TheSamba.com :: View topic

Sun Jul 09, 2023 11:02 pm

Hey there Subaru Conversion fans!

I'm starting the process on migrating our 1986 Westy to a FB25B platform. I've previously swapped a EJ25 DBW engine into my 1990 TinTop, so I've got some experience with the process. In this build I plan on using a subarugears reversed 5spd MT with LSD.

There are a couple of versions (at least) of the FB25B platform. One that has a manual power steering pump, and a newer version with electric power steering. I'm using a motor from a 2011 Forester with manual power steering. I was able to get the car from Copart, and sold almost enough to pay for the car (free engine, yay!).
As you may or may not know, these cars have an immobilizer that is tied to the key, ecu, and dash cluster. These all need to be present for the engine to run. I'll be using a dash cluster/canbus emulator from AGT engineering to work around this.

I will share my plans for the conversion parts below. The build is mostly Van Cafe/RMW and a little Small Car (intake, oil pan, coolant crossover pipe)

So far this is what I've learned from investigating:
The bolt patterns are the same between EJ25 and FB25. Can use an adaptor plate and VW trans.
The engine mounts are the same as the EJ25. I've confirmed that the RMW Engine Carrier mounts up perfectly. Will share photos
The FB25 Intake is much taller than an EJ25 non-DBW. Similar in height to the DBW from my 2005 EJ25.
The FB25 depth wise is maybe .5 inch deeper. Will measure tomorrow, comparing against my other vehicle's RMW carrier bar depth.
It looks like reversing the cooling similar to an EJ25 is not an option at this time. Will be using the small car wrap around coolant.
The Van Cafe Thermostat coolant pipe fits perfectly. Will share photos.

[*] DBW works fine. Just extend the throttle pedal wires up to the front with shielded cable.

Parts:
https://docs.google.com/spreadsheets/d/1z1Z4dwkaMo63uXGc7gcyvB0b10UqX9TD_OBSKyQ4xzQ/edit?usp=sharing

Engine Scan:
https://poly.cam/capture/80F33C8A-5792-4ADA-9397-FC7D9F33D588[/list]

I'll document here as I go. Would love to share any info I have.

Cheers!
-Montana

Sun Jul 09, 2023 11:21 pm

What benefits do you expect from this endeavor?
Other than the challenge? :wink:

I’ve never heard of the FB25 (but haven't paid a lot of attention outside of EJs)
What's better about the FB25 engine?
Are parts readily available?
Does EJ25 exhaust or engine mounts or oilpan fit?
Does "manual" power steering" incorporate bodybuilding? :wink: or referring to "hydraulic" vs "electric"?

=== EDIT ==========
I see you've added Seattle to your sig line.....?
I was unaware tht there was a 'new/different' 2.5L engine
Lower torque curve suggests taller gearing can be used and a lower freeway RPM.

from: Wikipedia, Subaru FB25

Unofficially, Subaru stated that "FB" stands for "FHI/Future and Brand New/Boxer".[2] It was announced in September 2010 as the third generation (following the EA 1st and EJ 2nd generations) boxer engine family with 2.0 litre and 2.5 litre naturally aspirated variants.[3] The FB has an all new block and head featuring dual overhead cams with intake and exhaust variable valve timing (which Subaru designates as AVCS, standing for Active Valve Control System), and a timing chain that replaced the timing belt. Moving to chain-driven cams is said to allow the valves to be placed at a more narrow angle to each other and shrink the bore of cylinder from 99.5 to 94 mm (3.92 to 3.70 in). It results in less unburned fuel during cold start, thereby reducing emissions. Subaru is able to maintain the exterior dimension substantially unchanged by using asymmetrical connecting rods like those in the EZ36 engine. The FB is only marginally heavier than an equivalent-displacement EJ. In Jan 2011, Car and Driver was told direct injection would be added soon.[4] Subaru claims a 28-percent reduction in friction losses, mainly due to lighter pistons and connecting rods.[4][5] A compact oil pump is also credited with contributing to the reduction in friction losses.[1] The FB has a 10% improvement in fuel economy[1] with the power coming on sooner and the torque band being broader.[6] The compression ratio is slightly higher, and the stroke has increased compared to the EJ engine; previously, the chassis precluded a longer stroke. These changes improve combustion efficiency and allow higher torque at lower speeds. The FB is built at Gunma Oizumi Plant and was initially available as a 2.5 litre displacement engine, starting in Forester models, with a 2.0 litre model to follow in Imprezas.[1][4] 0W–20 oil is used to help fuel economy, and approximately 1 litre more oil is used as the newly adopted timing chain requires an oil supply.[2]

Mon Jul 10, 2023 12:05 am

Nothing in the OP's profile about where they are . . .

Mon Jul 10, 2023 7:36 am

I think moving to the newer FB engine makes a lot of sense because it gets you back into engines that are new enough that they can be bought low mileage from a wrecking yard. That's the way it used to be with EJ25s, but since they stopped using them in 2012, they're all high mileage now.

The electronics have been the big missing piece of the puzzle for this engine, so I'm interested and excited to see what the OP comes up with for this aspect of the conversion.

Mon Jul 10, 2023 7:41 am

Yes that is worthwhile. Also 10% better fuel mileage, and the lower RPM. But using that requires gearing changes, which are expensive, troublesome, and will the taller gears remain available as time goes on?
But there's the 5MT...
I wonder what SmallCar is up to regarding the FB25....

