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Swapping ?91 740 B230FT into ?89 245

jordanderson

New member
Joined
Jul 26, 2019
Hello everyone,

I?m new to the page and have done some searching both before and since becoming a member but have not found the information I am seeking. I have a 1989 240 DL wagon with a 5 speed manual transmission and have available to me a 1991 740 sedan turbo (B230FT) swap, complete (as far as I can tell) with the turbo exhaust manifold, turbo, intake manifold, intercooler, piping, wire harness and ECU. I would consider myself mechanically inclined however I am not an expert by any means and have never swapped an engine before. I am wondering what obstacles I will come across (what won?t be unbolt, bolt back on / plug and play). Will the harness and ECU from the donor car work on my 240? Any other things to be aware of or would need to source in addition to what?s included in the swap? Obtaining the swap is kind of time sensitive so I appreciate any and all input very much and would love to make this happen if it?s within my abilities. Thanks in advance everyone! -Jordan
 
Also, I originally posted in engine modifications and was told that wasn’t the appropriate place to post this so if anyone can tell me how to delete that post, I would do so. I have to decide on obtaining the swap by the end of the day today so if anyone has any useful information on the matter, I would greatly appreciate it! Any obstacles or modifications I would have to make or parts I would need to get. Thanks everyone!
 
Just get the parts and work on swap. Learn as you go. This won't be a weekend job for a first timer. So if it's your only car, then swap won't happen. Just being realistic.
 
I just did this swap on my 242 last winter and I found there are a few things I did which made my swap easier.
First off the harness. I bought a conversion harness from Mr barton. Its pricey but it saved me hours of aggrivation with messing with wiring. However I am sure your 89 has a more compatable vehicle wiring hanress then my 83 242 did.

As you are aware the head mounted distributor from a 740 will not fit in a 240. So you will either need a block mounted dizzy and a toothed aux shaft to drive it OR
Set up wasted spark and be done with the mechanical dizzy. I went the wasted spark route and had no issues getting it working properly.

Another thing to consider is your oil cooling set up. The 740 oil cooler set up will not work on the 240 as the oil lines from the oil thermostat will not clear the 240's engine mount. You will need some custom oil lines to get the oil cooling circuit to fit or get lines and a thermostat from a 240 turbo.

There is a heck of lot more thing to consider but these were my main hurdels.

Best of luck!
 
Thanks to everyone who has replied. Does anyone know any further about the harness compatibility? At 223K on my stock, original mounts, would I need new ones? Any other info or input is appreciated.
 
My thoughts

You shouldn?t need a new harness, about the only wiring modification needed will be to relocate the AMM plug to the passenger side. You?ll also have to add a ballast resistor for each injector or (my preferred method) source high impedance injections from an 850 turbo. The ecu?s will swap with out issue. Don?t forget to swap the 240 coolant temp sender for the dash gauge.

You can convert the 740 engine to a block mounted dizzy by swapping the aux shaft from the 240 engine.

The upper radiator/ inter cooler mounts require modification for use in a 240 but the lowers are the same. The fan shroud is also different, I believe you can mod the 740 shroud to work.

Mounting the air box will require some creativity but many have done it.

The 740 exhaust pipe will not clear the firewall but you can source one for a 240 turbo.

Late model 940 turbos use a water cooled oil cooler that will not interfere with the 240 motor mounts if you can source the parts.

I agree this is not wise to attempt on a deadline. Without another car to drive for a month or three I wouldn?t consider it.
 
Further to the above re. the down pipe: I think the OEM 2 series turbo downpipes are truly hen's teeth today. Best bet IMO is to cut & fit the 9 series turbo DP to work with your 2 series.

Takes some skill.... likely best farmed out to a steely eyed muffler shop guy who has lots of experience with welding exhaust pipes. However IF you can find one of the elusive 2 series (or an aftermarket) I'd buy it to save the cut & fit effort.......
 
I just did this swap on my 242 last winter and I found there are a few things I did which made my swap easier.
First off the harness. I bought a conversion harness from Mr barton. It's pricey but it saved me hours of aggravation with messing with wiring. However I am sure your 89 has a more compatible vehicle wiring harness then my 83 242 did.

You didn't have to do this but who doesn't like having new parts

As you are aware the head mounted distributor from a 740 will not fit in a 240. So you will either need a block mounted dizzy and a toothed aux shaft to drive it OR
Set up wasted spark and be done with the mechanical dizzy. I went the wasted spark route and had no issues getting it working properly.

I wouldn't recommend a first timer going wasted spark. It's easy to swap auxlliary shaft and distributor

Another thing to consider is your oil cooling set up. The 740 oil cooler set up will not work on the 240 as the oil lines from the oil thermostat will not clear the 240's engine mount. You will need some custom oil lines to get the oil cooling circuit to fit or get lines and a thermostat from a 240 turbo.

You don't need a thermostat from a 240 turbo, the one from the 740 turbo will work. Doesn't require custom lines either. You can run the sandwich/plate with banjo fittings and run rubber oil cooler lines. I would just buy a new oil cooler as it will have an fittings. Instead of using the original oil cooler. You can get 10 an 1/2 npt barb fittings

There is a heck of lot more thing to consider but these were my main hurdels.

Best of luck!

Nothing will go as planned and it will take 3 times as long. You can budget all you want but there will be little expense that come up.
 
You can convert the 740 engine to a block mounted dizzy by swapping the aux shaft from the 240 engine.

Best idea

The upper radiator/ inter cooler mounts require modification for use in a 240 but the lowers are the same. The fan shroud is also different, I believe you can mod the 740 shroud to work.

740 mounts will work but won't look pretty. No one wants to pay for the 240 turbo specific fan shroud. The 740 shroud will not work unless you use an electric fan which is what most people end up doing.

Mounting the air box will require some creativity but many have done it.

If you're willing to pay for the 240 turbo air box and modify it. Then this is a good option and will give you a factory look. Otherwise people just buy a cheap cone filter for all the cool noises

The 740 exhaust pipe will not clear the firewall but you can source one for a 240 turbo.

It will fit with a little modification. You have to remove about 1.5 inches from the top portion and it will clear just fine. Perfect opportunity to buy a cheap welder and learn another skill

Late model 940 turbos use a water cooled oil cooler that will not interfere with the 240 motor mounts if you can source the parts.

Correct. These parts are not easy to find so probably not a realistic option

I agree this is not wise to attempt on a deadline. Without another car to drive for a month or three I wouldn?t consider it.

Plan and budget. Unless you have dedicated work space and another car(s), this cannot be done in a timely manner.
 
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