THE STAR (US) - 6.9 Test
- Thread starter Styria
- Start date
SEL_69L
Aristocrat
Googled two 6.9's at a drag meet. Result over 1/4 mile:
16.9 sec., 90 mph.
The cubic capacity of a 6.9 is 418 cubic inches. Only Mercedes had a big V8 at the time, with OHC and fuel injection.
Motor trend tested a 1971 Pontiac GTO HO (High Output) 455 c.i. engine. Result over 1/4 mile:
13.4 sec., 102 mph.
This engine was rated at 300 hp SAE, (220 kW), 413 ft pounds (563 Nm). This car was also a bit lighter than a 6.9.
With not that much difference of terminal speed, these figures suggest that the Pontiac would be noticeably quicker off the line to carry the higher speed for more of the track distance, resulting in a big difference in ET.
16.9 sec., 90 mph.
The cubic capacity of a 6.9 is 418 cubic inches. Only Mercedes had a big V8 at the time, with OHC and fuel injection.
Motor trend tested a 1971 Pontiac GTO HO (High Output) 455 c.i. engine. Result over 1/4 mile:
13.4 sec., 102 mph.
This engine was rated at 300 hp SAE, (220 kW), 413 ft pounds (563 Nm). This car was also a bit lighter than a 6.9.
With not that much difference of terminal speed, these figures suggest that the Pontiac would be noticeably quicker off the line to carry the higher speed for more of the track distance, resulting in a big difference in ET.
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Tony66_au
New Member
Having spent a bit of time at Calder with street legal cars id like to add the following points to bear in mind when looking at 400m times.
Tyres, Temperature (Air temp and track temp), Fuel load, Driver reaction time (This plays a huge part) and transmission set up.
Burnout also makes a difference depending on tyre and temp.
We built (As a joke which turned into a business) a Euro wagon with a small block Chev because the V6 originally in the car wore out and became a problem.
Calder generally gives you 3 runs and we drove the car there towing a clients car on a trailer.
The spec was 350 chev, TPI with a T350 3 speed thru the standard open wheeler diff and Toyo Z radials on standard 14 inch x 7 rims.
1st pass 14.26 @ 105 ish
2nd pass 14.13 at about the same a tad over 100 mph
4th pass 14.20 at 103 ish with a mate driving.
The following friday night I ran mid 13's for the 2 runs I made before I decided to stop hammering out only form of transport home.
The difference was staging and reaction time as we hadn't changed a thing on the car except the fuel which was standard pump unleaded.
Id guess at the difference being in the Transmission, weight and probably the K jet system and resulting smog stuff but not being familiar with the M100 its purely an educated guess.
Id also ask if the shifts were made manually or if the driver just nailed the throttle and held it flat till the beam.
Cheers,
Tony
Tyres, Temperature (Air temp and track temp), Fuel load, Driver reaction time (This plays a huge part) and transmission set up.
Burnout also makes a difference depending on tyre and temp.
We built (As a joke which turned into a business) a Euro wagon with a small block Chev because the V6 originally in the car wore out and became a problem.
Calder generally gives you 3 runs and we drove the car there towing a clients car on a trailer.
The spec was 350 chev, TPI with a T350 3 speed thru the standard open wheeler diff and Toyo Z radials on standard 14 inch x 7 rims.
1st pass 14.26 @ 105 ish
2nd pass 14.13 at about the same a tad over 100 mph
4th pass 14.20 at 103 ish with a mate driving.
The following friday night I ran mid 13's for the 2 runs I made before I decided to stop hammering out only form of transport home.
The difference was staging and reaction time as we hadn't changed a thing on the car except the fuel which was standard pump unleaded.
Id guess at the difference being in the Transmission, weight and probably the K jet system and resulting smog stuff but not being familiar with the M100 its purely an educated guess.
Id also ask if the shifts were made manually or if the driver just nailed the throttle and held it flat till the beam.
