My father and I have been restoring a Mercedes 250C coupe for many years. It's been fun, but I've always dreamed of a V8 stuffed into the engine bay to replace the dull iron block six that resides there. On top of that the transmission isn't in great shape. I'd pondered it for a while - get a cheap Mercedes S-class, rip out the V8 and tranny and stuff it in. It's been done before, and it's a better option that the typical small-block conversion (much, much lighter, lighter than the six, and nice free-revving power). But I never pursued the idea; besides, most North American Benz V8s from the 80s struggle to break 200 hp, even the monster 5.6 is only rated at 250 hp.
Last year I bought a 1991 Infiniti Q45. It was my winter beater, I paid next to nothing for it and it the engine is in fantastic shape. I'm now trying to get rid of it, but interest is nill. I guess 8 mpg luxo barges aren't popular on the market at the moment. Then my dad proposed an idea - why not part out the car and keep the engine and drivetrain to stuff into the Mercedes?
Suddenly the hot rod project is possible, with the engine and transmission at hand. The 4.5L in the Infiniti is an alloy block, four cam, variable valve timing design with rock-solid internals - and it's compact and light. On top of that it makes something around 300 hp and 300 lb/ft. It makes a load of torque and a great top end rush right up to 7000 rpm. In a two ton Q it flings the car to 60 in 7 seconds. The Benz weighs about 1000 lbs LESS, including the iron block six. That is a recipe for fun.
Now we just have to start working out logistics - making sure the thing actually fits into the engine bay, figure out how to mate a Nissan transmission to a Mercedes driveline, work out what electronics we need to tear out of the Q and how to bypass the bits we don't need. Then the real fun begins.
[popcorn]
Sounds like a fun project, keep us in the loop. [thumbsup]
You'll need to cut /replace the driveshaft and match the transmission output yoke, and the rear end input shaft. I expect this means a custom built driveshaft.
The Infinity is fuel injected, so you'll need to transfer the PCM and associated wiring to the mercedes.
You will need to fabricate new engine/trans mounts, and may need to make mounts to relocate the mounting points on the mercedes. The mounts may have to move transversely as well as laterally.
You will probably have to fab new shift linkages to get the mercedes shift lever to operate the infinity trans.
Good luck, and don't forget the pics!
How robust is the Benz rear end/ ring & pinion?
Not sure about the rear end strength. W114s had a specific differential for models up to 2.8L, V8 models had another (with LSD as an option). I know the transmission is rated to 250 lb/ft max, so it wouldn't be a stretch to imagine the rear end has similar limits. The real question is what is interchangeable, the easy route would be to get a beefy diff off a junk SEL/SEC/SL and call it a day. It's a shame I won't be able to use the Nissan final drive, it's the same LSD as a 300ZX and is pretty effective.
My main concern, aside from actually fitting the engine, is the mating of the transmission to the driveshaft. New engine mounts are easy to fabricate, and the engine bay is huge so there should be room. As mentioned it will need a customized driveshaft, assuming there is room for the tranny at all. These are the logistics that we need to start working out on paper before we rip the engines out.
Electricals are easy, in theory. Just need the ECU and TCU and associated sensors, bypassing redundant systems with resistors if they cause problems when disconnected. The main work is tracing the wiring and removing everything without damaging or mixing anything up.
Skinny tires can help limit load on the rear end. :P
What's the word on the street about rear end durability with a small-block?
Assuming the trans from the Q45 is an automatic?
A little more cutting and fitting and you *could* use the Q45 final drive. ;)
<threadjack>
Do you know what a dilapidated '74 280C is worth?
</threadjack>
The drive shaft is easy. When I stuffed a Richmond 6 speed into my Jag convertible I just brought the old drives haft with the front yoke for the Richmond down to the drive shaft shop along with the final length. They had a new aluminum drive shaft made up later that week for a couple of hundred dollars.
Several years ago I was contemplating dropping a built SBC into a '78 Mercedes coupe.
I was talking about putting a 'Vette rear end in it to maintain the independent suspension.
