I am asking this more hypothetically than anything, but I was just wondering about this since I don't have a good place to break in a new engine for my race car, due to the noise and smoke, and the fact that I do most of my wrenching in the evening and late at night.



I was considering building an engine stand with a quiet exhaust to break in a new motor, but then I got to wondering if you could use an electric motor with a pulley and a fan belt to spin the engine. This would allow me to skip the rad, fan, ignition, fuel, gauges, starter, etc on the engine stand.



If you had the oil system functional, and if you had the OMP working and an intake with carb to meter in the oil, would this be an effective way to break in a motor?



Do you need the motor to be at operating temps for all the parts to be correct dimensionally? Would all the un-burnt metering oil gunk up the motor? What other reasons are there that this is a bad idea?



-Neil

 

The lack of temperature would seem to be one problem. The other is that you need a big pulley on the engine and a smaller one (Two sheave) on the motor. I tried that with a 5 horse motor from my crank grinder, and it was all I could do to keep it going. The plugs have to be out of the engine, and that opens you up to dust in the air entering and doing damage. The noise was almost as bad as a running engine.



The motor turns 1725 RPM and that is about the right speed, but kept popping a 50 amp breaker.



A geared motor turning a bit slower would do the job. Maybe if you are building 3 or 4 engines a week it would be an option. Before we had an enclosed trailer, we just dragged the car to a incomplete housing project out of town and ran the engine with a aftermarket radiator fan clamped on the grill. A garden spray pump full of water was all that was needed to give the racer a spritz now and again to keep the temps in line. Just under 200 degrees is fine. Run it for two hours total before you scream it. Keep in mind that Bridgeported engines idle at 2,000 to 2,200 RPM. So you have covered quite a bit of engine time (wear) by the end of 2 hours.



Then at the track the first few laps under 8,500 RPM then 9,000 RPM by the end of the warmup. Then in qualifiying 9,000 for the first hot lap, then 9,600 after that. Never a problem. Run the movie of the dash gages between sessions, as the driver will remember none of the details.



Lynn E. Hanover



Lola based rotary powered My design

 

yeah we used to just idle the thing in the parking lot with a huge fan on it for an hour or so. for mine here at the house i've got a muffler i can stick over the tail pipe

 

Thanks for the responses



Yeah, I'm working on a add on muffler solution as well for use at my house.



Per Lynn's post, I'm surprised it takes 5hp to spin a motor to 1700 rpm, but I guess that makes sense.



If I get bored, I still might put together a stand to actually be able to start and run an engine for break in, but that won't really be relevant until I'm at the point where I have a spare engine!



Thanks again.

 

When I do an oil change, my idle is about one or two hundred RPM higher until the oil pressure builds up. You can hear the change in engine load as the needle comes up!

 

Motor needs to be running for things to seat, spinning it with a drill isn't going to do much. I'm surprised a 5hp motor worked; I figured it would be a 2x that..