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Engine break in without dyno.

Engine Building Fundamentals

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Hi Folks.

Ready to start freshly built engine (RB26) but Its not not looking like I’ll be able to do it on a dyno as tuner is now away on Holiday.

how much of a difference does it make breaking in on the street ?

Plan is to pull plugs and crank until I have pressure and try and check timing at this stage. Then set the idle speed to approx 2000rpm, start it up, spend a few minutes checking for leaks and then get it out and under load ASAP. Also using good quality running in oil

Car was built for a show this weekend which I’m determined to bring it to running or not. Now I’m planning on trailering it down anyway. But if the engine had already been broken in, it would mean I can drive it on and off the trailer and when it comes to tuning it properly when he’s back then I know there won’t be any issues with leaks.

Is this wise ? Would I be better just pushing it for the time being and waiting until I can get onto the dyno ?

The pros of breaking in on the dyno is that's a more controlled envrionment, you don't have to be watching for road hazards, you can control the load, check for leak, etc... But you can still achieve your breaking in on the road.

The best is to have a buddy with you that can help you with the base timing, check for leaks as you have the laptop on your lap and adjust the AFR so you don't foul plugs and get the engine to rev happily if needed. Once your happy with everything, you can hit the road and start putting the engine under load making sure that the AFR makes sense. RBs aren't known for their low end power so I try to keep it at a low-ish RPM and gradually opening and closing the throttle, cycling the load like this.

Once your done, change the oil, replace and inspect the oil filter and you should be good to go!

Breaking in on the road is almost as effective as dyno if done properly. Minimum idle time, constant verying RPM up to 3-3.5 kRPM when stationary, not semi or fully synthetic oil, gradualy increasing load to make up to 0.3-0.5 bar of boost by first 50 km (30 miles) up to 100-150 km as that is the most important time where fresh hone works the best in terms of rings filing...

Thanks for the replies guys.

I thought I was maybe being over cautious but I’ve put that much time and cash into it I didn’t wanna take any risks.

Will get it fired up tonight then if I can get a mate over.

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