2 ways to break in engine...which is best??

[FoxRacR17]

Hey guys i'm fairly new here and i just bought a used HPI Nitro RS4 MT2 RTR off ebay. Overall it is in pretty good shape but i think the guy shot the engine because it has hardly any compression. But thats ok because even if i bought a new one i was going to upgrade it. So i just bought a O.S. .18 CV-RX w/rotary carb. Now, here is the question, i was reading over at rcuniverse.com forums and a guy posted that there is another better newer way to break in engines. I read the noob guide in this forum and according to you guys the proper way to break in a engine is

Answer: OK, here goes. The first procedure is called "heat cycling", this is the most important part of break-in and almost no one does it. Start the engine and let it idle, after 1-2 minutes feel the cylinder head, you want it to be hot enough so you can't grab on to it for more than 10 seconds at the base of the head. Stop the engine, make sure the piston is at the bottom of the stroke, let it completely cool down, back to stone cold. Repeat this process at least 10 times !!! I usually dedicate the first tank of fuel to this process. It's going to take some time to do this so be patient.

Now you can take it out and run it. Open the main needle one full turn. The next 4 tanks, run at no more than 1/2 throttle and vary the speed up and down. Let it completely cool down between runs and always make sure the piston is at the bottom of the stroke while it is cooling. Try to run the engine in the 200 degree range during this period.

Now 4 more tanks running up to 3/4 throttle, run it in the same manner as before.

Now you can go wide open, make sure to run it on the rich side for another 6 tanks. Don't try to grab a lot of ponies yet. ( this is easier said than done !!)

Now you can let it rip. These engines run best at temps 220 to 240 degrees. There should always be a VISABLE line of smoke coming from the exhaust stinger.

Good luck with your break-in. Take your time and do it right and you will be rewarded with an engine that runs stronger and lasts longer than you have ever seen.

However, while reading the offical HPI Nitro MT2 thread at rcuniverse, this guy, 46u, said this:

If you are still idling at least a tank through during break-in, you're using the old-school accepted method (still works well for some!) but it's not the method that the top engine guys (Ron Paris, Dennis Richey, Rody Roem, Michael Salven are just a few I've spoken personally with about this) recommend anymore.
From the very 1st time you start your engine, plop the car on the ground & begin running it in a parking lot in 2-3 minute intervals, tuned only *slightly rich* getting the temps up in the 200F range on a normal day. Every 2-3 minutes, shut the engine down & let it cool completely with the piston at BDC, and then fire it back up; continue this cycle until you've run 15 min or so, and then bump up to 3-4 minute intervals. Vary the RPM and don't be afraid to get the temps in the 200's. What you want is heat cycling of the components without the incredible stress that comes with breaking an engine in when it's overly rich & cold. After cycling the engine in this manner for about 20-25 total minutes, it'll be ready for the track and race tuning. I realize this method goes against the old-school "idle on the box" routine, but you'll be amazed once you've completed this break-in routine, your OS will still have amazing pinch w/out sticking at the top AND your OS's compression will last far longer than it will with the "old school" method.
You say you run the engine at "factory settings" for the first FIVE tanks? That alone causes lots of stress, as the factory OS settings are very rich on every OS I've ever owned or tuned. The piston & sleeve haven't expanded to operating temps, and every time the engine turns over, the piston slams into the pinch zone at TDC. The not-so-surprising result can be a cracked con-rod at the crank pin--that's where the majority of the stresses occur as the engine turns over. I've only heard of about 6-8 OS engines breaking con-rods, and they're ALWAYS during the first gallon...and almost every time it's because the guys have performed the break-in procedure you described. Doesn't seem like a mystery as to why it's happening. Drawing out the break-in routine really stresses the engine & actually wears away compression along the way. This method I've outlined will feel weird at every step, but after you try it once, you'll notice a big difference in your engine's performance & lifespan.
Hope this helps; give this break-in method a shot--you have nothing to gain except longer life & more power

Now being a noob, i am really confused and just want to know which is the better way because i dont want to ruin my engine that i just spent 112 bucks on onder2:

EDIT: here is the direct link to 46u saying the above: http://www.rcuniverse.com/forum/fb.asp?m=3459212

 

[andrewtexas7450]

I think the best way to break in the engin is to idle through 4-5 tankes of fuel then slowly increese the speed once you get to the top speed you can let it rip. Have fun with your new truck.

 

[bustedgears]

What does your manual say to do? Every company has their "preferred method" of break in that should be best for your perticular engine.

 

[Plaidfish]

I think the best way to break in the engin is to idle through 4-5 tankes of fuel then slowly increese the speed once you get to the top speed you can let it rip. Have fun with your new truck.

