Xman
New member
- Joined
- Dec 27, 2005
- Location
- Fort Worth TX
240 Turbo Conversion using Volvo 740 Parts
I just finished my 240 Turbo conversion (‘93 245). I found a 1990 740 Turbo in the junk yard and grabbed everything I needed from the car for $200. The parts sat in my garage for a year as I searched and read the Internet until I felt like I was ready to tackle the conversion by myself without any major surprises. There is a lot of good data out there to read. If you are converting a 740 to a 740T it is very straight forward and basically bolts right up. However, contrary to what I expected, this is not the case with many 740 Turbo parts when added to a 240. It took me 5 weeks of working on the car during the weekends to complete the conversion. I ran into several unexpected install challenges that I had to solve that I did not find mentioned by others. There probably are not too many 240 owners left that will perform a turbo conversion, but here are some of my experiences to add the Turbobrick knowledge base.
Take lots of pictures of the parts before you disassemble them from your donor vehicle. You never know what you will need to reference. I also have a low-mileage 740T in my “stable” and used it extensively as a reference.
Some extra parts to grab off the 740 that are not typically mentioned. Windshield washer reservoir (740 wagon holds more than the sedan). Get the base plate with its two torx head screws, too. It fits nicely, albeit slightly sloped, below the passenger headlight next to your frame bolt. This will give you extra room for your air filter set-up and the ability to cut a section out of your 240 passenger fender wall for cold air induction. I also knocked/chiseled the 740 bracket for the overflow reservoir off the passenger fender and used it, along with a new 740 overflow reservoir, to give me more room for the air filter set-up. It was easy to hammer the bracket back out to be flat again. I suggest a new overflow reservoir because the cooling system in top condition is critical for a turbo engine. Loose your cooling system and you will most likely loose your engine. If and or when your coolant system fails and your engine begins to overheat, the turbo pressure will elongate your block (unlike a NA engine) and it will be toast. I’ve owned several Volvo turbos and this has unfortunately happened to me once, and I’ve seen it happen first hand to others. If there is any doubt about the condition of any cooling system part, replace it with a new item. It is cheap and easy and there is no better time. Also, grab the 740’s O2 sensor as it has a much shorter wire that you won’t have to coil-up and stow, as you will with the 240’s O2 sensor. Lastly, if you plan to use your 240 intake manifold, grab as many clips as you can for the vacuum lines. NA engines don't need to have secure vacuum lines but boost pressure can blow a line off. Also, you will need plugs with nipples for the turbo boost gauge and boost overpressure relief valve. I picked up the plugs I needed at Autozone.
I thought that the 740 inter-cooler would fit directly in a 240. Turns out that it is about ?” higher than the top brackets attachment so you will need to make offsets (not hard and can be made from alu tubing sections under the brackets to raise them to the right height along with using a longer bolt). You may also have to do some filing to get the intercooler to fit snug without interference with the 240 sheet metal. Not only is the intercooler higher when installed in the 240, it and the radiator are located about 2” further forward on the car relative to the engine than the 740. Thus, coming off your intercooler on the driver’s side to the tubing that goes to the intake manifold, the 740 hose is too short. You can get some truck radiator hose at NAPA to make a longer piece. You’ll need 2.5” diameter for the driver’s side and a thin wall tube to proper;y span the gap coming off the turbo. I used a 2 to 2.25 exhaust pipe coupling for $1.99 at Autozone. If your set-up has a curved pipe vice a rubber hose coming off the turbo you will also need a 2” diameter hose for the passenger side. You probably could try and stretch to make the connections but then you are setting yourself up for risk of your air induction system failing.
