Sway Tale

Subaru engines are compact but suck past 300hp. I decided rather than change platforms or convert my car to rear wheel drive, it would be better to just change the engine supplier.
Stock STi drivetrain, still AWD.

Note: Do not attempt this swap and expect to move the engine/transmission in any direction using factory suspension mounting point and a Subaru transmission. The only way to "lower" the engine is to do a body lift. Inspect and understand how and why Subaru achieved this on the Forester. If this does not make sense, then you will negatively impact handling by attempting to "lower" the engine and transmission.

There are multiple reasons I made no attempt to move the engine relative to the original design.

Car specs:
2002 Subaru Impreza WRX shell
2004 Sti front end, STi suspension, brakes, subframes etc. The only thing that's still WRX is the seats and trunk.
2007 STi Transmission, top secret modifications
2005/2006 STi harness/wiring/electronics/ABS/DCCD/(center diff control)...for now

Engine setup:
LS...stock ish, bolt ons
Victor Jr (EFI), 4150 wilson throttle body
Custom exhaust
Working STi cluster (Dakota Digital Tach converter helps here). DCCD, ABS and AEM CD-7
Pierburg CWA400
Clutch Masters/PTT 7.25" multi disc with Quartermaster HRB conversion for STI transmission
Radium stuff here and there

List of information I would like to have known before swapping an LS into anything:
Post #1 Cooling system related
Post #2 Oiling system related
Post #4 Intake Manifolds
Post #21 for weight of LS iron block and some other pieces
Post #22 and #24 for ARP bolts and stock rods, it doesn't work. Use new GM rod bolts instead.
Post #27 LS GEN III vs GEN IV rods and pistons
Post #29 Computers and electrical stuff
Post #40 Clutches for the LS that don't exist.
Post #46 Nonsense about 4150 throttle body single plane vs long runner FAST 102
Post #57 Melling oil pumps
Post #62 Crankcase venting
Post #66 LS2 Naturally Aspirated with LS7 headers and unequal length Y pipe Sound clip
Post #76 Head bolt thread repair
Post #83 STi transmission interesting facts
Post #94-103 Standalone EMS comparisons
Post #104 Adapter plate that Clutch Masters builds for me
Post #114 DR44G vs CS130D alternator size comparison + alternator pulleys
Post #116 LS vs other engine choices
Post #124, #125 front motor plate
Post #126 mid plate ideas
Post #129 Subaru Fuel tank explained

How version 1 was:






Now:



Some interesting things about the cooling system:

Steam Ports & Coolant:
It is not neccesary to use the rear steam ports if the front steam ports are higher. The rear steam ports will not form an air pocket and will instead circulate the coolant in a useless way. This depends on how your engine is mounted, the flywheel end of my engine is angled downward so much that the rear steam ports are lower than the front by more than an inch.
If your engine is angled level to the ground when installed then you may have a use for the rear steam ports. They only help if the steam ports are at the same height. GM stopped utilizing the rear steam ports on the LS at some point.

If you are using an electric water pump, do not use the rear steam ports. Electric water pumps for automobile engines do not create enough pressure to utilize the rear steam ports. It will be more efficient only using the front steam ports.
The LS mechanical water pumps make more than enough pressure at higher than idle RPM and do not have this problem.

A note about expansion tanks and steam ports. You have to use a restrictor for the steam ports, this also applies if you are venting the top of the radiator to an expansion tank.
If you are connecting the steam ports and/or the radiator top port to an expansion tank then you need to use some form of restrictor. 1.5mm - 3mm orifice is the requirement (1/16 inch -7/64 inch). Too much coolant can bypass the radiator through the expansion tank. Installing a restrictor will help with radiator efficiency and coolant temps. You can use a turbo oil feed line restrictor, they usually come 1/8 npt on one end and 4 an on the other.
OEM Corvette radiators already have a restriction for these hoses, the orifice for the steam port and the expansion tank vent from the radiator is 1/16 inch in diameter. Do not be fooled by the nipple on the radiator or the hose size. Knowing what size orifice to use takes some experimenting but 1/16 inch is a good staring point.

