Low engine power during break-in period?

[silver_power]

Re: Low engine power during break-in period?

Ok my friend,.....I will!

 

[sethjon]

Re: Low engine power during break-in period?

Also consider the boat itself. That will make a difference.

 

[silver_power]

Re: Low engine power during break-in period?

Also consider the boat itself. That will make a difference.

What do you mean with this?

 

[JustJason]

Re: Low engine power during break-in period?

Your 11.5hr MPI isn't making 300hp at the prop YET. It may need an additional 10-20hrs of run time to fully break-in,

That's a bit of bulljunk, and common misconception. Nothing mechanically changes between 0 hours 20 hours, and if you take really good care of your engine, nothing should change between 0 hours and 1000+ hours.

 

[silver_power]

Re: Low engine power during break-in period?

.....And what has changed in my engine so to reach +280rpm? (with the same fuel...). Sorry but this is not true. When i bought the boat with my previous engine (wot rpm 4200-4600), this came with 21P aluminium. The boat could not reach 4000. I changed with 19P aluminium and reached 4300. After 20-25hrs it reached about 4750rpm! Changed with 19P SS Laser. 4600rpm.....After about +20-25hrs it reached 4800. Changed with 21P Tempest. Back to 4400-4450! So when the engine completed 50-60hrs was completely different as it was with 0hrs! If i consider that comparing 21P aluminium with 21P SS Tempest, which has big diameter and so big load fot the engine, there is about 200rpm, the engine after has been operated for about 50hrs, it gained +600-650 rpm. I think that this is a BIG difference. The history seems to be repeated with my new engine. After about 15hrs, it gained about 280rpm!!
So i do not think that there is no diffenrence before and after break-in!

 

[JustJason]

Re: Low engine power during break-in period?

So i do not think that there is no diffenrence before and after break-in!

I've had this conversation multiple times, but here we go.

So what changes then? Before and after so called "break in"... What changes?

What are the air temps like when your running your boat. You can have as much as a 30% swing in power between a 90 degree day and a 60 degree day, that will certainly effect your rpms.

 

[silver_power]

Re: Low engine power during break-in period?

Every internal part of the engine, even block and cylinders need some operation time to give their best. I have seen my previous engine when i totaly reconditioned it, to operate rough for the first 2-3 hours and then real smooth. Anyway,. i have oposite opinion than yours and i do not believe that ths forum is the suitable place to write that there is no need for break in a totaly new engine...sorry..,

 

[KJSmitty]

Re: Low engine power during break-in period?

^^^^^

As for the OP, he doesn't need to put a finger on "exactly what changed." He has the proof under his feet and right there in front of him that "something" did, he is getting a positive change in performance as the hours on his engine accrue.

From a person that has built, driven, raced etc many an engine,,, they definitely can "change" in regards to performance from hour one to hour 50 etc. Some engines more than others. What changes: quite simply the engines machined parts, those moving, mated, honed etc. Basically engines just "loosen up" during their first hours of life - some more/quicker than others.

This fact is actually "common," and not a misconception....

Now, is it the cause and or reason behind every lack of, or increase in performance during a new engines life. NO. But someone mentioning or understanding this could be the issue should not be looked at as "impossible."

Cheers

 

[John_S]

Re: Low engine power during break-in period?

I was surprised by the amount of change. I would expect some, but the hp differences that would be required for these rpm increases seems substantial. Thats allot of hp being tied up in friction. Thats why I'm interested in continued reports. Thanks.

 

[silver_power]

Re: Low engine power during break-in period?

I will post Monday update (rpm and mph). Then i will have exceeded for sure the 20hrs break-in.

 

[MCL]

Re: Low engine power during break-in period?

This might sound weird and crazy to someone,but race engines are break in with mineral oil hard,helps the rings to seal.Had a smoking kx450f with lost ponies because of babying it and using fullsynthetic oil,put a new ring and hard break in with minerals and its all good.Hard break in=No wot but hard acceleration&deacceleration.

