle. Now quickly think about what is going on. Don't take too long or your tongue will hurt for a week. You are on the outside of the bottle in our world and the pressure in our world is trying to equalize the pressure inside the bottle and your tongue is in the way, so the 14.7 PSI in your tongue is being forced into the bottle. Now get you tongue out of there, your mother is going to see you doing that stupid stuff.



You cannot suck oil up a tube. You cannot suck a Slurpie up a straw. You cannot suck the air out of a pop bottle.



Don't feel bad. Nobody can do it. It just seems like we can. You can lower the pressure inside the straw and inside your mouth by spreading your jaw and pulling your tongue to the rear of your mouth. Increasing the volume in your mouth, and thus lowering the pressure in your mouth to a point lower than that in our world. So our 14.7 pounds becomes slightly higher than the pressure in your mouth and forces the oil, or better yet the slurpie up the straw. Or the air from the pop bottle flows into your mouth to equalize the pressure.



So, if our oil pump is a system of mechanical low pressure generators on one side

(the suction side) I know, it shouldn't be called that. It should be called the low pressure generating side.



At any rate the fluid or gas is forced by local air pressure up the pickup tube because of the differential pressure. The tube is submerged in the oil and the oil is forced to the low pressure at the end of the tube in a uniform manor and at a uniform speed inverse to the distance from the tube end.



The fluid moving into the tube from a location directly in line with the tube need not change direction in order to enter the tube. But there will be a large percentage of the liquid that is moving from areas that will require a 180 degree turn or less to enter the tube. The fluid is moving at high velocity, and has mass, so there at the very edge of the pickup tube, the oil making the 180 degree turn will tend to interfere with oil entering from any angle less than 180 degrees. The same for oil from 170 degrees, 160 degrees and so on. It will be as though the end of the tube has crontracted because this reduces the flow to what would be typical of a smaller tube. "Vena contracta" (the vein has contracted)



If there is no room for a long horn shape, you will see a horn that has the outer rim turned clear back to 180 degrees from the centerline of the tube. The larger the horn shape the lower the flow velocity of the fluid before it gets the the tube entrance and the less it can interfere with all of the other fluid entering the tube.



On the flow bench, the difference can be over three times better flow through the tube by adding the air horn, or trumpet bell shape to the end of the tube.



The more dense the fluid the better the effect. So in hot oil it works like magic.





When we say that the pump is a "positive displacement" design, never believe that. There is just no such thing. On the low pressure side, if there is not enough flow to completely fill the working chambers of the pump, what will be the effect on pump output? Say that the pumps calculated displacement is one cubic inch. But we have time to fill the working chamber only half full on each revolution. Remember we have only 14.7 pounds to work with in the attempt to fill that exposed volume, and only a very small part of one second, several thousandths of a second to do it.



The "Positive displacement pump" has become a variable displacement pump has it not?



The Chevy bell housing was used because the only transmission we could afford that had a good choice of ratios was the Richmond Gear road racing 5 speed. And it bolts up to any chevy bell housing.



To adapt the Mazda bell housing you just about have to have access to a vertical mill. The Mazda has the bearing retainer cast in place. That must be removed and a pilot hole that fits the Chevy bearing retainer must be installed. I don't have a mill, so I made a 1/4" steel plate adapter to fit between the S-10 bell housing and the rotary.



Lynn E. Hanover

[quote name='Lynn E. Hanover' date='Jun 26 2004, 02:07 PM']IO....110 degrees BTDC



IC.....85 degrees ABDC



EO.....80 degrees BBDC



EC.....75 degrees ATDC

Lynn E. Hanover


[/quote]





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Lynn, what runner length are you using for your exhaust, and have you done a lot of testing? I've got almost exactly the same exhaust duration as you, and maybe the same RPM target. My exhaust port timing is about 10 degrees earlier though.



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[quote name='TYSON' date='May 15 2005, 03:58 PM']https://www.nopistons.com/forums/pub...IR#>/smile.png

Lynn, what runner length are you using for your exhaust, and have you done a lot of testing? I've got almost exactly the same exhaust duration as you, and maybe the same RPM target. My exhaust port timing is about 10 degrees earlier though.



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I have 1 7/8" ID tubes 22" to the collector. A 6" long collector to a megaphone 24" long with a 2 1/2" start diameter and 4" end diameter. The most important feature of a rotary header, is that both tubes be exactly the same length. If you get nothing else right, get that right.



