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Old 04-27-2009, 04:59 PM   #1
elislider
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Default EJ20k rod knock rebuild?

I did what i knew i wasnt supposed to, and run my ej20k sti on 92 octane with the jdm sti 6S ecu. tried to not take it above 5k rpm to be "safe" but it apparently didnt matter because after 400 miles i have a rod knock now.

I dont want to spend the money on a usdm sti shortblock (ej257) unless i can find one for cheap. So my other option is just to tear apart the engine completely and rebuild it.

Were the parts used in the 20k engines somehow inferior? or is it just a product of my using crap gas on the sti ecu? My main question is, to rebuild it, can i just replace the bearings with the same/compatible parts and make sure i run it tuned from now on (powerfc or vipec) ? or should i use different bearings that are better to make it less prone to happening
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Old 04-27-2009, 05:10 PM   #2
Rei_Akira
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i doubt that a rod bearing going out is from the octane in the fuel, that would cause detonation and damage to the pistons, but not the bearings (at least i believe, could be wrong if someone wants to correct me).
i would suggest getting a good set of bearings if you're going to tear the bottom end apart, they really dont cost that much more, and you know you'll be safe in the long run. besides its a good chance to upgrade whenever things break.

from what i understand the 20k's are notorious for eating rod bearings, i havn't gotten mine up and going yet (same motor as you) but i plan on replacing the bearings in the bottom end before i do...
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Old 04-27-2009, 05:32 PM   #3
Matt Monson
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Detonation is also hard on bearings. Think about it. The fuel is igniting when it's not supposed to and pushing down on the piston before it has hit TDC. However, technically what I am talking about here is pre-ignition, which is slightly different than detonation. Pre-ignition is common from too low of octane, while detonation tends to be more from running too lean.
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Old 04-27-2009, 06:48 PM   #4
elislider
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yeah im sure its been running rich instead of lean. at any rate, the engine is knocking during the first second of acceleration from idle, and sometimes at idle. if the car is idling and i just barely tap the pedal (to rev it to 1500-2000 or so) i can hear it knock a few times. at first it would knock once or twice now it does it 6 or 7 times. i just stopped driving it
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Old 04-27-2009, 07:35 PM   #5
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Quote:
Originally Posted by elislider View Post
Were the parts used in the 20k engines somehow inferior?
Not really. Just think about it though... You bought a USED engine with no history.... At least thats my assumption it is used.
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Old 04-27-2009, 09:06 PM   #6
elislider
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i wasnt asking that because i was surprised or something that my engine started to knock. i actually wasnt surprised after everything i had read and that i was basically doing everything i wasnt supposed to. i had read plenty of stuff about the ej20k engines that have rod bearing failures and knocking and such because of many variables including the very aggressively tuned jdm ecu + corning hard + low oil + thin oil (or synthetic etc). i just never bothered to ask if it was because how the engines were used or if it was because there was something specific about the internals of a ej20k that made them more prone or less capable or something. i didnt really think there was but thought id ask

so my main question is, if im going to rebuild it, how and with what? should i get oem-replacement parts or go cosworth if thats too much more expensive. if its gonna cost more than $500 to rebuild then i might as well just find an EJ257 shortblock...
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Old 04-27-2009, 09:34 PM   #7
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Quote:
Originally Posted by elislider View Post
I might as well just find an EJ257 shortblock...
Correct sir.
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Old 04-28-2009, 01:36 PM   #8
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It's going to cost more than $500 unless your labour is free. A bearing set is about $70. The 257 is cheaper but you will likely want EM and tuning to getting the most from it, where as you could continue to run your 6S on a rebuild.
I got mine rebuilt when it blew and put in forged pistons. Cost about $2k maybe a little more including gaskets, bearings and cosworth oil pump. I wanted to stay with a high revving 2l to stay with the whole V3 theme of my car. The 257 is good way to go to get more power and early torque. Of course the extra torque may not be kind to your 5spd.
It likely wasn't your gas, but more like age and those other factors.
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Old 04-28-2009, 01:59 PM   #9
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I just went through this same exact thing with my engine. I ended up getting a longblock for 1K w/ warranty from a local importer. I thought I saw a EJ20K longbock while I was their. In the long run a rebuild will cost more gaskets, machine work, etc. and will not come with a warranty. PM me for more info. Your other option which is the cheapest kinda half as$, band aid, torcher for an EJ would be to drop your oil pan and change the bearings with the engine in the car. You can only get to 3 of 4 rods but its worth a try if you need the car back on the road and it'll only cost you time and bearing/oil/filter/liquid gasket costs.

Last edited by ckcadavona; 04-28-2009 at 02:06 PM.
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Old 04-28-2009, 04:42 PM   #10
elislider
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i actually think now it might just be my timing belt tensioner... ill be taking it apart and taking a look soon

Quote:
Originally Posted by ckcadavona View Post
I just went through this same exact thing with my engine. I ended up getting a longblock for 1K w/ warranty from a local importer. I thought I saw a EJ20K longbock while I was their. In the long run a rebuild will cost more gaskets, machine work, etc. and will not come with a warranty. PM me for more info. Your other option which is the cheapest kinda half as$, band aid, torcher for an EJ would be to drop your oil pan and change the bearings with the engine in the car. You can only get to 3 of 4 rods but its worth a try if you need the car back on the road and it'll only cost you time and bearing/oil/filter/liquid gasket costs.
not a bad idea, thanks.
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Old 04-28-2009, 10:34 PM   #11
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257 is probably the best idea in the long run ...
but your looking at

block
oil/water pump
gaskets
EM
Injectors
tune

~5k would be my guess
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Old 04-28-2009, 11:07 PM   #12
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Quote:
Originally Posted by Jaxx View Post
257 is probably the best idea in the long run ...
but your looking at

block
oil/water pump
gaskets
EM
Injectors
tune

~5k would be my guess
Yep. Used one's will run you around $5k...

http://forums.nasioc.com/forums/show....php?t=1301517 A friend of mine bought one of their motors and was very happy with the deal.
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Old 04-28-2009, 11:19 PM   #13
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I rebuilt my 20k (6S ecu also) about a year ago. I just stripped it down and had the rods turned down 10, mains were fine. Had my machinist order me some ACL Race bearings, about 100 bucks for rods and mains. Threw it back together and it runs like a champ. Havent had a problem with it since and Ive run it hard. I think it has to do with the fact that these motors are at least 10yrs old, sitting for who knows how long, and who knows what happened to them before you got it. A little motor that puts out almost 150hp per liter and revs to 8k wont last forever. I figure if I get another 30k miles out of this motor its worth it to me.


AND- If you do want to even think about rebuilding it, DONT RUN THE MOTOR AT ALL! Damage has already been done, dont make it any worse.

Last edited by fishheadback; 04-28-2009 at 11:27 PM. Reason: fail at reading
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Old 04-28-2009, 11:19 PM   #14
elislider
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im already planning on EM. powerfc or vipec

i bought a new automatic tensioner, picking it up tmrw and gonna tear into the timing belt and see if thats what it is
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