bottom end rebuild parts?

While the engine is out of my friends 98 2.5 gt for new heads, we are going to preemptively rebuild the bottom end and are just unsure of all we should do. Parts/suppliers, etc. We aren't trying to do anything performance, we just don't want to have to pull the damn thing out ever again.

 

Could someone please send me in the right direction?

I'm sure you'll get good answers from the members here, but I would also suggest you join RS25.com.

They have more members doing rebuilds of the 2.5.

 

O.

Not to whore myself out or anything but I started where you are 6 months ago so there's a lot of good info in this thread:

 

http://legacygt.com/forums/showthread.php/97-2-5-dohc-rebuild-165736.html

 

Short version is I used ACL Race bearings and Subaru rings. I reused stock rods and pistons since they were in spec. and just had the crank jurnals polished.

yeah I've had the engine out of my 98 gt a couple times. A machine shop provided me with the parts and I put everything together, and it didn't actually cost that much to do. I used their standard build main bearings (not sure on the brand) and ACL race HX rod bearings, had the bores honed, and used new rings.

 

If you're going to take apart the shortblock you really need have a machine shop measure the journals, crank, rods, bearings, bores, and pistons to ensure your clearances are right. Otherwise it's not likely to last very long.

 

I even took a bunch of pictures when i did it: http://jamalb.net/gallery/main.php?g2_itemId=391

(page 4-5 is when I did the headgaskets over the course of about 10 hours)

I have done a few rebuilds on these motors. I use topline bearings and rings most of the time. Make sure you have a good set of outside micrometers and a bore gauge. You will also need to have the cylinders honed if you use new rings and the crank polished and measured for new bearings. This is not something you can do without the knowledge. I am still scared to start a subi motor after I have it assembled, they are just not an easy motor to rebuild.

Just want to throw out there we found a shop in our local area (charlotte, nc) that knows their shit (so it seems) We were trying to figure out an engine shop in the area and I remember driving by the place and seeing a ton of WRX/STIs and evos. Found it again, walked in and talked to the shop manager - Alex - he was a real cool guy and him and his shop clearly know what they are doing. They get and sell parts cheap - Even subaru OEM. Quoted 1500 to do all the clearance checks for the parts - deck/clean block, polish crank, bearings, rings, oil pump. We aren't expecting any issues from pistons or rods so they werent quoted in the price, we had zero issues out of the bottom end - hell you could still see crosshatching in the cylinder walls at 170K.

 

Long story short - Need something done to your subie in the charlotte metro area, their labor rate is great too, give alex a call.

 

Motion Labs Tuning - http://www.motionlabtuning.com/

Make sure you still have the rods and pistons checked. Esp. the thrust side of the piston. Mine were pretty worn but just barely still within spec.

Update - Alex from Motion Labs gave us a call - needed VIN # since we brought the shortblock in out of the car. He is recommending piston replacement and as I had suspected - the skirts are about to the point of being noisy. He did say that they are completely useable, he just advises replacement as they would probably be out of spec by 50K. Also, went up there today to check everything out, turns out the engine HAD spun a bearing - just hadn't began to destroy everything. Bearings looked like shit, but didn't screw up the crank at all, I was amazed - didn't even think that was possible. It is a very good thing we decided to get it redone.

 

He said unless pistons take forever and a day to get to him, it will be ready for pickup by the end of the week.

Oem Block (yours)Sti pistons ,Sti rods ,Sti Head Gasket, your crank, cleavite bearings, Dohc heads = Torquey ,fuuuuuunnnn motor!

I believe the compression comes out to like 12.48:1

& NO the valves will not hit, I'm running this set up & have been for over 12k ,It's a Blast!

^How did you get 52mm rods to work on your 48mm journal crank?

how did you get 12.5:1 cr with basically a sti bottom end? wtf i hope that the sti has lower cr then that! thats what im putting if for my built motor.

 

this guys mental.

 

stock on our car is 10.5 iirc

 

sti is lower for boost

 

how the hell did you get 12.5? thats like NA race spec.

Stock is under 10:1.

 

An EJ521 short block with our heads milled 0.25mm and STi headgaskets only yields only about a 10.8:1 compression ratio.

 

You NEED to have your rod length, compression height, stroke and deck height to determine if it will fit, then with head volume and piston dome/dish volume you can find static compression ratio. Then you also have to worry about your quench area, this effects detention.

 

STi stuff has a 79mm stroke vs out 75mm stroke, 130.5mm rod vs our 131.7mm rod length and compression height of 30.25 vs our ???(I forget what it is). Deck height on all subaru's is 201mm if it has never been machined.

yeah. sti rods don't work on a phase 1 2.5, and sti pistons would bring the CR down to about 8.2:1.

