Early vs. late 3.0 cases

Joe Hayden · 05-20-2004, 12:23 PM

I’ve been reading Wayne’s book (thanks Wayne!) and have a question about early and late 3.0 engines. Early 3.0s being the 75-77 turbos and 3.0 Carreras. The late being the SC engines.

I am wondering what the differences are between the cases of these two 3.0 engines. The only difference that I’ve uncovered is that the earlier 3.0 share mains with the 2.7. Are there other differences? Ultimately, I am trying to understand whether it is possible to build a 2.8 or 3.0 RSR spec engine from an SC case. Has anyone heard of building up the mains and cutting for a 2.7 crank?

Seems like the latter case would be a great candidate for one of these engines.

Thanks!

Wayne 962 · Wayne 962's Garage

Nope, the 2.8 can't be done (at least I don't know of a way to do it with a 911SC case). I'm sure you can build a custom crankshaft (or custom cylinders), but that wouldn't be worth it.

The 3.0 RSR could be done on an SC case (same bore/stoke), however, the RSR engines had a lot of unique (not well-documented) characteristics about them (like the non-adjustable rockers).

-Wayne

BURN-BROS · 05-20-2004, 02:56 PM

cylinder head stud spacing on early turbo cases are unique, they only fit early turbo, RSR, 935 heads. I don't know about the euro cases,Wayne?

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by BURN-BROS
cylinder head stud spacing on early turbo cases are unique, they only fit early turbo, RSR, 935 heads. I don't know about the euro cases,Wayne?

Don't know - the stud spacing on the 1976 Turbos and European Carrera cases are the same as the later ones (got one hidden in my garage).

-Wayne

Henry Schmidt · Henry Schmidt's Garage

It is my experience that the stud spacing on the 3.0 turbo and euro Carrera are the same as the 911sc
86 MM. The only case that had the unique 83 MM stud spacing was the 3.0 RSR. Not the 935. The 2.8 you build with a 3.0 turbo case is 66 stroke x 95 bore. 66 is a 2.0 or 2.2 crank. Very close to the 959 which was 67 x 95. The only way to build this engine with an SC case is to destroke an SC crank or any other 9 bolt crank, this would require a set of custom rods or you could buy a 962 short stroke crank. It will fit the 911SC case and is 66 mm stroke. It is my opinion that it is worth the effort. The short stroke engine will spin as high as you like and live for ever with unparalleled performance. Our short stroke, 2.8 twin plug , slide valve engine makes 315 HP on street gas and will turn 8500 rpm all day.
The engine in these pictures is a 2.8 (66 x 95. 3.0 turbo case, 2.2"S" crank 911SC heads).

BURN-BROS · 05-20-2004, 04:03 PM

Henry,whats the cylinder stud spacing for the 935 then?

BURN-BROS · 05-20-2004, 04:05 PM

Wait, 86?

Henry Schmidt · Henry Schmidt's Garage

Right-935 stud spacing is 86 mm.
The head is a factory 935 ( note the 12mm spart plugs ) and the cylinder is a 3.0 RSR. Where did that stuff come from? Don't own an RSR or a 935

BURN-BROS · 05-20-2004, 04:41 PM

Were all 935 heads this way(earlier vs later)?

Btw I'll shut up now, I stole this post. Sorry

Henry Schmidt · Henry Schmidt's Garage

"All " is a very big word. If some 935s were built with 3.0 RSR cases then no. I have no reason to believe than any 935s were built that way. As far as I know early 935s were built with a version of the 3.0 turbo case. The late 935 were built with a late 930 case. 78-83. Who knows what the 935 Baby was built on. 60 stroke X 71 bore 1400 + cc ?
BTW the 1994 Benaton F1 v8 was 50 stroke X 95 bore. There's a revver for you.

BURN-BROS · 05-20-2004, 05:17 PM

Thanks Henry, my dad has some early ones that look a little different than yours in the pic.

Wayne 962 · Wayne 962's Garage

Quote:

Originally posted by Henry Schmidt
The only way to build this engine with an SC case is to destroke an SC crank or any other 9 bolt crank, this would require a set of custom rods or you could buy a 962 short stroke crank. It will fit the 911SC case and is 66 mm stroke. It is my opinion that it is worth the effort.

While I'll agree with you that the short stroke engines are very cool, I'm a bit surprised by this statement - perhaps I don't completely understand?

