Rebuilding a 1968 Porsche 911L engine

[Targa68]

Want more H.P. but also want reliability. Any suggestions.please help,thanks Louis.

[Steve@Rennsport]

While not cheap to do, make it a 2.2 with 84mm P/C's and you will be quite happy.

[Targa68]

Whats the best brand P/C? Any thing with the crank and cams?

[Steve@Rennsport]

I use Mahle whenever possible as these are FAR better than any aftermarket ones. Stock crank & cams are just fine for this application.

Now,..if you happened to have a set of the ultra-rare '69 S heads, you could use S cams, if you were willing to put up with a somewhat peaky engine.

[304065]

Many have gone this way before. . .

your trail of bread crumbs begins here. . . http://forums.pelicanparts.com/911-engine-rebuilding-forum/221927-suggestions-warmed-over-2-0-901-05-a.html

[Steve@Rennsport]

Originally Posted by 304065

Many have gone this way before. . .

your trail of bread crumbs begins here. . . http://forums.pelicanparts.com/911-engine-rebuilding-forum/221927-suggestions-warmed-over-2-0-901-05-a.html

Great blueprint for a good engine.

Some of our 2.0-based motors using 2.2 heads & P/C's performed VERY well, however these are not cheap to do. Still,.......they ran extremely well in those light cars, especially with the right gearstack.

[Targa68]

Peaky engine?

[Targa68]

What about torque,or is this the wrong engine for torque?

[304065]

I'll give you my opinion-- people who care about 68Ls don't do it for the huge power or the big tires or the modern creature comforts like face-level ventilation. They do it because a 68L is a time machine, a throwback to that funky transition between the raw SWB cars and the fat-fendered German hotrod of today. A 68 is particularly difficult to restore because it has all those one year only parts:

front suspension, steering tube, suspension geometry
interior elephant hide
US DOT pieces like the window latches, ashtray, knobs

Anyway you get the idea. The highest value (value is a consideration lately) comes from having a completely stock 68L.

All that said, the reason we got the L in the US was because the S motor was too dirty for our regulations. The 68S was the last car to NOT use an external oil cooler, so plumbing isn't really an issue.

As I describe in the thread above, all these questions were thoroughly researched and pondered. Building your "L" into an S motor is certainly a possibility. . . but. . .

. . . the larger ports reduce gas velocity at low engine speeds. The "S" cams have a nice torque peak that hits you in the back around 5300 RPM. The 2,0S is a great motor, but for street driving it's probably not as much fun as a Solex, E or T-cammed engine.

What? Heresy spoken about the 67/68S, that paragon of SWB virtue? Yes, this is one of those things that seems great on paper, an in an original 67/68S it's a must-have. . . but you don't have to replicate an ancient design to get great performance and you certainly don't have to spend big dollars porting your heads.

So how about some options.

Option 1 (best option in my opinion)-- spend your $15,000 rebuilding the 68L motor exactly to original spec, right down to the last nut and bolt. This will be the cheapest option and the marginal performance difference will be offset by originality and value preservation.

Option 2 (what I did) a mild, internal-only update. Bore Biral cylinders to 81 and use aftermarket 9.5:1 pistons for a small displacement increase and compression bump. Use stock ports and valves and modern camshafts with all the invisible but important updates. My engine made 137 HP at the flywheel with 32 degrees of timing on pump gas which is more than stock and more than enough to move it along like a scalded cat.

Option 3-- get yourself some 2,2 heads, these have larger ports and valves, and some 84mm Biral cylinders and pistons. Using the same crank and rods, you get a 200cc displacement increase while maintaining the high-revving character of the engine. Expect an incremental 15 HP with carburetors (155 HP 2,2 E -10 HP for MFI = 145 hp - 130 901/07 = 15 more HP)

Torque? At the torque peak, sure. Peaky? ALL German engines are peaky. . . but by using a lesser cam you can tame this for street operation.

Hope this helps. . . it's all in my thread above.

[Targa68]

Very good,thank you

[Targa68]

What about internally,anything can be done to keep the engine running cooler?