There are two other aspect to the radiator/intercooler install that deal with the fan and which position you install the radiator/intercooler. First, I couldn’t find a way to reuse the 240 radiator shroud even when I cut it down. It always interfered with the fan so don’t bother trying as you will ruin a good asset that someone else can use. I did end up using the 740 radiator shroud but it only worked because it was thin enough to fit in front of the fan as the circular opening in the shroud is higher than the fan on the engine block. Also, I wanted to keep the stock fan instead of getting an electric fan but this may be your best route. I avoided an electrical fan by locating the radiator intercooler as far to the passenger’s side as possible. You will notice on the 240 that there are two mounting locations on the passenger side and only one on the driver side. The bottom rubber brackets (with their insert tabs trimmed to fit the round hole) fit in the driver side slot and the inboard of the two on the passenger side. These positions mount up to the existing 240 mounting positions. However, in this location, the fan will most likely interfere with the lower radiator hose. At that point you can decide to go with an electrical fan or move the radiator/intercooler to the passenger side by 1.25 inches. This is really where the radiator/intercooler should be located but you will need to do minor modifications to the 240 driver’s side attachment. I trimmed the rubber away from the bottom bracket then filed the forward edge of the metal to fit in the depressed channel section that runs the width of the lower grill area. I just set the modified bracket in the channel and rested the seam of the radiator and intercooler on top of it – works fine. On top, I used a hammer and C-clamp to flatten the area just to the right of the 240 driver’s side attach point. I then drilled a hole 1.25 inches to the inboard and used a bolt underneath to secure it along with a longer bolt for the top bracket. I had to start the nut before I pushed the intercooler back, swing the bracket over the top, and was able to get a wrench in from the side after the radiator/intercooler were in their final positions. This may sound like too much to do but it took me less than 15 minutes to accomplish and it provided these other advantages; the transmission cooling lines are now clear of the turbo, lower radiator hose misses the fan blades, fan is now more central to the radiator, I can use the 740 radiator fan shroud, room for the oil cooler without modification, more room to get the battery out and the intercooler-to-manifold pipe is clear of the positive terminal, at the manifold the air ducts are now clear of the brake lines coming off the inboard side of the master cylinder. Glad I did it this way.
As for an air filter, I had seen other’s use a 740T air box but the fit was way to tight for my liking (240 is narrower than a 740). If you move the intercooler/radiator to the passenger side, there is no clearance. I found the AMM and bracket off the 240 repositions nicely from the driver’s side fender to the passenger side fender, like it was made to do this and connected up to the AMM to 740 turbo inlet induction hose. There was already an existing hole in the passenger fender to attach the bracket, too. Its easy to add a 90-deg chrome elbow from Autozone to the AMM along with one of their 3” cone filters for just $30 – and it looks like it was made to be like this. (Note, you’ll have to add some electrical tape to the AMM to increase its diameter to 3” and get a snug fit with the 90 elbow.)
I found that, with my wastegate actuator adjusted down in psi (by lengthening the actuator rod), I got around 6 psi but the waste gate was just off its seat (partially open all the time). Even with this low of boost, I was running a bit lean with 240 stock injectors (yellow-tops) and stock 240 fuel computer. You can use the 740T green-top injectors and fuel computer to get more fuel but you will need to get the resister pack off the 740 and wire it into your 240. I did not want to deal with any more rewiring than I had to so I bought orange-top injectors from an 850T that, by themselves, have the correct resistance to work with the 740T computer. Initially, I ran this set-up with the stock 240 ignition computer as some had told me that the timing was basically the same. My car pinged and knocked like a bad tune I hadn’t heard since the 80’s. I slipped in the 740T ignition computer and it ran just fine (I was changing one item so if the engine stopped working I would know what the cause was or I would have put it in right away).
The second longest task for me was drilling out the block to accept the oil return from the turbo. I read where several said that this is the best way to go as opposed to tapping the oil pan. I did this with the engine in the car with a ? inch drill and a series of drill bits stepping up in size. I didn’t drill through at first, just deep enough to run the tap and so as to not worry about excessive shavings getting inside. After the final pass of drill bits to open up the hole, I used 4 gallons of mineral spirits to flush out the shavings. I should have used a magnet oil plug (from IPD) to make sure I capture all the metal partials. It may be “best” to drill and tap the block but welding a bung on the side of the oil pan if far easier and quicker if you can get the oil pan off.
The longest task for me was fitting the down-pipe. I had read you can make the 740T down-pipe work. I finally made it work by cutting it up and having a customer motorcycle shop weld it back together. Once I found the trick to fitting the pieces, it took me two hours to complete what I had not been able to do in two days. I also needed two down-pipes to do the type of install I wanted. This is described in this post.
http://forums.turbobricks.com/showthread.php?p=1806616#post1806616
The turbo conversion is worth doing. The car will now get out of its own way plus some. Go forth and conquer!
