Bonomelli's LOST twin cam engine

[Biancaneve]

Wow, would love hearing one of these monsters revving!!! Any information on concrete applications of the engine? Was it a mere, albeit amazing, technical exercise? Rgds. Max

[Nine17]

Metzger experimented with multi-valve heads, but found that they weren't cool. Literally.

Remember that Porsche did the DOHC Typ-916 six-cylinder during the 911R program. It was a two-valve. This engine was the basis for the flat-8 908 engine. Metzger and company eventually tried four-valve heads on the 908 but couldn't get enough air around the valve-stems to prevent detonation and other heat-related problems. This is why the Typ-912 twelve-cylinder in the mighty 917 also sported two-valve heads. After the regime change at Volkswagen ended the subsidy to Porsche for purely air-cooled racing engines, water-cooling of the cylinder heads was considered to be an acceptable solution.

I imagine that Bonomelli's biggest roadblock was homologation. What good is an engine like this if you can't sell it?

-- David

[Flieger]

Mezger tried a water cooled 4 valve head on the 908 on the dyno. They therefore had the knowledge when the Moby Dick engine, 936, and 956 later needed the water cooled heads with 4 valves for more power. (I think Moby Dick had the water cooled heads).

[peekaboo]

Signore Gottifredi was a pilot also. For instance : 5th OA / 1st GT 2.0 at Targa Florio 72

Here he is at Coppa Valtellina 71 ...I do not know his navigator.

andrea70 , I think I read sometime back you said you could look up old IT registration by licence plaque number. Can you tell me , will these records provide a chassis number ? How far back are there records available ?

[Mr9146]

I think it's beautiful...

[Orbit]

Bonomelli was a very active racecar driver and it appears that he was experimenting with the Porsche Valve train for a long time. Looking at some race history on teamdan.com I found that Bonomelli was disqualified from the 1969 Targa Florio for "illegal valve gear". ( After he won his class)

http://www.teamdan.com/archive/wsc/1969/69tf.html

Great to read about sportscar guys who were pushing the envelope way back when...

[Nine17]

(I think Moby Dick had the water cooled heads).

Yes, both the 935/78 Moby Dick and the 1978 936 used the water-cooled heads. The reason that they weren't used earlier was that Volkswagen AG was subsidizing the Porsche racing program as advertising for air-cooling. Volkswagen suddenly changed course at the end of 1971 after Nordhoff's heir Kurt Lotz was subject to a palace coup by the Supervisory Board in favor of Rudolf Leiding -- and the overnight change from VW's frying in oil to boiling in water. Porsche was building kettles as well by then, so there was no more reason not to use the better breathing allowed by a four-valve head...

[911r67]

I think he used it in this car which is actually for sale Porsche 910!
http://raceline-feustel.com/#menue4_punkt21_2_4_0

[andrea70]

Frank, the correct body for the car would be this one: Porsche-Bonomelli 910:

[Biancaneve]

andrea70 , I think I read sometime back you said you could look up old IT registration by licence plaque number. Can you tell me , will these records provide a chassis number ? How far back are there records available ?

I'll take the freedom to answer on that, hope Andrea will excuse me and complement if needed
Yes, the records provide chassis numbers too. I recently asked for verification of cars registered in the early 70s (and still registered) and it worked for them. It's cheap (5.65 Euros) and quick (in real time via a web application). Here is an example (I edited some details for privacy reasons (e.g. the "xxx" ones) but they're visible in the original file):