W***el Engined R107

[grober]

Posted elsewhere but may be of interest to R107 diehards. A couple of pictures of Felix W***els personal rotary engined SL.

FROM http://porschecarshistory.com/wp-content/old/Mercedes/****el/

 

[Bellow]

Link isn't working (for me).
Was it the same engine as Mercedes played with for their mid engined C series (C111?)? Was it a Mercedes developed engine?

 

[grober]

http://porschecarshistory.com/wp-content/old/Mercedes/
and look for the appropriate folder name?
something to do with the ******??

 

[219]

It was quite a famous car back at the time . Mercedes took serious interest in developing the rotary engine and , as mentioned , ran them in the C111 test vehicles , as well as the R107 .

Alas , materials technology of the day could not make the rotor tip seals durable or reliable enough , unthinkable for Mercedes-Benz , so they didn't go any further with it .

 

[grober]

Link isn't working (for me).
Was it the same engine as Mercedes played with for their mid engined C series (C111?)? Was it a Mercedes developed engine?

I believe it was basically the same 4 rotor engine fitted in the later C111 cars.
The rotary piston engine in Mercedes-Benz SL W 113 and R 107experimental vehicles | Daimler Global Media Site > Classic > Mercedes-Benz Cars > Mercedes-Benz Passenger Cars > SL-Class

 

[Ted]

What's going on with that distributor cap?

 

[Bellow]

Alas , materials technology of the day could not make the rotor tip seals durable or reliable enough , unthinkable for Mercedes-Benz , so they didn't go any further with it .

Not so according to Grober's linked piece:

'' It was this birth defect in the ****el engine, its failure to offer an optimum combustion chamber, which was responsible for its rapid demise and not the constantly repeated suggestions of mechanical problems.”

 

[grober]

What's going on with that distributor cap?

4 rotors = 4 HT leads of the V8 8 lead distributor but no coil connection to the centre pillar BUT there is some form of coil connection, would need to see under that cap ??? complicated by the fact some ****el engines have two spark plugs- don't know about Mercedes designs.

 

[Bellow]

What's going on with that distributor cap?

I can't make out from the pic - looks to me like leads are missing.

4 rotors = 4 HT leads of the V8 8 lead distributor one after the other ???

Chances are it would have had two plugs in each chamber (each timed differently) so eight leads required!

 

[grober]

I can't make out from the pic - looks to me like leads are missing.



Chances are it would have had two plugs in each chamber (each timed differently) so eight leads required!

Beat me to it!

Found this though appears the later 4 rotor engines had single ignition whereas the earlier 3 rotor engines had dual ignition.
http://www.diseno-art.com/encyclopedia/vehicles/road/cars/rare_classics/mercedes-benz_C_111.html

The performance of the C 111, even with the three-rotor engine, was convincing right from the start. In 1969, the ****el engine developed 280 hp from 600 cubic centimeters of chamber volume per rotary piston and gave the car a top speed of 260 km/h; with this engine, the car accelerated from standstill to 100 km/h in five seconds. The C 111-II of 1970 was powered by a large four-rotor ****el engine which developed 350 hp and gave the car a top speed of 300 km/h. The second C 111 accelerated from standstill to 100 km/h in highly respectable 4.8 seconds. While some of the engines in the C 111-I cars had still featured dual ignition which was difficult to adjust, the four-rotor engine was equipped with single ignition exclusively. Both engines were direct-injection units.
The development department of Mercedes-Benz eventually succeeded in solving the engineering-design problems involved in the rotary-piston principle, especially in engine mechanics, but the problem of the ****el engine’s poor degree of efficiency, due to the elongated, variable combustion chambers of the rotary-piston principle, was not to be overcome with technical modifications. This problem was simply inherent in the design: in a ****el engine, the fuel burns within the space between the convex side of the rotary piston and the concave wall of the piston housing rather than the cylindrical combustion chamber of a reciprocating-piston engine. The variable, anything but compact combustion chambers of the ****el engine were responsible for poor thermodynamic fuel economy as compared to a reciprocating-piston engine, resulting in significantly higher fuel consumption for the same output. The engines of the first two C 111 versions were straightforward gas-guzzlers. And since the pollutant content in the exhaust gas of the ****el engines was also too high, Mercedes-Benz discontinued work on this type of engine in 1971, in spite of its impressively smooth running characteristics and compact size.

