i am about to rebuild an o.s. 21rzvo1b and got a questiong about breaking it it. i stopped by the lhs and say them braking in a motor. he said they usually run about 3 tanks for breakin. they run it with the carb wide open but so rich it is not much higher than idle or maybe 1/4 throttle. they said it was better because it flushes out the motor. i am just wondering if i should do this too or do it the normal way
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breaking in motor
- Thread starter Mudbug
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Engine break in is a personal prefference thing....I like them broken in on a stand but some guys will say that's crap.....read anything and everything you can written by the top engine builder/designers and see what makes sense to you...personally IMO running WOT with the engine on the car is not good unless they are driving it to create a load.....most guys set it like that and run the 3 tanks on a stand....that doesn't create any load on the engine...
vbgagnon
RCTalk VIP
Alot of people like the heat cycle method. I personally run one tank on the gound barley moving, 2nd & 3rd tanks up to 1/4 throttle, 4th &5th tanks 1/4-1/2 throttle, 6 &7 1/2-3/4 with a few WOT passes. I then tune a bit so its almost the tune that I'll run when fully broken in (staying rich) for 4-5 more tanks. Then race tune rember to always let it cool at BDC between tanks. And your temps should be right around 220* while breaking in. Any lower then 200* and your hurting more than helping.
Heat Cycle
Here is a little info about using the heat cycle that I found while looking at an OS engine on Tower Hobbies.
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 mannerfor 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.
Here is a little info about using the heat cycle that I found while looking at an OS engine on Tower Hobbies.
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 mannerfor 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.
WOT method is what I use on all my recent engines.
*Your running the engine VERY rich, and running at WOT keeps the temp up, meaning you don't need to lean it out to bring temps up.
Ed at Palmaris racing says himself the WOT method of running as rich as possible at WOT sounds very good because your simply running so rich while still maintaining the proper break in temp.
I posted a huge post on the WOT method a while back, not to many people agreed with me since a lot of the guys here are old fasioned I guess and have not tried it.
JMO.
Here is the thread btw, https://www.rcnitrotalk.com/forum/showthread.php?t=32063&page=1&pp=15&highlight=wot+method
*Your running the engine VERY rich, and running at WOT keeps the temp up, meaning you don't need to lean it out to bring temps up.
Ed at Palmaris racing says himself the WOT method of running as rich as possible at WOT sounds very good because your simply running so rich while still maintaining the proper break in temp.
I posted a huge post on the WOT method a while back, not to many people agreed with me since a lot of the guys here are old fasioned I guess and have not tried it.
JMO.
Here is the thread btw, https://www.rcnitrotalk.com/forum/showthread.php?t=32063&page=1&pp=15&highlight=wot+method
Last edited:
- Thread starter
- #6
well i won't be breaking in the motor for a while now. i picked up a new piston sleeve, connecting rod, wrist pin, clips and gaskets off of ebay for 97.00. along with the new piston and sleeve came an old 1 and i check the pinch of the used sleeve i got from ebay and the piston that i had in the motor already and it has a good bit of pinch to it. I ran it saturday night and i was extreamly impressed with it. so my total i have spent on the motor is 147.00 and i still have a new piston and sleeve. not to bad i think.
that's the RZ?
great engine....wish they redid that one instead of the newer VZ-b model (Not the V-spec)
great engine....wish they redid that one instead of the newer VZ-b model (Not the V-spec)
vbgagnon
RCTalk VIP
i,ve been looking for a zr for cheap. no luck yet tho.
bustedgears
Hardcore RCTalk User
Bouzouki said:
Works great for me.
