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Old 02-17-2009, 09:09 PM   #276
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^^ Agreed, plus engines that were not assembled correctly (poor clearances used and/or balancing and/or torquing) are also high on the list of reasons for failure.
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Old 02-17-2009, 11:43 PM   #277
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I split the block tonight to find that the rod bearing on 2 and 3 were both intact but lots of play. they look as though they were squeezed from the middle out, if that makes sense. Does that sound like a detonation problem or lack of oil? It is a OEM short block so I have no idea what the tolerances were. I am doing the work this time so I will be sure to rule that out for the next failure. When I had it tuned at Dent sport, I had them advance the timing slightly to avoid detonation. I'm not going to pretend I know what I'm doing but I assume most of you do. There must be a reasonable set up to combat this issue. 1250 for a crank isn't bad considering short block replacement at 2100 all said and done. does it make sense to clearance the rods to .002 but keep the mains tight? Should the rods and crank be replaced or just turned? I'm basically trying to keep this build under 2k. What mods are most important?
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Old 02-17-2009, 11:46 PM   #278
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Quote:
Originally Posted by mvcsk8r View Post
When I had it tuned at Dent sport, I had them advance the timing slightly to avoid detonation.
Um........yeah, I hope that's a typo.
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Old 02-17-2009, 11:55 PM   #279
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Quote:
Originally Posted by mvcsk8r View Post
I split the block tonight to find that the rod bearing on 2 and 3 were both intact but lots of play. they look as though they were squeezed from the middle out, if that makes sense. Does that sound like a detonation problem or lack of oil? It is a OEM short block so I have no idea what the tolerances were. I am doing the work this time so I will be sure to rule that out for the next failure. When I had it tuned at Dent sport, I had them advance the timing slightly to avoid detonation. I'm not going to pretend I know what I'm doing but I assume most of you do. There must be a reasonable set up to combat this issue. 1250 for a crank isn't bad considering short block replacement at 2100 all said and done. does it make sense to clearance the rods to .002 but keep the mains tight? Should the rods and crank be replaced or just turned? I'm basically trying to keep this build under 2k. What mods are most important?
Squeezing suggests the tremendous forces applied during detonation. An oiling issue would manifest as scoring and or excessive wear, not a crushing and or squeezing type of damage. And advancing timing is the exact opposite of what you want to do if avoiding detonation is your goal, FYI.
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Old 02-18-2009, 10:26 AM   #280
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It was a typo, way to tired when I wrote that, I meant retarded the timing. But none the less squeezing would mean detonation? But driving it home after it happened (5 miles) would also beat the piss out of what was left of the bearing too causing it to look like that. The crank did look scored on those two rods. I am running the hybrid set up, would getting shorter connecting rods to bring the compression ratio back down be a wise idea then, if in fact it was detonation not oil? When it happened I was at 7k shifting from 3rd to 4th. which is why I thought oil.

Last edited by mvcsk8r; 02-18-2009 at 10:33 AM.
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Old 02-18-2009, 10:38 AM   #281
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mvcsk8r it sounds like from your post you should not be trying to hotrod anything. Why don't you just get a new shortblock and reassemble your motor and sell your car and get a nice regular fast car and not try to do things you have no idea about. I think you will run out of money before you learn as you go. Sorry but hotrodding a subaru is very complicated and you either pay someone that knows or spend about three times that learning how to get started. Nobody can tell you how to correct your mistakes in a paragraph.
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Old 02-18-2009, 11:00 AM   #282
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First of all how are they my mistakes? My driving style might be an issue. But swapping in a 2.5 short block seems to be the most common solution anyone does on here. Clearly Subaru can't build a shortblock that can handle high revs otherwise there wouldn't be thousands of people on here that spun rod bearings. I am trying to find out why that happens. I'm not a professional engine builder but I am a mechanical engineer and not a retard. All I am asking for is suggestions not your opinuion to go buy a pos honda. yeah I'm learning but you gotta start somewhere.
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Old 02-18-2009, 11:19 AM   #283
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Well, subaru can build a motor that can spin high rpm's and reliably. Look at the EJ207 from the factory.
Was the rebuild motor a new shortblock or was it rebuilt by you or a shop (if the later, I can guess the problem). Also don't even think of shortening a rod to lower compression...that changes much more than just compression.
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Old 02-18-2009, 11:29 AM   #284
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I bought it from the local subie dealer brand new. but as I have read the tolerances can vary from .0008 to.0018. if it was on the tight side the film of oil may not have been sufficient. I'm not saying they can't build a decent motor but there is clearly a weak link.
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Old 02-18-2009, 11:40 PM   #285
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I'm probably a little late posting these pictures but I have been looking at the crank oiling and cross drilling recently.

This is an MY06 JDM 2.0 STi Sec C crank.
It's crossed drilled and nitrided stock





In these ones we have an EJ257 crank on the left, Spec C in the middle and an early EJ20 crank on the right.