 

[Bellow]

Twin plugs per chamber was commonplace on VVankels. Leading and trailing, in an effort to improve combustion in a chamber with massive area wrt volume which led to large quench zones where the mixture would be so cool as to not burn. That same large area leeches heat (compounded by the 'piston' being very slow moving - at one third of crank speed, permitting even more time for heat loss) hence their very poor fuel efficiency. Anyone who works with these engines will tell you 'they throw off heat' (to the coolant). An insurmountable (so far) problem which begs the question why did Audi propose a VVankel as a hybrid range extender?

 

[219]

Not so according to Grober's linked piece:

'' It was this birth defect in the ****el engine, its failure to offer an optimum combustion chamber, which was responsible for its rapid demise and not the constantly repeated suggestions of mechanical problems.”

I'm only going by what I recall from the time .

I'm pretty sure , that was also the given reason for the demise of NSU ; a friend had a couple of RO 80's , which I recall heavily raided the Audi parts bin of the day .

 

[Bellow]

I'm only going by what I recall from the time .

I'm pretty sure , that was also the given reason for the demise of NSU ; a friend had a couple of RO 80's , which I recall heavily raided the Audi parts bin of the day .

For sure the NSU Ro80 initially suffered from excessive tip seal wear but a solution was found and the chief engineer knowing the answer was close at hand pleaded that the launch be delayed but was overruled.

The Ro80 with four cylinder reciprocating piston engine and different frontal and rear aspects became the VW K70 and many features (eg inboard front brakes) were (or became) Audi features. Who got there first is a moot point as it appears NSU was independent until 1969 but the Ro80 was apparently launched in 1967.

 

[grober]

I'm only going by what I recall from the time .

I'm pretty sure , that was also the given reason for the demise of NSU ; a friend had a couple of RO 80's , which I recall heavily raided the Audi parts bin of the day .

There were certainly problems with NSU roller tip wear at the time--- said by some to be only adequately solved by Mazda years later. The thermal/fuel efficiency arguement would certainly not have been helped by the 1976 Arab oil crisis which presumably focussed MB management minds on the excessive fuel consumption issue.
Its possible Audi still held patents on the original NSU designs and perhaps the compact nature of the powerplant had packaging appeal??

 

[Bellow]

Its possible Audi still held patents on the original NSU designs and perhaps the compact nature of the powerplant had packaging appeal??

Good point re patents/rights. The compact nature was undoubtedly the appeal (and smoothness though a hybrid RE can be isolated in a way an engine coupled to the wheels cannot). Fuel inefficiency? The stupid unrepresentative EEC test wouldn't have noticed it as the test would no doubt be exclusively with battery sourced propulsion! Mad world....

 

[zipdip]

I had a Maxda RX7 rotary years ago great car went great,had leading and trailing plugs which were different,the only thing was when you got in it you had to drive somewhere,it was no good driving 5 miles down the road and then stopping and then starting again,those rotaries did not like starting from hot.

 

[Benzowner]

I had a Maxda RX7 rotary years ago great car went great,had leading and trailing plugs which were different,the only thing was when you got in it you had to drive somewhere,it was no good driving 5 miles down the road and then stopping and then starting again,those rotaries did not like starting from hot.

Anything like my mates old RX8, they were prone to flooding after short trips, called the AA out and certainly had his monies worth from them

 

[oldguy57]

Apparently the trend now is to transplant v8s or similar into the Mazda. Now an MB v8 powered RX7 would be interesting!