But race engines are built to much tighter tolerances.These chevy based marine engines are hammer&chisel technology,dont know if it applies to them too.

I would recommend cheap oil and alot of oil changes during break in,there is alot of filings and crap in the oil during break in.

 

[JustJason]

Re: Low engine power during break-in period?

Basically engines just "loosen up" during their first hours of life - some more/quicker than others.

More like basically you just don't know. That's why I asked for specifics....

1. Stroke doesn't change.
2. Bore doesn't change.
3. Combustion chamber volume doesn't change.

Those 3 things right there are what give you your compression numbers. The higher compression number you get, the more power you get.

If you built your engine correctly. You mapped out your piston to cylinder wall clearence, and checked your ring end gap, and those don't change either.
You would have to have about a 25% loss in compression PSI across the board before you started noticing a power loss. Or to say just the opposite, your compression would have to increase 25% across the board to notice and increase in power. That just doesn't happen. On a pig iron gm block, there's nothing fancy you have to do the the cylinders if they are bored correctly, and there's nothing special to the rings either... assuming you fit everything correctly.

The only engines that need break in these days, are real racing motors with nikasil sleeves in rocketbike engines. Now you do have to temper those in or you'll glaze them out. Everything else you can just run.

And if you don't believe me... then tell me specifically what measurment in the engine building process changes.

 

[KJSmitty]

Re: Low engine power during break-in period?

The only engines that need break in these days, are real racing motors with nikasil sleeves in rocketbike engines. Now you do have to temper those in or you'll glaze them out. Everything else you can just run.

And if you don't believe me... then tell me specifically what measurment in the engine building process changes.

As usual Jason, your reading and comprehension are excellent. No one said anything about "needing a break-in period," just that "performance changes" can take place from hour one to days down the road. PS - using the phrase "break-in" is synonymous with - "as it ages" - not that you have to perform some special "break-in procedure" - however that continues to be argued as well..

During the initial "aging process" are we talking huge 25% HP increases-no...

Depending on the engine build, there are a degree of internal frictions that definitely decrease over a relatively short period of time resulting in better performance - that is all we are stating and most likely what the OP is experiencing.
You can be as adamant as you want looking for a different answer - you always are. I've got nothing to prove however, my experience/knowledge/logic is what it is. - And, I'm not compelled to remotely fulfill your fantasy of instigating more keyboard pi$$ing contests..


Cheers

 

[JustJason]

Re: Low engine power during break-in period?

I'm not compelled to remotely fulfill your fantasy of instigating more keyboard pi$$ing contests..

Not looking to get into a whzzin match with ya buddy, just waiting for an answer as to what changes. If a motor is put together by the book then nothing does... I'm not sure what you mean by "internal frictions".
On a running engine all rotating assemblies ride on a thin coat of oil, cam and crank clearences don't change. If you plastigauge a bottom end on a motor with 0 hours on it vs say 50 hours... it won't change. 99% of all friction any engine sees ever is during cold starts, after they run there is very little friction. If there was any measurable friction enginges wouldn't last a week, let alone thousands of hours or hundreds of thousands of miles.

I get quit a few calls during the dog days of summer up here with customers stating that their boat lost/is loosing a couple of hundred rpms. Of course up here people use their boats twice a month, and are comparing the power they had back in april when the high temp outside was 60 and the water temp was 50.
EFI compensates for alot over a carb... But outside temp, humidity, barometric pressure, and overall air density can play a huge roll in overall power output. Even a 10% change in power output due to atmo conditions will equat to a few hundred rpms. Some small engines (and small outboards) are so picky that you have to adjust the idle mixture screws just to get it to run if there is a big enough difference in atmo conditions.

That's why I stated from the get go that it is a common "misconception". No critical dimension changes inside of motor build in 10, 20, 100 hours. And no dimension changes critically at all over the same time period. Yes there are a few exceptions, but not with pig iron. Only with HP motors that run exotic cylinder materials. And that break in is not for dimension, its for tempering.