^How did you get 52mm rods to work on your 48mm journal crank?

My 98 has 52 mm journals

how did you get 12.5:1 cr with basically a sti bottom end? wtf i hope that the sti has lower cr then that! thats what im putting if for my built motor.

this guys mental.

 

stock on our car is 10.5 iirc

 

sti is lower for boost

 

how the hell did you get 12.5? thats like NA race spec.

Stock pistons nare dished, sti's are domed , there is a bunch of numbers out there on cc volume of heads & deck height of pistons,also there is a online compression calculator, I gathered the info typed it in & thats what it spit out.

This engine is amazing & anyone who has drivin in it thinks the same

Stock is under 10:1.

 

An EJ521 short block with our heads milled 0.25mm and STi headgaskets only yields only about a 10.8:1 compression ratio.

 

You NEED to have your rod length, compression height, stroke and deck height to determine if it will fit, then with head volume and piston dome/dish volume you can find static compression ratio. Then you also have to worry about your quench area, this effects detention.

 

STi stuff has a 79mm stroke vs out 75mm stroke, 130.5mm rod vs our 131.7mm rod length and compression height of 30.25 vs our ???(I forget what it is). Deck height on all subaru's is 201mm if it has never been machined.

You guys are forgetting head cc also dictates compression.

yeah. sti rods don't work on a phase 1 2.5, and sti pistons would bring the CR down to about 8.2:1.

Sti rods & pistons do work on my 98 LGt phase 1 motor

I'll pull the numbers together & then everyone can see.

I'm not tryin to step on toes, I just put together what I had & when I put the numbers in

That's what came up.

sti piston are not domed. lmao

stock sti pistons:

 

http://jamalb.net/pictures/stuff/IMG_0900.JPG

 

not domed.

 

My 98 has 52 mm journals

 

Never heard of this...but I wonder if some how you had a short block swapped at one point in time.

 

 

 

You guys are forgetting head cc also dictates compression.

 

 

No I didnt lol, re read

there was a rare case that i saw some one find a phase 2 bottom end in a 99 outback

I think most 99 legacy/outback 2.5s are phase 2 blocks with dohc heads. But using sti pistons in one of those is still going to drop the compression ratio by a lot.

yup^^^^ this guys motor should be slower then ours.

Update: Just got the bottom end back from Motion Labs on Saturday. We had to wait for head gaskets from them (70/pair vs 120/pair from dealer). Just picked them up today and started working on putting it back together with the recently rebuilt heads (about 200 miles on them - someone had them rebuilt but didn't do shit to a 200K+ mile engine). New pistons, bearings, block was decked, crank polished, new oil pump, etc. Started about 6. and about 30 minutes ago this is where we got before saying that will be all tonight. Just want to say - words cannot describe how much I hate the tightening sequence for the heads....

 

http://img.photobucket.com/albums/v215/tweekshook/2012-02-25192442-1.jpg Cylinders 1/3

http://img.photobucket.com/albums/v215/tweekshook/2012-02-25192457.jpg 2/4

http://img.photobucket.com/albums/v215/tweekshook/2012-02-27221218.jpg Where we got.

 

 

 

 

Bonus: One of our next projects...

http://img.photobucket.com/albums/v215/tweekshook/2012-02-27171517.jpg

http://img.photobucket.com/albums/v215/tweekshook/2012-02-27171710.jpg

http://img.photobucket.com/albums/v215/tweekshook/2012-02-27171543.jpg

http://img.photobucket.com/albums/v215/tweekshook/2012-02-27171918.jpg

 

That will be fun. Still can't decide if we want to rebuild the v12, drop in a chevy 350, or go all out and drop in a 572

First thing you should do is to invest in a good leaf rake, next thing to do would be to come to your senses.

First thing you should do is to invest in a good leaf rake, next thing to do would be to come to your senses.

 

Tell that to his parents. Their house - Car was parked in 94' - shift mechanism just crapped out. It was his dad's car (so was the old ranchero we now have in our yard that is next in line) The motor still actually turns fine - just doesn't fire. Believe it or not - quarters and hood are rusted through, but frame and floor are a 7/10 - completely repairable. And about the 572 - that was a joke obviously 13 grand without a transmission. His dad signed the title of the car over to him on his 16th birthday - kind of as a joke, but it will be one of those projects that take forever and are barely worth it. Ranchero is do a little bit of body work - new brakes all around, good tune-up and a new carb - engine is alright.

 

Edit: their house is literally in the middle of the woods (roughly 8-10 acres) - a rake is almost pointless. I installed their Dish Network when I worked there... Dish is mounted about 30 feet up on a tree to clear trees on the other side of the house. Crazy thing is, their signal goes out less than mine.