Cheers,
Tony
- Thread Starter
- #5
Hi Tony, 6.9s are a very much understressed and 'conventional, user friendly' engine - in other words, they may be a "Bamker's Hot Rod" as one magazine described the car they tested, but really in the overall scheme of specifications, the 6.9 is a pussycat with a slight growl to it. Just ask Motec 69 and he will tell you all about restrictions in the M100 engine as found in the 6.9. The throttle body is the same size as the 450, or a V6 Commodore for that matter, the exhaust ports are wimpy, as are the inlets, and to give the 6.9 its proper description, it is a terrific Autobahn cruiser - as are many other modern cars today - yet, I still like the power and torque delivery of the 6.9. Regards Styria
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SEL_69L
Aristocrat
I think Mercedes deliberately restricted the performance of the 6.9 somewhat, relative to some of the U.S. muscle cars of the late 60's and early 70's, although the 6.9 was intended to match the general 'run of the mill' 400 cubic inch and over American cars of the time. Most of the American limos. of the time weighed much more than a 6.9, and were dimensionally much larger, with softer suspension, with drum rear brakes and live rear axles. The 6.9 can easily out handle most of the American genre of the time, and with a better ride.
The engine restrictions were partly to comply with various pollution laws, and partly the extend the life of the car. Certainly a lot of 6.9's have survived to still be in road regristration to this day.
Technically, the 6.9' nearest competitor would be the Rolls Royce Silver Shadow 11, with the 6.75 litre engine. In this regard, the coachwork on the RR is much classier (as you would expect), but the 6.9 is technically superior.
Nevertheless, the 6.9 was also conceived, I think, as the ultimate 'autobahn burner' par execellence which indeed, and was, able to transport four German business executives across the country in great speed and comfort. With it's higher speed and hudraulic suspension, the 6.9 would certainly beat a RR SS 11 around a race track.
Nevertheless, by 1979, it was rare to find an American car with more than 350 cubic inches (5.7 liters) engine capacity, seriously detoxed to comply with American air pollution standards. By that time, most the 400 cubic inch plus cars were no longer in production.
I have been reading a book:"World Cars 1979", which list EVERY car in the World, manufactured in that year. In 1979, the 6.9 was near to the fastest and most powerful 4-door sedan car in the World. 550 makes and models are listed. The only cars 4-door sedan cars for that year that are faster or are more powerful are the
De Tomaso Deauville
Maserati Quattroporte
Ferrari 400 Automatic
My previous post re the 1972 Pontiac 455 HO still applies.
The engine restrictions were partly to comply with various pollution laws, and partly the extend the life of the car. Certainly a lot of 6.9's have survived to still be in road regristration to this day.
Technically, the 6.9' nearest competitor would be the Rolls Royce Silver Shadow 11, with the 6.75 litre engine. In this regard, the coachwork on the RR is much classier (as you would expect), but the 6.9 is technically superior.
Nevertheless, the 6.9 was also conceived, I think, as the ultimate 'autobahn burner' par execellence which indeed, and was, able to transport four German business executives across the country in great speed and comfort. With it's higher speed and hudraulic suspension, the 6.9 would certainly beat a RR SS 11 around a race track.
Nevertheless, by 1979, it was rare to find an American car with more than 350 cubic inches (5.7 liters) engine capacity, seriously detoxed to comply with American air pollution standards. By that time, most the 400 cubic inch plus cars were no longer in production.
I have been reading a book:"World Cars 1979", which list EVERY car in the World, manufactured in that year. In 1979, the 6.9 was near to the fastest and most powerful 4-door sedan car in the World. 550 makes and models are listed. The only cars 4-door sedan cars for that year that are faster or are more powerful are the
De Tomaso Deauville
Maserati Quattroporte
Ferrari 400 Automatic
My previous post re the 1972 Pontiac 455 HO still applies.
You guys always forget one very important aspect of drag racing and that is the diff ratio.
As most Mercedes Benz vehicles were destined for German Autobahns, they were/are fitted with 'tall' diffs (lower numbers) that would allow very high terminal speeds.
American (and most other) cars on the other hand are not.
In the test between the GTO and the 6.9, you'd find that the Pontiac was probably fitted with a 3.27 or 3.55 (if not higher diff ratio-3.73 perhaps) and thus would trounce the 6.9's lethargic 2.6...something acceleration off the mark.
As most Mercedes Benz vehicles were destined for German Autobahns, they were/are fitted with 'tall' diffs (lower numbers) that would allow very high terminal speeds.
American (and most other) cars on the other hand are not.
