Hi Guys.

Im about ready to start up my rebuilt 20B, its got Atkins 3mm seals and a mild street port. Im gonna run it in n/a.

What your thoughts on the breaking in period? As far as I can gather people seem to agree on 30 min idle/checking for leaks oil/water, 500 miles max 2500 rpm, oil change, 1000-1500 miles max 5000 rpm oil change.

Cheers.

 

most of that is accurate but i disagree with a sub 2500RPM maximum to 500 miles. i give a maximum of 4k RPM so that the engine can run more normally without being labored but yet still not raced.

first oil change at 500 then every 3k. total break in miles should be 1k on a decently built engine, if it was built with junk parts then the number gets exponentially larger from there. engines built with all new parts for example are usually broken in by 500 miles.

technically speaking the break in procedure only needs to follow the guide until the engine has reached full compression, after that it is just wasting gas.

 

I usually do the 30 minute thing, then 50 miles or so at <4000 RPM, then 500 miles at minimal throttle, but using the whole RPM range, then start phasing in throttle/boost over the next 200 miles or so.

I do the 30 minutes on the cheapest oil I can find, then change it before driving the car (to normal racing synthetic). Then change again after my 500 miles, and again at ~1500 miles, then normally after that.

Also double premix (1.5oz/gal) during this period, or premix .75-1 oz/gal if you have an operable MOP.

One of the most important things is to NOT run a constant rpm for more than a few minutes at a time during this process. That is also partially the reason for my more open RPM limits. Running at a fixed RPM or within a narrow RPM range can glaze the housings and/or cause small step wear that will then be hard on the seals when you rev higher and they hit that step.

 

Its a low milage c-series, with a with a 13B cosmo re housing in front in great condition. all rotors look great and the two old housings were also in perfect condition, rear one changed under mazda warranty so even younger than the middle one. I do have the mazda compression tester available.
What numbers would you consider fully broken in? My other 20B (spare engine) shows between 0.88-10,0 on all faces, a b-seris seller claimed had only done 20.000 miles, seem a real genuine fellow.

 

It isn't a specific number, it is when it stops changing. If you measure it every 100 miles, it will be something like: 6, 7,7.5, 8, 8.2, 8.5, 8.8, 8.8, 8.8, 8.8. made up numbers but you get the idea.

 

So today we tried to start it but it didn't really go as planned.

We had turned the engine to build oil pressure without the fuel pump connected and turned it with the fuel pump on. It did fire up shortly after some 30-45 sec, then it died. (only ran about 10 sec)

We took the plugs out and they were all fauled up with goo from the rebuild. So we clean them, turned then engine without plugs, fuel pump on to wash out the grease, then without fuel pump, plugs back in, fuel pump on and…nothing. Took the plugs out, did the whole thing again, but this time with the plugs from the other engine, they were used but dry, did have a spark when tested outside the engine, but it still didn't fire up. It must be said that we didn't put oil in the chambers as some suggest but thats the only thing I can think of that we might have missed. Ive started several rebuild 13B's with no problems.

There is one thing though, we had left the oilcap off for some reason, and it looked like there where coming fuel/ oil fumes up from the filler neck like little smoke rings. We rang the builder who has a very good reputation and he was bait puzzled and didn't think that compression could get into the oil system, unless it was because it was a fresh engine and it was flood with petrol. He suggested we got it running to burn of the grease from the build but here the problem…we can't.

Any suggestions will be greatly appreciated!

 

Also the plugs were 10's trailing and 9's leading, second time we tried 6 9's…should we try some 7's in leading to help things come along?

 

Spark, Fuel, Compression, Timing...if you have all them you cant go to far wrong.

Depending on how tight your build was you might have a sticky seal, if your injectors are still firing and you have good spark, your engine is being turned over nice and fast...check your compression.

its not unheard of on a tight build

 

Hook it up to a battery charger to make sure you are spinning fast enough. Remove plugs. Disable ignition. Pull fuse for fuel injectors (or disable fuel in ECU if possible). Crank for ~30s. Spray a little bit of starting fluid in each leading plug hole. Reinstall (clean/dry) plugs. Turn ignition back on. If it fires, then turn fuel back on and it should start. If it doesn't fire, you have an ignition or timing problem.