EARL's steam port adapter clears the FAST 102. EARL's offers -3an, -4an, and dual or single outlet versions. Part number for 4an: LS9804ERL

Another note on steam ports. They are more efficient when they are tee'd together above the steam ports. As in seperate hoses from each steam port to a point higher than the steam ports themselves and then a tee/junction/etc then run them to an expansion tank. This is not possible if connecting the steam ports to the top of the radiator because the radiator is usually at the same height as the steam ports.
Do not go below the steam ports for any reason, it negates the whole air pocket removal idea. The point of them is to continually push air bubbles to a point higher than the engine such as an expansion tank. Air bubbles/pockets like to travel upwards.
A thermostat or restriction in place of one will help even more with this.
I ran a 10" x 24" x 2.5" radiator with an electric BMW water pump. It helped me learn how small changes in the cooling system can have drastic effects on your coolant temperature.


If you need a 3 wire coolant temperature sensor:
You can use the sensor from the following cars:

Subaru Baja 2003-2006
Subaru Forester 1998-2008
Subaru Impreza 1998-2007
Subaru Legacy 2000-2004
Subaru Outback 2000-2004
Mazda Miata 1999-2005
Mazda Protege 1997-2000
Saab 9-2X 2005-2006

Part numbers:
KLK1-18-840
CS-201
1802-98718
22630AA161

Any engine, any trim level. They all came with the same sensor whether it was an STI or a base model forester.

It has the exact same resistance as the LS coolant temperature sensor and does not need to be calibrated, tuned, or flashed on any ECU meant to run an LS. It fits the LS cylinder heads the exact same way as the GM sensor. Same thread and same size.
I am using this sensor on an Edelbrock Pro Flo 4 and my STI gauge cluster. Two wires go to your engine ECU and one wire goes to your gauge.

There is only one caveat with this, you need a used pigtail for the sensor. Luckily, used harnesses and pigtails are cheap for japanese cars. It is unique to this sensor and nothing else uses it.
There is a company called iWire that sells the connector and terminals for this sensor if you would like a new one.

Pierburg CWA400 and TinyCWA controller:
This water pump is an alternative to Meziere, davies craig, etc.
It is available off the shelf at most auto parts stores and is cheaper.

You do not need a controller for it, connecting the pwm wire to ignition will cause it to run at 100%, disconnecting pwm wire afterwards will cause it to run at minimum for a few minutes and then stop.
TinyCWA controller allows you to control duty cycle of this pump based on coolant temp in a lot of different configurations. Pulse mode, constant mode, variable duty cycle, etc. It can even turn on a fan relay based on coolant temp.
The coolant temp sensor that comes with it fits in place of the LS sensor (Same thread, same size). I installed it on the passenger head.

The pump uses 1.5" hose connections. It also requires a water manifold adapter or modifying the stock water pump. You can clock the orientation of the pump but it require removing the inlet/outlet cover and grinding a new notch in it.

Water Pump adapter/manifold:
I am using the 417 motorsport coolant manifold, it has four 16an ORB ports and two 1/8npt ports.

The individual fitting water manifolds take up more space than these two options and require a bunch of hose routing and fittings. Using a complete manifold takes up less space and allows you to just run a radiator hose and heater core feed directly to the manifold.

Thermostat:
Run a thermostat or a way to restrict flow somewhere, it will help keep the temperature more stable in the engine. My LH and RH head were showing a temperature difference of 30°F without one. Running no thermostat will not help lower temperatures, you will still need to introduce a restriction to flow somewhere. The reason for this isn't to "slow down" the coolant, its actually to speed it up. Restrictions cause higher pressure. Higher pressure causes higher flow velocity. Well, not exactly that simple but there is no such thing as "slowing down the flow" or "the coolant circulates too fast to absorb heat". The faster the coolant moves the more efficient your cooling system.
I ran my thermostat SBC style, at the top of my water outlet. In my case, top radiator hose. Katech makes a piece that fits in place of the stock LS thermostat exactly for this reason. Also very common to hear people mention about this on older platforms such as SBC, BBC, BBF. Unfortunately its usually accompanied by the phrase "to slow the coolant flow in the block so it can absorb more heat".

Sway Tale

Engine assembly and bearing clearances:
When measuring for main bearing clearance you must install all 6 bolts on the main caps and they must all be torqued correctly. Even the small side bolts make a difference in the clearance by as much as 0.0004" - 0.0007".
Same applies for rods, correct torque is required. Avoid plastigauge, use a bore gauge in a mic instead.

