i didn't read all of this BUT



you do know the knock sensor is on the front rotor housing.......

what Lynn has said here is what i've read so far, and i'm inclined to believe it over the intake manifold thing. i'm not trying to discredit it, because on the Mark II MR2 Turbos manifold runner length is an issue, but i'd tend to believe the difference in temperatures and torque deformation have more to do with it.



i never thought about that ... using bigger injectors for the rear. that's an interesting take.

Bigger, yeah...



If you're running for exemple 440cc on the first and 550cc on the rear, this difference will be way to much I think...



But what I understand on rotor failure with my 20B is: the rotor was full of carbon, apexes didn'tcome out after a night in parts cleaner, non of the side apexes survived it...



The front rotor had this also but not as hard, while the middle was as new!



But because there was alot of carbon on it, it could also be that there was something wrong with the ignition or apex lubrication system...



The was no wear on the apexes, the were like new... Not broken or so thus detanation wasn't the cause eightes..



Rub

No two injectors flow the same amount of fuel at any one pressure. So you have a collection of them flow tested and run the ones that are close together. When you get them back they will be marked (tagged) with their flow rate. So some will be richer (flow more) than others. It is the higher flowing set that could be run to the rear rotor. Not a bigger injector. More like the 339cc actual vice the 441cc actual.



Balancing the injectors is a big deal in spec Miata racing. They are digging for one extra HP.



Carbon build up has been a problem from day one in the rotary. Pure oil burns pretty well when heated. Motor oil has a long list of additives that have nothing to do with good clean burning characteristics. Just the opposite. They contain chemicals that keep them stable at high temps. The long chain polymers that make 10W40 work are among these. So we inject this oil into the combustion chamber and wonder why there is all kinds of crap all over the rotors. A good synthetic is even worse. It can withstand even higher temps before it starts to break down.



Premixing top oil is preferred over injecting crank case oil. Plus, if you premix, you can run a straight weight synthetic in the sump, and a clean burning 2 cycle oil in the chambers. Premixing is a giant pain in the ass, if the car is a daily driver.

For a weekend racer it isn't bad. I use 8 ounces of Redline racing 2 cycle oil in each 5 gallon can of fuel. I use straight 40 wt. Redline racing synthetic in the bearings. That 8 ounces is more than required for the street, but we try to stay above 9,000 RPM, and we have almost no wear to deal with year in and year out.



Richard Sohn makes adapter kits that fit between the stock oil metering pump and the front case that allows for using 2 cycle oil from a container on the fender or fire wall. That way you check the oil level once a week and you can run a full synthetic in the sump, without fouling the rotors with carbon.



Here is a gag that works for me. This is not for street cars that have converters, because it will plug the converter with carbon and sludge.



My first rotary race car had just a very tired junk yard engine with 9MM apex seals. It was so tired that in cold weather I would pour hot coffee and motor oil into the carb to get it to start. One outcome was that on disassembly the engine was clean like brand new inside. At least the rotors were clean. The sump was full of sludge as usual for an engine that had never had an oil change.



Then a friend that builds small block Chevys told me close to the same thing. If he has to R&R an engine for overhaul, he warms it up, and very slowly pours a pop bottle (soda in some areas) full of water through the carb. On tear down there is not one speck of carbon or even staining in the combustion chambers.



Saves a day of cleaning rotors or pistons. Only if you are tearing the engine down that day. Otherwise rust will be a big problem. It may also damage all kinds of things on a stock engine and may hose some of the sensors. But for off the road engines, and piston engines it is amazing to take apart a 100,000 mile V-8 and see a new looking combustion chamber. If you have ever blown a head gasket on a piston engine, remember the cylinder that failed a gasket into the water was clean?



Just something to think about.



Lynn E. Hanover

thanks for the clarification Lynn, i , too, was under the same misunderstanding of what you said about the injectors.



this should get pinned.

Wow, I'm glad you brought this up. Although this is probably off topic, I'm wondering how this premix thing is going to work for my car. I have a 13b Cosmo that I'm currently finishing up the wiring on. It's in my FB.



At any rate, I don't really "get" the premix thing. I've removed the OMP and oil injectors because I know it's not very reliable and because I was advised to do so. So the idea is to run a different oil in the pan (sump I guess) than what you mix in the tank? Is there a method to identify which oil to run?



TIA.



I should add that this car is not a DD, more of a fun weekend, gonna smoke some Z06s, car.

You would be down to personal favorites in the oil world. The highest film strength goes to synthetics hands down. So if you care enough to use the very best, it will be a synthetic. The better 2 cycle oils are vegetable based, and the synthetics have all of the molecules the same size, so they have a higher film strength.



So for the sump, in colder areas, a multigrade synthetic. In warmer areas a straight weight synthetic. For the top oil any brans name 2 cycle oil is fine. And since you burn it in less than one rotation anyway, a synthetic is a bit pricy. We do use the synthetic Redline, but we are trying to stay above 9,000 RPM.



I have yet to have a lubrication related failure, so I don't know what that looks like in a race engine.





Lynn E. Hanover

Hah, you're getting all the attachments!



Thanks for the advice.

Lynn E. Hanover,



I know that the engine oil isn't a good combuster, but my point was actually that only the middel rotor was "clean"



So if the oil would have been the cause, the middle one should also ave been bad..

But maybe not if only the middle il nozzle was failing..? damn, but I'll just remove the omp crap and run premix https://www.nopistons.com/forums/pub...#>/biggrin.png

Me too.