ydeardorff
New member
The allure of updating the Sterling to a modern drive train is a big one. Doing so gives you more power, reliability, economy, tons of spares, and hop up items. But there is more to this modification than just buying an engine, an adapter, the ECU (engine control unit) and wiring system and tossing it in your kit car. This is a ROUGH guide to whats involved, use this as a reference only. Each installation may be slightly different hence no one guide can be applied totally.
First let’s talk about the engines.
There are many types of engines created by Subaru dating back to the 80’s that can be used. We will discuss the more typical EJ series engines that are the more preferred and used in these swaps. They can be found in most vehicles made since 1990.
Information on the EJ series engines can be found here: Subaru EJ engine - Wikipedia, the free encyclopedia
The most common engines used for these swaps are the following:
EJ 20
EJ20 turbo
EJ20 Twin turbo (Japan)
EJ22
EJ22 Turbo
EJ25
EJ25 Turbo
EJ25 Turbo (STI)
Breaking this list down further is the most common US models to be found
EJ20 turbo
EJ22
EJ25
EJ25 turbo (STI)
Naturally Aspirated Engines
The EJ20, EJ22 and EJ25 are naturally aspirated, fuel injected engines and should work well with a VW transaxle. They are lower on power (peaking around 160hp) than their turbo charged cousins, but still equate to more than 3 times the power of the stock VW engine.
All engines will require some sort of mount, and adapter plate to be mated into the VW chassis and transmission. A Subaru mount designed for this can be found at Subaru gears website: Subarugears
If your choice is a turbo engine, more will need to be considered. For now we’ll continue talking about non turbo engines.
In order for this engine to operate correctly it will need the following items:
The engine control unit
The engine wiring harness
The wiring harness that connects the ECU to the engine harness
A custom made exhaust
Custom Fuel cell
Three custom made fuel lines, (pressure, return, vent)
A fuel pump designed for this engine (flow rate and pressure)
A radiator (cooling capacity must match or exceed engine hp rating (1x1x1” per hp typically))
A hand made cooling system (tubing, reservoir tank(s))
Kafer bars
Several other smaller items such as throttle linkage, ect.
Turbo Engines:
The allure of big power in a light car is obvious, however more must be considered. The turbo engines from the EJ20 to the EJ25 (STI) engine can produce more than 300HP with nearly as much torque.
Now a turbo has to be thought about, its heat can incinerate anything flammable next to it. So proper planning is a must in a fiberglass car.
The turbo engine will require Kafer bars, and also seam welding the transmission horns to strengthen them (at a minimum). This prevents the torque of the engine from twisting the transmission horns in the chassis.
Transmission options also have become much narrower too. Many at this point can opt for a Porsche 901 transmission, VW bus transmission, or a flipped differential Subaru TY55, or TY75 manual transmission.
A VW transmission WILL NOT be able to with stand the Turbo engines power and torque output. What this means is, they will do fine while you putt around cruising, but as soon as you drop the pedal to take use of that turbo engine, the torque will split the VW case apart sending its internal components everywhere. Even some Subaru manual transmissions cannot tolerate the turbo engines. So be prepared for this.
The turbo engines will need everything that the non-turbo engines do. But many of the parts will be considerably more expensive as they are designed specifically for the Turbo engine, and are built to handle more power and torque. When you go big, you will have to also think about upgrading the brakes. What’s the point of going fast if you can’t stop? The turbo engine may be more desirable, but it comes with a much larger price tag. This must be considered before you decide to drop your money on something.
Kafer Bars:
Kafer bars are a set of linkages that connect the transmission horns to the outer suspension horns. The help to arrest any torsional movement of the transmission horns.
Think before you leap!
Ok so you’ve looked on EBay and seen tons of JDM (Japanese Domestic Market) engines for sale for dirt cheap. They have the ECU, a manual transmission, wiring, engine,… everything! Well yes and no.
These are Japanese engines that are physically the same as their American versions. But the electrical components might be very different. DO YOUR HOMEWORK BEFORE YOU BUY! Many of the parts may only be available from japan, and not be compatible with USDM parts. So if something breaks, or needs replacement you might have trouble finding it here in the US. Some may be no different than their USDM cousins, making parts easy to obtain from both sources.
Usually the best idea is to buy an entire USDM car. Then by doing so you have nearly all of the Subaru parts you’ll need. Most of the custom items listed above will still need to be made as you are installing this drivetrain in a non-OEM application.