If you ever go to Mercruiser school, or probably even a GM school, they will tell you the same thing. Manufactors and Dealers tell people about "break in" to break people into a new piece of technology... ie~ so they don't go out and kill themselves the first time out. Pull just an owners manual for just about any 2010 automobile. There are no "break in" instructions in those anymore.

 

[silver_power]

Re: Low engine power during break-in period?

Pull just an owners manual for just about any 2010 automobile. There are no "break in" instructions in those anymore.

My '08 VW golf GTI owners manual sais not to exceed 3000rpm for the first 3000km.....
Anyway......i do not think that this conversations is interesting for anyone.....
I just started that post to share my first dissapointment about the new 350mag mpi in my boat.....but that dissapointment does not exist anymore as the engine has started to show me it's power amd i am almost sure that my boat will exceed 60mph (GPS). That was all i wanted for my boat.
Thank you very much and i will post again as the tacho will raise OR not refering the rpm's and mph for those who are interested.!

 

[JustJason]

Re: Low engine power during break-in period?

If your rpms are not the same day to day or week to week try and keep a log of temperature, humidity, weather, time of day... all that fun stuff. You'll probably start to see a pattern after a while.

 

[silver_power]

Re: Low engine power during break-in period?

I decided to change the prop because i do not want to push very much the new engine. Besides for now it seems that with the 22P SS it is out of the manufacture WOT range. So i now run my first 19P aluminium....but.....the engine reached 5050rpm@57,5mph(gps).
The boat comes to plane VERY FAST and the economy now is again 3.78mpg but @32mph and not @39-40mph as it was with the 22Enertia. Now with aluminium@40mph engine consumes 3.2mpg. The only bad is that this propeller can not handle a lot of up-trim. The enertia was continuing to push the boat even at full up trim!
Anyway...the boat has started to go fast....faster than with the old engine, and i can tell for sure that i really love the way the boat run at this speed.! I am sure that at the end of this summer i will succeed my target of 60mph@gps!!

 

[mariner1900]

Re: Low engine power during break-in period?

Jason whilst you are correct that no internal measurements should change during the "run in" process there is one item that does change. The surface of the bore and rings. On a new engine or re-built engine the surface of the bores and rings are not smooth but a grainy finish from honing.

After proper "running in" the honed surface and ring face tends to obtain a smoother finish and hence less friction. The use of mineral oils helps the speed at which these surfaces "bed in". Any extreme loading of the engine during the "bedding in" process can and does lead to what is called micro seizure and has detrimental effects on the engine. This is well documented by some of the worlds largest engine manufacturers' who all list a very detailed process for running in new liners and rings.

Would the early part of the running in cause a 20% power drop I doubt it very much though.

My car hand books states to vary the RPM and not exceed 3000 during the first 1500km as weel.

 

[JustJason]

Re: Low engine power during break-in period?

After proper "running in" the honed surface and ring face tends to obtain a smoother finish and hence less friction.

Actually you don't want a smooth finish in the bore. You want a nice cross hatch pattern, with lands and grooves, to give oil a surface area to stick to. If cylinders were smooth to a mirror image, then oil wouldn't stick to it, and you'd burn out the rings and the liner.

Any extreme loading of the engine during the "bedding in" process can and does lead to what is called micro seizure and has detrimental effects on the engine.

Don't midget epleptics suffer from the same micro siezure problems?

 

[mariner1900]

Re: Low engine power during break-in period?

Yes there is a nice cross hatch pattern on the bores of a nicle honed engine. However that pattern is formed by peaks and troughs in the noe pattern from the moment you start the engine the peaks of that cross hatch pattern start to wear down. If you have ever had an engine pulled down you would have noticed that the honing pattern is partly worn away and can be completing gone, on engines with lots of hours, and the bores will be smooth. Not to a mirror finishas caused from glazing.

To make snide remarks like you did about midget epileptics tells me you obviously do not understand the mechanics of what happens when breaking in any engine or you wouldn't such remarks. May be you should try educating yourself by using Google occassioanlly.