Dom_C

Ok by no means am i out there over revving my new engine. I just want to know what would happen? Where do the numbers come from, like 1500 or so before bringing it above 4 grand then gradual increase up till 2000 or so. What justify's these numbers. I know the seals have to seat and junk but that just seems like a long time for them. Any insite would be great. I have about 1450 miles on my rebuild and it is pulling pretty strong, but i let a friend take it for a while and i have suspisions that he brought her right up to redline at least. Any info would be great. I havn't done a comp check yet sense the rebuild I will be doing that soon though. Thanks
Dom

Dom_C

bump

RotaryEvolution

iTrader: (30)

500 miles is standard for a rebuild with new rotor housings, the worse the condition of the housings the more time it will take to break in.

if your rotor housings were in good shape then you are well out of the break in period.

i have redlined my motor with 100 miles on the rebuild several times and i didn't see any excessive wear when i tore the engine back apart, i don't suggest doing it until at least 500 miles have passed but there certainly are a lot of myths floating around about rotaries and rebuild break in requirements.

ddub

Myths? How come every builder suggests these "myths" then?

RotaryEvolution

iTrader: (30)

1500+ miles for break in? i would have to check but i don't recall seeing any of the major rotary engine builders suggesting that many miles before letting some of the power flow. if they are then i am skeptical and i believe they only say it to cover their *** in case of a mechanical failure.


some say 500, some say 1000 some say more, it all depends on how much of a burden you want to put on your customers. i don't know that i could pussyfoot my engine for a whole 1000+ miles but that is just me. these engines, when they accumulate some miles can be very tempermental and it gives them a bad reputation for being unreliable but they are more resilient once rebuilt than alot of people give them credit for.

ddub

Here's a couple that list it on their site, and I've heard others that talk about it on nopistons.com


Kevin Landers -
Breakin should be completed as follows.Keep rpms under 4000, oil changes at 500 and 2000 miles, and no boost above atmospheric(turbo models).

Great improvements in starting, idle quality and overall smoothness/power will begin occurring immediately, but most improvement will be reached by 1500 miles, at which time you can gradually increase rpm and boost. By the time the engine reaches 2000 miles, it is basically broken in and can be treated as you wish within reason.

Ted -
First 1,000 miles Gradual increase revs up to 4,000RPM maximum NO BOOST Vary engine RPM's as much as possible
Change oil and oil filter at 500 miles

Next 500 miles Gradual increase revs up to 6,000RPM maximum Gradual increase in boost up to half of max boost or 5psi, whichever is LOWER
Next 500 miles Gradual increase revs up to redline Gradual increase boost up to maximum boost levels Change oil and oil filter after break-in

If new bearings are installed, double recommended mileage intervals.
"First 1,000 miles" = First 2,000 miles
"Next 500 miles" = Next 1,000 miles

RotaryEvolution

iTrader: (30)

well as i said it is a bit on the safe side of a rebuild, i know Kevin protects his rep and i like to as well but until i have seen proof that a rebuild with decent housings and new seals will not accept a little abuse post 500 miles leaves me skeptical, i believe those numbers are to protect themselves and their reputations.

i will see how my 4k abused rebuild is holding up this weekend and will let you know.


i doubt the engines off the assembly line were run for more than a few hours if at all prior to shipment for delivery from the factory, give these engines some credit for their durability.

ddub

Here's one for your argument from BDC:

"Without bearings replacement, 500 to 1000 miles. With bearings replacement, 2000 miles."



Best way to know is to start taking compression readings from the beginning and once compression plateaus and reaches a peak you can pretty much call it done, as long as new bearings weren't used. In the case of new bearings they need more time.

ddub

That was for all completely brand new parts, though, it's a bit different. How many people that build their engine can say that every single part and seal in the engine was completely brand new?