Flipped Diff conversion transmissions:
The flipped differential kit offered by Subarugears is a very good way to go if you have the funds, and skill to do it. The kit with the reversed ring and pinion, output shaft adapters, and case plug will set you back around 2000 dollars. You will have to buy a Subaru TY57 or TY75 manual transmission from a 1999 or newer Subaru legacy or impreza which can cost as much as 1500 dollars, but can also be had for less than half that if you’re resourceful. You will have to modify the transmission cases, and take apart the transmission to do this modification. It is not too difficult for the average person to do. But refer to your local transmission shop, and the subarugears.com website for more information on anything you’re not comfortable doing. Remember you will have to disassemble the transmission, clearance the case, modify the center case, and get everything welded up before you can even assemble the transmission to install it. Again, ask questions before you dive in…
Clutch and flywheel:
Another thing not often thought about is the clutch and flywheel. In order to do this swap, you must find the right Clutch and flywheel for your transmission. If mixing VW and Subaru components there may be very limited options on what flywheel and clutch you can use. So again, ask questions.
Fitting the engine into a sterling:
This is not a direct fit scenario. The engine bay opening for the VW engine will need to be opened up so you can reach all of the components on the engine, and clearance for the throttle body and intake. There is also a main cross brace forward of the engine bay opening that you will need to cut and then reinforce if going to a turbo engine, or when not using and engine adapter. The adapter will push back the engine an inch or two from the transmission. This modification will require you to do some fiberglass work on the back engine deck to create a lid to cover the engine (if you want it covered).
Oil Pan:
The OEM oil pan on a Subaru engine is too tall to work in a sterling (once its installed) you will need to purchase a low profile oil pan kit, or a dry sump kit to ensure there is enough clearance to the ground.
Engine electrical:
The rats’ nest of wiring you typically see, looks a lot worse than it actually is. For most Subaru engines you have 5 connectors to worry about. Two big connector one brown, and one black, then a smaller grey connector with 6 wires in it, then finally two very small connectors for the EGT (exhaust gas temp) and one of as many as three O2 sensors in the system. Here is where being a bit OCD is a good thing. If you are using everything from the same make/model/year then you have a lot less to deal with. Just get the plugs connected. If you mix and match differing years but the same engine you must go through the wiring schematic wire by wire, pin by pin. Even if the O2 sensor wiring goes to the correct plug on your engine, it might be oriented on your schematic as pin 1 then pin 2. But if you’re not careful, it could be on the engine harness pin 2 then pin 1. So be careful, and triple check everything before you plug in the power!
If you use a complete and uncut harness, you will need to extend the engine, exhaust, and transmission connectors to the rear of the car. Since this harness was designed for a front engine car those connections will be at the front of the car, not the back where they need to be now.
So now you’re thinking why the heck would anyone go through all this?
With all this complication, and expense,… What’s the point you ask? Well, let’s see... To do this swap gives you a modern fuel injected, virtually maintenance free engine that can typically go more than 150K miles with proper maintenance. You get more power, reliability, ease of finding parts, compared with the aging VW stuff. Let’s face it VW’s have been around for many, many decades, but the people who sell their parts are asking more and more as time goes by. Eventually, these parts will become scarce, and even possibly prohibitively expensive. Subaru parts are plentiful pretty much everywhere. Many of the parts are still in production today. Another perk of doing this engine swap is the ability to use the OEM Subaru AC system components, heating, and even power steering systems. There are kit available for VW’s yes, but they are prohibitively expensive for many, and a liquid based heater is much safer than the Exhaust mounted heat exchanger used for VW’s. The resale value of having this conversion done in the car might play into the cars value down the road, but it really depends on the buyer. Some just like the VW stuff. In the end all this fuss, and expense gets you a sterling kit car, you can just get in, any time and go. No fiddling with valve adjustments, carb adjustments or anything else. It effectively turns this kit car into a normal every day drivable car, and adds a significant amount of grin factor due to the HP increase.
To do this swap will require skill and planning.
It will require tools you more than likely don’t have, so add that the expense of doing this. Remember if you go for a turbo engine you will add considerable expense and time to complete this project. Do your homework, think ahead, and be prepared for time and money to be expended to do this that you didn’t plan for. This is not a weekend project. Nor is this brain, or rocket surgery. It requires a set of open eyes, and allowance for “things that come up” during the install. You will need tools, and space to do this. You will also need the skill to do this, or the ability to acquire them. So plan ahead. In the end if you choose to do this, you will have a very nice reliable engine setup that will give you years of use. Also, you must think about what you want out of your car. If you toss in a WRX STI engine with 300 HP you may well create a car that is too much for you to handle. Consider this before you choose your engine.