You can use a bore gauge/mic and then plastigauge to check if you main journal bores are out of alignment. Compare your measured bearing clearances to the runout on the crnakshaft and decide if your block needs a line bore/hone.


The only rule is aluminum blocks should be assembled with at least 0.0005" less main bearing oil clearance than you would use for an iron block. It doesn't matter how much power you are making.

I like tighter clearances. 0.0015" on aluminum block mains and minimum 0.0020" on the rods. Depending on how worn your crank and block is you may have problems with clearances. Sometimes you may even have clearance taper or misalignment on the mains or very rarely the rods.
OEM GM bearings usually give me 0.0020" - 0.0025" oil clearance on mains & rods. What type of bearing material or coating is also an important factor.

Bi-metal bearings are good with cast cranks and tighter clearances
Tri-layer bearings will wear rapidly with too small of a clearance
Coated bearings can be either type and the same rules apply

Operating oil temperature and viscosity play a very big role. Your oil pressure will not be very good at 245°F with mains at 0.0030" and that will cause a lot of wear (metal on metal contact) on the bearings.

Oil Pans, dipsticks, and windage trays:
All the OEM GM oil pans are crap. They are only good enough for a street car that does some roll racing, don't require mounting an oil filter adapter, and the fulfill the silly NVH reduction/Transmission mounting nonsense. The biggest downside to them is actually the oil filter contraption.

The worst oil pan is the AWD pan, all cars with this pan have a lot of wear on the bearings and oil starvation at the pickup is a non stop problem.

The GTO oil pan is a very overpriced piece of ****. I have seen them go for $400 used and $750 for new. Even the normal price of $370 is steep for how shitty it is. It doesn't even clear subframes on most swaps. There are much better aftermarket front sump pans.

Corvette C6, Camaro 2010+, F-body pans are really not that much better. The oil sumps are very long, not tall enough and control oil slosh about as well as a bathtub. The C5 batwing is no exception.

The van/truck rear sump pan actually has a good design if the engine is installed with the typical 3° or more rearward angle, the oil always drain to the rear due to gravity and oil pan angle, the sump is shorter in length and taller in height which is better at controlling oil movement. Unfortunately the baffle doesn't do much and the oil pan is too tall for adequate ground clearance on most cars. The holley pans are like this but they at least have oil trap doors.

For some reason, that I haven't figured out yet, GM setup up various styles of bypass valves that limit oil pressure....or flow??...or something?? After the pump at the oil filter. Why they did this modification on the oil pan I don't understand because its present on some Gen III, Gen IV, and AFM LS engines (in various forms and styles). AFM engines require generous amounts of oil pressure for the hydraulic lifters and solenoids in the valley cover. Yet, they still have this crap and collapsed lifters are very common on AFM equipped engines. If you are removing AFM or don't have it, get rid of whatever valve is in your oil pan for the oil filter.

I recommend buying an aftermarket pan with useful baffling or at the very least replacing the baffling with something from improved racing. Remote mounting an oil filter and deleting the bypass valve from the pan is a great idea.
Increasing your oil capacity is a solution to oil starvation, on both wet and dry sump systems. Accusump is a booster meant to prevent lack of oil pressure that should not normally occur. It's a backup to prevent engine failure, please don't use it to fix oil pressure issues related to oil capacity.

Dry sump is generally used for remote mounting the oil system and can also suffer from inadequate capacity. Dry sump can have other advantages such as windage control, crankcase vacuum, oil pressure regulator, etc but it is not a solution to an oiling problem.

Some blocks like the ones that come out of awd cars, do not have a provision for a dipstick drilled in the block. The dipstick goes into the oil pan on these cars. The dry sump LS engines such as the LS7 is another example of this, the dipstick is in the oil tank. You will have to drill the block in order to use a dipstick, it's not that big of a deal. Post #22 has pictures relevant to this, my LM4 came out of an AWD Trailblazer.

The oem windage tray is nothing special but it works. An aftermarket crank scraper is much more effective though. Be mindful of the crankshaft stroke, most windage trays and scrapers are for the 3.622" stroke. GM doesn't even make a windage tray for the 4.000" stroke, they use washers instead to space it.

