Race car break in?
 

How do you race car guys break in your fresh motors?

1st choice on an engine dyno before it hits the car
2nd choice would be in the car on jack stands, the neighbors love that with the new bearing procedures

You just let it run for a few days, or what?

real race cars get broken in during the race lol.

You need to run conventional oil ( there are some like Joe Gibb's, Shell rotella etc ) with a good additive package. The best way is on the dyno and it takes about 6 hours. Lacking that, you can do 1-2 hours running it on jackstands, and one session on track 20-25 minutes running with a lower redline 7-7500+-. Then change to full synthetic oil and go for it.

I drove mine on the street not really gettng into any boost, making sure temps stayed low for about 400 miles and finally changing conventional oil to synthetic. Seemed to work for me.