In the test between the GTO and the 6.9, you'd find that the Pontiac was probably fitted with a 3.27 or 3.55 (if not higher diff ratio-3.73 perhaps) and thus would trounce the 6.9's lethargic 2.6...something acceleration off the mark.
- Thread Starter
- #8
Hi Michel, you raise a very valid point. If memory serves me right, that 'doyen' of Australian muscle cars, the Ford Falcon GT, with a four speed manual box and a diff. ratio of 3.92 (?) dispatched of the 0-100 time in about 6.1 seconds. The 6.3 of that era - 6.5 seconds with a 2.85 diff ration, and presumably more weight.
I recall speaking to the previous owner of the 6.3 that now belongs to abl567 - he told me of a drag race along Victoria Road between the 6.3 and one of those 2-door Falcon Coupes with the prominent blue body stripe over bonnet, roof and boot and he reckoned that the 6.3 absolutely killed the Ford. A bit of bench racing perhaps, but nevertheless.... Just think what a 6.9 would get up to with an automatic four or five speeder, and, say, a 3.01 diff ratio - I reckon the 0-100 time couild easily drop down towards the six second mark. Regards Styria
I recall speaking to the previous owner of the 6.3 that now belongs to abl567 - he told me of a drag race along Victoria Road between the 6.3 and one of those 2-door Falcon Coupes with the prominent blue body stripe over bonnet, roof and boot and he reckoned that the 6.3 absolutely killed the Ford. A bit of bench racing perhaps, but nevertheless.... Just think what a 6.9 would get up to with an automatic four or five speeder, and, say, a 3.01 diff ratio - I reckon the 0-100 time couild easily drop down towards the six second mark. Regards Styria
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And one more aspect for the difference in diff ratios between Europe and the USA was the cost of fuel. Very expensive in Europe, dirt cheap in the USA!
For those who don't get it... a taller diff revs less (thus uses less fuel)
Probably not fair to compare cars from the early 70s to those from the late 70s, as the emission restrictions meant that that latter really struggled to retain anything like the performance of the former. As well as that the GTO was designed to compete with all other muscle cars of the era. The GTHO was a purpose built race car, which had to be available to the public so it would qualify for competition use. The 6.9 was designed for a completely different purpose... the Autobahns. I feel sure that if MB decided to make a four door sedan to be used as a basis for race cars, it'd nail all of the competition! If one spent their money wisely it wouldn't be hard to get a 6.9 to out accelerate all but dedicated drag cars & be able to carry 5 people in comfort as well!!!
SEL 69L when the book states "the fastest" is it referring to top speed, or acceleration? I didn't know those manufacturers actually made 4 door cars way back then!
SEL 69L when the book states "the fastest" is it referring to top speed, or acceleration? I didn't know those manufacturers actually made 4 door cars way back then!
SEL_69L
Aristocrat
The 6.3 should be a better drag racer than a 6.9. Weighs less and has 4 speeds.
But that's was not what Mercedes-Benz were trying to do when they replaced the 6.3 with the 6.9. The 6.9 is faster though, with much more crash protection development. That line of engineering development is still being pushed hard by Mercedes-Benz 30 years later.
And ask Styria which car he would prefer to work on.
But that's was not what Mercedes-Benz were trying to do when they replaced the 6.3 with the 6.9. The 6.9 is faster though, with much more crash protection development. That line of engineering development is still being pushed hard by Mercedes-Benz 30 years later.
And ask Styria which car he would prefer to work on.
Well I'm biased, but I prefer the 6.9, as it's far more sophisticated than the 6.3. The W116 was designed for the M100; the chassis & suspension is far superior. And who needs 4 gears when many drag racers get by with only 2 (eg Powerglide)? To me the 6.3 was a car where the M100 was literally shoehorned in; evident by the fact that the engine is canted over to the near side. The W108 was never intended to carry such an enormous engine. It's a far more primitive experience, but that's why many like it... and it's styling harks back to MBs of previous generations, where the grilles stood tall & proud. To me the W116 looks more menacing, especially when fitted with that subtle air dam (which yearns to kiss bloody everything)!
- Thread Starter
- #13
This thread has 'blossomed' into something far more than originally intended. However, that's perfectly okay as any thread or post that generates further discussions of various kinds certainly has its place on topklasse and what it stands for - information, opinions, sometimes facts, sometimes fiction, but it caters for the enthusiast.