I am using a mid sump oil pan, meant for an RX-7 swap, made by Sikky. This pan has a decent baffle and trap doors. The mounting angle of my engine forces oil from the front to drain faster and the short ledge on the rear prevents oil accumulating outside of the sump. On my swap the steering rack is in the way of running a rear sump. The only saving grace is I have a lot of ground clearance that allows for an oil pan with a very tall sump, I could possibly increase my oil capacity to 10 quarts. I am not using the bottom two bolts for the transmission. I had to cut that part off the oil pan and get two shorter bolts for the oil pan to rear crank seal cover. The subaru transmission does not come with a provision in that spot anyway. The subaru engine/transmission have a gap in this area to clear the subframe/steering rack. The subaru flywheel is exposed normally on the bottom and usually has a sheetmetal cover like an SBC would.

Oil Pumps:
Only use the stock oil pump if you are using a stock oil pan. They are designed to complement each other.
There is no reason to change a thing in your oil system if you are not doing any kind of racing. The stock oiling system is more than capable making sure your engine lasts for 300,000+ miles. Do not mistake needing an "upgraded" oil pump for using shitty oil, forgetting to change your oil, leaky valley cover/cam retainer, or not checking your oil level. Its really not necessary for this. Fuel economy, emissions, oil service life, NVH (yes, as silly as that sounds) etc. influence the oil system design more than you think.

Iron blocks have less issues with oiling, the oil clearance does not expand much and the block may flex less than aluminum.

If you have a remote mounted filter, an aftermarket oil pan and/or an oil cooler then you can get something like the Melling 10296. I have not confirmed it but supposedly the LSA oil pump is the AFM/DOD oil pump or similar to it. A higher pressure and/or flow oil pump will help when the oil temperatures go above 225° F and the stock pump is then unable to provide adequate oil pressure over 4,000 rpms.

There is no such thing as too high of an oil pressure, no one makes an oil pump to accomplish such a feat, you can't "wipe" the bearings. Too high of an oil pressure is more like 250 psi. Oil seals also don't magically pop out on modern engines, they are part of the crankcase system. German origin engines such as BMW are an exception, they leak even with no oil pressure.

If you are worried about "emptying your oil pan" then overfill your oil level by a quart or two and ask yourself where is the oil hiding while your oil pan/oil sump is empty.
Overfilling oil by a quart or more is actually very common with budget limited race teams and an extra quart does generally solve oil starvation problems. Most of the time they are running used factory engines and the extra quart helps keep the bearings from spinning by the end of the race.

The full mark on your dipstick is usually below the crankshaft so if you start the car the oil level will go down and may not affect windage. You can't pool 8 quarts of oil in the cylinder heads. If you are starving your oil pan all the time then its not a street car and there are no rules. The worst you can do is overfill the oil to the point the pistons pick it up and it enters the combustion chamber, if you are still emptying the oil pan then stop reading this. You have bigger problems.

Pressure is a measure of restriction so if your oil pressure goes up that doesn't necessarily mean your flow increased. 100 psi of oil pressure is not high and oil will not aerate at that level, nor could you reach such a pressure running a bolt on oil pump and a proper oil on an LS at operating temperature.

There is some truth to running a higher oil pressure, you will lose horsepower....not much, depends on clearances, oil viscosity and your oil pump, maybe 5-10 horsepower throughout your rpm range. Even switching to a 5w40 from a 5w30 is a 2-3 horsepower loss. The horsepower loss from metal on metal contact is much higher. You may actually slow down how fast your oil temperature goes up due to increased flow velocity. Oiling system components need to complement each other, not supplement.

The LS is nothing special in terms of oiling requirements, 50 psi at 6,500 rpm with an oil temperature of 215° is already inadequate. It's not that you need much higher pressure, it's that it starts dropping rapidly with higher oil temperatures and changing oil viscosity may not help.

lemming104

So, here's a question. I realize you went with the carburetor-style intake manifold, but do you have any idea how using a factory (LS6 or similar) manifold mounted backward would have been? I'm sort of wondering whether that'd fit, or if the pitch stop and transmission slave cylinder would make it impossible.