Mazda recommendation for new car from the 1985 owners manual

"break in period

by following a few simple precautions for the first 1,000 kilometers (600miles), you can add to the performance, economy and long life of your vehicle.

do not race the engine

run the engine at varying speeds up to 4,000rpm.

avoid hard stops, except in emergemcies this will allow the brakes to seat properly

avoid full throttle starts"

RotaryEvolution

iTrader: (30)

i know people will bash me for this but the same principles still apply, bearings do need to seat in, in worn engines they need more time to seat in properly, basically the more that is physically abnormal with the engine will cause the engine to take longer to get into it's proper running positions and tolerances. IMO the numbers are to protect the builder, which i fully understand and maybe some day i will also use those numbers when i begin building more engines but for now i feel it is a little excessive and for personal protections.

the more worn out a rotor housing is the longer it takes to seat up properly, until it is seated up the seals can be burnt, depending on the seals as well it may take longer to seat, RA seals are hard and may take longer to seat up where Atkins seat up quicker as well as stock seals.

i just need some proof not policy.

Dom_C

this is good stuff. I would really like more on this subject if anyone has more to say. Everyones opinion is different i guess. some people say you can rebuild a piston engine and then start her eup run it for like 20 minutes then she's ready to race. .but other firmly beleive in a break in period. I dunno either way this is good info. .thanks
Dom

RotaryEvolution

iTrader: (30)

i doubt the people who drag their rotaries do a break in process but they also tear the engine down after every event.

ddub

Yah, and they use all new parts usually in the beginning, and replace stuff when they start to get worn at all, so it's a lot different.

Corbit

Dave Atkins claims a 9.91 1/4 mile with over 300 passes on the engine and the only thing he changed was plugs.

ddub

Yah there are exceptions, I've also heard of people that do road racing that use an engine for 1 extended race.

casio

i was actually going to say this. seems i've read more than once people talking about how long an engine runs, not how often they change it.
as for breakin for racecars, the FM cars (that i worked with) didnt even know what breakin was. "breakin" was done when the engine builder (a certain guy/company in CA) dyno'd the engine before sending it back. they race those engines (road course/circle track) until they die or loose compression badly (depending on how rich and hardcore the racer is).
"breakin" is of course theorhetical in a sense, but only because the "magic numbers" arent set in stone, just "right-abouts" estimations.

WonkoTheSane

iTrader: (2)

I'm pretty sure break in is directly related to how many new to used surfaces you expect to mate properly. The more new to used surfaces, the more breaking you want, this is due to the engine tolerancing. New to New surfaces don't require as much break in time, as they were produced to tight tolerances and won't have to fill grooves and pits like a New to Used seal would.. Obviously Kevin and Ted are going to recommend a longer break in than what was required from the factory, as I know Kevin doesn't get to use as many new parts as he'd probably like, and Ted probably rebuilds rotaries from spare parts for fun

the point is:

more new to used mating surfaces (seals to housings, seals to endplates, bearings to eccentric shaft), the more you want to break in the engine slowly.

If you have a new housings, new bearings, a new eccentric shaft, and new plates, you won't have to worry about them adapting to a looser tolerance.

RotaryEvolution

iTrader: (30)

i don't fully agree nor disagree with the statements made but if an engine can't hold it's own after 10 hours of minor labor it ain't worth a **** to me.

speedieFC

so dom what do u think of the number of miles should be. I think the builder sets a number even after the engine is done doing its thing he doesnt want somthing to happen to it. but if you believe i over reved your motor and stopped you from making a little power your wrong
the only thing i did that day was help you out by the exhaust and breaking in your motor by not evan 1/10 of the recomended time so you'll be fine.

Dom_C

you put over double the miles i asked you two, and didn't do ****, you welded one side of the exhaust. not that i don't appreciat that but yea. . I understand that over revving it may not have done much damage but it also may have. All of the housing were used, all of the seals were new. . if you read you would understand why this makes for a longer break in time. when you drove the car it was at 940miles on the rebuild. Anyways, the rebuild is doing pretty well, I'M still going to wait to bring it up to readline for another 100 miles at least. I'm excited to see how it will pull once i can really rev her, and using the VDI. thanks
Dom

Dom_C

One more question, what are the negative effects of "burning" a seal? Will this inturn glaze the seal and make it harder for the seal to seat? Maybe make it brittle or soemthing?