Subaru EJ257 :idiots
Mitsubishi 4G63 :nod
We’ll see how this rebuilt EJ257 goes…hoping that it runs forever this time…or at least for more than ~9k miles. :angry2
Well I had a long talk with Seth this morning just bullshitting about our work and brought this up. Apparently I was mistaken and that the tune on this car was a bit on the agressive side as Justin was looking to exploit the stock system as much as possible.
What did the long hand of detonation say to the ringland???..“SNAP, BITCH!!!”
;D
Define “aggressive”?
I’m guessing afr’s a tad higher than ideal and ignition timing right on the verge of knock?
So would I but I was looking for specifics. 
AFR was conservative…timing was not. On the Torco map, anyway.
The street map was conservative all around.
48* of timing up top. :wow
No, AFR’s dead on. This was most likely a case of excessive RPM and a bad case of detonation, followed by massive blow by burning off the oil film on that side of the cylinder(thus the galled skirt). Why the det…who knows. Bad batch of fuel, injector lockup, slight low mix of injection water in that cylinder at that moment. It apparently happened on the “street” tune and not the torco map, where a poor distribution/mix of fuel additive would be a likely culprit.
In reality I’m surprized the motor held this long since a couple months prior, the thing was spun to ~10K rpm during a very bad missed down shift. It SHOULD have blown then and there. The main failure to these motors is oiling at the crank and rods, where the oil going to the rod must overcome centripetal force to get to the bearing. You’d think ~60+ psi would push the oil where it’s got to go but once these motors start getting above 6.5-7K it takes ALOT of force to overcome the rotational force of the oil trying to be thrown back out of/down the oil galley. So much so that it requires extensive crank drilling/machining/plugging to redirect oil where it needs to go when being subjected to high RPM loads(8K+). Expensive work, even at my rates. Again, Justins engine should have blown at that kind of RPM but the suby gods must have been overlooking that day. Typically even at that high of RPM the stock rods bolts would/should have failed and let go.
Unless you’re building a subaru engine for strictly all out race purposes, rpm should stay below 7K. There’s absolutle no reason to swing them out past that on a street car. Shimming the oil pump for added pressure and machining for more volume helps tremendously, but is still a mediocre fix to a much bigger problem. A 3 stage dry sump system would be the big ticket fix(plus crank work) because the sustained volume of the oil at slightly increased pressure is what keeps these motors alive. It’s why you don’t see this problem on Porsche engines(drysump). Pull apart an EJ257 case/crank and lay it next to a 7R case/crank and you’ll see the similarities and oiling issues that a boxer motor faces, but RARELY do I get a Porsche engine here that failed from oiling ailments like the suby’s have. When I do, it’s becasue of some other issue like stuck reliefs(common) or overrev(very common with 915 5speed and 930 4 speed transaxles). The array of internal drysump oil pumps Porsche has released since the debut of the 911 is mind boggling, but even the oldest and smallest of those provides more oil volume and pressure than the best and current suby pumps.
Anyway IMO this is the exact reason why not to go nuts with agressive tuning on a DD street car, especially one that’s your only way back and forth to work. Tune race/toy car agressive and if they blow up, well it’s the nature of that game and to be expected now and then. Tune street cars conservative for more power and fun but retain reliability incase you local fuel station dishes out shit fuel one day, which here in the NE is more common than you’d think.
Well that’s my piece for today. I’m sure Paul will have some insight to this thread as well when he get’s time. I know I have little myself.
Wow. Subarus suck :haha
I keep the AFR always the same regardless of octane but adjust timing based on octane/boost/meth/etc…
Timing has a MUCH bigger impact on power which also can lead to other issues.
:nod
I’m surprised to hear that all the pistons were extensively damaged, must have been pretty bad. The #2 cylinder had the cracked the piston on yours and on jays motor the headgasket blew in #2.
I think another one of the reasons they spin bearings is straight up lack of oil. A lot of the EJ25’s will burn a surprising amount even at a young age. Most owners are not fully aware of this and find out the hard way. My co-worker had a legacy gt and it would burn 2 quarts of oil in under 1500 miles. Most all of the sti owners I talk to have to keep a close watch on the level, especially being driven hard like most are.
All parts for the build are now with BoxerSix…hopefully she’ll be making noise and burning gas…SOON :banana
Parts list updated and cleaned up for an easier read…car is coming along nicely!
I should have time tomorrow to start assembling the bottom end at the very least.
Don’t forget the photos :nod
Otherwise we’ll never hear the end of it from the likes of Benny :crackup
it’ll be sold by december :lol
I better get a ride in it before then though :nod
Unfortunately I’m stuck with this one…after the deer incident and now sinking all this cash into the motor…the STI and I are going to be getting engaged.
well I’m glad to hear that, even though it is a subaru
it’s offically in the process of being put back together again!