Sway Tale

I tried it and it fits but its taller towards the front, the back has enough clearance but you lose space for coolant hose routing.

Intake manifolds:
The LS6 intake manifold is around 6 inches tall.
The FAST 92 is 6.5" tall
The FAST 102 is 7.25" tall

The FAST 102 angles the throttle body compared to the LS6 and FAST 92.
FAST 102 has a slightly different snout for the throttle body.
FAST 102 has clearance issues with the throttle cable. the top cover of the manifold cause varying levels of misalignment with the cable. This is dependent on throttle cable bracket and throttle body. I am using LOKAR cable with a FAST 102mm Big mouth. My cable is angled steeply because of this.

Radium Fuel rails fit the FAST 102 using LS3 injectors but require washers under the rail mounting brackets and fuel injector spacers. This means it is possible other oem manifold fuel rails may work. Long injectors such as LS1 will fit with the radium fuel rails and need no spacers/washers.

Edelbrock/magneti marelli injectors do not fit the FAST 102.

Edelbrock Vic jr single plane is very versatile, takes up less space and is more compact than the long runner manifolds. Even when it comes to wiring.
The ultra low profile Edelbrock elbow is not useful above stock power levels
You have to make brackets to use short injectors with the edelbrock fuel rails unless they already came with correct ones.
My Vic Jr came with brackets for using long LS1 style injectors. I wanted to use LS3 injectors, So I bought the brackets for "PICO" injectors. Guess what? They are too long. They don't even fit with the Edelbrock branded injectors. You have to cut them down and drill new holes in the brackets. I have not been able to find the right part number for the brackets. I know edelbrock sells a setup that includes the rails, injectors and manifold. That kit should come with the right fuel rail brackets but I could not find it available for sale seperately

lemming104

Yeah, that factory "car" intake clears better than I thought it would at the back, but it definitely makes hood fitment even more problematic!

Definitely an interesting swap. As an owner of a Forester XT and a turbo LS-swapped Mustang, the idea of actually having torque and AWD traction in a compact car seems appealing. I'm kind of surprised that there's even enough left-over depth in the engine compartment for it to fit at all (even with the electric water pump so you're not jamming a water pump pulley into the core support), considering that the factory flat-four engines are cantilevered so far over the front crossmember.

Where are you planning to hang a turbo? It sort of seems like you'd need to use the area at the rear of the engine compartment like the factory Subaru setup.

I wonder how the STI transmission holds up to that level of torque. It's certainly a better starting point than the 5MT, but it's gotta have a limit.

Sway Tale

The water pump did fit depth wise but I cut the housing and welded inlet/outlet fittings to make space for coolant hoses.



The radiator is lower than the ls water pump and I wanted to be able to control flow. Supposedly this pump with a thermostat (which I don't have, for now) flows close to an LS pump.

Sway Tale

I went motor plate eventually....I highly recommend it instead of motor mounts. Don't worry you can put motor mounts on a motor plate too.

Mockup of motor mounts, engine mounting, oil pan

ryeguy2006a

iTrader: (27)

Very cool build. Any more pictures/details on how you mated the LS with the Subaru trans?

Sway Tale

I am using a custom flywheel and a transmission adapter plate. Flywheel fits an STi clutch and bolts to the LS crank. Adapter plate just bolts on to the LS block and is drilled and tapped for a subaru bellhousing. I am using an LS pilot bearing and a bushing to make up the difference from the smaller diameter subaru input shaft end. The flywheel has a ring gear for a subaru so my starter is bolted on the transmission.

I did have to do some cutting to the adapter. I cut off the section where there are 2 oil pan to bellhousing bolts. My subframe/steering rack would have been in the way.

A company called subarugears, from Australia, makes these adapters for various engines. They actually make a lot of stuff to run subaru transmissions in volkswagen vans.

imma_stocker

iTrader: (19)

I would also like to see more about this transmission adapter and how it could be made the other way, mating an EJ to GM trans.

Sway Tale

Can you tell me why you want to do that?

imma_stocker

iTrader: (19)

Side project without a subaru chassis.

Sway Tale

NASIOC has several members that have access to such adapters, I have seen them for sale before.
Outfront motorsports should also be able to help as they build plenty of non-subaru vehicles (sandrails) using subaru engines.

