Topic: I'm a sucker for high displacement engines, this time it's a 6.9L benz

So a few weeks ago I came across NSF's old 6.9L mercedes benz. the motor needs a bit of a tune-up, but all the expensive bits appear to be in great shape.
http://frankensteinmotorworks.com/6.9LBenz/photo%203.JPG

I also have a rusty miata suspension that has been sitting around in the shop waiting for a project:
http://frankensteinmotorworks.com/6.9LBenz/photo%202.JPG

and I just scrapped a porsche 944 but kept the transaxle:
http://frankensteinmotorworks.com/6.9LBenz/photo%201.JPG

The benz body (especially the floor) is just completely unusable for racing anymore. so that is out of the question. but with a simple adapter i'll mate the audi 016 trans and it's torque tube (from the porsche 944) to the 6.9L engine.

my original plan had me placing these bits in a wrangler frame and body, but that's where i need your help guys. it seems that everyone with a wrangler even in non roadworthy shape has an "awesome rockcrawler project" in the making and thinks it is worth $4,000.

i'd really like to stick to the wrangler but i need someone to help me find the frame and body for no more than $500. I'm about $800 ahead of zero right now but i am figuring $200 worth of tune up to the benz, $500 worth of clutch and flywheel, $100 for the missing fuel system bits so that leaves the original budget's $500 worth of room for a body and frame. and as an added complication, as with all my builds i will be driving this thing on the street so i need a title that matches the VIN on the jeep's body.

after seeing how easy this thing starts and how well it runs (considering the abuse it's had recently) i can easily see how these mechanical fuel injection systems were awesome compared to the carbs they were trying to replace.

Thanks for the help everyone!

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

oh and for anyone that is curious, there's a certain noise that can only be replicated by making power in the 30hp/L range. i can't wait to hear what this thing sounds like with a modified exhaust, but at low revs it is very reminiscent of the radial engine (that one made 18hp/L) but then the revs just keep coming. the documentation i've found says the red-line is 5800, the dash says about 5300 and from what i can tell the car only has an ignition cut that kicks in somewhere around 6k.

and yes, i realize the 016 trans is a bit weak in the torque handling capability. but my plan is to disable 1st gear to reduce torque multiplication. as long as the weakness isn't in the input shaft, the rest of the trans won't see loads any higher than it did with the stock motor. plus then it gives me a 4 speed transmission with a dogleg 1st. with the short final gear that the stock 944 gets (3.89:1) it makes the transmission ratios work out alright with the 1st gear removed. 1st will go to 45mph, 2nd to 65, 3rd to 90 and 4th to 120. of course, cruising on the highway will be a bit noisy at 3500RPM, but i'm not looking for a highway cruiser.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Marc, no price on this one but has to be cheap.
http://stlouis.craigslist.org/cto/4357305314.html

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

You know I've been using the hell out of auto tempest. i don't know how i did not spot that one. e-mail sent out. 14hr round trip isn't that bad. I've done worse for even worse ideas smile

plus, being an '87 i get to call it my AMC AMG smile

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Marc, I'm 88% sure there is a wrangler FS locally for under a grand. not terrible rusty. will talk to someone about it tomorrow

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

That transmission in the MB is very desirable.  Sell it.  It cost me 2500 bucks 20 years ago, used - not installed.      What you don't know is that rusty POS was my DD for about 15 years.   




b

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

tSoG wrote:

Marc, I'm 88% sure there is a wrangler FS locally for under a grand. not terrible rusty. will talk to someone about it tomorrow

cool, keep me posted. the guy on craigslist that Brett found above wants $2200 but he's willing to part it out. so i may be able to get that chassis for cheap. but certainly i'd like to keep looking until a deal is made

NSF wrote:

That transmission in the MB is very desirable.  Sell it.  It cost me 2500 bucks 20 years ago, used - not installed.      What you don't know is that rusty POS was my DD for about 15 years.

Yeah, i completely believe the DD thing, this thing is a strong runner. the trans feels like it's a bit shot but maybe it gets better when the fluid gets warm. but even if it is in need of a rebuild, they are rare enough that it will be worth something to someone. i've conservatively earmarked that i can sell it for $300 in my budget calculations. if i get $1000 for it that i can do that much more with the Lemons.

I'm planning on keeping the hydropneumatic stuff. i want to use it in the jeep. but even if i don't use it, the stuff will sell well if i remove it carefully.

That mercedes is a whole big bucket of awesome I go out to the garage and just start it every once in a while just to hear it smile i can't wait to hear it under load on the track.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

I don't suppose you still have the title for this thing, do you? it'll make it possible to recycle the shell instead of disposing of it. adding back to my budget a bit more.

also, any idea when the timing chain was last done if ever?

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Can't you use a DJ-5 mail Jeep instead of a Wrangler? Those things are butt cheap.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

The postal jeeps are based on the old CJs which have too short of a wheelbase (80").