Mon Jul 10, 2023 7:58 am

D Clymer wrote: I think moving to the newer FB engine makes a lot of sense because it gets you back into engines that are new enough that they can be bought low mileage from a wrecking yard..

except...

this generation of engine from about 2010-15/16 were all oil burning piles of trash....no better or worse than any other mfgr of that time period trying to meet CAFE/EPA standards

there were issues with the ACVS systems, screens getting plugged up with oil sludge etc

so a used mystery engine isn't always the best idea no matter what brand.

all I'm saying is be careful. the VVT is really where the magic happens on these engines

Mon Jul 10, 2023 8:22 am

Thanks Skills for dropping some knowledge. My girlfriend has a 2015 Forester with this FB25. No oil consumption issues that I am aware of but I will start checking more often.

Mon Jul 10, 2023 8:58 am

shagginwagon83 wrote: Thanks Skills for dropping some knowledge. My girlfriend has a 2015 Forester with this FB25. No oil consumption issues that I am aware of but I will start checking more often.

IF you do proper oil changes at the interval LESS than the OEM suggested you should be fine.

some reading:

https://www.torquenews.com/1084/now-subaru-s-oil-consumption-lawsuit-settled-what-should-you-do

and some more:

https://static.nhtsa.gov/odi/tsbs/2016/MC-10120985-9999.pdf

I would like to add...

this isn't a Subaru problem, it's a government problem that turned everything into a fucking 2 stroke from about 2010-2016+/- to meet these asinine CAFE/EPA regs. It impacted almost every vehicle made in this timeframe

the fix? go back to the old style rings (and sometimes pistons) and ditch the 'low tension' garbage they were forced to make

Mon Jul 10, 2023 9:02 am

Cool project ! I'm in Seattle with a 2011 ej2.5 in my doka and an extracted collection of ez30 engine+install parts to sell.
Just wanted to chime in so I get notifications on your build. Good luck !

Tue Jul 11, 2023 9:36 am

While I was all about the new fb engines when they came out because of the timing chain, I have since changed my mind after owning a 2012 Impreza with one.

I would personally avoid these engine due to the complex mating of all the machined surfaces. The front timing cover, valve cover, cam carrier tray and head all come together and are rtved together. Fixing a leak in a fb Subaru requires pulling the engine because of access, typically a $3500 job to fix a timing cover leak.

This is in addition to the oil burning issues and all the complexity of swapping.

The ej likes to leak but at least all the seals are very simple to replace with the engine in car. Until Subaru discontinues the ej short blocks I see no reason to force an upgrade to the fb. You can essentially get a brand new ej25 using the block with rebuilt heads.

Tue Jul 11, 2023 11:00 am

This video elaborates a bit more on the technical changes with the development of the FB25 that Skills has already mentioned.

Tue Jul 11, 2023 1:47 pm

The guy is a thinker and quite thorough.
But one thing.....he poo-poos a 6-8mpg mileage increase. That's 25%. That's huge fuel$ saved. And a huge contribution towards for 'fleet sales' targets.

1,000 miles at 18 mpg and $4/gal costs me $222. If I could get 25% that's $55 every 1,000 miles.
In 100,000 miles, 25% saves $5500. That would pay for a few oxy sensors & cats.

OTOH I don't know where he gets that 25% 6-8mpg increase number.
6-8mpg seems unreal. I'm thinking 1-2mpg for those efforts but whadduIknow.

Gotta wonder what the pollution increase is for more oil burned, and degraded emissions control components.

Thanks for the video.

Tue Jul 11, 2023 5:11 pm

Sodo wrote: The guy is a thinker and quite thorough.
But one thing.....he poo-poos a 6-8mpg mileage increase. That's 25%.

except it's false

depending how the car is optioned and driven....1, maybe 2 mpgs

the fix? lighten the f*cking car up. We had carbureted... carbureted imports (honda, toyota etc) getting 40+ mpg's in the 80s

cars just got heavier and heavier to the point that today a new car gets the same mpg as a '55 chevy convertible. sad....

plus, lets not forget the owners repair cost/frustration and environmental impact of ripping these apart (under warranty if you're lucky) and replacing the low tension rings with what is tried and true.

put the goddam cars on a diet. there is no reason we're back in the 60's and have to open up a modern engine at 60-80K today like we did back then.

we have gone further backwards than forwards

Fri Nov 29, 2024 5:57 pm

Hey man! I did the same conversion, but with a 2017 forester. I'd love to be in touch :) my security system has just gone haywire, so I'm thinking of changing to a 2020 engine.

I'll PM you once my account isn't new anymore and samba lets me. It's been quite the adventure!

-Kurt

Sat Nov 30, 2024 1:19 am

Welcome!

Sat Nov 30, 2024 7:43 am

trukrupes wrote: Hey man! I did the same conversion, but with a 2017 forester. I'd love to be in touch :) my security system has just gone haywire, so I'm thinking of changing to a 2020 engine.

I'll PM you once my account isn't new anymore and samba lets me. It's been quite the adventure!

-Kurt

Please create a thread and post pics of your conversion. I'd love to see your van.

Sat Nov 30, 2024 11:54 am

Timely video about the Subaru engine types and comparisons.
https://youtu.be/CiqCBQujTq0?si=qU9RSSMf23EkLPfG

BK

Mon Dec 02, 2024 2:17 pm

4Gears4Tires wrote: trukrupes wrote: Hey man! I did the same conversion, but with a 2017 forester. I'd love to be in touch :) my security system has just gone haywire, so I'm thinking of changing to a 2020 engine.

I'll PM you once my account isn't new anymore and samba lets me. It's been quite the adventure!

-Kurt

Please create a thread and post pics of your conversion. I'd love to see your van.

I will, once it's finished. Right now things are very hairy, and tbh I think people should go with the direct injection models because the wiring is simpler. Mine is a nightmare I wouldn't want someone to go through.