Are you saying that you would recommend finding a short-stroke 962 crankshaft (or making a custom one) and putting it into a 911SC case over the other option of using the standard early 66mm crankshaft with a 3.0 Turbo/Euro Carrera case?

One would have the 9-bolt flywheel flange, and the other the early six-bolt flywheel flange. Of the top of my head, those would be the only differences I could think of, except that I would imagine that the short stroke 962 crankshaft would cost a heck of a lot more than a 3.0 Euro Carrera case (they range about $1500).

I can't think that the additional cost of the 962 crank would be worth it just to get the nine-bolt flywheel end. I guess if you can't find an early Turbo/Euro case then this could potentially be your only option? Unless I'm missing something?

-Wayne

ber911 · 05-21-2004, 03:18 AM

Henry

Any idea of the HP I would get out of a 2.8 motor on a 3.0 Carrera case with 10.5 JE pistons, GE80 cams, 3.0 Carrera heads and 40 Webbers? What would the torque be like and would it be a streetable motor?

Robert

Joe Hayden · 05-21-2004, 06:29 AM

Wow, I thought that there was something worth talking about concerning this!

The reason that I originally asked about building one of these short stroke/big bore engines with an SC case is that these cases are obviously more readily available. But if it requires a 962 crank then that probably negates whatever cost savings the case gives.

In any case, there are alot of SC cases out there for a good aftermarket 66mm crank to find a home in :-)

BURN-BROS · 05-21-2004, 06:45 AM

You can try Pauter or Scat to see if they have the equipment to do a six cyl crank. The 4 cyl variety was in the 4500.00 range When Beck had his made for a 4 cyl 911 engine. But you are right about any cost savings.

Henry Schmidt · Henry Schmidt's Garage

The nine bolt crank is important if hp is produced. There are other bennies to the 9 bolt crank. It will run in a Carrera case ( much stronger) big rod journal radii, 3.0 style rods, better oiling ( cross drilled ) and full counter weights . All of these mods can be performed on a 3.2 destroked crank.
Don't get me wrong , all of my short stroke 2.8 engine were build with either 3.0 RSR, 3.0 turbo or euro Carrera cases. The question was" can you do it" the YES.
The result a magnificent engine worth building. P.S. We need 3.0 turbo and euro Carrera cases, call me if you have one for sale.[QUOTE]

Henry Schmidt · Henry Schmidt's Garage

All of that sounds good except the 40 mm Webers. The reason these 2.8 engines are so cool is that they revvvv. The higher they rev, the more air they move and surprise hp. Your 40 can be changed to 46mm then you have a happy combination. Streetable is a matter of degree. What makes a car streetable for me is: It starts easily, runs on street gas and transitions from idle to full throttle relatively smoothly. Perhaps the 10.5 to one would make street gas a challenge. As for torque " High Revvvs= no torque"

ber911 · 05-22-2004, 03:42 AM

If I have to purchase nickasil cylinders for this motor would it make more sense to then go to 98mm and make it a short stroke 3.0 or would that negate the high revng nature of the 2.8 to some extent?

Robert

Henry Schmidt · Henry Schmidt's Garage

Why not make it a 3.1 with a set of 100mm? Bill Kieth ( Honest Bill) build one of these and put it in a 914-6 and swears it's the nicest engine he ever raced. The main reason for the 2.8 is that the it's small and it revs. The 66x98 would rev the same but 3.0 just doesn't sound as cool as 2.8 or does it?

Wayne 962 · Wayne 962's Garage

Here's what I have on my plate to be built later on this summer. It's a street engine for my 914-6:

- 3.0 Euro Carrera Block (no messing with clutch setups - will plug right into the 914's 901)
- 98mm big bore kit from Mahle (10.5:1)
- 2.7 crank & rods
- Turbo heads, ported and twin-plugged (I forget the sizes)
- Weber 40s (streetable)
- Mod-S cams from Elgin
- Dual Electromotive HPX ignition systems with Rick Clewett's triggers

This will make it a short-stroke 3.2, and is the best engine I could design that would be streetable and easily compatible with the 914-6. Estimated 270 HP peak with good driveability.

Of couse, I have all the parts, but haven't had time to assemble it yet. In the meantime, I bought a stock Motronic 3.2 for the car (which I also haven't had time to install yet).

I need more time...

-Wayne