940 NA to Turbo Engine Swap

Hello All,

Other projects have conspired against working on the the 940. My last post on this subject was in Nov of 2018.

I did manage to swap the rear axle; 4:10 to 3:73 (majority of my driving is highway).

Yesterday I started looking at the actual engine swap requirements. To clarify, my wagon is a 'non-turbo' (NA), and the donor is a turbo. Both are 1994 940s manufactured within months of each other using LH2.4. The NA engine compartment is a mirror image of the turbo; ABS is on opposite fenders, same for the air filter housing, MAF, battery, washer fluid container, etc.

It has been suggested that this is an easy 'plug and play' swap but I feel it isn't. According to a chap on YouTube that did the same swap (took him 7 days). The wiring harness under the dash was swapped by 'cutting/soldering'. (https://www.youtube.com/watch?v=4blRkU5Rvoc this is a '7 day' video)

According to the Mitchell wiring diagrams, there are differences but the sensor connections do end up at the same pin outs on the ECU.

Some questions to challenge you;

1. Has anyone done this exact swap without the 'under dash wiring nightmare'? I've already had the complete dash apart to replace the dual diaphragm HVAC servo (PITA). So I'd rather not do it again.

2. I can rewire the MAF connection BUT the ABS pump will conflict with the MAF due to the design of the hose between the MAF and turbo. I could remove the ABS system completely to work around this.

3. The turbo does not use the WOT output on the TPS. The purpose in the NA cars is to enrich the fuel. Pros and cons of leaving it connected or not?

4. The turbo uses an 'air preheating resistor' in the hose between the MAF and turbo. Pros and cons of its purpose and how/where to best connect this to the NA engine harness?

5. I would prefer to move the battery to the drivers side (like the turbo), to allow me to use the factory air filter housing (yes, the ABS pump would need to be moved/removed). To do this the under hood 'power distribution' needs to be changed. Anyone done this?

As always, your feedback is appreciated!

You're making it harder than it has to be. You don't need to move battery. You will have to use some sort of cone filter. Moving the abs pump would be ridiculous. There is no under dash wiring that is needed. With the correct turbo ecu, you don't need to clip wire on tps. The only wiring issue is the maf. All your doing is extending wires. You can get an intake hose that doesn't use the heating resistor. All turbo cars up until 89 used an intake hose that just had the nipple for hose that goes to flame trap. You can buy a new hose on ebay.

As above.

Points 1-5 are absolutely unnecessary waste of time and effort.

Here's the guide condensed:

1. lengthen MAF harness
2. Plug in turbo computers
3. Add an oil return for your turbo
4. bolt on turbo and exhaust
5. Swap coolant hoses for Turbo application
6. drop in intercooler, hoses, intake pipe with cone filter
7. Do accumulator mod on your AW71L

1. Has anyone done this exact swap without the 'under dash wiring nightmare'? I've already had the complete dash apart to replace the dual diaphragm HVAC servo (PITA). So I'd rather not do it again.

Click to expand...

What the **** are you talking about? If plugging in an EZK by the steering column seems like an unsurmountable task I suggest you buy yourself something that does what you want it to straight out of the box or you pay a shop to do the project a to z.

2. I can rewire the MAF connection BUT the ABS pump will conflict with the MAF due to the design of the hose between the MAF and turbo. I could remove the ABS system completely to work around this.

Click to expand...

As white855T said, cone filter. Make a bracket out of steel or aluminum bar if floppiness makes you nervous. The approach you are seeking is taking the most complicated approach possible to resolve a simple problem. Again, if you want to use a stock air box, buy a 940T.

3. The turbo does not use the WOT output on the TPS. The purpose in the NA cars is to enrich the fuel. Pros and cons of leaving it connected or not?

Click to expand...

Doesn't matter

4. The turbo uses an 'air preheating resistor' in the hose between the MAF and turbo. Pros and cons of its purpose and how/where to best connect this to the NA engine harness?

Click to expand...

Also doesn't matter; the thermistor does ****all anyway.