DO NOT do that....
everyone has a "method" to do this but the basic priciple is what matters.....getting the mill up to 200 deg F...running it smoothly and shut it off bring the piston to BDC (bottom dead center) and redo that procedure for about 5 tanks...what you are trying to accomplish is 1: mating th episton to the sleeve and creating your airtight seal....2: "tempering" the metals inthe sleeve......Idling your mill will NOT bring it up to temp.....
Personally I do the WOT on a stand method and heat cyle it there....alot faster and it's more consistent.....which method you use is personal prefference.....I persoanlly won't do another "in car" breakin on my stuff ever again...too many variables to deal w/....traction, irregular throttle control, parts failing while you break in.....

 

[FoxRacR17]

What do you mean by "in car" break in? Do you mean breaking an engine in while it is in your rc car? How do you break it in while it is not in your rc car if that is what you mean? So then Plaidfish you are saying that 46u way is a better method? You must understand that i am new to the nitro rc cars so i have no idea which would be better. Thanks for your help guys.

 

[truthseeker]

i'm kind of a fan of the traxxas method. it's sort of a combo of the heat cycle and a mechanical cycle. it gradually gets the temps and the rpm's up without running too cool/too slow for too long or too hot/too fast. i think that's what plaid meant by the "in car" break in, though. it can be a pain if everything isn't just right on the car (batteries, ignitor, etc.) since you're actually driving it around. i find that break-in is kind of a personal preference just like fuel or tires. Some guys do some really strange stuff on break-in and they all say it's the best way to do it. i think as long as you gradually bring up the temp and the rpm's, it's probably going to be ok no matter how you do it. Plaid pretty much summed it up, though. and i bet his engine runs just as good as mine even though he does it different. he just gets to go inside and have a drink while i'm still putting around the parking lot....

 

[NSantana]

...for normal use, go with the suggestion in the manual (idle for a few tanks then slowly increase speed)...for a racing app (high-eng mills that DON'T come with manuals!) i'd suggest the WOT method..there use to be a VERY knowledgable pair of brothers on this site who brought me up to speed with this and one of them had a mill with about 7gal. on it using this method and it runs fine...but as a newbie, i would wait until you get more experience tuning engines first as it is VERY easy to mess up your engine this way.

 

[vbgagnon]

NSantana, they are still around, just taking a break for a while.

 

[MEGA MAXX]

I've just bought an engine secondhand, and they guy said that he's run it in over 5 tanks on idle.

and then ran it from there.

I'm guessing from the posts that the engine isnt going to last very long?

 

[NSantana]

well,



if you've haven't got too many tanks through it, you can still make good with it...if it IS too late, you'll start noticing as it will not hold tune too well..in either case, make sure you do it right next time when its time to buy a new piston/sleeve

 

[MEGA MAXX]

the thing is. its a sirio.18tx which is discontinued.

so ill probably have a hard time finding any parts for it.

also, the guy has been running 10% nitro through it, 2.5 litres of it.

do you think i can still salvage a decent engine out of it?

 

[Plaidfish]

What do you mean by "in car" break in? Do you mean breaking an engine in while it is in your rc car? How do you break it in while it is not in your rc car if that is what you mean? So then Plaidfish you are saying that 46u way is a better method? You must understand that i am new to the nitro rc cars so i have no idea which would be better. Thanks for your help guys.

Yes I mean in the car..
I used to have a stand.....it's gone but when I get a new engine I'll be buying a stand to break it in.....
For 99.99999% of hobbiests (myself included since I just putz around on the track and not too serious about the racing) the heat cycle method while driving the car is the easy way to go....I helped build a stand w/ a friend and got used to doing it that way....on a stand you mount a propellor to th eshaft on your engine (that's the resistance or Load)...then fire it up....right away go full throttle and peg the carb linkage in place.....you fatten up the high speed needle til the temps are at 205...with this method you can set a specific temp since the load is constant.....adn then heat cycle it 3 times per tank...every 2 tanks raise the temp 5 deg....after 5 tanks tune it on th e6the tank to run right.....this is a close final tune....mount it back in the car/truck and tune for performance......this is NOT the way you should be doing your breakin unless you have someone who knows what they are doing to help...I almost fried my first mill cause I didn't pay attention to what I was doing and did 2 heat cylces and let the temps get way too high 260......once the temp is tuned in though you can count on it getting higher as the break in goes on....you have to adjust the HSN to keep temp down about ever cycle for the first3-4 tanks...so whoever said I can go get a drink is a lil off in the theory, but it's a lot better than futzing w/ a car on th eground that 's tough to start...blah blah blah....

I explained this process not to say it's the way to do it....just to show the basic principles of what needs to happen during break in.....the idling method is not good because you run the mill cold...the sleeve won't expand and the rim on th episton head will get rounded off and allow compression leak.....break-in defines the engien's life span....do it right the first time and you have a much better engine.....