First start new engine vs break in?
 

I hear two things that are possibly contradictory and I'd like to sort it out.

First, you don't want to run the engine long before break in.

Second, in order to get the coolant system fully burped you need to let it get up to temperature with the nose in the air.

Obviously if I do a thorough job with the cooling system I may be harming my motor correct?

Does this mean I just do my best getting the coolant system topped off and proceed immediately to break in? Or, does idling with no load not hurt my motors ability to seal the rings etc?

I'm trying to wrap my head around the best way to get TO break in.

Turn motor on... Drive car... It's broken in.

+1. Been thinking about this too. Saw someone talk about heating the oil with a hot plate. Sounds like overkill.

From what I've read (and people have told me). Start it up, check for leaks, make sure nothing is falling off. Drive to your nearest country road and it should be warm. Vary rpm on the way.

This is my plan. Someone correct me if I'm wrong :)

I've only put about 1,150 miles on my engine since building it but here's what I did:

• Check, double check, triple check that everything is right so it starts up on the first go.
• Prime oil pump and turbo by either popping the injection fuse or disconnecting coils.
• Start it up on jackstands, quickly check for leaks, take down from jackstands, idled briefly on the ground. Maybe 10 minutes total time from startup at this point.
• Take it out on the road and do a bunch of 3rd gear full throttle to full vacuum pulls. I probably did 10 of em.
• Park and change oil.

From there I drove it pretty gingerly, not using more than 70% throttle, staying out of boost if you're turbo (I broke it in n/a), trying not to cruise at the same rpm for too long.
Changed the oil again at 50 miles (later that day). Again at 100, then 500, 1000. All SAE 30 'straight weight' oil.

ITT: we take overthinking and paranoia to the next level

I've built a few NA bottom ends, I'd turn it over with fuel harness unplugged, then start it up and rev the engine as we burped it. Seemed to work for us, leakdowns were always good.

It's easy to get enough coolant into the system to not overheat during break-in without doing a full nose-up burp.

I kept the front of the car up in the air on axle stands when starting the car for the first time. This meant i could get the car running, top off the coolant, then hit the road.

The most difficult part was actually getting the megasquirt working properly. Of course you can do a lot with just key-on but it'll need tweaking with the engine running to get it to idle and drive.

My break in went: Get car idling, get autotune running, top off coolant, get the car on the ground, quick leak check, then hit the road.

My aim was to have the engine running properly before the thermostat opened up but its tough. I probably spent a bit longer idling than i should have getting the tune approaching accceptable. I've read a ton about excessive idling stopping the rings seating properly and that worried me so a was working quick.

Also, because i was starting from a fresh tune, my first full throttle pulls were a mess, but within a few goes autotune had it running well enough to pull okay. Did ~10 pulls then changed the oil.

Sure, but for myself and probably OP & others, this was the first time starting up a newly assembled engine. Can't hurt to be careful. I'm sure I'll be a lot more comfortable the second time around.

In my case, the car runs and drives on megasquirt with a very similar engine. I am currently 10.5:1 and I think my new engine is the same or at worst 11:1.

I am upgrading to a vics manfold from a VCTS and I have a built/ported head...

Crap - maybe my tune WILL be off quite a bit. Either way, I think I should be able to get it idling pretty easily and I'll try and have a passenger adjusting my tune for the break in as we drive.

Yes, probably overthinking. And yes, first time ever building an engine and I would rather overthink it and be close to 95% likely to succeed vs just going with it and being 90% likely. Partly because if something did happen I would be forever kicking myself for not asking these questions.

I'm not hating, but the more you dig, the more you'll see varied opinions. It's literally a never ending rabbit hole.

I usually tell people to change oil real soon after 1st start up, then do lots of varied pulls at varied throttle (not wot) to varied rpm and get as much vacuum on the rings as possible. Then just drive the car normally trying to never hold a steady rpm in cruise for long. for a few hundo miles

for whatever it's worth. it's not failed me thus far.

I literally just drove my car as if it didn't have a built engine. I was more cautious to not damage the clutch during it's break in.

As my builder said: "if it fails, it will fail before you even exit the driveway".
It still hasn't failed and i have treated it like trash.

My break in procedure followed as
Turn car on, check for leaks (I had a few)
Let idle for 30 seconds
then slight throttle until up to operating temp
Drive for 10 miles at varying loads
change oil and filter, check for anything major
Drive for 400 miles, change oil.
I then after 800 miles had a thrust bearing and oil pump failure. Should I have to "Break in" new bearings or does it not matter because I'm not seating any rings?