Has Porsche ever made gear driven camshafts for their flat boxer engines for road use or racing? If not, how come? I could understand not wanting gears for road cars because of the whine noise of the gears but wouldn't it be advantageous for racing?

Also, can flat boxer engines be used as a stressed chassis load bearing member bolted directly to the chassis like a V engine can without the use of a space frame? I ask because I remember when Formula 1 was thinking of new engines that the inline 4 was proposed but Ferrari rejected because they don't make i4's and also the chassis/aero guys (Adrian Newey) said that i4's need a space frame and are not as rigid, the V engine can be bolted directly to the chassis.

 

Yes, the 547 engine, designed by Fuhrmann.

https://www.rcnmag.com/blog/familiar...uhrmann-engine

http://type550.com/blueprint/build/engine/

No, not as a stressed member, IIRC.

The first use of an engine as a stressed member was the Ford-Cosworth DFV, IIRC, in 1967.

 

Porsche built 4 cam versions of the aircooled 911 motors, but to my knowledge they were chain driven. In the 1950s and 60s, they did build gear driven 4 cam 4 and 8 cylinder racing engines.

Not sure about using a 911 based engine as a stressed member without a sub-frame. I believe in the 962 it wasn't fully stressed.

 

Depending on the number of gear, the backlash can become an issue. There is a member in our PCA region who used to have a Spyder. He said it took a bit to get the lash right in everything to have stable valve timing.

 

Road Scholars, a few miles from my house, builds as many four-cam engines a year as most specialists do in ten.

Simon, their Fuhrmann specialist and who worked in my Ferrari shop many years ago, periodically gives me tours. He has developed jigs, tools and a workflow that avoids the lengthy set-measure-repeat of the cam timing operation, as the second cam on each side is dependent on the first.

I think there is a “Four-Cam Jam” happening at Laguna Seca in a little over a month from now. Looking forward to that!

 

Cool engines. I heard it takes a week (literally) to do the cam timing on one.

 

Hmmm, reading up on the link above on the Porsche Fuhrmann’s Type 547, it uses the Bevel gears which is different than the gear driven cams on F1, Indy cars, MotoGP and Honda motorcycles (VFR, RC30, RC45, RC51 VTR1000R).

https://www.rcnmag.com/blog/familiar...uhrmann-engine

 

Yep, they had to transfer the motion to a different plane, hence bevel gears. Just like the Crosley 750 and a bunch of others.

Your gear driven cams are just all in one plane, that's all. Still gear driven.

 

Would it be possible to design/build a flat six boxer engine with the gear driven cams seen in more modern designs all in one plane like Honda did?

 

Why? Out if curiosity or for a reason?

 

I was curious if it was possible for flat 6 boxer type engines to have a gear driven cam setup, not the Bevel design though.

I really like gear driven cams over belts and chains.

There are couple benefits: No chain tensioner. Very easy camshaft removal. Maintains very precise timing at all RPMs. No timing chains to stretch, or belts to change. The gears outlast the engine. Many Honda VFR, RC30, RC45, VTR RC51 have over 170,000 miles on them and never once had to change the gears.

Formula 1, Indycars, MotoGP use them. In MotoGP, Yamaha were using chain drive while the Ducati, Honda and Suzuki were using gear drive. Yamaha were forced to switch over to gear drive because the gear drive gives a HP advantage and no chain stretch during races.

In 2010, in World Superbike the Aprilia used gear driven cams while the other teams used chain drive. The gear drive gave Aprilia a HP advantage and they won the championship that year causing the the other manufactures to protest and change the rules, the gears were banned in 2011.

https://www.asphaltandrubber.com/racing/aprilia-rsv4-gear-driven-camshaft-3-5-horsepower/

https://www.cycleworld.com/story/bikes/about-motorcycle-engine-cam-drive-systems/

Since so many Porsche owners track their cars, I see many benefits with gear driven camshafts for performance and reliability/durability.

 

Would be interesting to see if something could be developed. Might be a challenging retrofit though?

 

Of course. Duplicate the motion transfer of the existing chains, sprockets and tensioners.

Oil control and room for preserving the transfer ratios would be the main challenge.

 

There’s always this, the 1967 DOHC 2-liter flat six racing engine designed for the 910, type 916. Nothing to do with the 916 road car project, which came along three or four years later.

 

The 917 was gear driven, same plane.