History - 917 "genes" in the 914 2.0L, The Porsche Racing Dept Engineering input Options

[Tom_T]

UPDATED 12/21/09 & (IMG:style_emoticons/default/santa_smiley.gif) to all!

While the 917 is not strictly 914, it is historical info from the period & definitely original info. from the factory & race drivers of the day. And the pay-off for the link after this "shameless hook", is the info in the thread of how an Engineer from the Porsche Racing Department was able to make the lowly VW 1.7L 4 banger into a respectable "Porsche-bred" 90-100 hp 2L engine - when VW thought it was impossible to go any bigger & had been max'ed out at 1.8L (+/- 200% - recall it started in the 1930's VW as only about 900 cc).

See the videos at the link below, & also peruse the additional clips at the sidebar after viewing this one linked below, including those linking to racing 914/6's.....

<snipped>
If you like racing and the sounds of Porsches, you will love this video:


YouTube - Porsche 917
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Enjoy! Courtesy of our local PCA-OCR membership chair! (IMG:style_emoticons/default/biggrin.gif)

Then read the lively discussion on the link between the 917 & 914-2.0 engines, of which even the "Master of 914 O&H" was not aware! (IMG:style_emoticons/default/biggrin.gif)

...Heck! - even I'm learning stuff I didn't know from others of you out there, which I always do! (IMG:style_emoticons/default/biggrin.gif)

[carr914]

I don't recall where I saw the piece on how the 2L was derived in part from the 917's engine.

Dang!!!! (IMG:style_emoticons/default/sad.gif) - it was a great connection & I thought I could tie the two stories together. If anyone else has seen that write-up where they talked about engineering the 914-2.0 engine redesign of the prior 914/411 1.7L, in connection with the technology of the 917's 10 cyl. air-cooled racing engine, feel free to add in here! I think it had to do with the cams, timing, etc. on the 917...????

The Connection is Hans Mezger, The Engine Designer.

Here is the Qoute from Hans Mezger that I was searching for

[JFJ914]

I don't recall where I saw the piece on how the 2L was derived in part from the 917's engine.

Dang!!!! (IMG:style_emoticons/default/sad.gif) - it was a great connection & I thought I could tie the two stories together. If anyone else has seen that write-up where they talked about engineering the 914-2.0 engine redesign of the prior 914/411 1.7L, in connection with the technology of the 917's 10 cyl. air-cooled racing engine, feel free to add in here! I think it had to do with the cams, timing, etc. on the 917...????

The Connection is Hans Mezger, The Engine Designer.

Here is the Qoute from Hans Mezger that I was searching for

I think Mezger meant rod bearings not main bearings as that was the mod that allowed the stroke increase to 71mm.

[Tom_T]

I don't recall where I saw the piece on how the 2L was derived in part from the 917's engine.

Dang!!!! (IMG:style_emoticons/default/sad.gif) - it was a great connection & I thought I could tie the two stories together. If anyone else has seen that write-up where they talked about engineering the 914-2.0 engine redesign of the prior 914/411 1.7L, in connection with the technology of the 917's 10 cyl. air-cooled racing engine, feel free to add in here! I think it had to do with the cams, timing, etc. on the 917...????

The Connection is Hans Mezger, The Engine Designer.

Here is the Qoute from Hans Mezger that I was searching for

I think Mezger meant rod bearings not main bearings as that was the mod that allowed the stroke increase to 71mm.

The quote below which TC found & posted above on pg 1 for me was correct - as far as it went:



(IMG:style_emoticons/default/agree.gif) However, you're also correct that the Push Rod Bearings were also changed to make them smaller with better materials to allow the 71mm stroke, but the above noted smaller crank bearings made room for that to happen within the center case castings that were also changed a bit for all of that to happen IIRC. So all of the bearings, crank, pushrods & case are different from the 1.7/1.8 is some respect or another to accomplish the 300cc boost, which is why Jake Raby, FAT Performance, et al can only go up to "1.9L & change" with a 1.7/1.8 case, whereas they can go up to +/- 2.5L with a 2.0 case!

(IMG:style_emoticons/default/idea.gif) Also IIRC, when I read some other articles on how the 1.7 was enlarged to 2.0 - the Porsche Racing Dept. also tweaked the pistons, rings, sleeves, valves, etc. in both desing & materials to improve the performance, reliability & longevity of the now somewhat over-bored & over-stroked motor - in VW's opinion anyway - but not in Metzger's because he'd used the "better materials" in his racing engine for the 917 & earlier racers.

Ergo, these are all "connections" between the 914 & the Rodney Dangerfield "I don't get no respect" 914-2.0 !! (IMG:style_emoticons/default/biggrin.gif)

Also, someone was opining somewhere else here on 914world that Porsche went to water cooled technology on their motors at least in part to be able to use 4 valves per cyl. &/or DOHC. However, a quick look at McMark's post of the 917 12 cyl. engine on pg 1 clearly shows 4 valves & DOHC each side of that AIR cooled engine. IIRC, the 1950's souped-up 356 Carrera motor was likewise a $-valve DOHC air-cooled motor, albeit a limited production one. (IMG:style_emoticons/default/idea.gif)

And in all cases, when we call our motors "air cooled" - they are in truth "air + oil cooled"!! (IMG:style_emoticons/default/biggrin.gif)

So I hope I now stand redeemed for starting this post topic in O&H - in Pat's eyes at least - that there was in fact a fairly critical link between the 914-2.0 - and Porsche's Racing Dept. & their 917s of that same period.
(IMG:style_emoticons/default/popcorn[1].gif)

[Bleyseng]

I don't recall where I saw the piece on how the 2L was derived in part from the 917's engine.

Dang!!!! (IMG:style_emoticons/default/sad.gif) - it was a great connection & I thought I could tie the two stories together. If anyone else has seen that write-up where they talked about engineering the 914-2.0 engine redesign of the prior 914/411 1.7L, in connection with the technology of the 917's 10 cyl. air-cooled racing engine, feel free to add in here! I think it had to do with the cams, timing, etc. on the 917...????

The Connection is Hans Mezger, The Engine Designer.

Here is the Qoute from Hans Mezger that I was searching for

I think Mezger meant rod bearings not main bearings as that was the mod that allowed the stroke increase to 71mm.

The quote below which TC found & posted above on pg 1 for me was correct - as far as it went:



(IMG:style_emoticons/default/agree.gif) So all of the bearings, crank, pushrods & case are different from the 1.7/1.8 is some respect or another to accomplish the 300cc boost, which is why Jake Raby, FAT Performance, et al can only go up to "1.9L & change" with a 1.7/1.8 case, whereas they can go up to +/- 2.5L with a 2.0 case!

IIRC Jake likes to use the "W and EA" cases as they are stronger for the larger motors. The 2.0L cases have less metal in certain areas and show fatigue quicker.