5. I would prefer to move the battery to the drivers side (like the turbo), to allow me to use the factory air filter housing (yes, the ABS pump would need to be moved/removed). To do this the under hood 'power distribution' needs to be changed. Anyone done this?

Click to expand...

Same as question 2. You are thinking about using an AIM-9 missile to shoot down a housefly.

Hello white855T, Harlard,

Many thanks for the feedback and insight. Having been a an IT project manager in a previous life I tend to approach projects from a very detailed perspective coupled with a lot of research. Sometimes it comes back to bit me.

Harlard, I do take issue with some of your comments. If you took the time to look at the YouTube video link in my post you would have seen that the chap replaced the majority of the under dash wiring as part of his 940 NA to turbo swap. This included splicing/soldering numerous wires at the firewall. Hence my question about the 'under dash wiring'. I'm quite capable of swapping an ECU or EKZ module, in fact I have designed and built numerous electronic circuits over the years. Also, I like to elicit feedback from others to see a better or simpler solution exists. Sarcastic and/or glib comments are never effective communication tools especially in a 'help' forum such as this one.

Once again, thanks for the feedback and putting me on a simpler path.

Uh yeah I made it about 45 seconds into that video before I had to turn it off. The electrical tape on the headlights was the clincher.

I didn't bother watching the youtube video. The guy is a member on here. It shouldn't take anyone more than a few days to do this especially if you have everything ready to go. In fact, you could make it easier by just swapping a modified oil pan which would you take half a day to do and then swap turbo parts on the next day. Be running by the third day. If you're sticking to a stock setup, the block and transmission will hold the power with no issue. You already have the good transmission(aw71L) so that doesn't require swapping. Take Friday off, be running by Sunday. This is very straight forward. No need to over think it but it's always good to ask questions, even dumb ones.

Fresh Air Inspector said:

Hello white855T, Harlard,

Many thanks for the feedback and insight. Having been a an IT project manager in a previous life I tend to approach projects from a very detailed perspective coupled with a lot of research. Sometimes it comes back to bit me.

Harlard, I do take issue with some of your comments. If you took the time to look at the YouTube video link in my post you would have seen that the chap replaced the majority of the under dash wiring as part of his 940 NA to turbo swap. This included splicing/soldering numerous wires at the firewall. Hence my question about the 'under dash wiring'. I'm quite capable of swapping an ECU or EKZ module, in fact I have designed and built numerous electronic circuits over the years. Also, I like to elicit feedback from others to see a better or simpler solution exists. Sarcastic and/or glib comments are never effective communication tools especially in a 'help' forum such as this one.

Once again, thanks for the feedback and putting me on a simpler path.

Click to expand...

Regarding the sarcasm/glib note: There is no sarcasm there; simply foul-mouthed tomfoolery. As for glib, thank you for noting my eloquence but I take issue as far as the solidity of my knowledge of old Swedish ****boxes is concerned, particularly when I spew opinions, however abrasively put. With that said, welcome to Turbobricks, we really are as awful as we appear

The two other guys are right, pay no attention to that video. The guy is clueless.

I did forget to comment on the rear end: yes the 3.73 is completely fine. They usually also have lockers, which are great when in decent shape.

Hello All,

Fantastic feedback. Within the next few weeks I'll pull the B230FT out of the sedan and begin to prepare it for the transplant. Although it could be done quickly I'll take my time. Plus I just discovered my deck has damp rot that has migrated into the sheathing under the Tyvek. Not good - need to repair this before the Fall rainy season. So, another project to delay the Volvo.

Harland -

Rear axle - yes, it is a 3.73 locker just like the 4.10 that was originally in the wagon.

Appreciate the honest insight and opinions. The latter is always welcome, it often helps one evaluate the feedback to see if it aligns with ones plans. Although some threads include spicy comments and opinions the value is immeasurable. Over the years I've been a member of at least 10 car forums and I've lost count of the number of times the feedback has saved the day. So, keep sharing your 'Swedish' technical knowledge.