An individual whom I trusted very much on the subject said "no need. Mercedes rear ends back then were WAY over-built."
He did advise changing out the axle shafts in favor of a beefier option though.
And if your driveline has flex-discs I'd ditch those for u-joints when you replace the driveshaft. [thumbsup]
[popcorn]
This sounds like a fun project!
JM
+1 on the driveshaft comments. Usually $200-$400 will net you the desired shaft all balanced and ready to go.
+1 on the skinny tire comment for torque limitations on the diff, but hard launches become tire-smoking-exercises real quick.
+1 on the 'dare to be different' chalkboard.
--and lastly--
+1 [popcorn]
Quote from: Duck-Stew on January 24, 2009, 04:54:25 PM
+1 on the skinny tire comment for torque limitations on the diff, but hard launches become tire-smoking-exercises real quick.
...what's wrong w/ smokin' tires? [evil]
74 280C isn't worth a lot. Ours (72 W114 with 2.8L twin carb) is worth MAYBE 7K, if someone were willing to pay that (not many are), and it's considered more collectible than the later models (probably because it is prettier). We've invested over 15K in restoration. In other words, we will be keeping it for a while. We paid 1500 for it originally, and that was probably too much.
Not sure if it has flex discs. I swapped out the driveshaft years ago and I don't recall anything other than a beefy driveshaft on U-joints. I may be wrong. The axles are pretty spindly though, just a thin steel rod on CV joints. They will probably the weak point.
The Q tranny is auto, unfortunately. It's also a mediocre design, if we had unlimited funds I would have it rebuilt with stronger internals, new valving and a performance torque converter. Nissan never made a manual that fit the VH45 (the only car it was ever put into was the Q/President) so that option is out.
Quote from: derby on January 24, 2009, 05:04:57 PM
(http://i13.photobucket.com/albums/a252/rockhopper1998/GetYoPopcornReady.gif)
I like yours the best. [thumbsup]
She's a bit nipply in that pic...
Quote from: NeufUnSix on January 24, 2009, 05:07:45 PM
74 280C isn't worth a lot. Ours (72 W114 with 2.8L twin carb) is worth MAYBE 7K, if someone were willing to pay that (not many are), and it's considered more collectible than the later models (probably because it is prettier). We've invested over 15K in restoration. In other words, we will be keeping it for a while. We paid 1500 for it originally, and that was probably too much.
Not sure if it has flex discs. I swapped out the driveshaft years ago and I don't recall anything other than a beefy driveshaft on U-joints. I may be wrong. The axles are pretty spindly though, just a thin steel rod on CV joints. They will probably the weak point.
The Q tranny is auto, unfortunately. It's also a mediocre design, if we had unlimited funds I would have it rebuilt with stronger internals, new valving and a performance torque converter. Nissan never made a manual that fit the VH45 (the only car it was ever put into was the Q/President) so that option is out.
It doesn't have anything in common with stuff like the FX45, M(?)45 or Titan engine? Although, I'm not even sure any of those are manual either.
The VH45DE was a unique design found only in the early Qs, later "4.5" models were completely different. Cost saving was put into effect in the mid 90s and the more recent engines are built to a price. The VH45DE was a cost-no-object V8 at the time, with polished internals, heavy duty rods and crank, sodium filled valves, variable valve timing, and all sorts of goodies. People who have rebuilt them say it's like opening a race motor. They are pretty durable, but they had one fatal flaw - plastic timing chain guides that would disintegrate. Mine has already had the guides and timing chain replaced; aside from that it is original with 250 000 kms and it still runs damn strong with zero oil consumption.
Great project and a big +1 to all the [popcorn]
If you're converting to fuel injection, don't forget the fuel system. You'll need to add a return line (or use the existing supply line as a return), properly sized supply line (with filter) and a pump. If it were me, Id pull the pump/sender unit from the donor and figure out how to graft it onto your existing fuel tank- top mount style.