6.3 vs. 6.9 - hardly a fair comparison, as fundamentally they are such different cars, and each has its own very loyal following. As an everyday driver, I need to prefer the 6.9 - it is more user friendly, easier and probably less costly to maintain. The location, for servicing purposes, of various components on the 6.3 are quite awkward - for instance, the fuel filter, the alternator, adjustment of the power steering and air conditioning belts are quite 'nightmarish' - if there is such a word. On the other hand, I prefer the air suspension on the 6.3 - far easier to maintain by way of replacement cost, especially as far as the suspension valves are concerned, but air bags and the like can be expensive. At least, they are still readily available. The handling of the 6.3 would also appear to be more 'planted' - by that I mean that it appears to be glued to the road. 6.9s can be a little 'floaty' and probably have more understeer.
The 6.9 has a far easier to maintain fuel system, which is a very important facet when considering a car as a daily driver. The ignition system is also more refined, and by and large it is an easier car to work on and maintain. As far as performance is concerned, and I am talking 6.3 vs. 6.9, at the end of the standing quarter mile both cars are just about dead equal. Accelerating from a rolling start from about 20 km/hour, I'd fancy the 6.9 because by then it is no longer handicapped by the three speed auto and the tall gearing.I reckon that a modern and strong five or six speeder (auto) would completely transform a 6.9. If I was a few years younger, and had more money than what I certainly do now, I'd be prepared to spend five or six grand to fit another box behind that 6.9 engine. Regards Styria
6.3 vs. 6.9 - hardly a fair comparison, as fundamentally they are such different cars, and each has its own very loyal following. As an everyday driver, I need to prefer the 6.9 - it is more user friendly, easier and probably less costly to maintain. The location, for servicing purposes, of various components on the 6.3 are quite awkward - for instance, the fuel filter, the alternator, adjustment of the power steering and air conditioning belts are quite 'nightmarish' - if there is such a word. On the other hand, I prefer the air suspension on the 6.3 - far easier to maintain by way of replacement cost, especially as far as the suspension valves are concerned, but air bags and the like can be expensive. At least, they are still readily available. The handling of the 6.3 would also appear to be more 'planted' - by that I mean that it appears to be glued to the road. 6.9s can be a little 'floaty' and probably have more understeer.
The 6.9 has a far easier to maintain fuel system, which is a very important facet when considering a car as a daily driver. The ignition system is also more refined, and by and large it is an easier car to work on and maintain. As far as performance is concerned, and I am talking 6.3 vs. 6.9, at the end of the standing quarter mile both cars are just about dead equal. Accelerating from a rolling start from about 20 km/hour, I'd fancy the 6.9 because by then it is no longer handicapped by the three speed auto and the tall gearing.I reckon that a modern and strong five or six speeder (auto) would completely transform a 6.9. If I was a few years younger, and had more money than what I certainly do now, I'd be prepared to spend five or six grand to fit another box behind that 6.9 engine. Regards Styria
SEL_69L
Aristocrat
If I want to accelerate my 6.9 hard, I get the most fun from it by getting it roling with only mild acceleration, for a second or so, THEN plant it, before the transmission upchanges into 2nd.
Big Boys Toys up North sold adapter plates to attach a TH400 behind the M100. I'm not sure if they're still available, or whether that'd be the best transmission to use... Maybe you could add a Gear Vendors overdrive unit for 6 or more speeds?? The biggest problem with that option would be the cost, weight & space needed for the components.
Most late-model transmissions are electronically controlled along with the engine, so I'd imagine they'd be difficult to adapt. But how good would a twin-clutch 7 speeder be, nestled behind that monster engine? And if it was connected to a fly-by wire throttle you'd constantly be slowing down just so you could listen to the engine blip as it changed down through the gears! A good transmission can completely TRANSform the way a car performs!!!
Most late-model transmissions are electronically controlled along with the engine, so I'd imagine they'd be difficult to adapt. But how good would a twin-clutch 7 speeder be, nestled behind that monster engine? And if it was connected to a fly-by wire throttle you'd constantly be slowing down just so you could listen to the engine blip as it changed down through the gears! A good transmission can completely TRANSform the way a car performs!!!
WGB
New Member
Or an M-B 7 speeder.
Bill
Bill
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