Built EJ205 + Specs - Understanding Break-in Procs

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LaszloToth

LaszloToth

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We strengthened the internals with 4032 Al allow forged pistons (head studs, STi rods, etc) and improved the oiling system and the builder is now recommending 5W-40 oil following break in. However, the break in process is elaborate with: 1. 20 min oil change - warm for 10 min, run at 2000 rpm for 5, 2. 100 km oil change - intentionally vary the rpms constantly in this first drive, but do not to exceed 5500 rpm, and 3. 1000 km oil change - avoid constant rpm running. Happy to follow the break in process as recommended, but have you any insight into the purpose of a recommended break in like this? Here's some tech trivia on forged piston alloys: EngineLabs TECH5: Trey McFarland of Mahle Motorsports Reveals Piston Secrets Built EJ205 Build Specs
 
Originally Posted By: LaszloToth
Also, I'd prefer to use this oil:
15w40? LOL, just use a stout 5w30 or maybe 5w40 if you will really be beating the [censored] out of it.
 
Were the stock pistons from Subaru cast aluminum? 4032 would be a good upgrade over a cast alloy. In my opinion, the Mahle guy in the article overly minimized the advantage that 2618 has over 4032 in high temperature fatigue strength. But 4032 has a lower thermal expansion rate, so the engine can be built with tighter piston to bore clearance. I'm hoping that the rod bearing clearances they have written on the build sheet are actually .0019, .0021, .0023, and .0021. The .019, .021, .023 and .021 numbers they have written down would be crazy. The 20 minute oil change is normally done to change the filter and get the Moly break-in coating out of the system, which may cause the filter to plug. Varying the rpm's is a way of assuring that the engine will see many acceleration events, which loads the rings against the cylinder walls, and helps them break in with the bores. In the past, ring manufacturers would say to do 10 hard accels and decels to progressively break in the rings, then let it go at that. Then dumping the oil at 100 km gets the wear debris from the bores out of the system. My oil recommendation would be to use PUE 5w40 or M1 0w40.
 
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The builder gives you a relatively meticulous break-in procedure but doesn't recommend a particular oil?
 
Originally Posted By: LaszloToth
... However, the break in process is elaborate with: 1. 20 min oil change - warm for 10 min, run at 2000 rpm for 5, 2. 100 km oil change - intentionally vary the rpms constantly in this first drive, but do not to exceed 5500 rpm, and 3. 1000 km oil change - avoid constant rpm running. Happy to follow the break in process as recommended, but have you any insight into the purpose of a recommended break in like this?
From what I've read since it's highly massaged from stock, the rapid changes are for: 1. Most junk is produced the first few minutes, plus the intent is to wash out assembly lube and any other contamination. 2. Steady state doesn't contribute to the best break in, the variable loads are required to insure that every ring surface is exposed to pressure. 100 miles isn't that far, but there will be more junk produced during this stage. Did they also tell you to do numerous heavy throttle/lower rpm accelerations? 3. Easing into normal driving, avoiding steady state for the reasons above. I've always been a fan of early OCI on new engines, and after reading up on this awhile back agree completely, especially for a highly modified engine.
 
Originally Posted By: A_Harman
Were the stock pistons from Subaru cast aluminum? 4032 would be a good upgrade over a cast alloy. In my opinion, the Mahle guy in the article overly minimized the advantage that 2618 has over 4032 in high temperature fatigue strength. But 4032 has a lower thermal expansion rate, so the engine can be built with tighter piston to bore clearance. I'm hoping that the rod bearing clearances they have written on the build sheet are actually .0019, .0021, .0023, and .0021. The .019, .021, .023 and .021 numbers they have written down would be crazy. The 20 minute oil change is normally done to change the filter and get the Moly break-in coating out of the system, which may cause the filter to plug. Varying the rpm's is a way of assuring that the engine will see many acceleration events, which loads the rings against the cylinder walls, and helps them break in with the bores. In the past, ring manufacturers would say to do 10 hard accels and decels to progressively break in the rings, then let it go at that. Then dumping the oil at 100 km gets the wear debris from the bores out of the system. My oil recommendation would be to use PUE 5w40 or M1 0w40.
What I would say is getting the engine in boost at 60-70% throttle for the rings but don't go wide open just yet. I don't know what kind of a tune you have on it but all big turbo builds I have done, I just give it that 3/4 throttle using the turbo (don't be afraid to get it in boost but don't have the wastegate open basically) I would use some cheap Rotella T5 for break in and then MI 0w40 for your application.
 
Folks, Thanks for the insight and comments. Stock pistons are cast and their replacements are forged. It's a build sufficient for 300 wheel HP power, but I only intend to run Stage 2 power levels, which are 285 HP and 285 TQ for this motor. It's overbuilt for reliability. What's the advantage of the Mobil 1 recommendation?
 
Originally Posted By: LaszloToth
Folks, Thanks for the insight and comments. Stock pistons are cast and their replacements are forged. It's a build sufficient for 300 wheel HP power, but I only intend to run Stage 2 power levels, which are 285 HP and 285 TQ for this motor. It's overbuilt for reliability. What's the advantage of the Mobil 1 recommendation?
The M1 0w40 works well in lots of boxer engines, especially high heat ones (Turbos). Lots of folks that were doing track days ears ago found they lost less oil with that particular oil and some folks had good luck with Rotella T6. I myself used M! 0w40 in a VER VI STI motor I used.
 
You'll find many different recommendations for breaking in a built EJ engine. Here's Cobb's recommendations: http://www.cobbtuning.com/Technical-Articles-s/70721.htm The most popular break-in oil is probably Rotella 15W-40 so you're on the right track there. Motul, Amsoil, and RP break-in oils are good as well. Most don't switch to synthetic until after some of the initial short intervals. And the Built Motor forum at nasioc is a good resource: http://forums.nasioc.com/forums/forumdisplay.php?f=144 Just don't be one of those guys that doesn't follow the builders' advice and ends up needing a rebuild. -Dennis
 
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Thanks bluesubie, that is very helpful. The builder says the built motor will be more sensitive to warmup, and that a block heater is a good idea if it's not garaged. Cheers,
 
This is standard engine break-in 1. Is for valve train break-in 2. Is for piston ring break-in. 3. Is for general break-in. Use Rotella 15w40 and maybe M1 0w40 in winter.
 
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