Here is a comparison of the engines and what they offer:
Subaru engine:
Reliability (low maintenance)
Average to high power
Economy 30+
AC
Power Steering
Liquid based cabin heating (safe)
Turbo engine option
Electronic Fuel injection
Parts spares (common and inexpensive)
OBD diagnostics (make troubleshooting easier)
VW engine:
Reliability (requires more maintenance)
Low power output (typically <100hp)
Economy 30+
None but AC kit option
Power steering None
Exhaust heat exchangers(can be dangerous when worn through)
None but Turbo kit available
carbureted
Parts spares (getting more expensive as they become more scarce)
OBD None
Remember, VW's were produced for decades, and sold more units than any other car in history. However, Most Air cooled VW's went out of production in 1977, and in Mexico in 2003. So good spares are becoming scarcer every day, and due to that will continue to increase in price as time goes by.
The Subaru engine represents an evolved version of the VW engine to many. Tons of spares across many models some of which are still in production. This make the Subaru engine an idea candidate to replace the VW engine.
So now that you’ve read through this book, understand this is only the tip of the ice berg when it comes to all the little details. But these details are where you get busy reading, and researching yourself.
The VW unit is a simpler, (but not always) cheaper option in most cases due to the fact it’s already in the car (typically). Many people opt for that so they can get the car on the road, and start enjoying it. That’s great, but if the maintenance requirements of the older VW design, and it lack of power are a factor to you, then going to a Subaru engine might be worth looking into. Parts are plentiful, as well as your options. So think about your budget, think about the time required to do this, think about your skill level and how much you might have to hire out for. Is this overly hard? No. Is it easy? No. It will require some mechanical, fabrication skills, and attention to detail. But to those who want a car they can just get in and drive, even cross country in, then the Subaru option may be your way to go. If you want to ask questions, please do so. There are members on this site that are knee deep into their conversions. Some have already completed them and have running and driving cars. There is an abundance of knowledge here, use it. Going to a Subaru engine is a personal choice, a personal preference for your build, on your car. So approach this decision as what best fits you, and what you want. But the reward will be an amazing car, and the pride that you did this yourself, and have gone where many people have jealously watched, but feared to tread.
Final disclaimer: Use this as a guide as to what you need to think about BEFORE you start this conversion.
VW engines in our sterlings can be cheap and reliable, however they can also not be. Many upgrades to make the VW unit compare to the Subaru engine (especially a turbo) can quickly cost more than doing a subaru swap. Doing these types of upgrades can interfere with the VW engines reliability. So figure out what you want, and go from there.
As the old saying goes, "Speed costs, how much you willing to spend?"
First let’s talk about the engines.
There are many types of engines created by Subaru dating back to the 80’s that can be used. We will discuss the more typical EJ series engines that are the more preferred and used in these swaps. They can be found in most vehicles made since 1990.
Information on the EJ series engines can be found here: Subaru EJ engine - Wikipedia, the free encyclopedia
The most common engines used for these swaps are the following:
EJ 20
EJ20 turbo
EJ20 Twin turbo (Japan)
EJ22
EJ22 Turbo
EJ25
EJ25 Turbo
EJ25 Turbo (STI)
Breaking this list down further is the most common US models to be found
EJ20 turbo
EJ22
EJ25
EJ25 turbo (STI)
Naturally Aspirated Engines
The EJ20, EJ22 and EJ25 are naturally aspirated, fuel injected engines and should work well with a VW transaxle. They are lower on power (peaking around 160hp) than their turbo charged cousins, but still equate to more than 3 times the power of the stock VW engine.
All engines will require some sort of mount, and adapter plate to be mated into the VW chassis and transmission. A Subaru mount designed for this can be found at Subaru gears website: Subarugears
If your choice is a turbo engine, more will need to be considered. For now we’ll continue talking about non turbo engines.
In order for this engine to operate correctly it will need the following items:
The engine control unit
The engine wiring harness
The wiring harness that connects the ECU to the engine harness
A custom made exhaust
Custom Fuel cell
Three custom made fuel lines, (pressure, return, vent)
A fuel pump designed for this engine (flow rate and pressure)
A radiator (cooling capacity must match or exceed engine hp rating (1x1x1” per hp typically))
A hand made cooling system (tubing, reservoir tank(s))
Kafer bars
Several other smaller items such as throttle linkage, ect.
Turbo Engines:
The allure of big power in a light car is obvious, however more must be considered. The turbo engines from the EJ20 to the EJ25 (STI) engine can produce more than 300HP with nearly as much torque.
Now a turbo has to be thought about, its heat can incinerate anything flammable next to it. So proper planning is a must in a fiberglass car.
