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Looking to make your car turbocharged? READ FIRST

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.

240to740Conversion.jpg


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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Well since dropping the oil pan is usually the biggest job when it comes to a +T, I might as well share a trick I found when I was replacing my broken one. Getting the new/modded oil pan on is hard enough by itself, but keeping the gasket on while doing so is harder. I found that using about 6 evenly spaced twist ties to keep the gasket on the pan helped keep the gasket from falling off while you let the 4 letter words fly. Just my .02.
 
740 parts in a 240

Hi I am doing a 240 +T conversion and I am heavily documenting it for you guys. I was wondering what and maybe where the 740 resistor pack is so I can get it and wire it into my 240. Thanks. -Chase
 
where is the 740 resistor pack?

It is located on the forward driver's side fender. If you use 850 Turbo injectors (orange tops) you don't need the resistor pack or have to change wiring. Best to post a new thread with your experience. It will pop-up on the search function.
 
+TI conversion

Ok thanks for that info. I will try to find a 850 for those injectors. It all depends on whats available. I have a few questions about the parts you used.

Did you pull the oil cooler and radiator off of the 740?

And what would be faster, the green top injectors out of a 740 with the resistor pack or just the orange top injectors out of the 850.

Also when I find my donor 740 for the turbo parts is it better to pull off the intake manifold and use it or is it better to keep the one off the 240?

Thanks -Chase
 
http://forums.turbobricks.com/showthread.php?t=132867

http://forums.turbobricks.com/showthread.php?t=135726

These two links show you the problems I had and my solutions. I used my 240 radiator and intake manifold. Oil cooler adapter that remotes the oil filter did not fit after I got the down-pipe on. I'm going to have to use an aftermarket sandwich block to connect to the oil lines (oil cooler is last priority in the turbo conversion). Again, best to start a separate thread to get answers to questions and post your results.
 
Ok I have a quick question. Does it really matter if you grab the 740 o2 sensor for the 240 +T conversion? because its shorter? Thanks -Chase
 
FOR THOSE OF YOU WORRIED ABOUT THE RESISTORS:

I've done some research while amassing parts for my LH 2.2 conversion on my '84 244ti and came up with this.

In place of greentops, you can use S80 T6 injectors (bosch P/N 0 280 155 831, Orange BODY) or 850 Turbo injectors (bosch P/N 0 280 150 785, Orange TOP). EDIT: Ford Thunderbird SuperCoupe injectors (Red TOP - Bosch P/Ns 0 280 150 756 and 0 280 150 945) will also suffice, and might be easier/cheaper to come by in the US. However, these along with the 850T injectors are conventional pintle injectors. The S80 T6 injectors are 4-hole disc injectors, which produce a far superior spray pattern.

In place of browntops, you can use S60 T5 injectors (bosch P/N 0 280 155 811, White BODY)

These will all drop right in and are HIGH IMPEDENCE injectors, meaning you do NOT have to use the 740/940 turbo resistor packs.
 
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how to pics?

does any one have info and pics on how to convert a b230f block to a b230ft block? and is it worth it? I heard it's possable and that you can run higher boost levels is this true?
 
I'm planning on doing a +T to a '85 740. I have access to a complete '88 740 turbo for parts. The long block has been claimed already, but I can take all of the other parts. I also have access to a '82 240 turbo. I've ready through most of the info here and have a decent idea of what I'm getting into. The question is this: I'm thinking I'll be better off using the long block from the b21ft and then taking the rest of the parts from the b230ft. I'll give up a little displacement, but have a much more durable motor. Will this cause me any problems? I'm assuming that because the lh2.2 injection is MAF based that it won't matter ( although idle Co might need adjusting ). I'll probably run a fairly mild setup to start with, but would like to run some serious boost later.
 
I'm planning on doing a +T to a '85 740. I have access to a complete '88 740 turbo for parts. The long block has been claimed already, but I can take all of the other parts. I also have access to a '82 240 turbo. I've ready through most of the info here and have a decent idea of what I'm getting into. The question is this: I'm thinking I'll be better off using the long block from the b21ft and then taking the rest of the parts from the b230ft. I'll give up a little displacement, but have a much more durable motor. Will this cause me any problems? I'm assuming that because the lh2.2 injection is MAF based that it won't matter ( although idle Co might need adjusting ). I'll probably run a fairly mild setup to start with, but would like to run some serious boost later.

Shouldn't be any problems. The b21ft has a bunch more sensors, but you can just leave them there. LH2.2 makes use of a knock sensor... the b21ft doesn't have one, but the boss is cast into the block, so you could easily drill for one.

I'd use the 530 head from the 88 block. The b21ft head is probably a BCP (big coolant port) head.

Go for it.

Mike
 
Ok, I've read and searched and now have a good idea of what has to be done....kinda. Although I currently have an 84 244tic, I will be aquiring an na 79 242 gt and also a b21ft along with it. I would rather just swap the b21ft in the car, but after that I'm at a loss on fueling. I don't want to go ms yet since I'm not familiar with wiring and such, so would it be a better bet to go kjet or maybe lh2.2 or 2.4? Also, I have a 90+intake....how do I work that on the head with the injectors since there are ports on the mani and the head? Thanks!
 
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