Welcome to the North American Subaru Impreza Owners Club Tuesday March 26, 2019
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Built Motor Discussion

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 02-22-2019, 12:54 AM   #1
thebetguy
Scooby Newbie
 
Member#: 132962
Join Date: Nov 2006
Chapter/Region: BAIC
Location: bay area-near SF
Vehicle:
06 2.5i supersport
crystal grey metalic

Default Fa20dit used longblock selection for build

I'm starting to plan a ground up build for my 16 wrx and am looking at buying a used longblock I can tear down, build, and swap it to reduce time without my car. There appears to be lots of options out there but I want to be sure I'm not blowing it buy buying something that's missing sensors or has less efficient oiling or who knows what.

Besides no tgvs and different rods and pistons(won't matter), is there anything that would inhibit a jdm fa20dit from dropping right in and wiring up the same? Also, differences between the wrx and Forrester XT other than compression?

The reason for wanting a direct swap is so that if for some reason I decide to sell the car instead of going full race car down the road, I'd like to be able to throw the stock setup back in.

If there is a smarter way to go about this other than buying an sti, please share. Thanks for your time
* Registered users of the site do not see these ads.
thebetguy is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 02-22-2019, 01:14 PM   #2
Turn in Concepts
NASIOC Vendor
 
Member#: 93646
Join Date: Aug 2005
Chapter/Region: MWSOC
Vehicle:
Many Track Records
Let us help you go fast!

Default

There is a smarter way to do this. Stick with me and I'll explain.

I am operating under the assumption that you are building it for more power. With that in mind you're going to want to do rods and pistons. So no matter what you do that's a sunk cost.

From there you need a case and a crank.

MOST Subaru owners are not proactive in their engine upgrade such as you are being. MOST Subaru owners go the route of an upgrade when there's a failure. MOST failures on these engines are due to one of two things - bent rod or dead bearing.

Lets talk about the crank first.

In either of those common failure points the crank is toast so chances are you will need a new one.

Now lets talk about the case.

A Subaru case is a floppy bag of aluminum that just holds in the guts. As such it moves around quite a bit. When you are starting with a fresh motor you will need and want the case to be straight and true. This means one of two things. Lots of machine work or new case.

GOOD machine work to straighten a used case will cost MORE than just buying a new case. I KNOW THIS FOR A FACT as I JUST paid the invoice to have that machine work done on an FA20 build.

So here's where we are:
You know you need new rods
You know you need new pistons
You can be pretty sure that if you buy a used motor you're going to need a crank
You know for a fact that if you buy a used motor you're going to need machine work that when done properly costs more than a new case.

Here are my recommendations:
1) Purchase a pre-assembled build block from a reputable builder.
2) Purchase the components new and assemble it yourself

This fixes a lot of the maybe and gotcha problems you'll run into buying a used engine/shortblock.

Now for the heads.
Your heads will need work. Whether or not you use the ones off your existing engine or buy used ones head work is a sunk cost, and whichever you choose you should have them completely gone through and checked (remember that floppy aluminum? yeah, heads too).

Now since this is a sunk cost and sunk effort AND you're looking to save time in this case I would recommend buying used, have them refreshed, and then assembled onto your new shortblock.

Now you've got an assembly that is pretty much most of the way there. At this point you pull your old motor, swap over the intake, exhaust, sensors and accessories. Plop it in, check for leaks and tune.

At this point in time strip the heads off your old motor sell them to the next guy who follows this logical path for what you paid for the used heads you purchased, and it's a net zero. Yes, you could sell them for more even, but that's up to you.

Also at this point you can sell your old short block to the next guy who is dumb enough NOT to follow this logical path.

For those of you that are astute readers you may now be questioning me. You may very well say "WTF Clint?!" In one part you told him to get a new case, but in another you told him to get used heads. How does that make sense?

It's very simple. Cost. A new case is just under 1K. New head castings are 579 each. Then you need cam carriers at 193 each. and cams at 211 each, and cam gears and bolts, and valves and springs and retainers and keepers and covers and cover bolts and then and then and then and then and then and then. It's cost. Pure and simple.

So by following this clear, concise, logical, and if I may say so, masterfully written plan you will find that you can get a built motor into your car with actually very little downtime.

-Clint

Last edited by Turn in Concepts; 02-22-2019 at 01:22 PM.
Turn in Concepts is offline   Reply With Quote
Old 02-23-2019, 06:07 PM   #3
thebetguy
Scooby Newbie
 
Member#: 132962
Join Date: Nov 2006
Chapter/Region: BAIC
Location: bay area-near SF
Vehicle:
06 2.5i supersport
crystal grey metalic

Default

Wow thanks for awesome reply. That sounds like a great plan. The problem now is deciding how far down the built motor rabbit hole I should go. From what I can tell, with a properly sorted out short block with rods, pistons and bearings, that the head and fueling will become the limiting factor. So then I'm looking at oversized Valves and a port injection kit.

Then being limited by California 91 so water/meth setup. And then limited by drivetrain. I really appreciate your input and what I'm taking away is that I need to decide on what I really want out of this build and write it all out.
thebetguy is offline   Reply With Quote
Old 02-23-2019, 08:01 PM   #4
adam99
Scooby Newbie
 
Member#: 480524
Join Date: Jan 2018
Location: Pa
Vehicle:
2015 WRX
Black

Default

Quote:
Originally Posted by Turn in Concepts View Post
There is a smarter way to do this. Stick with me and I'll explain.

