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Old 06-20-2013, 08:22 PM   #1
Wrxphilzyej25
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Default Hybrid build, what do you guys think?

I have recently lost compression on the hybrid build, What my plans are was
E257 block bore to 100.5
Ej20heads
Ej257 oem head gasket
Wiseco piston
Acl race bearing
Stock ej257 crank and rods
272 crower cams
Sound alright?
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Old 06-22-2013, 11:21 PM   #2
subi400
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Are you going to have someone widen the combustion chamber on the wrx s20 (2.0 L) heads to match the 99.5mm bore of the sti block?

If not, then you really need to consider it.... don't listen to the idiots that say you don't need it.. When it comes time to tune it will be much easier with the combustion chambers of the heads widened.

What bearing clearances are you going with or the shop going to use?
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Old 06-22-2013, 11:25 PM   #3
Wrxphilzyej25
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Acl bearing are already used. But good thinking. Ive had ran it like that as it is with out problem.
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Old 06-23-2013, 10:53 AM   #4
danger1138
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Also to note when purchasing gasket kit, make sure u get the gasket kit that matches the heads your using. If using ej257 heads on ej22 block, you must use the ej257 gasket kit; ej205 heads with ej257 block then ej205 gasket kit is required.

Not sure what heads your using as u only stated ej20 heads, im assuming its ej205 heads, if so go with the 205 gasket kit.
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Old 06-23-2013, 03:14 PM   #5
scby rex
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You talking about head gaskets? If so your wrong. You need the head gaskets for the short block your using.
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Old 06-23-2013, 06:31 PM   #6
kellygnsd
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100.5mm is beyond the recommended bore limit of the stock SB. Use at you own risk, it would be wiser to get a new SB

FYI, there are many "Idiots" out there that believe and have proven that while machining the heads to match the bore is a good way to go about building a hybrid its not the only way to skin this cat. If you have the time and money to send them out and get the heads machined it opens your build up to using OTS pistons and may be an easier option. Custom pistons that bring you CR in check with whatever head package you use also work along with slight chamber polishing. I've been running the same hybrid head and block combo for about 40K cumulative miles on two different Subies on 91 CA octane at 400+ whp.
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Old 06-23-2013, 06:43 PM   #7
03SubyWRX
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Quote:
Originally Posted by kellygnsd View Post
100.5mm is beyond the recommended bore limit of the stock SB. Use at you own risk, it would be wiser to get a new SB

FYI, there are many "Idiots" out there that believe and have proven that while machining the heads to match the bore is a good way to go about building a hybrid its not the only way to skin this cat. If you have the time and money to send them out and get the heads machined it opens your build up to using OTS pistons and may be an easier option. Custom pistons that bring you CR in check with whatever head package you use also work along with slight chamber polishing. I've been running the same hybrid head and block combo for about 40K cumulative miles on two different Subies on 91 CA octane at 400+ whp.
This man speaks the truth. Do what fits your situation. You can absolutely find pistons to lower your CR. I personally went the machining route, but I had no time limit for my build. It was easy to send out my heads and have it done.
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Old 06-23-2013, 06:55 PM   #8
Wrxphilzyej25
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Thank you guy, i have been running ej20 heads on ej257 block that was stock on ej257 gasket for about 40k until i decided to anti lag the car lol, well in all cases. Would manley piston and stock ej257 rods be okay.?
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Old 06-23-2013, 07:54 PM   #9
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Quote:
Originally Posted by scby rex View Post
You talking about head gaskets? If so your wrong. You need the head gaskets for the short block your using.
Yes u Are right regarding the "head gaskets", which i didnt mention at all. I said "gasket kit".
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Old 06-25-2013, 03:00 PM   #10
subi400
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Widening the combustion chambers on the wrx s20 heads is much easier and cheaper. I widened the combustion chambers on a set of NA 2.2 heads to go on a ej251 block and it took me only a few hours to do it, really not that hard to do.

With doing the pistons, you have to get the pistons, then split the block, replace the bearings since you are in there, have the crank checked just in case, then have the bores honed to work with the new pistons.

The sti pistons by themselves are just fine... But add bad tuning and knock and not soo much. Even forged ones won't hold up too long to knock if it is bad enough...

Get the chambers widened with the proper head gasket and tune it accordingly and you WILL NOT have to worry about it...period
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Old 06-25-2013, 04:01 PM   #11
03SubyWRX
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Quote:
Originally Posted by subi400 View Post
Widening the combustion chambers on the wrx s20 heads is much easier and cheaper. I widened the combustion chambers on a set of NA 2.2 heads to go on a ej251 block and it took me only a few hours to do it, really not that hard to do.

With doing the pistons, you have to get the pistons, then split the block, replace the bearings since you are in there, have the crank checked just in case, then have the bores honed to work with the new pistons.

The sti pistons by themselves are just fine... But add bad tuning and knock and not soo much. Even forged ones won't hold up too long to knock if it is bad enough...

Get the chambers widened with the proper head gasket and tune it accordingly and you WILL NOT have to worry about it...period
He might not have the equipment/skill to do it himself, which means he will have to send it out to a machinist.

He's putting in 100.5mm Weisco pistons, so he has to split the block anyone to have it bored/honed. He can just put in lower CR pistons and not touch the heads. This is an option.
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Old 06-25-2013, 06:14 PM   #12
scoobyrex123
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I have about 15k miles on my hybrid build non machined ej20 heads, Manley forged rods je forged hybrid pistons to correct cr. I'm making about 400 wheel reliably.
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Old 06-25-2013, 11:02 PM   #13
WoodsWagon
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The other benefit to opening up the combustion chambers to EJ25 specs is that you help unshroud the valves a bit. You don't need a machine shop to work the heads, a die grinder with a good burr and a flap wheel will get the job done. Look at pictures of the STi head, use the 2.5l headgasket to mark a line showing the cylinder bore on the head in permenant marker, and get to grinding. Be careful not to slip with the grinder and gouge the gasket surface or the valves. With a piece of clear plastic and some water you can CC each combustion chamber to make sure they match when you're done.

Pistons are the other good way to deal with the problem. Thick headgaskets are not. Spacing the heads up off the block messes with the cam timing and eliminates any quench areas between the pistons and the heads. That's what leads to tuning issues because a cylinder with no quench is more susceptible to detonation.
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Old 06-26-2013, 02:25 AM   #14
kellygnsd
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Quote:
Originally Posted by WoodsWagon View Post
The other benefit to opening up the combustion chambers to EJ25 specs is that you help unshroud the valves a bit. You don't need a machine shop to work the heads, a die grinder with a good burr and a flap wheel will get the job done. Look at pictures of the STi head, use the 2.5l headgasket to mark a line showing the cylinder bore on the head in permenant marker, and get to grinding. Be careful not to slip with the grinder and gouge the gasket surface or the valves. With a piece of clear plastic and some water you can CC each combustion chamber to make sure they match when you're done.

Pistons are the other good way to deal with the problem. Thick headgaskets are not. Spacing the heads up off the block messes with the cam timing and eliminates any quench areas between the pistons and the heads. That's what leads to tuning issues because a cylinder with no quench is more susceptible to detonation.
My name is Kellygnsd and I approve this message.
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Old 06-28-2013, 03:33 AM   #15
Wrxphilzyej25
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Got cha, machinist is what i'm doing. I trust hin mire than i trust myself. Laser machining,
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