 

Im pretty sure I don't have an ignition/timing problem, its a fairly new harness on a motec 84, build and ran fine not 6 month ago, engine threw an apex seal and got a rebuild. Even with a sticky seal wouldn't it fire on the 2 other rotor? It could still start before the rebuild…(not that I did it more than twice.)

 

Maybe the problem that broke the engine is still there. There is always a reason why engines break. Double check your wiring and ignition.

 

Nope. the problem that broke the engine stopped when the car did no longer travel at 120 mph…
Good thought though. (having smoke an Aston Martin db9 I let go of the throttle, put it in neutral,
let it roll for a while then put in back in fifth only to realize the engine had stalled. Being pulled back to
life from 0-5000 rpm by a stage 3 clutch killed the engine…)

 

work through in a logical sequence, rule one of the four things out at a time that I listed. never assume...as it is the mother of all **** ups.

If you know you have spark, confirm your injectors are firing, double check your timing, compression check

if it had only had one seal stick yes, it should still fire on the other two rotors.

 

Check your injector connectors. Mine kept me from firing mine up at one point also. Front rotor was all good but the center and rear connectors were loose. 20b don't really like to start unless you get fire on all 3 rotors.

 

Good points guys. I will go through the list step by step tomorrow. Thanks

 

also don't attempt to fuel wash a rotary engine, when the injectors are active you always want the engine attempting to run. flooding a freshly built engine can turn into a nightmare of subsequent flooding issues.

pull the plugs and disable your ECU with the EGI fuse or ECU fuse if it has a standalone and crank it until no vapor comes from the engine, let it sit for 15 minutes then crank it for a few minutes, rinse and repeat about 4 times. install known good plugs and then try to fire it with partial throttle applied.

if that doesn't work then you have 1 of the 3 necessities missing:
spark
compression
fuel

if it is just severely flooded then a pull start might be the best option, on a fresh engine you always want to try and keep it alive for at least 15 minutes to build up initial compression.

 

Hello again my fellow rotor heads.

Having gone through the wires, connectors, plugs and what not, I decided to try the "oil down the runners" approach and guess what…It fired right up, smoke all over, idle around 3500 rpm so we shut it down again and fixed some water and oil issues that had quickly arisen. I think the engine is getting
"falsh air" from the UIM not being bolted down with gasket and all. We tried to start it again but it will only fire up with a cap full of oil down each runner. No worries it will get there in time just gotta run a few hundred miles a build compression.

Could there be any other reason the idle is that high? (throttle caple isn't to blame).

It did smoke a bit!!!

 

@trocio same happen to me racing a SL 55 Amg smoked his ***, went fron neutral back to 5th

 

Really? makes me feel a lot better. I thought it was just me being a dumbass not paying attention to my gauges!

 

We do about 30 min of idling while bleeding the coolant system and checking for leaks. After that 500 miles minimal boost (if applicable) and conservative rpms (4000 or so). You don't have to be as easy on these motors as you think. You need some load to help the seals and bearings break in. At 500 miles we change the oil and filter, do another 500 miles with a little more rpm and do another oil and filter change. We use 15w40 Shell Rotella T for breakin. Afterwards any quality 20w50 synthetic. 1000 miles is more than sufficient for a break in. All our motors receive all new seals and bearings. We don't re-use anything.

 

So engine now starts on its own after 10-20 sec at WOT, otherwise it won't start. Idle is crap, rough and uneven and still dies below some 1000 rpm however the engine pulls fine and even out on the road (still N/A). Im getting slightly concerned about the idle, its like its thrown an apex seal. Should I be worried or just drive it some more and wait for compression to increase?

 

Why not do a compression test and see if they are low+ even, or there is one low face?

 

What changed from the last time?

 

i don't think he ever mentioned that it started and ran fine without some aids. i'd just do a compression test now, a major compression issue will never correct itself so may as well find out.

 

It no longer requires oil to start, but I guess you guys are right, ill test it as soon as I can.