How soon is too soon for an Autocross?
 

My 2.7 stock rebuild is done and I have put about 200 miles on the car in the past week.
It runs very well, pulls hard, and sounds great. Rings look to have seated since the exhaust is nice and clean. I've been through several heat cycles, accels and decels according to the rebuild book. I've tried to keep revs under 5k, but have hit 6k a few times :) That red line keeps mocking me!

Anyway the goal for the car has always been to use as something I can really learn how to drive with. So naturally AutoX is something I can't wait to do. (So much so that I took the wifes car to an SCCA Autox last month) And the local PCA is further taunting me by offering an AutoX this weekend.

But at what point is it safe to start doing this?
What are the ramification if one was to I do it too soon? (assuming I avoid missed shifts and over-revs ofcourse.)
I guess the real question is, how do you know when your rebuilt engine is ready to tackle hard accelleration and redlines?

I realize there are a few schools of thought here and would like to hear comments from both sides.

One extreme is obviously the often cited: http://www.mototuneusa.com/break_in_secrets.htm
The other extreme is to be easy on it for the first 1,2, 5, or 10K miles.

Thanks,
Pat

Get it to 1000 miles and then readjust the valves and tighten the head studs. I wouldn't stress it until it was completely broken in...

-Wayne

I avoided autocross like the plague.....for the first 100 miles.

Perhaps my thinking is barbaric, but I figure "If this thing is gonna blow, let's get it over with NOW". I don't recommend this approach for anyone but myself. It's just a motor. If it breaks, I'll fix it......actually I've been fighting the urge to tear it down and see how "things" are holding up. It's not making any rude noises :D

The motor now has a couple hundred AX passes and a bit of track time on it. I got to feeling sorry for it and replaced the 7300 rpm pill with a 7100.

So, what is everyone's break-in procedures for track-only cars? 1K miles does not seem practical on a car without tags.

JP
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It seems that the method mentioned above would be appropriate for a race motor. http://www.mototuneusa.com/break_in_secrets.htm
Although I am in the "run it hard" to break it in school, I would still suggest getting some miles on the engine before autocrossing. I only say that because the really heavy 1st gear engine braking you often see in Auto-x seems like kind of a harsh thing to do to a new engine.

Pat,

I was looking forward to seeing your car yesterday...sorry you didn't make it. Nov. 9 starts the first of the SCCA Winter Series events. No trophies, and we can ride with each other whenever. Get the mileage on the car before that one. Drive it to Vail and back a few times.

See you then!

mto

Yeah, I was planning on going. I spent Saturday driving to Golden, Lookout mtn (very fun at will over the recommended 15mph), Evergreen, Morrison, Castlerock and more. Got to my 500 mile mark and was adjusting valves that afternoon when I double checked the cam timing and noted that it had drifted.
I guess that's one of the reasons why the 1000m break-in is important :)
Should have it fixed this week and will try to get another 500 on it in the next two weeks :)

Pat

Let me know...I'd be happy to join you for a little tour/drive. Estes park perhaps? It's pretty nice to live in the rockies when it's car break-in time, huh? :)

Ask a racer how long they take to break in one of their engines. Dyno time is typical. In fact the entire life of a race engine, typ 20 hours, is less time than the break in period of a new car.

Go out make several full throttle accelerations, and decellerations, that breaks in the rings. After that start driving it. If it gets hot, then back off for a while, if not, GO.

This is a lot differen't than a typical break in for a factory car. Why? Well a well built engine should not take a whole lot to break in. The rings are the main thing. In a well prepped race engine, the honing operations are taken to the max and no real break in is needed, except for the first 20 or 30 minutes.

This sounds radical, it is not IF the engine does not get hot, and it should not. If the engine does get hot and a little time dosen't rapidly fix it, then maybe the honing wasn't adequate and you will have to wait until the heat subsides to GO for it.

Note: Newer cars do not seem to need the extended break in periods the older ones did. Part of the reason is that they are so well made and the rings are pre lapped, therefore needing little or no break in period. In any case with a new car always follow the mfg recommendations if you value your warrenty.