About time to get another debate going why do people run in there engines. Can anyone say they\'ve killed there motor through thrashing it from the off.
Any motor of mine gets run up to temp checked for leaks and pressure then driven. Speaking to the RX8 guys they are told by Mazda fluctuate the revs for the first 600miles (don\'t just sit at one rev) no limit to what revs they use, then abuse it. So why is it so many spends months babying there motors after rebuild? Especially when you look through the rebuild posts and it seems its not apex or housing damage that kills most motors but water seal problems.
Kevin:driving
Yes i would also like to know the thoughts on this , as i have just finished my rebuild, and done 60 miles, and have been advised to keep it no higher than 3000rpm for the first 500 miles, then 1000 miles at 4000rpm.
i personally think that most of the reason is for it to be run in for the longest period possible so its longer before it comes back having been detonated.
most tuners map their cars straight after rebuild.
It may need a few hundred more miles if you have new bearings, but to be honest 4000 rpm is a massive amount of revolutions so not a great deal of difference between 4 and 8.
Some people say compression gets better after a few miles, that may be the case but compressions constantly changes throughout the life of the engine regardless. It gets a bit higher then slowly gets lower...
was just thinking the same 2 nite ive just covered 450 with a rebuild and im wondering how long to keep off the loud pedal get my new plugs 2mrw to keep up with the fueling, then seeing greg for a map update then to start building boost . happy days hopefully
The RX8 is N/A, a turbo\'d car must put so much more pressure on an engine that the smoother the surfaces can be worn together the smoother the car must run.
I guess?
now now leighton, take that lead out of your shoes :rollin
be good to the engine and it will be good to you......... (now its had its tantram)
Quotei personally think that most of the reason is for it to be run in for the longest period possible so its longer before it comes back having been detonated.
Bit controversial that one Tony i like it.
hamc my own personal opinion and its only that is its a complete waste of time running in. When you first fire up the seals settle themselves in place or at least you hope they do. No one uses running in oil anymore so that reason is out the window also and to be honest if you lose a seal in the first few thousand miles you will do that anyway. Its not down to lack of bedding in but a underlying problem that was there anyway. Much better to find out in a month rather than waste a load of fuel playing with the thing then find out the first time you open it up you\'d got a problem.
Quotebe good to the engine and it will be good to you
Don\'t forget Dave Mazda also recommend taking it to the red line every time out is that being good to the engine?
Once again Guys before i get flamed personal opinions only just trying to start a bit of a debate on this to see if we can get some hard technical reasons for running in when Mazda don\'t seem to think its required on a RX8.
Regards Kevin
I only put 500 miles on mine before getting mapped. Apparently i have read and understood (and posted on here somewhere) that if you just get going straight away from the off you\'ll get more power but shorted engine life.
Quote from: davehgnow now leighton, take that lead out of your shoes :rollin
be good to the engine and it will be good to you......... (now its had its tantram)
me lead in my shoes ! would i im paranoid at the moment every little abnormal noise makes that big smile go to worry !!! keep telling myself it will be ok hav faith ,the first time i redline with no problem i may smile with out my spine tingling out of my body:Talking1
hi kev, i always take mine to the red line at least nce in a drive 8,300rpm cough cough and its good for the engine, ive doene both on engines ie run them in by gradually building up the revs and leterally starting it up and thrashing it down the road.
PS thats on a T04R single
Hamc,
as you have used ALL new parts, i would give it a few hundred miles of getting up to temp and cooling down before getting it mapped for high rpm, boost, but most engines only use new rotor housings, but as kev says, just opinion. My engine will only be given a couple of hundred, but this to make sure there isnt a problem with a leak or something similar. So far so good......
Best reason for running in, I would have thought to bed in the seals, I know for a fact you get better compression after a gentle bedding in period [run in] of 500+ miles thus more power.
Depends what you intend the engine for, on race / drag applications runnin in is done after the 1st lap / 1/4 mile:Giggle
As stated at the start though John how many engines die of old age. Water seal failure seems to be the main cause of the rotary demise in the UK
I suppose if you\'ve a turbo\'d car, then running it in under 3000/4000 RPM keeps the boost levels low, which must reduce the stress on the seals and housings as they \'bed in\', once this process has been observed - and it may only need a couple of hundred miles - who knows, the engine should be well sorted for all out power.
