A 6.9 into a W123 -- Is it possible? The ultimate AMG beast - PeachParts Mercedes-Benz Forum

greazzer · #1 03-17-2019, 09:14 AM

I purchased a 6.9 engine around 13+ months ago for a seperate project which went sideways. Found a few 450SELs without an engine so I grapped the engine thinking I could grab one of the two cars .... but, it went sideways. For the last 10 years I wanted a 450SEL 6.9 ... but, I am thinking I will just stick to my W123 and graft the HPN suspension system into it. I got virtually all the parts and figured out how to rebuild the struts. Just need a few odds and ends to have everything I need.

Had a mini-circus on CL trying to sell the engine. Engine has been on eBay for a while now. Actually sold it twice except the "buyers" never paid. So, it still sits for sale. I got it out of my driveway to my HOA's and wife's delight. It's on a stand now in my garage under its own lights for tinkering when I have an off moment.

My OM617 turbo engine is headed back soon from the machinst. I have my "super-turbo OM617" on the stand getting ready for some fininshing touches.

So, would a 6.9 really fit inside the engine bay of the W123? I would say yes. They look totally different but I am thinking it would fit. Another forum member says yes too. The problem is the tranny. Need to modify the tranny tunnel which I am not going to do. So, maybe a T-56 six speed from a corvette? That might just work ... not 100% sure yet.

So, any thoughts ?

The weight between the two engines is pretty close. Although it's a giant, a 6.9 is around 750 pounds and I can shave off at least 50 pounds without any issues or causing any real need for a mod. The fully weighted OM617 turbo is around 675 pounds. Does 25 pounds really matter? Battery in the trunk should fix that difference ?

Any thoughts on a hack oil tank? Fuel pressure PSI ? Mounting on a reinforced pallet with wheels so I can move it in and out of the garage is a must. Overall, without a huge investment of money, I am thinking I can get the engine running on a temp basis to see how it runs. I can get the aluminum plate pretty cheap for the T-56. I have a great machinist who could fabricate the plate and figure out the flywheel/clutch issues.

Any pictures of anyone really having a 6.9 in W123 ?????????

fonzi · #2 03-17-2019, 12:14 PM

I’ve seen them in 107 chassis cars.

I’ve seen henric / 48hp’s w123 wagon with a m117 5.0 and tri-y pipes in it I believe.

I think the steering box and the exhaust is what you may want to focus on. I think the w116 does have the same style suspension as the w123, but don’t quote me on that. Steering box location definitely can be an issue for the exhaust.

I am unsure whether anyone has done a 6.9 in a w123.

Plan on some heavy duty shocks and maybe having to get the beefiest front springs available for a w123.

Always interested in any manual trans on MB v8 details.

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Frank Reiner · #3 03-17-2019, 12:20 PM

Quote:

Originally Posted by greazzer

So, would a 6.9 really fit inside the engine bay of the W123? I would say yes. They look totally different but I am thinking it would fit. Another forum member says yes too. The problem is the tranny. Need to modify the tranny tunnel which I am not going to do. So, maybe a T-56 six speed from a corvette? That might just work ... not 100% sure yet.

So, any thoughts ?

Why do you hate your 123?

greazzer · #4 03-17-2019, 12:38 PM

Quote:

Originally Posted by Frank Reiner

Why do you hate your 123?

I guess I "hate" my W123 to the same exact extent pre-merger AMG did back in the day. Horrible isn't it ...

disqo · #5 03-17-2019, 04:22 PM

This was a dream of mine for sure!

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Roncallo · #6 03-17-2019, 11:50 PM

I'v seen them in 113's and 107's. I would say anything can be done with money. There was also a guy making plates to bolt up manual transmissions for them. I personally prefer the M100 6.3 just because it looks cooler.

Tony H · #7 03-18-2019, 12:38 AM

You could build a mock up engine out of foam/plywood. Common Ford/GM foam short/long blocks are available so the idea is not new.

greazzer · #8 03-18-2019, 12:44 AM

I am thinking much more primitive ... Remove the exhaust manifolds and drop it in and see if it "fits" so that I can physically see it with my own eyes.

The OM617 and the 6.9 are just about the same length which is amazing IMO. I just measured them again.

They are about the same width when it comes to where the motor mount arms are sticking out on the L & R sides which is also amazing since the 6.9 appears so much larger and bulkier.

cth350 · #9 04-08-2019, 05:45 PM

it will fit. You will have about 1,000 pounds of steel up front, most of which wasn't there before, so there will be front end and suspension issues to work out, but it will fit.

-CTH

greazzer · #10 04-09-2019, 05:34 AM

It weighs around 750 pounds and I could shed a few more. A fully accessorized OM617 turbo is 675 pounds so the weight difference isn’t a bunch. Relocate the battery to the trunk and it should be close to even

rwd4evr · #11 05-12-2019, 02:27 AM

Only guessing but it should go in. A w126 would be easier since they are identical suspension but wider track width. Oil pan shouldn't be a problem. Biggest concern is steering box I would say. Some custom headers may be a necessity.

Stretch · #12 05-12-2019, 05:11 AM

Even with all of the available parts and "solution providers" I don't see why you'd want to do this especially if you've got an OM617 that could go in there. I think you'll have more fun with the tuned OM617 - the M100 is just going to suck fuel that even in the US of A is going to hurt the pocket.

In modern terms the M100 isn't an impressive engine - despite the ebay frustrations I'd try and sell it and move on.

Sorry to give a negative reaction

If you decide to proceed with the project I will (try to) be positive about the engineering solutions!

rwd4evr · #13 05-12-2019, 05:05 PM

Quote:

Originally Posted by Stretch

Even with all of the available parts and "solution providers" I don't see why you'd want to do this especially if you've got an OM617 that could go in there. I think you'll have more fun with the tuned OM617 - the M100 is just going to suck fuel that even in the US of A is going to hurt the pocket.

In modern terms the M100 isn't an impressive engine - despite the ebay frustrations I'd try and sell it and move on.

Sorry to give a negative reaction

If you decide to proceed with the project I will (try to) be positive about the engineering solutions!

I would somewhat agree. Big m100 cool factor but a dieselmeken pump and big turbo and the om617 will make more power. Adapters are out there to bolt up tons of different trans.run it on anything pretty much and get pretty good mileage. I've got a 617 project in the pipeline myself.