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I’ve recently rebuilt my IAG stage 3 ej257 with new rods, crank, cam etc. My builder is recommending a 3000 mile break in period and keeping it under 4000 RPM during that time. While I agree with keeping it under 4000 RPM for a while and varying the RPMs and all that, maybe 3000 miles maybe a little too excessive? Any thoughts?
 

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Yeah, don't listen to the guy who built your motor. Just get another thread primed for when you blow your built motor and blame it on the EJ.
 

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The Legendary Bad Ass (aka; Buzzz)
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I am a builder of race engines. I don't know the clearances, the ring package or any of the other variables they put in your mill, but just do what they say. The main thing is the ring seal. I don't mind rpms in a break in period, as it won't leave that lip on the inside of the cylinder wall that will knock ring lands when you do rev the thing, but you don't really want lots of cylinder pressure. (Boost and throttle when not at a larger rpm.) And the changing rpm thing is a bit of an old schooler deal with things like cam break in, harmonics and all those new metals mating and making sure they have a nice range of break in with metal on metal. Valves spin around in different frequencies, as do piston rings, with different rpms, etc. That is why they want those variations. But these are clutch cars. They will always be varying.
Just do what they say. That gives you a way better chance that they will help you down the road if you need it. And suck up to them and at 1500 miles, ask if you should change the oil or the filter and what brand they recommend and all of that jazz. That will signal to them that you are doing what they recommended. This is an investment. Both the engine and the relationship with the builder(s).
 

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I’ve recently rebuilt my IAG stage 3 ej257 with new rods, crank, cam etc. My builder is recommending a 3000 mile break in period and keeping it under 4000 RPM during that time. While I agree with keeping it under 4000 RPM for a while and varying the RPMs and all that, maybe 3000 miles maybe a little too excessive? Any thoughts?
This situation calls for a grand old saying. Better safe than sorry!
 
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