I tend to let mine hit the buzzer at least once on a journey, conditions permitting, but I did observe the running in ritual, as it\'s part of Rotechniks warranty.
My engine is running nicely now, so hopefully fate will smile and the insurance man will let it live for a while longer.
Water seal failure is by far the most common cause of engine failure from hearing most peoples stories. However, that\'s got nothing to do with your running in period of course! :p
Most stock engines die as stated from water seal failure thats because of poor maintenance, modified? well thats another matter, its all well and good having a nice shiney newley built engine which is just as likely to go pop if you have crap wiring, poor ignition, blocked rad ect.
In a perfect world there is no need for the 1-2k runin period, as Ant has said give the new bits a couple of hundred to bed in and away you go.
there is an argument that if you thrash it straight after you build it you will end up with higher compression.
Well 107 views so far and no reasons for a excessive running in period yet posted i suppose that tells a story.
Kevin
Have a read of:
http://www.mototuneusa.com/break_in_secrets.htm
Basically this is the way all the racers I know breaking engines, it\'s not mean but has purpose! Then they last and make good power for their whole lives.
Now rotaries don\'t have the same hatching on the housing I assume to bed the seals onto the housings, but I don\'t see why it would make much difference if you just make sure verything\'s up to temp and then give it some decent load so that the seals do infact bed in better due to more pressue IYSWIM.
my idea of running in is simply to use the car as if using it for normal day to day driving...no WOT. thats how im running mine in. mild boost and no more than 6k rpm.
Quote from: RemarkLimaHave a read of:
http://www.mototuneusa.com/break_in_secrets.htm
Basically this is the way all the racers I know breaking engines, it\'s not mean but has purpose! Then they last and make good power for their whole lives.
Now rotaries don\'t have the same hatching on the housing I assume to bed the seals onto the housings, but I don\'t see why it would make much difference if you just make sure verything\'s up to temp and then give it some decent load so that the seals do infact bed in better due to more pressue IYSWIM.
that was pretty much what I was reffering to.
According to Mazda a proper bedding in period will lead to a better service life and a more even power output across the rev range but I\'ve never heard htem actually say why.
Mazda official advice for breaking in new engines is gradually increasing power for the first 200 miles, but not approaching redline and then short birsts of redline for the next 100 miles, after that change the oil and you\'re away.
Quote from: kev-yorksWell 107 views so far and no reasons for a excessive running in period yet posted i suppose that tells a story.
Kevin
Although none of the builders have have commented. A warranty no doubt plays into this, and also the fact that there are different driving standards..ie some know more about rotaries than others, so treat their engines accordingly.
I won\'t be going too lightly on the new spec engine during it\'s initial couple 200mile run in, but will be treating it with alot of care and attention.
John
Pretty much would be my feelings on the matter, make sure you load the engine as well, full throttle up some hills etc... Even in a higher gear at low RPM, but get full breath into the engine IMHO.
Bearings and such like are so precise now they really don\'t need any kind of breaking in etc... They\'re gong to be pretty much like that until they fail ;)
The only difference I can see is the rotary nature of the engine... But if, for example, the apex seals have a softer tip which only lasts a few hundred miles for that inital bedding in then surely it\'s exactly the same principle?
It\'d depend somewhat on the tips used - softer metal seals need less running in to form a \'perfect\' seal. Ceramics (as I\'m currently running in) need a little more - they don\'t wear as much as they wear the housing (although less than steel as they\'re much lighter).
Ant - there is a massive difference in the acceleration forces involved at 8k vs 4k. IIRC from my physics A-level (failed :)):
F = ma (Force = mass * acceleration)
as mass is constant force increases with the acceleration which (unless the square rule applies meaning we have an exponential increase) it\'s a linear relationship - doube the revs and the forces involved double.
http://www.mazdamotorsports.com/webapp/wcs/stores/servlet/Tech?storeId=10001&subject=misc
Cool
Only 300 miles, huge difference to the 2000 I have done in the past.
I guess at the end of the day if you built it yourself then do as you please, but for warentee sake you will ave to stick with what your builder asks.
Shocking...
Here we have people that give advise on a regular basis, also build and play with engines, But questioning and Cannot understand the reason for breaking in an engine!
