V8 swap into I6 280SE W108 - Page 10 - Mercedes-Benz Forum

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post #91 of 162 (permalink) Old 05-11-2010, 05:56 PM
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Originally Posted by Gustav View Post
my 250SE's engine was pulled and replaced with a 1990 Corvette TPI mill hooked to a 700R4 transmission. The physical challenges with this swap were:
- lower area of transmission tunnel needed to be clearanced
- custom rear transmission cross member built using GM transmission mounts
- custom engine/chassis mounts built using GM engine mounts to attach engine to stock engine cross member
- custom exhaust
- custom built all aluminum high efficiency radiator
- engine oil pump/oil pan and stock Benz steering wanted same space - modified oil pan built
- stock steering box and rear left corner of engine wanted same space
- replaced stock steering system with rack&pinion system
my car has a 3.92 Ring & Pinion which was great for the stock engine, but is too quick for the V8 - the car is stupid quick but horrible at cruise speed. It needs either a 3.27 (from a 4.5) or a 2.8:1 R&P (from a 6.3)

There are still a few things to address, but overall this modification is a blast. Have patience.
That looks like a great installation Gustav, you definately need a diff ratio of between say 2.75 & 3.0:1 .The performance ratio in a c4 vette was 3.08 as a guide. That gave approx 2000 rev/min at 60mph/100km/hr with the o/d 700r4 trans.
Those TPI motors are torque(truck!) motors cause of the very long runners ,and run out of puff at 5000 rpm, unless you go to big mouth manifold or LPE super ram.Great for off the line stuff !! lots of wheelspin. very easy to get an easy 300hp at the rears & 27-30mpg ,0-60mph 5.3-5.6 sec with the right gearing.(very tall 1st gear in 700r4) .
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post #92 of 162 (permalink) Old 05-31-2010, 10:16 AM
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gwunta - I just looked at your webpage. Very impressive project. We all must tip our hats to you for overcoming the massive challenge you have to deal with. I like your idea of the Jag rear end, but where I am at, those are not very cost effective.
Our "friend" Mercmad is undoubtedly knowledgeable, but does appear to miss vision of thinking way outside of the box. My original idea for my car was to install a 6l V12 from a W140, but the procurement of that engine was not phisable. The same goes for the new 6.3 liter AMG engine and transmission. I wanted to keep my car an "all-Mercedes" but when a good friend of mine gave me the Chevy engine, all was done. But of course if Mercmad wants to donate 6.3 liter Mercedes powerplants to us, I will happily install it in my car.
As for the rear end - my search for a 300SEL 6.3L rearend is failing. I have sourced one from a 4.5L but the 3.27 ratio is still a little too quick and I doubt that it will hold the torque of my soon to be modified engine very well for the long term. On a recent trip to Germany, I inquired with Mercedes about purchasing a R&P for a 6.3L and was told that Mercedes no longer has that part number available globally.
My dream is the IRS from Kugel Komponents (Kugel Komponents), but its a little rich for my blood. The fall-back is the IRS from Heidts (Heidts Hot Rod & Muscle Car Parts - HEIDTS Superide IRS - Complete Package). As an alternative to both, I have been trying to find installation pictures of a Ford 9" solid rear axle (no lip from Mercmad here).
If anyone has installation pictures of a Ford 9" rear axle (or other live rear axle) into W108/109, it would be much appreciated if you could post them here or email them to me at bugracing@yahoo.com
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post #93 of 162 (permalink) Old 05-31-2010, 02:13 PM
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Originally Posted by 66 hellkatt View Post
also been reading about the brake conversion thing,thursday night i'm test fitting hubs/rotors/calipers from a 2wd w203 (early 203) and a 2wd w210.compared my old calipers i never returned (core) to the front calipers from a brake job on a w203 today.......bolt spacing exact match,even the mounting bolts screwed right in haha!! i'll let everyone know how it went if intrested.it will certainly be cheaper, and easier service for sure if it all lines up correctly.bearing part #' same for w108,and w203 at any dealership sooooooo maybe,just maybe............................
How did it go?

Also a W124 rear end is a good option. You can weld a W124 valance available new and this eases fitting. Pagodino can tell you more about it.
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post #94 of 162 (permalink) Old 06-01-2010, 06:25 AM
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noob question here:

when upgrading the engine why exactly is it important to upgrade the breaks as well?

I understand the the car will go faster but going from 80 to 0 is still 80 to 0 no matter how quickly you get there.

