1994 Volvo 850 Tranny/Engine swap

mmd94 · Post by **mmd94** » 25 Aug 2014, 06:51

I am currently working on my 94 850 base model. I plan on dropping a turbo engine in and need to know if the transmission is the same between models from 1994 850's and if anything should be changed on the transmission when I swap motors. My main concern is that the turbo models have a different transmission all together, and besides converting to a turbo setup, will my tranny work or no?

I can provide more information if needed, I don't believe I have the transmission number but I should be able to find out if its needed.

Thanks!

Post by **rspi** » 25 Aug 2014, 07:48

Tranny is the same.

There are so many things you have to do to convert a NA car to a turbo, why don't you simply buy a turbo car for $400 or $500 and fix it? I recently purchased a very clean '98 S70 T5 with 105,000 on the clock. It had a burnt valve so I fixed it. Now I'm working on a V70 GLT that cost me $400.

I don't get it.

Post by **polskamafia mjl** » 25 Aug 2014, 19:08

No personal experience here but it seems like if you are dropping an entire turbo engine in then that should be much simpler than trying to add a turbo to an NA engine? Assuming you have an entire parts car handy that you are getting the engine from, if you pull the entire wiring harness and ECU's then it should be pretty plug and play. I think...

I may have missed a fundamental step that would complicate this whole process so I'm open to corrections.

Post by **jblackburn** » 26 Aug 2014, 10:26

NA -> Turbo is quite a difficult conversion, especially with a 94.

You would honestly be better off starting with a turbo model from a similar year (96-98 or 94-95) and doing the transplant.

Wiring harnesses, oil line/coolant line plumbing is all very different. 94 base models used an entirely different computer system from the 94 turbo, which was different from the 98 turbo.

Transmission between 94-98 models is different, and non-turbo models have a different final drive ratio from turbo models.

Post by **erikv11** » 26 Aug 2014, 11:47

This is not the main point of the thread but just to clarify: the transmissions are different between the turbo and non-turbo cars. The final drive ratios are not the same.

EDIT: Never mind, I didn't read jblackburn's entire post, this info is already in there ...

mmd94 · Post by **mmd94** » 06 Sep 2014, 09:03

erikv11 wrote:This is not the main point of the thread but just to clarify: the transmissions are different between the turbo and non-turbo cars. The final drive ratios are not the same.

Thanks Erik11, And for others who see this post, I do plan on dropping a turbo engine in, and as for the final drive issue, I might change the transmission with it. Another question since the final drive ratios are different, can I change the final drive? or easier to swap tranny?

Post by **Ozark Lee** » 06 Sep 2014, 10:19

You really need to do some more home work. Your 1994 base model N/A car has a Jetronic LH3.2 ECU system. The turbo engine has either a Motronic 4.3 or 4.4 system depending on what model year the power plant is coming out of. The ECU is entirely different as is the wiring harness to the ECU and TCU. Even things like the climate control unit and the instrument cluster are wired differently between the years so the changes are not all contained under the hood.

If the donor car is a post '95 model the speed sensors on the transmission are totally different. The early versions had a speed sensor on the transaxle. After 95 the speed sensor on the transmission went away and the speed sensor signals went from an analog sine wave to a digital pulse train that is generated from the later model ABS modules. The transmission control modules are different based on the speed signals from the input.

I'm not going to say that it isn't possible but it will take you a tremendous amount of time and effort, more that it is worth.

Snag the schematics from here and check out the differences to get a handle on what you are facing:

http://www.volvowiringdiagrams.com/

...Lee