Sorry I thought this was basic engineering principles/knowledge...
Shocked....... :Hammer
What if your intention is to maintain the colling system correctly, and actually get MORE than 50/60 k miles?
Quote from: TRexShocking...
Here we have people that give advise on a regular basis, also build and play with engines, But questioning and Cannot understand the reason for breaking in an engine!
Sorry I thought this was basic engineering principles/knowledge...
Shocked....... :Hammer
Nothing shocking about it at all just some of us are willing to think outside the box and what is perceived technical knowledge all opinions where just that and the thread has achieved its goal in that people are now at least thinking about it. Hence the starting comments "opinions only and the goal was to start a debate" if you want to stick with the old school of thought because it was always done that way then fair enough. Just to throw another spanner in the works once again personal opinion only the reason we have so many water seal problems in the UK could well be down to the way people start there cars and won\'t drive them until they are up to temp, just leaving them ticking over for 10/15 Min\'s or so. Instead of starting and driving straight away (off boost) to get everything up to temp within minutes.
Regards Kevin
Old school of thought?
My friend it\'s basic knowledge that new materials need time to work/bed in! A most important factor among others on the subject.
With regard to engines not seeming to last, agreed thats possibly down as you said to peoples choice of opperating styles, meaning their warm up and cool down procedure and also their driving style!
I can tell you one thing, it\'s been noted that there is a lot and I mean alot of people doing their own rebuilds now... this is worrying, I mean fair play, have a crack... but you won\'t get me ever buying a car that has had a homer done on it...
This again will only add to the unfortunate ever increasing bad rep of the Rotary engine and the Cars overall value! :3Confused
Rgds
One reason for starting the engine then getting it warm before thrshing it is that you have two different metals in the engine,Aluminium and iron,they both expand at different rates if the engine is driven hard from cold,so it is better to warm up your engine gradually.
That having been said,it is also better to drive the car straight away as the engine will get up to temperature quicker,and so will the oil.
I allway\'s keep to around 3000 rpm until the engine is warm because the oil filter has a by pass valve in it that can allow it to not be filtered if the Oil pressure get\'s to high which it will when cold as the viscosity is higher until warm.
Regards
Carl
Quote from: TRexOld school of thought?
My friend it\'s basic knowledge that new materials need time to work/bed in! A most important factor among others on the subject.
Well metal work has changed a lot!
For example, I know it\'s a different kettle of fish but, the new Ford Transit. No run it period at all and first service at 12,000 miles!
Tolerances are so much tighter now, metals get worked and heat treated as part of the build process, nikasil, ceramics and other new alloys mean that you\'re not wearing a "rough" iron block into a rough iron piston ring. Plus synthetic oil are another world apart to the old monograde minerals, just read oilman\'s posts!
I know it\'s not a Ford Transit engine and essentially the design at origional manufacture is 15 years old but there\'s still some differences in these to the old iron block of yore.
All IMHO ;)
P.S. Don\'t get me wrong, I never give an engine any kind of throttle or revs until it\'s all up to temp, that\'s a decent amount of time after the water is up to temp as well!
Once it\'s warm however, the redline is, in theory, within the manufacturers tolerances :D
Quote from: TRexI can tell you one thing, it\'s been noted that there is a lot and I mean alot of people doing their own rebuilds now... this is worrying, I mean fair play, have a crack... but you won\'t get me ever buying a car that has had a homer done on it...
This again will only add to the unfortunate ever increasing bad rep of the Rotary engine and the Cars overall value! :3Confused
Rgds
I don\'t know about you chap, but when I take on the risk of doing a job of any kind on my house or my car, I take time to read about how to do it, I make sure I have the correct tools to do it, and then I take my time doing it. Whether your doing central heating, house electrics or rebuilding an engine, there is nothing wrong with a \'home rebuild\' provided that care has been taken and no corners cut, and the correct materials are used. The only thing you won\'t get is a warranty.
It\'s up to you whether you buy a car with an engine rebuilt by an amateur - but don\'t forget, some of our expert vendors started out as talented/gifted amateurs.
As to the purpose of this thread - it was to invite discussion - which it has done - I think it would be prudent to read the whole thread before posting up on it, and present your argument(s) in a clear form rather than just reactively.