I am operating under the assumption that you are building it for more power. With that in mind you're going to want to do rods and pistons. So no matter what you do that's a sunk cost.

From there you need a case and a crank.

MOST Subaru owners are not proactive in their engine upgrade such as you are being. MOST Subaru owners go the route of an upgrade when there's a failure. MOST failures on these engines are due to one of two things - bent rod or dead bearing.

Lets talk about the crank first.

In either of those common failure points the crank is toast so chances are you will need a new one.

Now lets talk about the case.

A Subaru case is a floppy bag of aluminum that just holds in the guts. As such it moves around quite a bit. When you are starting with a fresh motor you will need and want the case to be straight and true. This means one of two things. Lots of machine work or new case.

GOOD machine work to straighten a used case will cost MORE than just buying a new case. I KNOW THIS FOR A FACT as I JUST paid the invoice to have that machine work done on an FA20 build.

So here's where we are:
You know you need new rods
You know you need new pistons
You can be pretty sure that if you buy a used motor you're going to need a crank
You know for a fact that if you buy a used motor you're going to need machine work that when done properly costs more than a new case.

Here are my recommendations:
1) Purchase a pre-assembled build block from a reputable builder.
2) Purchase the components new and assemble it yourself

This fixes a lot of the maybe and gotcha problems you'll run into buying a used engine/shortblock.

Now for the heads.
Your heads will need work. Whether or not you use the ones off your existing engine or buy used ones head work is a sunk cost, and whichever you choose you should have them completely gone through and checked (remember that floppy aluminum? yeah, heads too).

Now since this is a sunk cost and sunk effort AND you're looking to save time in this case I would recommend buying used, have them refreshed, and then assembled onto your new shortblock.

Now you've got an assembly that is pretty much most of the way there. At this point you pull your old motor, swap over the intake, exhaust, sensors and accessories. Plop it in, check for leaks and tune.

At this point in time strip the heads off your old motor sell them to the next guy who follows this logical path for what you paid for the used heads you purchased, and it's a net zero. Yes, you could sell them for more even, but that's up to you.

Also at this point you can sell your old short block to the next guy who is dumb enough NOT to follow this logical path.

For those of you that are astute readers you may now be questioning me. You may very well say "WTF Clint?!" In one part you told him to get a new case, but in another you told him to get used heads. How does that make sense?

It's very simple. Cost. A new case is just under 1K. New head castings are 579 each. Then you need cam carriers at 193 each. and cams at 211 each, and cam gears and bolts, and valves and springs and retainers and keepers and covers and cover bolts and then and then and then and then and then and then. It's cost. Pure and simple.

So by following this clear, concise, logical, and if I may say so, masterfully written plan you will find that you can get a built motor into your car with actually very little downtime.

-Clint
Welp that settles my big question. You guys are obviously very knowledgeable and give out tons of great info for free. Looks like ill be going with TiCs shortblock when the time comes.
adam99 is offline   Reply With Quote
Old 02-25-2019, 01:37 PM   #5
Turn in Concepts
NASIOC Vendor
 
Member#: 93646
Join Date: Aug 2005
Chapter/Region: MWSOC
Vehicle:
Many Track Records
Let us help you go fast!

Default

Quote:
Originally Posted by thebetguy View Post
Wow thanks for awesome reply. That sounds like a great plan. The problem now is deciding how far down the built motor rabbit hole I should go. From what I can tell, with a properly sorted out short block with rods, pistons and bearings, that the head and fueling will become the limiting factor. So then I'm looking at oversized Valves and a port injection kit.

Then being limited by California 91 so water/meth setup. And then limited by drivetrain. I really appreciate your input and what I'm taking away is that I need to decide on what I really want out of this build and write it all out.
Do NOT do oversized valves at this time! At least the exhaust valves. The OEM valves are inconel and sodium filled. They are the current pinnacle of exhaust valve materials at this time. The aftermarket has not caught up yet.

The reason I caution you about this is these motors run very hot in terms of combustion, and from our and other very good shop's experience they are just cooking through the aftermarket valves.
Turn in Concepts is offline   Reply With Quote
Old 02-25-2019, 01:38 PM   #6
Turn in Concepts
NASIOC Vendor
 
Member#: 93646
Join Date: Aug 2005
Chapter/Region: MWSOC
Vehicle:
Many Track Records
Let us help you go fast!

Default

Quote:
Originally Posted by adam99 View Post
Welp that settles my big question. You guys are obviously very knowledgeable and give out tons of great info for free. Looks like ill be going with TiCs shortblock when the time comes.
Hang tight for a bit... We have something in the works that should be ready for release soon... I hope soon (we've been working it for 1.5 years now).
Turn in Concepts is offline   Reply With Quote
Old 02-25-2019, 01:58 PM   #7
BlueGoldWRX
NASIOC Supporter
 
Member#: 443842
Join Date: Apr 2016
Chapter/Region: Tri-State
Location: Long Island NY
Vehicle:
2015 WRX Premium
WR Blue Pearl

Default

That’s good to know about oversized valves. I kept my stockers, just cleaned them up.
BlueGoldWRX is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 10:17 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2019 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.