Ever since I took these photos and looked at an aftermarket cross drilled crank I wondered why they only cross drill the mains.
Does anyone have any idea why they wouldn't bother with the rod journals?
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Old 02-25-2009, 03:43 AM   #286
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wow those cranks all look so damn similar

I wonder how much a difference cross drilled mains makes
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Old 02-25-2009, 03:05 PM   #287
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[slams head into wall]

they are all crossdrilled!! The only differences being

left = 79mm stroke
middle = double crossdrilled with oil timing altered 45 degrees (like all newer EJ20 cranks) and nitrided (Spec C only from the factory)
right = same as 'left' crank but with 75mm stroke (same as 'middle' crank)
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Old 02-25-2009, 03:11 PM   #288
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Quote:
Originally Posted by Homemade WRX View Post
[slams head into wall]

they are all crossdrilled!! The only differences being

left = 79mm stroke
middle = double crossdrilled with oil timing altered 45 degrees (like all newer EJ20 cranks) and nitrided (Spec C only from the factory)
right = same as 'left' crank but with 75mm stroke (same as 'middle' crank)
That's what I meant Double crossdrilled
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Old 02-25-2009, 04:02 PM   #289
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Quote:
Originally Posted by Homemade WRX View Post
[slams head into wall]

they are all crossdrilled!! The only differences being

left = 79mm stroke
middle = double crossdrilled with oil timing altered 45 degrees (like all newer EJ20 cranks) and nitrided (Spec C only from the factory)
right = same as 'left' crank but with 75mm stroke (same as 'middle' crank)
That's sort of correct...

The left and middle crank are rear thrust (from rear thrust block) and the right crank is centre thrust.

Apart from that what you say is essentially correct.

The photo was to illustrate the double cross drilling and 45 degree phase difference as well as the factory nitriding.
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Old 02-25-2009, 07:14 PM   #290
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Quote:
Originally Posted by bjm View Post
That's sort of correct...

The left and middle crank are rear thrust (from rear thrust block) and the right crank is centre thrust.

Apart from that what you say is essentially correct.

The photo was to illustrate the double cross drilling and 45 degree phase difference as well as the factory nitriding.
well, they could all have the 3&5 main thrust locations...subaru does that from the factory now for one part# per stroke
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Old 02-25-2009, 07:28 PM   #291
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I did know the later cranks have both thrust positions available.

I have to plead ignorance on this one though... how do you tell the thrust position of the earlier cranks? Is there a quick and easy way to tell?
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Old 02-26-2009, 04:01 PM   #292
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Originally Posted by modaddict View Post
I call B.S.

It might spin there for a couple seconds.

8k is realistic. 9k on a stock untouched crank is marketing.

I'm just throwing that out that bro, I'd like to hear from them you know.
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Old 02-26-2009, 04:52 PM   #293
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My Ej22T spun a bearing after about 10k miles of hard driving almost everyweekend and 3 lapping days with a drift day as well. The engine has seen 8000rpms a few times this summer but rev limit was dropped back down to 7500rpms. Spun a bearing testing revs at 5500-7500rpms.

'03 WRX heads stock valvetrain
'91 Ej22T shortblock NEW OEM std bearings on 170k mile EJ22E crank
EJ22T oil pump

I did talk with a Machine shop that builds engines as well. He said that having a constant oil feed to the bearing when they're at TDC is a good thing. They done that to 4G63's and it worked for high RPMs. This double crossed drilled will make the difference in rod bearings bring constantly pressured with oil. Even double cross drilled, oil still has to go through the rod bearing and crank.
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Old 03-18-2009, 04:26 AM   #294
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Subaru Stars we come from the land down under