I just finished my 240 Turbo conversion (‘93 245). I found a 1990 740 Turbo in the junk yard and grabbed everything I needed from the car for $200. The parts sat in my garage for a year as I searched and read the Internet until I felt like I was ready to tackle the conversion by myself without any major surprises. There is a lot of good data out there to read. If you are converting a 740 to a 740T it is very straight forward and basically bolts right up. However, contrary to what I expected, this is not the case with many 740 Turbo parts when added to a 240. It took me 5 weeks of working on the car during the weekends to complete the conversion. I ran into several unexpected install challenges that I had to solve that I did not find mentioned by others. There probably are not too many 240 owners left that will perform a turbo conversion, but here are some of my experiences to add the Turbobrick knowledge base.
Take lots of pictures of the parts before you disassemble them from your donor vehicle. You never know what you will need to reference. I also have a low-mileage 740T in my “stable” and used it extensively as a reference.
Some extra parts to grab off the 740 that are not typically mentioned. Windshield washer reservoir (740 wagon holds more than the sedan). Get the base plate with its two torx head screws, too. It fits nicely, albeit slightly sloped, below the passenger headlight next to your frame bolt. This will give you extra room for your air filter set-up and the ability to cut a section out of your 240 passenger fender wall for cold air induction. I also knocked/chiseled the 740 bracket for the overflow reservoir off the passenger fender and used it, along with a new 740 overflow reservoir, to give me more room for the air filter set-up. It was easy to hammer the bracket back out to be flat again. I suggest a new overflow reservoir because the cooling system in top condition is critical for a turbo engine. Loose your cooling system and you will most likely loose your engine. If and or when your coolant system fails and your engine begins to overheat, the turbo pressure will elongate your block (unlike a NA engine) and it will be toast. I’ve owned several Volvo turbos and this has unfortunately happened to me once, and I’ve seen it happen first hand to others. If there is any doubt about the condition of any cooling system part, replace it with a new item. It is cheap and easy and there is no better time. Also, grab the 740’s O2 sensor as it has a much shorter wire that you won’t have to coil-up and stow, as you will with the 240’s O2 sensor. Lastly, if you plan to use your 240 intake manifold, grab as many clips as you can for the vacuum lines. NA engines don't need to have secure vacuum lines but boost pressure can blow a line off. Also, you will need plugs with nipples for the turbo boost gauge and boost overpressure relief valve. I picked up the plugs I needed at Autozone.
I thought that the 740 inter-cooler would fit directly in a 240. Turns out that it is about ?” higher than the top brackets attachment so you will need to make offsets (not hard and can be made from alu tubing sections under the brackets to raise them to the right height along with using a longer bolt). You may also have to do some filing to get the intercooler to fit snug without interference with the 240 sheet metal. Not only is the intercooler higher when installed in the 240, it and the radiator are located about 2” further forward on the car relative to the engine than the 740. Thus, coming off your intercooler on the driver’s side to the tubing that goes to the intake manifold, the 740 hose is too short. You can get some truck radiator hose at NAPA to make a longer piece. You’ll need 2.5” diameter for the driver’s side and a thin wall tube to proper;y span the gap coming off the turbo. I used a 2 to 2.25 exhaust pipe coupling for $1.99 at Autozone. If your set-up has a curved pipe vice a rubber hose coming off the turbo you will also need a 2” diameter hose for the passenger side. You probably could try and stretch to make the connections but then you are setting yourself up for risk of your air induction system failing.
