Good Morning All,



Im writing to you from sunny Scotland.



I have just successfully finished rebuilding my 13b and fitted it back into my FD.



The engine chipped a tip back in december so I tore it apart and was lucky to find that it had not caused any major damage other than breaking the tip itself.



The engine had been rebuilt previously by the last owner and therefore most of the parts were all in excellent condition and well within tolerance.



I used new Hurley Race tips, New main E-Shaft bearings as mine were worn and all of the other parts were able to be reused.



Compression is good and sounds nice and even when you turn it over with no plugs in it.



I did manage to get her fired up but it did take some starting, now it will fire up off the key but does take a bit of turning over.



My question is, is this normal for a rebuilt engine until its got some miles on it ? I have heard various people say that they need to run a bit to build comprression up but then Ive also heard folk say thats not true ?



It does run and seems to run sweet now but like I say starting is just a bit harder than I was expecting it to be at the moment. Its only ran for about 30 mins in total so far and has not yet been driven.



please tell me this is normal and that im just being paranoid!



Its my first Rotary rebuild but about my 10th Engine rebuild So I am familiar with engines and everything that was reused was checked for clearance and tolerance according to the Mazda factory workshop manual.



Just thought maybe some of the old hands on here would be able to give me some advice on whether or not something may be wrong !

There could be tons of things wrong, but if it starts with just the key, then you are probably OK. New rebuilds require that great care be taken in fitting new apex seals. Note that the end measurement from max to min will cause a compression leak

as the corner piece is moved in and out. So if this be the case, the corner piece must wear a bit before a great compression seal can develop. So you must assume that there will be some amount of leakage until the pieces wear in a bit.



You can help out by using a low quality oil for breakin. A low film strength lets the pieces get worn down quickly. If it is very hard to start, you might add a low quality oil to the fuel as a premix, to help seal things up. This makes for more time to get it done. About one ounce for each 5 gallons of fuel. This is with the OMP operating.



If you put synthetic oil in it from the first day, it will be months to breakin no matter the distance you drive. Pile on the time at low power. Try to stay off of the turbos. It isn't the RPM, but the load. BMEP loading the seals. Rotaries have 6 end gaps on each side of each rotor, plus a bit of a leak from the corner piece, so 15 places to leak, where a piston engine has just one. Those get worse as the engine wears. Only the apex seal and end piece can improve with time. So rotaries are sensitive to starter RPM, as the leak rates are high. So a crisp starter, and a fully charged battery are a must. Clean terminals and connections and so-on. It should have improved substantially after a month of heavy use.



Lynn E. Hanover

Thanks for the reply Lynn, I used Mineral oil as I never use Synth in my FD anyway even before the rebuild. What do you mean when you Say "BMEP loading the seals" ? Im not familiar with BMEP ?



Thanks again for taking the time to reply to me ! https://www.nopistons.com/forums/pub...IR#>/smile.gif

There is a convention for writing that suggests that Acronyms be spelled out after their first use in a paper. I violated that convention. Sorry.



BMEP is an Acronym for Brake Mean Effective Pressure. The avarage pressure on the piston or rotor over the power stroke. Used to calculate Horse Power. Just a raw number that does not give you a realistic number that a brake dynomometer would give you. Just a working number.



Stay off of the turbos. No full throttle anything. Drive it like a an old man for a month. It will be fine.



Google BMEP and the answer goes on for hours.



Lynn E. Hanover

usually when we see the long cranking after rebuilt thing on the FD its a used rotor housing engine, it takes a while to break in. they are always fine after they get some miles on them

Lynn, John,



Thats me now done 200kms and she starts up great now however I do have to use my fuel pump kill switch initially from cold in teh morning as it wants to flood easily.



Im assuming this is just due to my hard wired high Flow fuel pump providing too much fuel for initial startup and will hopefully not be an issue once I get a proper map in her ?



Im just running the Stock ECU map at the moment with the emanage doing nothing other than recording some data for me. I figured since Im driving her off boost and very gently that she should be safe enough for now. Only downside is that im seeing AFR's of between 9 and 10 pottering about which seems excessively rich to me ! Its drinking fuel like I drink Cider at the weekends !! haha !

possible theres something hooked up wrong, AFR should be in the 14's cruising