You have gotten the better of my curiosity because subaru has a lot of transmission choices for their engines. Even rwd automatic is possible with the 5EAT unless your're appproaching 800whp. You can build the subaru automatics for power. For manual you can just weld the center diff.
There was a red impreza coupe 1998ish model year a couple of years ago that was running 9s or 8s in the 1/4 with a TH400 using an EJ25. So I'm sure they're not hard to find.

On legacy forums Frank_ster swapped an old late 80s buick v6 into a 2005+ legacy and kept the automatic 5 speed. He converted his 5EAT to drive the rear wheels. If I remember correctly I think he cut & balanced the flexplate on a fork of a forklift and cut the adapter, himself, out of thick steel plate.

https://legacygt.com/forums/showthre....html?t=208444 <RWD conversion on automatic
https://legacygt.com/forums/showthre....html?t=140053 <somewhere in this thread should be pictures of him making an adapter plate and flexplate

imma_stocker

iTrader: (19)

Cool I'll dig around NASIOC, must have looked in the wrong section or at the wrong time. For reference, that's when Outfront was just getting their closed deck sorted out with IAG and other shops testing them (right after I started building a sleeved EJ25 of course ). They had adapter to various VW/Porsche transmissions for mid or rear engine setups but I didn't see anything for RWD. My hesitation with the AWD to RWD welding is I've seen them break with enough traction. The billet sleeve adapter things seem to hold up well enough for drift applications so they should hold fine in a lightweight project.

Thanks for the info and links

Sway Tale

Did some more work on the hood

Sway Tale

Still trying to put it together.

Jimbo1367

Any plans for gusseting the motor mounts?

Sway Tale

Nope. The transmission crossmember is very sturdy and does a lot of the work. Its not just a simple brace to support the weight, it's meant to control movement. There is also a pitch mount on top of the bellhousing to the firewall. The STi transmission is big and really heavy (It turns out its much heavier than a T56). Edit: I needed to change the bushings in my shifter linkage, guess what? I removed the transmission mounts completely and I couldn't get the trans to move, it didn't even tilt. I had to loosen the motor mounts as well. I overdid it, those PFADT style motor mounts with the corvette brackets swapped left to right are perfect.

The sti subframe is decent out of the factory and I welded tubes to where the original motor mounts were located (the slotted holes on the subframe). The subaru mounting pads on the subframe are already reinforced from the factory. The tubes themselves are actually part of a tie rod bar from an 18 wheeler, Steer suspensions on trucks are rated at 12,500 lb capacity. The wall thickness is so thick that it can support the weight of the car on only one of the tubes. I did do reinforcements/gussets where the tube sits inside the subframe, take a look at the pics in post #2. The motor mount brackets on the engine are C5/C6 but I swapped left and right side and that moved them back to the middle of the block (as opposed to front on corvette).

I can see how it may look flimsy or needs more support but......let's just say I use the motor mounts on the subframe to jack up the car, the chassis flexes while the subframe doesn't.



I do have an update and an interesting piece of information. I know LS engines came with a 3 wire coolant temp sensor in 1998 but they are kind of hard to get. Most subarus come with a 3 wire coolant sensor (1998-2007? I think) and I already have one and a spare pigtail.
The Subaru 3 wire coolant temp sensor has the same resistance for a given temperature as the LS. Just to make sure I checked ohms at various temperatures on both sensors and they are identical. So now I have the Edelbrock PRO-FLO 4 reading coolant temp from my original subaru sensor and my original cluster still shows coolant temp. Which means....

Long story short; You can use a SUBARU 3 wire coolant temperature sensor with any LSx ecu (OEM or aftermarket) without any calibration changes and connect it to a gauge at the same time. It works identical to the LSx 3 wire temperature sensor and has the exact same thread. It is readily available, the only downside is the pigtail is subaru.

I'll try to get some pics up later.

Jimbo1367

I did see the gussets in the first pic in post two. I also seen the well built trans crossmember too. That’s why I was wondering if you planned on any external gussets on the engine mount. I’m really interested in this build, I like seeing how people overcome obstacles when they swap motors.

Jim

Sway Tale

Came up with an idea of where I could mount the 2 pin alternator controller




I decided to throw in CHE trunnion kit.