There are two other aspect to the radiator/intercooler install that deal with the fan and which position you install the radiator/intercooler. First, I couldn’t find a way to reuse the 240 radiator shroud even when I cut it down. It always interfered with the fan so don’t bother trying as you will ruin a good asset that someone else can use. I did end up using the 740 radiator shroud but it only worked because it was thin enough to fit in front of the fan as the circular opening in the shroud is higher than the fan on the engine block. Also, I wanted to keep the stock fan instead of getting an electric fan but this may be your best route. I avoided an electrical fan by locating the radiator intercooler as far to the passenger’s side as possible. You will notice on the 240 that there are two mounting locations on the passenger side and only one on the driver side. The bottom rubber brackets (with their insert tabs trimmed to fit the round hole) fit in the driver side slot and the inboard of the two on the passenger side. These positions mount up to the existing 240 mounting positions. However, in this location, the fan will most likely interfere with the lower radiator hose. At that point you can decide to go with an electrical fan or move the radiator/intercooler to the passenger side by 1.25 inches. This is really where the radiator/intercooler should be located but you will need to do minor modifications to the 240 driver’s side attachment. I trimmed the rubber away from the bottom bracket then filed the forward edge of the metal to fit in the depressed channel section that runs the width of the lower grill area. I just set the modified bracket in the channel and rested the seam of the radiator and intercooler on top of it – works fine. On top, I used a hammer and C-clamp to flatten the area just to the right of the 240 driver’s side attach point. I then drilled a hole 1.25 inches to the inboard and used a bolt underneath to secure it along with a longer bolt for the top bracket. I had to start the nut before I pushed the intercooler back, swing the bracket over the top, and was able to get a wrench in from the side after the radiator/intercooler were in their final positions. This may sound like too much to do but it took me less than 15 minutes to accomplish and it provided these other advantages; the transmission cooling lines are now clear of the turbo, lower radiator hose misses the fan blades, fan is now more central to the radiator, I can use the 740 radiator fan shroud, room for the oil cooler without modification, more room to get the battery out and the intercooler-to-manifold pipe is clear of the positive terminal, at the manifold the air ducts are now clear of the brake lines coming off the inboard side of the master cylinder. Glad I did it this way.
As for an air filter, I had seen other’s use a 740T air box but the fit was way to tight for my liking (240 is narrower than a 740). If you move the intercooler/radiator to the passenger side, there is no clearance. I found the AMM and bracket off the 240 repositions nicely from the driver’s side fender to the passenger side fender, like it was made to do this and connected up to the AMM to 740 turbo inlet induction hose. There was already an existing hole in the passenger fender to attach the bracket, too. Its easy to add a 90-deg chrome elbow from Autozone to the AMM along with one of their 3” cone filters for just $30 – and it looks like it was made to be like this. (Note, you’ll have to add some electrical tape to the AMM to increase its diameter to 3” and get a snug fit with the 90 elbow.)
I found that, with my wastegate actuator adjusted down in psi (by lengthening the actuator rod), I got around 6 psi but the waste gate was just off its seat (partially open all the time). Even with this low of boost, I was running a bit lean with 240 stock injectors (yellow-tops) and stock 240 fuel computer. You can use the 740T green-top injectors and fuel computer to get more fuel but you will need to get the resister pack off the 740 and wire it into your 240. I did not want to deal with any more rewiring than I had to so I bought orange-top injectors from an 850T that, by themselves, have the correct resistance to work with the 740T computer. Initially, I ran this set-up with the stock 240 ignition computer as some had told me that the timing was basically the same. My car pinged and knocked like a bad tune I hadn’t heard since the 80’s. I slipped in the 740T ignition computer and it ran just fine (I was changing one item so if the engine stopped working I would know what the cause was or I would have put it in right away).
The second longest task for me was drilling out the block to accept the oil return from the turbo. I read where several said that this is the best way to go as opposed to tapping the oil pan. I did this with the engine in the car with a ? inch drill and a series of drill bits stepping up in size. I didn’t drill through at first, just deep enough to run the tap and so as to not worry about excessive shavings getting inside. After the final pass of drill bits to open up the hole, I used 4 gallons of mineral spirits to flush out the shavings. I should have used a magnet oil plug (from IPD) to make sure I capture all the metal partials. It may be “best” to drill and tap the block but welding a bung on the side of the oil pan if far easier and quicker if you can get the oil pan off.
The longest task for me was fitting the down-pipe. I had read you can make the 740T down-pipe work. I finally made it work by cutting it up and having a customer motorcycle shop weld it back together. Once I found the trick to fitting the pieces, it took me two hours to complete what I had not been able to do in two days. I also needed two down-pipes to do the type of install I wanted. This is described in this post.
http://forums.turbobricks.com/showthread.php?p=1806616#post1806616
The turbo conversion is worth doing. The car will now get out of its own way plus some. Go forth and conquer!
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