Planet Express needs some more expressness. Mercedes W116 repower ideas

I am one of the idiots involved with Idle Clatter Racing in LeMons. Our original racecar is the Planet Express, a 1979 Mercedes 300SD. She's a magnificent creature. She weighs in at 3500lbs with a half tank of fuel and me in the drivers' seat. The original OM617.950 puts out 110 bhp through a very very sloppy 722.120 four speed automatic transmission. In 9(?) races we've taken IOE and a C class win. In the quarter mile we've managed a staggering 19.6 at 67mph. What a beautiful performance machine.  

Sadly in the fall of 2016 Planet Express grew a bit warm on track. After 3 years of racing with distilled/tap water in the radiator we created a blockage. The driver came off track with the gauge reading 230F and no water in the radiator. The rotella t4 was no longer oil but some weird slime. After cooling down and changing the oil Planet Express once again roared to life but with much more glow plug and a slightly different sound.

Since then I have put about another 1000 miles on the old girl. She now takes a full 30+ seconds of glow plug, even when warm and I don't feel like she still has 110bhp. After sitting for a week or two at a time it's a long ordeal of glow plugging and possibly spraying ether to fire the engine. The poor girl is sick and needs a new heart. The race team has expressed that they are no longer interested in racing Planet Express, instead opting to drive our sister car the Toyocedes and that I am the one person who cares about the car the most so I should chose it's fate.

I currently have more cars and projects than I need but I am happy to remove a few of them from myself to make Planet Express again. While the team no longer wants to race PE I still would like to have it perform as more than a parade float. Can I also mention that I am super cheap and have a BMW e36/5 that also needs a new engine? So the main thing is that my swap doesn't break the bank. Also, I'm a mediocre fabricator at best. I can probably get help with engine and trans mounts but otherwise I'm more comfortable doing electrical and plumbing on cars.

The main goals

• Engine fits in bay
• Powerful enough to tow a small trailer if asked
• Not weigh a (half) ton

The big questions though.

• Do I try to keep it diesel? (our name is Idle Clatter...)
• Do I keep it auto?
• Is it worth it to have a "cool" engine instead of a common swap?

The simple button is probably carbureted 350 with a th350 and be done. It will be lighter, faster, easier to work on, easier to find parts for and be fine for towing a small trailer.

The fun button would be a more powerful MB diesel swap, OM603 or OM606. This would keep the car to it's roots while making it slightly lighter and slightly more powerful.

The cool button may be a 4bt/4bd2t. She'd gain a bit of weight but also a more torquey engine with easy power upgrades although at a higher cost.

The second cool button would be a VW TDI. Lighter, more powerful, good aftermarket but a lot more money and complexity.

The lottery winning option would probably be an OM648. 200hp and 370ftlbs from a rev happy MB I6 diesel. Mmmmmm

The correct answer is to remove the S52 from my bmw, rebuild it and install it in the Mercedes right?

I'm not sure what the right answer is, as I'm not a mechanic.  But as one of the Three Pedal Mafia drivers, I just want to see you back on track.  I always enjoyed running with you guys when I was driving "the Boat" or now our Hombre (or even the one sad race our Datsun 720 ran at Barber).

Whatever newer runner you can get cheap off the local CL/facespace. Starting with a running engine, and knowing you've got everything it needs to run already, should help get this done. Sounds like starting with looking at available Merc diesels makes sense. I'd probably progress from there to whatever other full size sedans are available. Maybe Jeep's? Big torquey inline 6?

Olds 350V8 Diesel.

The truck version made 120/220

I’m a pretty big fan of my om603... I’d go with that option. 

If you really want to get crazy, you could go with the 2L diesel out of the 2014-15 Chevy Cruze. 151/250 from the factory and easily into the 200+/300+ with a tune and minor mods. Probably not very budget friendly and I have no idea what trans you could use.

I had a 4.5 v8 w116. It wasn't really slow but wasn't fast. I also had a modded w123 with a om617 running 15psi off a vgt turbo with a manual trans behind it. It was fun!

If you repower it with another Mercedes diesel then remember that you'll have to modify the injection pump to get good power. The OM603 and OM606 (the 2jz of diesel engines) can make a lot of power. The 606 just needs a big turbo and injection pump modification to make 500hp all day every day. You can run a Mercedes transmission behind it, whatever trans that bolts up to the m104 and there are kits out there. It isn't a cheap adventure. 

I recommend doing a sbf 5.0. I've seen them in w116's with the manifolds flipped to exit forward of the engine. They're easy, they fit, and they're cheap. 

Might want to swap in the rearend from a 6.9 though 

I'd say do something unloved. You're not going to win the sharp end of the speed classes with that car, but the ioe and stuff you have already done an excellent job of capturing are going to be that car's bread and butter.