Cheers,
Prof. :cheers
it\'s alright saying metal work has changed a lot and new designs built in the factory using ALL new parts and very carfully matched parts from batches of 100\'000\'s of parts don\'t require as much of a running in regime
BUT .... step back a bit here and look at what we are talking about. Mazda rotary engines
Engines that haven\'t changed vastly in design or material for 30 years and rebuilt engines that hardly ever have 100% new parts and even then it would have been a part selected from a batch of 1 of 1 (OK so some parts are catagorised for assembly tolerances as spares as well but you know what I am getting at ... it\'s not a factory assembly)
some good points here, Carl made a good point in his thread that it gives a good opportunity to ensure all other aspects of the car are working well with less chance of causing damage.
One thing that needs differentiating, letting your engine warm up and cool down properly is completely different to letting it run in for an excessive period. I may not run an engine for more than a few hundred miles but i always let the car warm up and cool down and i run a decent coolant system and ensure my air temps are low and my oil is never too hot. I also change my oil regularly. As Jon mentioned, some people know more about rotaries and how they should be set up and run and what parameters are ideal and safe,
Some people who know a little less and are more likely to damage an engine they spent 2000 miles running in because they dont let it warm up or run it when its too hot and dont maintain it properly.
As for metals bedding in, just think about how fast 4000 rpm is, does a tip really know the difference between 4k rpm and 8 rpm, does a lot change in the engine between the two? the tips are moving at one hell of a speed at what ever running revs they do, as do the bearings, its not like its run at 200 rpm for 50 hours to bed in. If the engine is at running temp and you open it up i dont reckon the tips know any difference, same goes for boost.
Trex, you dont even believe in water injection........ :)
certain loads will go up "roughly" with a square law with relation to RPM so 4000-8000rpm would be 4 times the load.
Throw a spanner into this soup.... Bare in mind that the rotors are rotating at a 3rd of the rpm...;)
Quote from: CarlThat having been said,it is also better to drive the car straight away as the engine will get up to temperature quicker,and so will the oil.
Regards
Carl
The other reason for this is, it brings the gearbox and diff oils up to temperature as well. So you\'re not giving them a hard time with cold oil when the rest of the car is warm.
Fish
PS. Nice to have a good technical type thread. :)
Quote from: 88GT-RThrow a spanner into this soup.... Bare in mind that the rotors are rotating at a 3rd of the rpm...;)
i like it.......
Mike, where is the load in a rotary engine, its not like a boinger where the forces fight against each other..............
i\'m no technician BTW
I\'m not exactly sure but .... thinking alloud there is some eccentric movement so I guess there will be two loads from the rotors on the eccentric shaft at an angle to each other, both combining and causing a bending load on the shaft, then there are the reaction loads at both bearings. It\'s not an easy one to visualize ... I\'m not sure what loads the eccentrics will put on the shaft as well.
It gets more complicated as you start to think about how the rotors load the stationary gear etc. and I get a bit lost with what is happening. It\'ll all be quite simple stuff but it\'s breaking it all down and understanding whats going on thats important.
100% rotary "engines" are easier ;)
Quote from: MikeLMRit\'s alright saying metal work has changed a lot and new designs built in the factory using ALL new parts and very carfully matched parts from batches of 100\'000\'s of parts don\'t require as much of a running in regime
BUT .... step back a bit here and look at what we are talking about. Mazda rotary engines
Engines that haven\'t changed vastly in design or material for 30 years and rebuilt engines that hardly ever have 100% new parts and even then it would have been a part selected from a batch of 1 of 1 (OK so some parts are catagorised for assembly tolerances as spares as well but you know what I am getting at ... it\'s not a factory assembly)
True, however as we all know you can\'t just use a 13B from a FC and drop it into a FD (13B-REW) as they\'re different, I\'ve heard that the bearings in the REW are near full race spec.
And you get a decent choice of bearings when you order them, so should find something suitable. Also if you\'re serious then when replacing rotors go somewhere where you can weight a load of them and get a matching pair.
Really piston engines havn\'t changed in 100 years! It\'s just the materials and processes that have improved, along with oils and such like.
