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kggkgg 04-27-2005 03:53 PM

v8 into a W!24 cabrio
I love W124 cabrios but there are none available with V8 power units which is a shame as having driven them I think it needs it. I dont think they made any with engines bigger than 3.6litre straight six?

So ....I am trying to build up the bottle to implant a 400 or 500 V8 into an E cabrio , preferably with an auto shift?. I can pick up an e320 or 280 fairly cheaply here and hope to find a merc V8 at a knackers yard.

If so are there any particular issues and which MB engine varient is the easiest match to a late model 94/5 E cab?

would be interested in any success stories of V8 into E cabs to help build up my determination!


mike690003 04-27-2005 07:32 PM

The problem you might encounter is space. The V8 will be a tight fit. You have to swap the ECU wiring harness, and other accessories for it to work. Don't forget about a transmission upgrade, which you might surely need. The transplant sounds like a cool idea, but it takes patience and money to have it done.

pentoman 04-27-2005 07:45 PM

It should be reasonably easy to do, and perhaps not as silly as it may sound, given that a V8 doesn't weigh that much more than a straight six.

It would be nice... nicer perhaps than a 500SL?

Given that they put the V8 in the saloon, I can't imagine it would be too hard.
You can search for pages (try googling "300E 722" for example) and find pages like this which show the transmissions for the different models. For example the 722.4 is only good up to the 280 engine so no good for a V8, you need a 722.3 car (i.e. a 300CE or 320CE, though I'm not sure if that would guarantee to hook up to the V8 or if the other numbers after the '3' mean large or small differences.

The W124 cabrio doesn't seem to loose value either, so you wouldn't end up with a special but worthless car at the end, like you might if you did a TE Estate (wagon) or coupe.

have fun


kggkgg 04-28-2005 06:20 AM

better than an SL
you hit the nail on the head. I briefly owned an SL which was nice but just impractical due to only 2 seats. I also think the E cabrio has got class written all over it, it just needs a bit more vroom to be a good drivers car.

Is there are reason why only some chassis would not take the V8 for space. I thought the E cabrio was identical at the front end to a saloon E class which has always been available with V8 to my knowledge?


chazola 04-28-2005 06:41 AM

I think you need the AMG 124 cabrio- that had a suped-up 104 in it. :)

y2kimmel 04-28-2005 07:01 AM

i seem to remember someone writing about this conversion before. The problem that they were discussing is the extra girth required in the transmission tunnel to accomodate the V8's larger tranny. THis would make it very hard to do the conversion - how would you enlarge the tranny tunnel?

If you find a way, then good for you. That would be one nice car.

1995 E420 93k

kggkgg 04-28-2005 07:50 AM

good point on the tranny , think I will get my tape measure out and check out an E500 and a cabrio if I can find them.

I wouldnt want the M104 , I know the AMG was suped up to 3.6 litres but i dont have confidence in the M104 following the head gasket and wiring loom design faults (maybe I'm prejudiced). I think the V8 so much more umph and (if i am totally honest) it sounds much better too. :D


pentoman 04-28-2005 08:15 AM

The 500E was built by Porsche and they modified the transmission tunnel on each shell to fit the wider transmission.

BUT, did the Mercedes built 400E/E420 have this modification done, or does the lower torque 400 not require such a big box, hence no modification required?

And would the 400/420 therefore be the engine to go for? I reckon the 500 might be excess and you'd need to spend some good time just making the chassis harness that 326 bhp sensibly! The 400 would probably be plenty for a cruiser...


kggkgg 04-28-2005 12:36 PM

does 400E have same size tranny tunnel as 320E
good idea

does anyone know the differences between tranny tunnels sizes on 320, 400, 420 and 500 E's ie which ones are the same - this would be really useful .

I agree the 400 would be fine for the cabrio.


TROVERMAN 04-28-2005 01:01 PM

Obviously you can fit the 4.2 (m119) V8 in a '94 or '95 E-Cabrio, as the nose is the same and you could get this engine in the sedan. Go for a later m119 engine, you get 275bhp and 295lb-ft torque. You also should be able to fit the trans from the 400E or E420 into a 320 Cabrio, as the tunnel size is the same (or appears to be) You will also need to change the rear differential. The E320 with m104 engine (stock) uses a 2.65:1 rear diff; the m119 powered E's use a 2.24:1 diff.

About the above comment, "I wouldn't want an m104 because of wiring / headgasket, etc" all I can say is many members of this forums and many MB experts would probably tell you the m104 engine is one of the best engines in the world, if not just in an MB. It produces 217bhp, 229lb-ft, 3.2L I-6, all-aluminum construction, DOHC 24V, gets 27mpg on the road, has variable timing, and the engine just does not wear out. Mine needs a headgasket right now. So it leaks oil. But it does not hurt the engine. The headgasket change will cost about $1,000, done by an MB specialist. On later m104's, the wiring harness was not such an issue as on earlier models. It is not an issue on my '95, for example. And, oh, BTW, that wiring harness was an issue on EVERY model of Mercedes during the 1990-1993 years, or so. The 400E, between 1992-1993, was just as likely to have a failed harness as any 6-cyl model. The truth is, the harness costs about $800, and it is an easy D-I-Y. It takes maybe a couple of hours. And, the problem was with a material MB chose as part of an "environmentally responsible" campaign for degradeable auto parts. In some cases, an MB dealer will GIVE you a harness free of charge.
So at this point we have $1800 of known maintenance. If you got the harness for free and changed the gasket yourself, that number would be a couple of hundred. Compare that to the lifespan of a well-maintained m104, which can be upwards of 400,000 miles of eseentially trouble-free motoring and who's complaining?

pentoman 04-28-2005 03:26 PM

The wiring harness is more of an issue in hotter climates too, am I right?

Still, the M119 V8 is highly rated too..

gerryvz 04-28-2005 06:03 PM

Here's a photo of an M119 getting put into a 124 coupe....


grober 04-29-2005 05:00 AM

v8 into w124 convertible not easy!
As a previous poster stated the whole front end of the w124 was altered by Porsche including the engine compartment and transmission tunnel. :( :( The standard w124 was designed to accept straight 4s and 6s from the outset. :confused: I guess you would have to reduce the two chassis members that accept the engine mounts back to the chassis rails and modify the firewall in order to get the v8 low enough. :eek: :eek: You really need to see a e500 with the engine out to ascertain exactly what was done. The transmission tunnel was widened to accommodate the 2 catalytic converters that came with the 5 litre v8. the body rear end was also strengthened and the rear end was virtually a SL transplant as were the 4 pot front brakes. the electrics were a one-off also using the new CAN-BUS to link tranmission, throttle, ABS and ASR. I believe the later 420 model did not require the widened tunnel but the engine compartment modifications were the same. If you want more power then why not install the mosselman turbo systems twin turbo conversion? :cool: but if you really want that V8 noise then you will have to get out the welding torch.:D :D

kth286 04-29-2005 05:25 AM


Mosselman's twin turbos is the way to go, as it is a bolt on and unbolt off system to enable the car to easily be reverted back to standard.

Better performace than V8 also, and if driven as normal better economy.

The Merce Enthusiast mag dated Jan 2004 quoted 340 bhp and 320 lb/ft with 0-62mph in 5.9 secs - and that was for the previous 3000cc model !!!

Go for it and let us know how you get on.


kggkgg 04-29-2005 09:57 AM

mosselman sounds good
thanks everyone this is good input. Certainly sounds tempting to go the mosselman route except for the lack of V8 sound :( .

My wife has her eye on a 2000 CLK430 :eek: so I need to get moving with the E cab if I am to avoid becoming trendy :pukeface:

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