cach22

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 thanks in advance



cheers



Lance

Lynn E. Hanover

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

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

Drago86

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.

Lynn E. Hanover

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

Judge Ito

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.

Lynn E. Hanover

IO....110 degrees BTDC



IC.....85 degrees ABDC



EO.....80 degrees BBDC



EC.....75 degrees ATDC







Lynn E. Hanover

setzep

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

Thanks

Cam

Lynn E. Hanover

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.

cach22

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 which would probably work out a lot cheaper lol. Thats some very interesting info regarding the oil pump etc



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 Now i just got to get myself a dial indicator and make up a degree wheel



cheers



Lance