The turbo engine will require Kafer bars, and also seam welding the transmission horns to strengthen them (at a minimum). This prevents the torque of the engine from twisting the transmission horns in the chassis.
Transmission options also have become much narrower too. Many at this point can opt for a Porsche 901 transmission, VW bus transmission, or a flipped differential Subaru TY55, or TY75 manual transmission.
A VW transmission WILL NOT be able to with stand the Turbo engines power and torque output. What this means is, they will do fine while you putt around cruising, but as soon as you drop the pedal to take use of that turbo engine, the torque will split the VW case apart sending its internal components everywhere. Even some Subaru manual transmissions cannot tolerate the turbo engines. So be prepared for this.
The turbo engines will need everything that the non-turbo engines do. But many of the parts will be considerably more expensive as they are designed specifically for the Turbo engine, and are built to handle more power and torque. When you go big, you will have to also think about upgrading the brakes. What’s the point of going fast if you can’t stop? The turbo engine may be more desirable, but it comes with a much larger price tag. This must be considered before you decide to drop your money on something.
Kafer Bars:
Kafer bars are a set of linkages that connect the transmission horns to the outer suspension horns. The help to arrest any torsional movement of the transmission horns.
Think before you leap!
Ok so you’ve looked on EBay and seen tons of JDM (Japanese Domestic Market) engines for sale for dirt cheap. They have the ECU, a manual transmission, wiring, engine,… everything! Well yes and no.
These are Japanese engines that are physically the same as their American versions. But the electrical components might be very different. DO YOUR HOMEWORK BEFORE YOU BUY! Many of the parts may only be available from japan, and not be compatible with USDM parts. So if something breaks, or needs replacement you might have trouble finding it here in the US. Some may be no different than their USDM cousins, making parts easy to obtain from both sources.
Usually the best idea is to buy an entire USDM car. Then by doing so you have nearly all of the Subaru parts you’ll need. Most of the custom items listed above will still need to be made as you are installing this drivetrain in a non-OEM application.
Flipped Diff conversion transmissions:
The flipped differential kit offered by Subarugears is a very good way to go if you have the funds, and skill to do it. The kit with the reversed ring and pinion, output shaft adapters, and case plug will set you back around 2000 dollars. You will have to buy a Subaru TY57 or TY75 manual transmission from a 1999 or newer Subaru legacy or impreza which can cost as much as 1500 dollars, but can also be had for less than half that if you’re resourceful. You will have to modify the transmission cases, and take apart the transmission to do this modification. It is not too difficult for the average person to do. But refer to your local transmission shop, and the subarugears.com website for more information on anything you’re not comfortable doing. Remember you will have to disassemble the transmission, clearance the case, modify the center case, and get everything welded up before you can even assemble the transmission to install it. Again, ask questions before you dive in…
Clutch and flywheel:
Another thing not often thought about is the clutch and flywheel. In order to do this swap, you must find the right Clutch and flywheel for your transmission. If mixing VW and Subaru components there may be very limited options on what flywheel and clutch you can use. So again, ask questions.
Fitting the engine into a sterling:
This is not a direct fit scenario. The engine bay opening for the VW engine will need to be opened up so you can reach all of the components on the engine, and clearance for the throttle body and intake. There is also a main cross brace forward of the engine bay opening that you will need to cut and then reinforce if going to a turbo engine, or when not using and engine adapter. The adapter will push back the engine an inch or two from the transmission. This modification will require you to do some fiberglass work on the back engine deck to create a lid to cover the engine (if you want it covered).
Oil Pan:
The OEM oil pan on a Subaru engine is too tall to work in a sterling (once its installed) you will need to purchase a low profile oil pan kit, or a dry sump kit to ensure there is enough clearance to the ground.
Engine electrical:
The rats’ nest of wiring you typically see, looks a lot worse than it actually is. For most Subaru engines you have 5 connectors to worry about. Two big connector one brown, and one black, then a smaller grey connector with 6 wires in it, then finally two very small connectors for the EGT (exhaust gas temp) and one of as many as three O2 sensors in the system. Here is where being a bit OCD is a good thing. If you are using everything from the same make/model/year then you have a lot less to deal with. Just get the plugs connected. If you mix and match differing years but the same engine you must go through the wiring schematic wire by wire, pin by pin. Even if the O2 sensor wiring goes to the correct plug on your engine, it might be oriented on your schematic as pin 1 then pin 2. But if you’re not careful, it could be on the engine harness pin 2 then pin 1. So be careful, and triple check everything before you plug in the power!
If you use a complete and uncut harness, you will need to extend the engine, exhaust, and transmission connectors to the rear of the car. Since this harness was designed for a front engine car those connections will be at the front of the car, not the back where they need to be now.
