Break in process for Savage X 4.6

[bobbd]

Hpi manual says to run 2 tanks of fuel on idle with x4.6 up off ground . Does that sound right and is alright to run first 2 tanks in one day then run the next 2 tanks when the weather gets nicer which could be maybe a month or 2..or should full breaking be done all in one day ?

 

[olds97_lss]

Whenever I break an engine in, I don't start unless I have enough time to at least get through the first 10 tanks of break-in in one sitting.

I don't let engines idle through tanks of fuel anymore though. That lets the engine run too cool and it's just hard on it IMHO.

 

[bobbd]

Olds can you share your break in procedure ?

 

[Jam Racing 1]

https://www.hpisavageforum.com/threads/how-to-heat-cycle-your-engine-for-newbies-pros.6972/


I use the heat cycle method on my engines for the last 15 years or so....

 

[olds97_lss]

Olds can you share your break in procedure ?

I do a variation of the heat cycle method, starts on page 9:
http://gmarquee98.x10host.com/myPic...aris racing break-in and tuning-formatted.pdf

I deviate from it some though as I don't allow for hardly any "sit and idle" time, other than the time it takes me to get the truck down on the ground. The first few tanks can be a chore, but I set the tune near factory as it won't get up to proper operating temp until the piston wears into the sleeve a bit. Usually by the time you get 125-300cc's through the engine, then the temps start climbing up closer to 200F. I drive it easy for 4-5 minute increments for the first 625cc's of fuel or so typically (5 125cc tanks) while shutting it down every 4 to 5 minutes and letting it cool down to less than 80F. I adjust the tune more after the first 300cc's to do what I can to get the temps up to 200F and less than 250F while driving it around easy. After I get 5 tanks of repeated heat cycling through it, the temps are usually up around 220-240F and then I start running 2-3 tanks between shut downs. As you get more and more fuel through the engine, it starts waking up and I do relatively slow count full pulls to WOT and slow let off. I don't keep it at WOT at all, just ramp up, ramp down, turn around, ramp up, ramp down.

Typically, by the time I get 1000cc's through an engine (usually 750cc's for small blocks, 1000 for big blocks), then engine is responding well to tune and starting easier, I start driving it. For the entire first 3/4-1 gallon, I'm very easy on it without much WOT running. You can usually tell when an engine is ready to be beat on by how it sounds, feels and performs. Some take more, some take less. Depends on the quality of the components. Cheaper RTR engines usually take less. A decent picco/omega/lrp/OS tends to take more fuel before they really settle down and get consistent.

The last engine I broke in that I felt a bit worried about was an OS21TM. It took more fuel than I expected before it's temps settled down and become solid. After about 1.5 gallons, it's temps stabilized very well and it really started performing great and just got better each time I ran it. I kind of expected it to take a bit less fuel considering it's size/rpm's it ran at. The last time I had it out, I ran it hard in my 3.3 chassis revo for nearly 1000cc's and the temps varied about 20F the entire time and didn't require much fiddling with the tune at all. Reminded me how nice nitro can be.

One thing I always do is monitor temps and any time the engine is off, I put the piston at BDC. I do that throughout the life of the engine. I don't usually "tune" for temps, but I keep an eye on them as most engines I've had give temps between 225-275F when running well and keep an ear on how it's sounding while watching for smoke out of the pipe when accelerating. If I see the temps jump up 30F+ out of the blue, I inspect to see if I have something wound up in the drive train causing drag, cb bearings spinning smooth, fuel lines are good, no cracks in the tank... etc.