OM617 Miata Brainstorming

I'm bored and this 85 Mercedes 300sd keeps popping up on FB marketplace for $500. 
 

I don't know much about these, but I figure I could gut it for Rallycross and maybe even the challenge this year and then see about swapping the engine into my Miata shell later on. 
 

Any info is helpful. Dimensions, common issues, etc. 

Weak points: Heavy, tall, gutless.

Strong points: Chugging along at stock power levels for eternity.

We've put about 12k miles on two OM617s in Lemons. In that time we had a radiator issue and a fuel tank issue. We kept the boost and fuel stock and they make an estimated 80whp. I ran my  3250lbs Sklasse down the 1/4 to a blistering 19.7@66mph. The engines are very easy to work on when you do need to, parts are generally available and not over priced.

The factory automatic is bulletproof at factory power. It's a non-overdrive 4 speed. Pairs well with the stock 3.07 gears while a Miata's 4.10s will be a bit deep. There are a few transmission conversion kits out there. The big thing to remember is that these engines are externally balanced so you'll have to transfer the balance from the flexplate. I've seen another racecar kill it's bearings from having the wrong balance.

As far as fitment, that'll be tough.

Weight: ~600 engine and ~125 trans

Length from pulley to rear mounting surface: 28.5"

Height from top of valve cover to shallow end of oil pan: 24"

Height from top of valve cover to shallow end of oil pan: 27"

Oil pan is aggressively front sumped.

I've never actually measured the width. My factory engine bay is 29" wide so we know the engine is less than that.

Whatever happened to the one that was bouncing around here forever? Did it finally get parted out?

Ew.

A Miata with 80s MB diesel power does not sound like it would be fun to drive.

Sounds like you could buy the car for $500, pull the engine to sell to a 4x4 guy who is looking for one as a swap, part or scrap the rest, and pocket some decent profits. 

I would entertain the newer 2.0l VW common-rail TDI (CJAA) if really interested in a diesel swapped Miata. The dimensions and powerband would be a better fit, and they're comically cheap on car-part.com. 

In reply to buzzboy :

Thanks for all that info. 
 

Sounds like my best bet if I really felt like it would be to gut the 300 and run it for a while. Still tempting. 

OM617 is nothing to write home about, but turbo it and do some pump mods and it can be at 300hp/400tq with basically hand tools and a weekend.

Incidentally, 400tq is about where the factory rods like to start bending.

OM606 on the other hand, the bottom end of it has been shown to be good for about 750hp/1000tq before things start to break.

Here is one that put 680hp/928tq stuffed in a Mopar in the UK

I think instead of a Miata a swap into something like a Jeep DJ-6 or Scout 80 would be cool.  

I had one that I daily drove for years, and still have a 300sdl.  I'd say if it's drivable just use it, otherwise it's not really that useful for a project.  The om617 isn't very efficient or powerful and they are getting harder to find parts for.

In reply to Tk8398 :

If it had a title I'd definitely be getting it. Without the title it'd be a lengthy process to be able to street drive it, and I don't really feel like messing with that. 

In reply to Curtis73 (Forum Supporter) :

Those pump mods don't come easily or cheaply. You're overselling that. 

I had a 240d with a om617 that had a vgt turbo and a2w intercooler. Built by a GRM member. Was fun but no means fast.

Om606 is good for tons of power if you want to go there. That's true.

Om606 crank in a m104 and you have a 2jz beater.