I\'m kind of playing devils advocate here, but also feel that 3000 miles is a massive run in period! Everything should be bedded in within 300 miles, ideally nothing should be touching as a nice film of oil is keeping it all apart ;)
However when it comes to rebuild time, then I\'ll really know what side of the fence I fall into! Plus if the builder said run in for 3000 miles, I\'d do so.
Quote from: MikeLMRI\'m not exactly sure but .... thinking alloud there is some eccentric movement so I guess there will be two loads from the rotors on the eccentric shaft at an angle to each other, both combining and causing a bending load on the shaft, then there are the reaction loads at both bearings. It\'s not an easy one to visualize ... I\'m not sure what loads the eccentrics will put on the shaft as well.
It gets more complicated as you start to think about how the rotors load the stationary gear etc. and I get a bit lost with what is happening. It\'ll all be quite simple stuff but it\'s breaking it all down and understanding whats going on thats important.
100% rotary "engines" are easier ;)
Mike,
I have never changed the bearing in a rotor and never seen it done either, i\'m sure at some point one of the tuners have done it, but you dont often see worn out rotor bearings, so that load doesnt change from the original engine.
I think the higher mileage that the americans do wear the rotor bearings out but a lot less common in this country.
another thing I was thinking is cold-hot-cold cycles these strike me as being the key things for bearings to bed into each other. How many miles does each engine warm up cool down cycle equal and how may cycles results in a properly run in engine? maybe this is where the run in mileages come from in an OEM\'s calculations ?
Well this thread has had the desired effect a few people are thinking now. :)
As Tony alluded to how many rebuilds include new shafts and rotor bearings? new housings, plates possibly and seals then yes. So assuming the rebuild has required housings plates and seals the main friction area\'s we are bedding in are the apex seal to housing, side seals to plates and any shaft bearings that may of been changed. Shaft bearings are essentially the same as crank shaft bearings in a boinger with the same loads so can we assume that all the piston motor manufacturers that no longer require a run in are right? apex seals rely on the centrifugal forces to seal so it follows if you are reving harder during run in then they are sealing better so higher revs should aid bed in? which leave us the side corner seals are these the only reason we are running in?
Once again theres no rights or wrongs on this thread its purely a academic exercise to get the Grey matter working. Its up to each individual or builder to do his own thing.
Yes the rotary engine is old technology but so is a piston motor what is different is the evolution of the modern motor oil even mineral oils bear no comparison to what they where 10yrs ago let alone the advances with cracked mineral, semi and synthetic oils!:Hammer
Kevin
I think I heard that at a given rpm the apex seals start to lose compression so have to assume there are bouncing away from the housings or lose the force necessary to keep them there?
Dont even start on oils, it aways gets messy.
The oil type doesn\'t even come into it Gary even if we all ran mineral it still bears no resemblance to what it was 10yrs ago. It comes out of the ground and is called oil still, but the addative list that is put in is pretty extensive nowadays
I thought the apex / side seals were the smae as piston rings, in as much as, it\'s LOAD that compresses them against the side / rotor housing (or Cylinder wall).
So not revs that are important, but LOAD of all different types, but make sure you get full throttle even if it\'s from 2000 rpm to 4000rpm. This would force the seals out and surely bed in quicker?
Quote from: rotaryart.uk.comI think I heard that at a given rpm the apex seals start to lose compression so have to assume there are bouncing away from the housings or lose the force necessary to keep them there?
The force for teh end seals will only ever increace with RPM - think about a kiddies roundabout - the faster it spins the harder it is to hold on. Side seals may well be different though...
Interesting thread this :)
Having only ever done \'homers\' I can\'t comment on the warranty aspect. However given personal experiances and the amount of work involved on any rebuild, be it the old capstan lathe I used as an apprentice or the 13B rebuild on my first Rx7 I would always want to stick religiously to running in guidlines. IIRC I used a 1000mile running in period, with engine speeds no higher than 4500rpm, but kept the revs pretty varied during that period. The amount of bedding in required will be (previously stated) dependant upon the number of new surfaces. It is my understanding that during this intial period (I think this is what Trex is reffering to) you are allowing the components time to clearance against each other. I know how different these engines feel from 0 miles to 1000 to 5000, to 15000, to 155000 and I because of that I fall firmly into the \'Run it in properly\' school of thought. :wave
Any clearancing should be done on the build though Brett.
Kevin