Is it because the engine will be putting out more force at idle?
The weight should be relatively similar from what I understand.

Hell I'd like to upgrade my breaks on my w114 250 just because they aren't that great in the first place, but I don't understand why it's so deadly important once you put a v8 in there.

The only thing that makes sense to me is you're planning on doing 0-40 and 40-0 in 3 seconds to move 30 feet between stop signs
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post #95 of 162 (permalink) Old 06-25-2010, 07:43 AM
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Gustav, I know of a guy who has done the 9 inch conversion into a W108. This is a twin turbo 308 holden into a W108 with nitrous thrown in for good measure and yes, its for sale. There are some pictures of the 9 inch in place in the car but it looks like the rear chassis cross member section was cut to fit it in (I dont know if it affects the structural integrity of the car. He emailed me through my website a few weeks ago so if you need to ask some questions I can give you his email address.

Anyway, here's a link for the ebay listing for the car, which has the pictures you are after. TWIN TURBO NITROUS 308 DRAG CAR TUBBED MERCEDES $$SPENT (eBay item 220613112165 end time Jun-07-10 20:31:26 EST)

Mate, I had a look at those IRS rear ends, particularly the HEIDTS kit and it looks like a shiny version of my jag rear end. I just sold the jag diff yesterday actually, but I can tell you its a hell of a lot cheaper than the HEIDTS kit, but of course, I spent some time getting it to fit. I would recommend going down the jaguar diff path if you are constrained by budget, or consider a 4 link rear if you are going high horsepower. The other option may be a Holden Monaro rear end, which is remarkably similar (at least in looks) to a 114 4.5 diff. The Monaro's handle up to a 6.6L engine. I think over your way they are called a Pontiac GTO.
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post #96 of 162 (permalink) Old 06-25-2010, 08:23 AM
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That Heidts rear end looks like a nice unit. Price goes up to almost $10,000. if you want it all polished and with posi though. Later.

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post #97 of 162 (permalink) Old 06-25-2010, 11:06 PM
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this link here will basically give you the ideal of how to back half a car--- it is for a 79-99 mustang. yet same theory/method applies for our uni-body benzes.

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on a side note, my vision of a prostreet/pro touring benz may be starting earlier than i thought. I may drag home a 70 6.3 tomorrow that i will use to chop up for my build. haggling price now. it needs a total rebuild of every system to be road worthy. but would be a decent shell for my build. Added bonus is i get a 6.3 engine. i still have dreams of old 6.3 built up w/ modern forged internals, efi and a turbo or supercharger setup...
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post #98 of 162 (permalink) Old 06-26-2010, 12:17 AM
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Awesome work on finding a shell. I would be very wary about an engine that needs work done to it though. Anything you do to those engines is super expensive. To give you an idea, a second hand fuel injection pump (which only matches the M100 engine - read 6.3) is around $5000 and to get one reconditioned will be at least that much again. To use an aftermarket intake and EFI would require a lot of fabrication I imagine and even if you could find aftermarket stuff for it, then that gear would be super expensive too. Just be cautious man, budget around $30 000 for a rebuild of one off those engines, add another 5000 if you are looking at aftermarket internals. If that seems a bit much, then sell the engine and use the cash to get a newer engine (like something from a 560/580) or build a REALLY NICE supercharged ford, GM or lexus motor for it.

Just my 2 cents

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post #99 of 162 (permalink) Old 07-14-2010, 08:23 AM
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1968 w108

I have a 1968 w108 (280se) sedan. The engine had electrical problems and the transmission had broken parts (no reverse gear). I pulled the motor and put a 5.0L Ford with an AOD transmission. We replaced the rear with a 4.5 rear with better ratios. An offset starter cleared the steering rods, fabricated headers routed it all nicely to the exhaust pipe, and Walt's motor mounts made it all bolt together. We didn't have to, but replaced the radiator and it's a daily driver now.
Not a hard job, but lots of details to work through. We spliced the Ford parts into the MBz things and it ran very nicely. Just not fast enough for the owner. We did some hop-ups to the engine, It still gets good mileage (for a heavy car) and is a lot of fun to drive. It turns heads with the little 5.0L sticker on the back.
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post #100 of 162 (permalink) Old 07-30-2010, 12:35 AM
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What's the most modern mercedes engine that is a drop in to the w108 4.5s?

Is it just the M117s? Any of hte modern 6 cylinders fit?

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