Alfa Romeo Forums banner

1 - 5 of 5 Posts

·
Premium Member
Joined
·
5,474 Posts
Discussion Starter #1 (Edited)
Breaking in a rebuild on a dyno

I was looking at the cardisc shop manual and ran accross this engine break in schedule. I got to thinking about breaking in an engine on a dyno and wondered if anyone had done this and if so what their experience was. Frankly, the thought of running WOT for ten minutes after 50 minutes on the bench is a bit gutsy IMHO...

Break in.jpg
 

·
Registered
Joined
·
4,501 Posts
Glenwood Motors (to mention just one with whom I happen to have quite a bit of experience in the Alfa motors), bench-runs EVERY single motor that they build on the dyno UNDER LOAD! (Dawie has been doing this for AGES, so I trust the man!) He and I have done about 16-17 engines together over the last 3 years or so and they were ALL done like that!

A motor is either right or it is not! He starts it up, brings it up to temp a bit, checks the basics and rolls it right on to the dyno to start putting load on it! Not high revs - just low rpm load! A tuner hops on it with an AFR meter and the laptop and starts mapping fuel right away too and as he is mapping from left to right in the load-cells and works his progressively up in the rpm-ranges the motor gets all the run-in that it needs!

In less than an hour that thing already sees 4-5K rpm WOT (basically all load) runs! (Made me cringe the first few times that I saw this and then I started to get used to it!) You guess that you WANT that heavy (low rpm) load to help seat the rings!

The old-school thought-process of "stick it on the highway at 2,200 rpm and put it on cruise-control on a flat road for 3,000 miles" is just not how it is done - especially on a performance motor where you run pretty loose piston-clearances any way!
 

·
Registered
Joined
·
4,040 Posts
I don't know if you can say an engine is totally broken in after a dyno session for mapping F/A? My engine builder recommended not driving at a constant rpm when I picked up the Spider and it had multiple dyno sessions on it.
 

·
Registered
Joined
·
5,969 Posts
My dad had a Chevy small block built up last year, and they put about 8 hours on the engine before he collected it. Apparently they rigged up the output shaft to a long transmission shaft which is connected to a kind of propellor in a water tank. This creates a load on the engine which effectively mimics the work an engine has to do in pushing a car along, thus helping to seat the rings. The factory manual specifies the use of a hydraulic brake, too.
 

·
Premium Member
Joined
·
5,474 Posts
Discussion Starter #5
It seems to me that the factory breaks in the engine using a dyno. Then it is handed to the customer and told to break it in too.

Break in - owner's manual.jpg

I am ok with that.

I just like the idea of putting some time on the engine before I go through the effort to put it in the car. I have a parts car that I could turn into a dyno "mule".

OTAH, I like Alex's idea:

invaquada.jpg
 
1 - 5 of 5 Posts
Top