You'll for sure need the ECU, TCU and all the associated wiring but that's all plug and play. A wiring diagram for the donor will be worth it to procure.
If you have a big engine bay, can you use the nissan radiator in the Merc? That's the easy way out if it fits, as far as cooling the motor goes.
Exhaust shouldn't be too hard.
Keep the original drive shaft. Once the engine and trans are in you can measure for your custom one. They can chop both shafts and put the Nissan front with the Merc rear section.
Cool idea [thumbsup]
I think we could use the Nissan rad, maybe. The engine bay is spacious, to say the least. It fits a big straight six with about 8 inches free space at the front and a good two feet of open air on either side. It would certainly make things easier, with regards to coolant sensors in the rad.
Fortunately I have a complete shop manual for the Q so sorting the wiring will be simple. It even details how to remove the engine and transmission properly, which will come in handy. I just need to figure out what needs to be bypassed. Keeping it simple is the goal, so if it is not needed to run the engine and transmission, it won't be tranferred.
I'm a little worried about the fuel pump assembly; the Q uses an upright tank (mounted behind the rear seats) with the pump inside the tank, bolted in from the top. It's cooled by being submerged in the gas, so using it externally it not possible (it's probably a flat pickup too, as opposed to a tube pickup). But it might be too tall to fit into the Mercedes tank. Does anyone know of an aftermarket fuel pump that can be mounted externally? I've seen it done but I have no clue what to chose, or what kind of flow rates I'd need.
Here's a question for hot rodders - the Q uses an independent suspension of some kind, while the Mercedes uses a swing axle at the rear. How much trouble would it be to move the Q diff and axles into the Mercedes? Would it screw up the suspension geometry? Can some sort of hybrid (Q diff, Merc axles) be fabricated easily?
My $.02 & experience: Using an external pump will be noisy. The submerged pumps run quieter and cooler too. Figure out the psi and flow needed to run the Q45 motor and just find a cheap pump from another car with a similar tank as the 'Cedes. Buy the other tank and take them both (other car and the 'Cedes) to a competant welding shop to have the other cars fuel pump flange mated to the 'Cedes tank. All the wiring the fuel pump needs is a fused, switched on 12V power source and a ground and it's happy. No need to try and make the Q pump work if it's going to be a nightmare.
Also, figure out if the TCM and ECM talk to each other. If they don't (transmission control module completely seperate of the engine control module) it may be possible to have a different transmission adapted to the ass-end of the Q45 motor (I know at this point I'm sounding like I'm made of money but I'm just offering options...) and therefore it may solve problems like space/torque capacity/# of gears/etc...
Oh, and Derby?!? I never said smokin' the tires was a bad thing!!!!
Quote from: NeufUnSix on January 26, 2009, 08:20:41 AM
I think we could use the Nissan rad, maybe. The engine bay is spacious, to say the least. It fits a big straight six with about 8 inches free space at the front and a good two feet of open air on either side. It would certainly make things easier, with regards to coolant sensors in the rad.
Fortunately I have a complete shop manual for the Q so sorting the wiring will be simple. It even details how to remove the engine and transmission properly, which will come in handy. I just need to figure out what needs to be bypassed. Keeping it simple is the goal, so if it is not needed to run the engine and transmission, it won't be tranferred.
I'm a little worried about the fuel pump assembly; the Q uses an upright tank (mounted behind the rear seats) with the pump inside the tank, bolted in from the top. It's cooled by being submerged in the gas, so using it externally it not possible (it's probably a flat pickup too, as opposed to a tube pickup). But it might be too tall to fit into the Mercedes tank. Does anyone know of an aftermarket fuel pump that can be mounted externally? I've seen it done but I have no clue what to chose, or what kind of flow rates I'd need.
Here's a question for hot rodders - the Q uses an independent suspension of some kind, while the Mercedes uses a swing axle at the rear. How much trouble would it be to move the Q diff and axles into the Mercedes? Would it screw up the suspension geometry? Can some sort of hybrid (Q diff, Merc axles) be fabricated easily?