You cannot make a big HP change with headers alone, but you can kill off a ton of HP with a bad design. Find a flex hose that will be a slip fit inside of your header tubes. As you build the system keep inserting the hose and marking the depth with tape. Both tubes should get to the collector with the same length of hose showing.



Lynn E. Hanover

I already drew them in AutoCAD https://www.nopistons.com/forums/pub...IR#>/smile.png At 20" they're less than a millimeter different in length. From looking around it looks like about 24" is what I was expecting. thanks!

Actualy the RX-8 pump took the design a little further. There's now an extra cavity/notch in the pump to allow the rear section of the pump to feed the pressure section of the front housing. The pump rotors are the same dimensions as the FD's one though.

mr hanover im not very sure exactly wat u guys are talking about with the oil pump and pickup tubes can you show where exactly to make these modifications on the pump and tube.

The only mods to a stock pump that I would do/ have done, is to shorten the housing so as to get the end clearance of the internals down to about .002". Just run the open end or the housing on some wet (with Kerosene)

on a dead flat surface. Like a sink cut out or a pane of glass. Wet the back of silicone carbide 400 grit paper

so it sticks to the glass. Run the pump body in a figure 8 motion and assemble the parts and measure end clearance with a straight edge and feeler gage.



The separator plate between the pumping elements have razor sharp corners. Gently break the sharp corners with a deburring tool, and smooth with 400 silicone carbide. Just a bit here or things start going backwards.



On the pickup tube, remove the bug screen and cover. Install (braze or weld) a large diameter washer right at the end of the tube as in the drawing. Grind a large radius into the entrance of the tube. Build yourself a separator plate or baffle with a 3"X5" hole dead center in the plate. Drill out for the oil pickup and mounting bolts. Drill the mounting holes through the oil pan. Install the plate with a gasket above and below, and bolt the oil pan on the whole thing. Shorten the dipstick until it just touches the plate, Run the oil level to just above the plate.



Now you can race or autocross without loosing oil pressure, or foaming the crap out of the oil. Use a straight weight racing oil, and premix for racing.



Do not drop crap into the pan. With no bug screen it will kill the pump.



Lynn E. Hanover

thanks hanover next motor i do will try to see the difference appreciate the knowledge. i left a thread on the sixport housings in this section if you can give some insight on anything you have done or heard about doing this.

Drago, think you can take a pic of the instrument you used to get the accurate timing mark using your degree wheel? Also would this degree wheel work just as good? http://www.jegs.com/webapp/wcs/stores/serv...amp;showValue=1



Jay7..

so just to confirm i am thinking right here,the intake tdc is at exact 90deg eshaft angle to the left(looking at front of engine with intake on left),also another way of saying it is the clearance volume face of the rotor is at 90deg to the ground/sump surface whatever u want to call it at intake tdc.(straight up and down).



basically ,all the major points eg intake tdc is e/shaft at exactly 90deg to the left,and intake bdc is exactly 270deg around,which is e/shaft pointing straight down.



also intake bdc is where the rotor face is exactly the same volume on each side of the "lump" in the middle of the housing.



am i think all of this is correct? i understand the inake /zorst tdc/bdc just confirming the positioning of the rotor/shaft at intake tdc/bdc etc.



http://www.yawpower.com/dectech.html

Well, the Yawpower drawings are dredfull for learning anything. They have enough numbers on them to start a new civilization.



Imagine a box drawn onto the picture of a housing. That box has corner seals as its corners. two corners on a vertical line is a TDC. Two corners on a horizontal line is a BDC.



Easy.



There are two of each. Two TDCs and two BDCs.



A BDC on the bottom is BDC in the exhaust cycle. Largest volume.



A BDC on the top is BDC in the intake cycle. Largest volume.





Likewise, there are two TDCs.



A TDC on the spark plug side is TDC firing. (TDC on the compression stroke). Smallest volume.



A TDC opposite the plugs is TDC in the overlap. (end of exhaust stroke and beginning of the intake stroke). Smallest Volume.



If you need to know where the crank lobe is for anything.



It will be pointing to a small volume and away from a large volume.



The rotary is an Otto cycle 4 stroke engine, that tunes like a 2 cycle dirt bike engine.



Events in the engine like port opening points and closing points are in crankshaft degrees, and called out as being before or after one of the above 4 locations. This keeps the numbers managable, and everyone knows of what you speak. And can replicate on their own engines what you are talking about. Fill in your profile, please.





