W108 280S Project - PeachParts Mercedes-Benz Forum

7450SE · #1 07-31-2007, 03:44 AM

I'm starting on a project... a W108 280S (beautiful car with head issues) with a Holden 308 V8 (5L) and Supra 5 speed gearbox.

Why I hear you ask...

Why not. I have the Merc. I have the V8, all I need is the gearbox, some money and loads of time and knowledge. The last part is why I am here...

Has any one here done such a conversion?
What parts may need changing?
Will the standard diff be able to handle the extra power, or would I need to change this too? If I need to change it, what (cheapish) will fit?

Any help, feedback and info would be greatly appreciated.

Now I also hear some of you saying "You bastard, how dare you defile such a classic" - I understand... but I do have my W108 250SE for total restoration... my 280S is for fun. I shall post pics along the way for your enjoyment, or torment if you are one of those saying the "you b..." line...

Any way, thanks for tuning in, hope to hear from you all

Mark DiSilvestro · #2 07-31-2007, 09:49 AM

Try a Forum Search under user-name '68_Mercedes' for more alternative-powered W108s.

Happy Motoring, Mark

cth350 · #3 07-31-2007, 10:53 PM

not too many purists here. We might call you names if you car is prettier than ours, but that's just us (in spite of the fact that, "All mercedes are DB040 in the dark").

As for your holden question, I'd suggest talking with a few of the guys down under. When it comes to unnatural acts like this, the first name that comes to my mind is Ron Bunting (User Ron B at www.m-100.cc). But, maybe it's just his affection for the large spiders and his collection of 6.3s that are all nicer than mine that brings his name to my lips.

-CTH

7450SE · #4 08-01-2007, 05:09 AM

Thanks for your input, just read through some of 68_Mercedes' posts... it all seems do-able, especially since the Aussie 308 and the Chevy v8 are so similar, the 308 is smaller than the 350 (well duh!)... Now however, I'm not too sure on what I'm gonna do with transmission... keep the 4 speed Merc auto, use the turbo hydramatic 400 3 speed auto or purchase the supra 5 speed manual... Where can one find conversion bell housings for the Merc - Chev engines, here is nothing that I've found available in Aus.
I guess I'll start the project n see what happens as it happens... who knows, I may surprise myself

lol

Mark DiSilvestro · #5 08-01-2007, 09:41 AM

Quote:

Originally Posted by 7450SE

Thanks for your input, just read through some of 68_Mercedes' posts... it all seems do-able, especially since the Aussie 308 and the Chevy v8 are so similar, the 308 is smaller than the 350 (well duh!)... Now however, I'm not too sure on what I'm gonna do with transmission... keep the 4 speed Merc auto, use the turbo hydramatic 400 3 speed auto or purchase the supra 5 speed manual... Where can one find conversion bell housings for the Merc - Chev engines, here is nothing that I've found available in Aus.
I guess I'll start the project n see what happens as it happens... who knows, I may surprise myself

lol

If you have Chevy - Supra conversion adapters availible, that 5-speed might be the way to go. Otherwise, custom-make a driveshaft and use the turbo-hydramatic if it will fit. You might have to downsize from the 400 to a 350 or smaller tranny to fit the Merc. At least the W108 doesn't have an enclosed driveshaft tunnel like the Ponton Mercs.

Another issue is highway revs with the stock rear end ratio. Especially in the US, Mercedes geared the small sixes for maximum power, so they were really screaming at highway speeds. Even with the original six, some have swapped in the rear axle assy from one of the V8s for more relaxed highway cruising and better fuel mileage.

Happy Motoring, Mark

pyrOman · #6 08-01-2007, 02:28 PM

I too contemplated the same idea way back when. Do a little research. I did and found a few have tried it already and succeeded while others are STILL at it even though they started their project many many years ago!!!

Good luck and do show your progress!

7450SE · #7 08-16-2007, 10:27 PM

Holden-Toyota adapters are readily available here, in fact I've seen some supra 5 speed with holden V8 bell housings on ebay fairly cheap, so I think thats what I'll do, Holden 308 with supra (or celica) 5 speed.

Highway cruizin' is not going to be a major concern for me, just the actual strength of the diff. The car will be a "burn out/drift" car, just because I have not seen one of these cuttin' sick on the track

Time is also not an issue, as it isn't my daily. The only issue is time and money, so the project will be slow, as the cash dribbles in...

First however, I am forced to move house

this makes the project a little more difficult as she's now parked 50Km away.

Such is life. Thanks all for your input, if any one has suggestions or opinions to offer, all is welcome.

7450SE · #8 09-19-2007, 09:00 PM

Ok, things have stopped for a while due to the inconvenience of moving - an exercise I desperately HATE! The new place has less room for my babies so I'm contemplating selling some (I don't want to, so I won't be unhappy if I don't sell any of them. They are all so precious to me...)

Tomguy · #9 09-19-2007, 10:26 PM

I don't know if the 108 is - stock - a good drift candidate. No rear sway bar (Anti-roll bar to you, probably) on a swing axle.

Of course, that's what a welder and a length of spring steel from another vehicle are for!

7450SE · #10 09-20-2007, 01:49 AM

This is Ik suppose why I chose it, I love the looks of the old merc's, they just need some "help" of what technology can offer, this and welders... lol

7450SE · #11 01-10-2008, 12:57 AM

Ok, moving out of the way, and petrol prices on the rise... rethink of project: conclusion - will fit a m103 3.0 with manual gearbox, if I can find a complete damaged Mercedes 300E manual some where for CHEAP. Any ideas any one?

PS. I think I may sell my W116 450SE (My baby) asking approx $AU4500

cth350 · #12 01-11-2008, 08:10 PM

Find Ron Bunting. He's down there someplace (forget which city). He thinks along the same lines as you. -CTH

7450SE · #13 01-15-2008, 02:46 AM

Quote:

Originally Posted by cth350

Find Ron Bunting. He's down there someplace (forget which city). He thinks along the same lines as you. -CTH

So I took your advice, I contacted Ron (He's in Brisbane). Now I have another avenue... a M110 2.8L. These are more readily available, but then I'd want one of the later models - as Ron suggested from a W126. The question is, will this give me better fuel efficiency or more power than the M103? He also advised against finding a manual, so maybe for my daily I'll stick with an auto... The W108 is a heavy car, so then maybe I put a M117 4.5L from my w116 450 SE or SEL into it... or go back to the original choice of a Holden 308 V8... I adjusted my line of thought for fuel economy's sake...

WHAT TO DO?.?

7450SE · #14 01-16-2008, 09:47 PM

Well, just about to purchase a w116 280se just for the motor and gearbox (and some other bits and pieces)...

7450SE · #15 01-23-2008, 09:30 PM

Umm... anyone out there know what happens to a M110 when you add a huge turbo???

The project is happening, all my original ideas out the window, conclusion: W108 280S with a W116 280SE motor and gearbox, complete respray (dark blue I think would look nice with lots of chrome) and do something with the interior (not sure what that something is yet). Drive it like that for a while (do a dyno with it), then get a megasquirt engine management system (maybe do another dyno run), then get bigger injectors unless the injectors on the m110 are mechanical injection in which case I'll get the bigger injectors at the same time as the megasquirt, big turbo and intercooler set (not sure where I can hide the intercooler in a W108) and re dyno it... lets see how great the mercedes M110 really is! I'll post some pics of my progress soon...

PS. Huge thanks to http://www.jaimekop.com/ for the help on removing the woodwork from my mercedes.