I'd say air cooled vw or rx8 take out, but both would be sooooooo bad in that car it would not be worth the effort.

Maybe a Ford 300 i6? I like the Jeep 4.0 idea too. Honda v6 swapped into the trunk? (Or one Honda v6 swapped into each end...)

Or, figure out what is wrong with yours? Maybe it's just a head gasket?

I like the Mercedes turbo diesel idea. Our Lady of Perpetual Downforce guys have been down that road, and it sounds like they've got some speed picked up now.

Klayfish said:

I'm not sure what the right answer is, as I'm not a mechanic.  But as one of the Three Pedal Mafia drivers, I just want to see you back on track.  I always enjoyed running with you guys when I was driving "the Boat" or now our Hombre (or even the one sad race our Datsun 720 ran at Barber).

Dont' worry, ICR isn't going anywhere. Our other car is still racing multiple times per year. We've lost a few drivers and have two very similar cars that are uncompetitive in B class so there isn't much reason for us to drive both of them at the same time.

bluej said:

 Maybe Jeep's? Big torquey inline 6?

I've been DDing a cherokee for a few months now. The thought has crossed my mind. The gearing would be a bit high for trailer towing I think sadly. The cool thing is that my teammate built an H Pattern manumatic shifter for an AW4 that he's been dying to put in a car. It was going to go into our first lemons car that never was built due to a catostrophic head gasket failure.

FooBag said:

If you really want to get crazy, you could go with the 2L diesel out of the 2014-15 Chevy Cruze. 151/250 from the factory and easily into the 200+/300+ with a tune and minor mods. Probably not very budget friendly and I have no idea what trans you could use.

I'm seeing dollar signs and a project that is never finished.

yupididit said:

I recommend doing a sbf 5.0. I've seen them in w116's with the manifolds flipped to exit forward of the engine. They're easy, they fit, and they're cheap. 

Might want to swap in the rearend from a 6.9 though 

Is that a good reason to go SBF over SBC? I'm more of a bow tie fan when it comes to small blocks but that's more of a displacement thing in this case. We do have a 6.9 rear end sitting around but I don't see it helping too much. The 6.9 rear end is a 2.63LSD where the car currently has a 3.07 open. Sadly there is a carrier break and you can't fit the LSD into the 3.07 gear set.

Robbie said:

I'd say do something unloved. You're not going to win the sharp end of the speed classes with that car, but the ioe and stuff you have already done an excellent job of capturing are going to be that car's bread and butter.

Or, figure out what is wrong with yours? Maybe it's just a head gasket?

We're done racing the car so I'd rather have a reliable weekend driver engine for it. Having it faster on the street though would be pretty fun. The om617 is tired. It's got tons of blowby after 165,000 street miles and about 5000 race miles. Maybe I can sell it off for a little bit towards a better engine.

In reply to buzzboy :

Yes, that's the main reason people use the sbf over the sbc in r107, w114, w116, and  w123. swaps. It fits better, just as affordable. Have you thought about a bigger m117? Like the 5.6? then megasquirt it. Could save you making mounts. 

Um...or you could do something I always wanted but don't have the skills to do....m120 V12 from a w140 

Do like these guys and feed an OM606 with both a Holset turbo and a junkyard Eaton blower.

dculberson said:

I like the Mercedes turbo diesel idea. Our Lady of Perpetual Downforce guys have been down that road, and it sounds like they've got some speed picked up now.

Our Lady is a B20 VTEC swapped EF sedan. It's fast, but very much not a mercedes turbo diesel. Also, after this year's Barber race, it's dead.

In reply to buzzboy :

Sorry, I was thinking of the duff beer guys!

Yeah, we taught Duff Beer a lot about w123 chassis MBs when they were switching from the Honda game. Planet Express is a bit heavier than their car and has a bit less power stock. Our other car is a good bit lighter than their car but with an automatic. They're a good matchup, except they have more driving experience than us.

It's hard to find an empty engine bay shot of a w116. Most of the love of these cars seems to be in Australia so I found an engine bay with the steering rack on the wrong side. The only thing that sticks out to me is that there is a second crossmember(suspension brace?) behind the engine crossmember. That only makes me think about which end of the oil pan has a sump. It looks like it would have to be very far back or very far forward. I think I'll try and sell the SBF/SBC idea to the guys though. This doesn't look impossible. There's so much room in there for the M100 that a small V8 shouldn't have any trouble fitting in there.

 Here's mine with a m117 fully dressed. Not a small engine!

302 w116

I’m picking up a 1980 300sd tomorrow with a bad engine,  so this thread is relevant to my interests.   I already have another turbo diesel engine and 4 speed auto out of an 85 300d,  so will probably go that route,  but at this point I won’t rule out a swap.