So now you’re thinking why the heck would anyone go through all this?
With all this complication, and expense,… What’s the point you ask? Well, let’s see... To do this swap gives you a modern fuel injected, virtually maintenance free engine that can typically go more than 150K miles with proper maintenance. You get more power, reliability, ease of finding parts, compared with the aging VW stuff. Let’s face it VW’s have been around for many, many decades, but the people who sell their parts are asking more and more as time goes by. Eventually, these parts will become scarce, and even possibly prohibitively expensive. Subaru parts are plentiful pretty much everywhere. Many of the parts are still in production today. Another perk of doing this engine swap is the ability to use the OEM Subaru AC system components, heating, and even power steering systems. There are kit available for VW’s yes, but they are prohibitively expensive for many, and a liquid based heater is much safer than the Exhaust mounted heat exchanger used for VW’s. The resale value of having this conversion done in the car might play into the cars value down the road, but it really depends on the buyer. Some just like the VW stuff. In the end all this fuss, and expense gets you a sterling kit car, you can just get in, any time and go. No fiddling with valve adjustments, carb adjustments or anything else. It effectively turns this kit car into a normal every day drivable car, and adds a significant amount of grin factor due to the HP increase.
To do this swap will require skill and planning.
It will require tools you more than likely don’t have, so add that the expense of doing this. Remember if you go for a turbo engine you will add considerable expense and time to complete this project. Do your homework, think ahead, and be prepared for time and money to be expended to do this that you didn’t plan for. This is not a weekend project. Nor is this brain, or rocket surgery. It requires a set of open eyes, and allowance for “things that come up” during the install. You will need tools, and space to do this. You will also need the skill to do this, or the ability to acquire them. So plan ahead. In the end if you choose to do this, you will have a very nice reliable engine setup that will give you years of use. Also, you must think about what you want out of your car. If you toss in a WRX STI engine with 300 HP you may well create a car that is too much for you to handle. Consider this before you choose your engine.
Here is a comparison of the engines and what they offer:
Subaru engine:
Reliability (low maintenance)
Average to high power
Economy 30+
AC
Power Steering
Liquid based cabin heating (safe)
Turbo engine option
Electronic Fuel injection
Parts spares (common and inexpensive)
OBD diagnostics (make troubleshooting easier)
VW engine:
Reliability (requires more maintenance)
Low power output (typically <100hp)
Economy 30+
None but AC kit option
Power steering None
Exhaust heat exchangers(can be dangerous when worn through)
None but Turbo kit available
carbureted
Parts spares (getting more expensive as they become more scarce)
OBD None
Remember, VW's were produced for decades, and sold more units than any other car in history. However, Most Air cooled VW's went out of production in 1977, and in Mexico in 2003. So good spares are becoming scarcer every day, and due to that will continue to increase in price as time goes by.
The Subaru engine represents an evolved version of the VW engine to many. Tons of spares across many models some of which are still in production. This make the Subaru engine an idea candidate to replace the VW engine.
So now that you’ve read through this book, understand this is only the tip of the ice berg when it comes to all the little details. But these details are where you get busy reading, and researching yourself.
The VW unit is a simpler, (but not always) cheaper option in most cases due to the fact it’s already in the car (typically). Many people opt for that so they can get the car on the road, and start enjoying it. That’s great, but if the maintenance requirements of the older VW design, and it lack of power are a factor to you, then going to a Subaru engine might be worth looking into. Parts are plentiful, as well as your options. So think about your budget, think about the time required to do this, think about your skill level and how much you might have to hire out for. Is this overly hard? No. Is it easy? No. It will require some mechanical, fabrication skills, and attention to detail. But to those who want a car they can just get in and drive, even cross country in, then the Subaru option may be your way to go. If you want to ask questions, please do so. There are members on this site that are knee deep into their conversions. Some have already completed them and have running and driving cars. There is an abundance of knowledge here, use it. Going to a Subaru engine is a personal choice, a personal preference for your build, on your car. So approach this decision as what best fits you, and what you want. But the reward will be an amazing car, and the pride that you did this yourself, and have gone where many people have jealously watched, but feared to tread.
Final disclaimer: Use this as a guide as to what you need to think about BEFORE you start this conversion.
VW engines in our sterlings can be cheap and reliable, however they can also not be. Many upgrades to make the VW unit compare to the Subaru engine (especially a turbo) can quickly cost more than doing a subaru swap. Doing these types of upgrades can interfere with the VW engines reliability. So figure out what you want, and go from there.
As the old saying goes, "Speed costs, how much you willing to spend?"
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