Plus, also wheelbase/track width related, since i'm using a miata suspension i need a wheelbase near 90" to keep the ackerman angle correct. i can move the steering box around to alter the ideal ackerman number around a bit, but not more than 2-4" or so.

11

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Ya I think it is in a drawer at NSFIRHQ

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

"would look great sitting in a yard"

http://cincinnati.craigslist.org/cto/4333269537.html

are you serious? people actually think that about busted cars?

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

NSF wrote:

Ya I think it is in a drawer at NSFIRHQ

That would be awesome if you can find it. and if you can't i'll happily pay the cost to get a new title from the DMV.

14 (edited by tSoG 2014-03-09 10:17 AM)

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

he has two, 800 and 1500. one has steering linkage issue, and the other has a blown headgasket. not sure which is which. don't have more details yet. I'll go check it out tomorrow weather permitting.

dead rabbit society: cultured 'n shit.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Hmm, certainly find out more.  at least we are in the right ballpark now. i don't care about steering or engine issues. as long as the frame and body isn't rotten from rust i'd be happy.

I'll have to sell some parts from it to make it come to $500 or less, but if they are complete it should be doable.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Hows the miata suspension going to take the weight of the 6.9? Something tells me it weighs a "little" more than the 1.6

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17

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Most all of the suspension parts are in like new condition.  But several years old to be sure.  I have several bottles of the MB suspension juice.

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

FPRbuzz wrote:

Hows the miata suspension going to take the weight of the 6.9? Something tells me it weighs a "little" more than the 1.6

the only number i can get on the engine weight at the moment is "about 500lbs" but i'll know more when i remove it. and with the rear mounted trans and the lightweight wrangler body, it won't be much more than stock miata front axle weight (about 1200lbs)

also, the spec miata guys appear to be using stock knuckles and pulling way more cornering force than i will. so the knuckles should be up for it.

as for the springs/shocks, i'm planning on using the Mercedes' hydropneumatic shocks. so they'll certainly be up for it.

i figure at worse i have to do front wheel bearings before every race, but that isn't that much work. and if it gets annoying there are always options to fabricate a bit to fit something else on there.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Why even use a Jeep? How about one of the many full-frame small pickups you could get in the 1970-1990 period? Or, better still, some weird small 1950s car?

20 (edited by Parkwod60 2014-03-09 01:29 PM)

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

To quote from the only online list of engine weights: http://fixrambler.com/engineweightchart.txt


Mercedes SOHC V8 alum.  452     (2)
Mercedes SOHC V8 iron   540     (2)

(2)  Complete Handbook of Automotive Power Trains, Jan Norbye, 1981

Now what does the Miata motor weigh?

EDIT: a little google says Miata motor is about 300lbs

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

Judge Phil wrote:

Why even use a Jeep? How about one of the many full-frame small pickups you could get in the 1970-1990 period? Or, better still, some weird small 1950s car?

Right, those are other options. i just think the jeep would look better and be lighter.

to simplify this build since i want to do a quick throw it together build i want something in the 90-100" WB range, with a body on frame construction.

i did find a $300 1989 toyota pickup locally that i may use. but if i use a toyota pickup i'd really rather use the terrorist's favourite 83 or earlier model.


Parkwod60 wrote:

To quote from the only online list of engine weights: http://fixrambler.com/engineweightchart.txt


Mercedes SOHC V8 alum.  452     (2)
Mercedes SOHC V8 iron   540     (2)

(2)  Complete Handbook of Automotive Power Trains, Jan Norbye, 1981

Now what does the Miata motor weigh?

EDIT: a little google says Miata motor is about 300lbs

540lbs seems acceptable for that lump. it should do just fine.

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

The Merc engine, tranny, suspension is all bombproof stuff.  I know you've decided on this crazy MB-944-audi-miata mashup, but it would be much simpler to shorten the merc driveshaft, and swap all of it's mechanicals into a '79 fairmont sedan or the like.

Just sayin'


If you can't be persuaded that it's a terrible idea, then I recommend raising your terrible orphan mashup to the next level by using FJ40 parts instead of YJ.

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Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

I just don't do automatics. I hate them with every bit of my being.

everything i own, even my 1 ton tow rig is a manual. so this race car isn't going to be any different.  I know i take this to an extreme, but it is what it is. i may be talked into a different trans, but i have -$100 in this one, so it's a good place to start.

as for an FJ40, i'd do that instead of a jeep in a heart beat, any idea where i can find a frame and body without excessive rot for around $500?

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

If you used an old Toyota pickup, you could do a Khyber Pass theme, complete with a dozen animatronic mujahideen brandishing AKs in the back. Maybe with nice WE (heart) REAGAN emblems on the doors.

25

Re: I'm a sucker for high displacement engines, this time it's a 6.9L benz

with over 400 ft lbs of torque, choose the transmission wisely and make sure you like to take them apart.  The engine will pull you over 144 MPH if you keep the rear @2.65.  I think the max RPM is 5500 RPM.

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