Lynn E. Hanover



16X rotor on left. 13B on right.

yep,i understand all that,just wanted to know if intake tdc was exactly vertical beetween the corners.which u have now confirmed.thanks



do u have any mroe pics of ur tdc rig as im having trouble seeing how urs wrks via that one pic u have.i hate pics,if i just could be there with ur rig im sure it would be easy to see how it works.im better hands on if u know what i mean.



i do understand how and what the tdc rig is tryin to achieve ,how to use a degree wheel etc.just hard to see what exactly ur fulcrum setup is etc is doin and how it gets the tdc from the dial indicator.

OK.



The aluminum angle pivots on a piece of case bolt. The crank lobe is in the approximate TDC position.



The dial indicator is touching the angle with a bit of preload. So now the crank is sticking through the front stationary gear and main bearing.



Now.



The degree wheel.



Bolted to an old flywheel nut with two 10-32 screws. You need to make the nut hold onto the crank firmly enough that it takes some effort to move it. You don't want it moving relative to the crank unless you want to move it. You can deform the nut a bit in a big vice.



I made a cut through one side of the nut. Milled off a flat land and drilled and tapped the hole. deformed the nut so it would be very stiff when screwed onto the the crank. A 10-32 screw threaded through the hole pushes the slot open more sot the nut turns. Loosening the screw locks the nut on the crank again.



I can draw you a picture of that.



So the big degree wheel will now screw onto the crank.



Now you need a pointer that will align with the edge of the degree wheel. I used a piece of 1" steel strap stock from the hardware store. Majic marker the end black and bend it over so the last 1" is level with the surface of the degree wheel. Scribe a line in the black ink pointing right at the center of the crank.



Bolt the pointer to the front iron with any bolt hole or stud available. It does not matter where.



Now move the crank back and forth and watch the dial indicator. Just try to find TDC in this way by look to find a null in the needle movement. Once you have done the best you can with this method. Turn the shell of the meter to put the zero under the needle.



With no reguard for what number the pointer is pointing at, turn the crank until the indicator has moved .050" in one direction. Make a kark on the degree wheel next to the pointer.



Move the crank back passed TDC until the indicator is again showing .050".



Make a mark on the degree wheel next to the pointer.



True TDC is half way between the two marks. Count off how many degrees there are between the two marks. Divid by 2. That answere when counted off from either of your marks is the correct TDC. Make a mark next to the pointer on the degree wheel. That is true TDC.



Now your wheel is sitting on true TDC. Move the shell of the indicator (don't move the degree wheel)

so that the needle is again pointing at zero. Run the crank back and forth across TDC to that .050" point several times to be sure you have true TDC.



Now with true TDC shoing on the degree wheel and on your indicator. Without moving the crank at all.



Loosen the locking system on the flywheel nut. Gently turn the degree wheel but not the crank until the zero mark on the degree wheel is next to the line on your pointer.



Now lock the degree wheel to the crank again. Recheck TDC using the .050" trick to be sure that the zero on the degree wheel ends up beside the pointer.



So long as the nut and degree wheel do not move relative to the crank you can take this apart and lay on a rotor in the TDC position and start marking up the iron with variuos closing lines. Just ink up the port area with a majic marker and scratch the lines with a brass brad, so as not to hurt the iron.



I am going to do a picture series for doing this, as it is difficult to explain and many want to learn how to do it.



Lynn E. Hanover

good explanation,nice work.thanks

OK, if you got this far fine. If you didn't here is a picture of what you need. For the degree wheel, buy the biggest you can find. If you don't like writing on the new degree wheel, use strips of masking tape.



When you modify the crank nut, drive a screw driver blade into the saw cut, to pry the nut open just a bit. This so you can wind the nut onto the shaft quickly and then sinch it down with the screw. Once you have the TDC mark very close you can tap the steel pointer strap back and forth to make very fine adjustments. The dial indicator and magnetic base are available from Harbor Freight for about $15.00.



If you have a junk rotor available, cut a notch out of one corner, so that about 3/16" of a face is left, then cut away the back of that notch with a 45 degree angle about 2" deep. Now you can look through the back of a corner seal hole and scribe lins to establish the paths of the leading and trailing ends of the side seals. You can scribe a line that shows the actual location and angle of a side seal as it crosses the closing line. Scribe stuff with a brass brad so as to avoid scratching the iron.



Here is the picture.



Lynn E. Hanover

does anyone have any good pp port timming spec im want to pp my motor myself but not sure what port timming would net the best results it will be a street/race enging peak rpm around 9g any ideas would be good

steve