Likely, you’ve heard about proper break-in procedures for a new engine. Typically the break-in process is performed on the engine dyno before your new engine undergoes its power pulls. Modern engine dynos even have an automated break-in program where it performs the process without any input needed from the dyno operator, allowing for repeatable results.
But, what if you don’t have access to an engine dyno? What if you built your engine and you’re throwing it right into the vehicle? As Total Seal’s Lake Speed, Jr. and Shaver Specialties’ “Dyno Don” McAskill cover in this video, you have a viable break-in method without the use of a dyno. “There are a few procedures you need to follow for a successful break-in,” McAskill says.
“What we’re going to do in a car is try and replicate what we’d do on an engine dyno,” says Speed. “But there is a technical difference between the two methods that we need to touch on first.” That difference is the viscosity of the oil being used. “Because you can’t put the same load on that engine in the car as I can on the dyno, you’re going to need to use a little bit lighter-weight oil,” explains McAskill.
“When I’m breaking in a sprint car engine, I’ll usually use BR40. But, if it were being broken-in in a car, then I’d switch that to BR30.” The reasoning behind the switch is that the lighter weight oil will flow easier, get to the components a little faster which is critical for a wet-sump engine according to Speed.
Defining What You’re Breaking-In
McAskill points out that two things are getting broken-in during engine break-in — the camshaft and the piston rings. “Most guys these days will probably be using a roller camshaft in their builds. For a roller camshaft, break-in isn’t that important. It just needs oil,” McAskill explains, “But, if you are using a flat-tappet camshaft the procedure will be totally different. With a flat-tappet camshaft, the very first thing you need to do is bring the RPM up. It’s gotta be 2,500-3,000 rpm for at least 20-25 minutes.”
McAskill goes on to explain that you can’t accomplish that by driving around with the new engine and that the new procedure needs to be accomplished with the car stationary in the driveway. You’ve likely learned that spinning the engine without load is actually counterproductive to the break-in process. McAskill acknowledges that, explaining, “That’s one of the reasons it’s important to have the lighter oil in the engine, since the rings will be starting to break-in during that time. But it’s more important that the camshaft gets broken-in correctly.”
Keep in mind, that is only for a flat-tappet camshaft, and that it is a conscious prioritization of breaking in the flat-tappet camshaft with RPM and no load before seating the rings. “That is why having the right oil, with the correct additives in there, is so important,” reiterates Speed. Both McAskill and Speed warn that in breaking-in a flat tappet cam, if you don’t have fuel and spark, and just continually crank the engine with the starter, you are depriving the camshaft of crucial splash-oiling, and risk wiping out the cam lobes and lifters.
Once your camshaft is broken-in (or, in the case of a roller cam, right out of the gate) the goal is to get the car out to an open stretch of road and get some load on the engine. “The idea is to simulate an engine dyno,” McAskill says. “The way to do that is to hit the accelerator while in gear and put some torque into the motor. That is what is creating cylinder pressure to exert force on the rings, which is what is needed to break the rings in.”
By accelerating the engine under load — no need to get to the rev-limiter — and then slowing down and repeating the process, you are essentially recreating the pulls on the engine dyno. “Every hard pull you make in the car is like pushing the handle forward on an engine dyno,” says Speed. “It may take nine or ten pulls to get the rings fully broken-in. People sometimes worry about babying their new engine, but once you’ve warmed up the engine you can safely apply that load. Peak cylinder pressure happens at peak torque, and peak torque happens way before redline. You don’t have to go near the engine’s redline to properly break in the engine.”
With that, you now know how to properly break-in your new or rebuilt engine, without having to take it to an engine dyno.
In this video, McAskill and Speed go through the process of a proper engine break-in on an engine dyno. You can see the similarities, and what you are trying to achieve in the car.