Hey guys what an interesting thread, some pretty heavy reading, heres a thought and i'm not sure why it hasn't been mentioned yet but the rigolli boys from australia have the fastest drag wrx in the world, they use custom stuff inside their motors however i am sure this is all made by the company PAR in aussie as a friend of mine has built pretty much the same motor using parts sourced from them. His crank is a double cross drilled mains and single crossed drilled rod end unit that runs different sized holes from the outside to center on the main journals, i mean the center main journal has a larger set of holes than the two outer ones, this is done to compensate for the lower oil pressure and volume seen at the center of the crank because it feeds the two rod ends. it is a formula 1 design crank with knife edge and scallopped counter weights to reduce rotating mass. Also he has dowelled the two crank case halves on all the main bolts to prevent the small amounts of twisting that occurs under high rpm which seems to be one of the biggest problems with bearing distortion as the two halves of the crank case move the main bearings change clearance causing them to go out of round. i would love to post some pics of this crank for you all but he is gearing up to run the car this season and the motor is all assembled now, also on the oil pump side of things the word has it here in nz that one of our superGT wrx race cars uses 2 oil pumps stuck together on the end of the crank not sure if the block gets machined or there is a spacer plate but essentially it is running a 20mm gear set inside the pump housing, and yes both of these cars pull over 9000rpm and make big hp. One of the other race cars here runs a moroso baffled sump to reduce oil starvation and some of the rally cars run a standard sump with baffles and oneway trap doors welded into the sumo to prevent the oil pickup from starving under high corner loads. Crowesport owned by Trevor Crowe in christchurch has also raced cars here in NZ for a long time and they also suggest running an extra 0.5L of oil so basically fill to the top notch on the dipstick not the top hole to allow the sump to have more oil in the corners, they have 500hp mid mounted rear drive subaru justy race car and many numerous wrx race cars all making the numbers, i guess maybe the JDM stuff we get here in NZ is different to the USDM stuff, there are still breakages as with any racing it cannot be avoided at the end of the day it is just a matter of time with highly stressed engines in racing conditions. you just build it to last as long as possible with the budget you have
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Old 03-18-2009, 09:10 AM   #295
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yes, rigoli does run PAR's parts...in fact they have their own special heavier duty (super beefy) rod from PAR as they were bending the standard beefy rods.

I'll have to dig through my old email and see if I still have pics.


I have never seen one of their cranks; however are you just saying the #3 (you called it middle) main journal has a larger oiling hole in the crank? if so, that makes sense and has been kicked around before because of it having to feed #2 & 3 rod journals.

Anyhow, always nice to have some more input.

-Micah
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Old 03-18-2009, 03:22 PM   #296
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Default rigoli crank

Yes that is correct the crank my mate has used does have a larger set of oil holes in the center of it he is the local PAR dealer for nz and said the theory behind it is that the oil wants to take the least path of resistance first meaning that the center of the crank still gets good supply as the oil demands increase. Are you guys doing the dowelling on the main bolt holes? I know that this is a fairly inexpensive excersise and if it does help with longevity of the main bearings it is probably worth doing, i have a version 7 sti jdm spec and even though it is a phase2 motor with the revised factory rods is still not strong enough to support my mods i have planned so i will be rebuilding it with argo i beam rods and after reading some of the other threads here will probably be using mahale pistons, factory sti crank(JDM spec is double crossdrilled) acl race bearings and a set of Kelford cams heads they are a custom port cam lift and profile and heavy springs good for revs an hp. the guy with the super gt wrx race car has a cnc setup for doing the crank case dowelling at a reasonable price.

Just a quick note i will be using a factory vf36 turbo rebuilt with a ported p20 single scroll exhaust housing and much larger compressor wheel, has only cost me $850NZD so about $500USD, this turbo setup has been run recently here in nz (albeit using the p25 twin scroll housing) on a version 8 jdm spec c sti and is making 310kw atw and is good for a 10.9sec quatermile (Speedsource is the tuning shop that owns this car) its damn fast for a reasonably standard car. check out NZ performance car magazine for a full run down.

some thoughts or comments on the engine bulid are much appreciated cheers
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Old 05-15-2009, 09:45 AM   #297
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For built blocks that come with a modified cross drilled ej257 crank, what oil modifications should someone be looking into to keep the oil pressure up in the high rpms? I already have a shimmed sti oil pump and process west oil cooler, but should I look into something like a moroso oil pan?

Anything else?
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Old 05-15-2009, 11:17 AM   #298
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^^^see your other thread for discussion.
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Old 05-16-2009, 03:49 PM   #299
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been meaning to post this, just kept forgetting. I know these are two different platforms but evo's cranks are crossdrilled, with the oil throw at the center of the main just like the subaru crank shaft. Here are some differences between the cranks. The evo ROD bearings are wider than our widest MAIN bearings. Each main feeds one rod. Obviously the geometries are a bit different considering that have almost a square engine (85mm bore x 88mm stroke) They also have a rod to stroke ratio 1.70 (150mm rod x 88mm stroke).

Not making any bold statements just throwing out some food for thought.(still does not change my plan to convert my extra 2.5L crank to a straight shot oiling)

Both of my buddies evo engines that we have built use stock bearing clearances with Clevites in one and ACL in the other. The cranks are NOT modified other than being polished by the machine shop. Stock oil pump and and oil coolers. They both rev to 8-83000 DAILY, and 9000 at the track. and yes they have turbos to utilize the extra RPM usage.

DK
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Old 05-18-2009, 01:29 PM   #300
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yes, the 4G63 platform does have a taller rod ratio than the EJ25 and shorter than the EJ20 and should only be utilized for an apples to apples comparison without running actual numbers and forces from the difference in rod and piston weights

Its two greatest differences however are the smaller and lighter piston and the much wider oil wedge for the bearings. These help to reduce the force seen by the bearing.

Note 4" Subaru piston vs. 86mm Evo piston
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