Early vs. late 3.0 cases
 

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!

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

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

Let it spin
 

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).http://forums.pelicanparts.com/uploa...1085095410.jpg http://forums.pelicanparts.com/uploa...1085095422.jpg

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

Wait, 86?

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 http://forums.pelicanparts.com/uploa...1085098968.jpg http://forums.pelicanparts.com/uploa...1085098979.jpg http://forums.pelicanparts.com/uploa...1085098989.jpg http://forums.pelicanparts.com/uploa...1085099001.jpg

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

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

"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.

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

Re: Let it spin
 

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

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

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 :-)

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.

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]

ber911
 

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"

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

More is better ?
 

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?

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

I think you mean short-stoke 3.2...

-Wayne

Wayne

I am probably going to use a 66mm crank.

Robert

Whoops - the original poster said he had the SC case, thought you had one too.

Okay, so you're going to make a big bore 2.8 (short-stroke 3.0). Yes, this will be a very high-reving, short-stroke 3.0L.

However, you will need to have custom pistons made for the engine from some place like JE. I am not aware of any 98mm pistons that have the correct piston-pin bore to run with the 66mm crank and rods.

I would assume that you're doing this for class restrictions? If not, I would just build the short-stroke 3.2 out of the engine (using a 2.7 crank).

-Wayne

Just weighing up all the options at the moment. I only get the motor next week - a 3.0 Carrera longblock with unknown history that has been standing a long time. If all is good with the crank and the cylinders are Nickasil then I will just rebuild it with 95mm 10.5 JE's. However from a cursory look at the motor I suspect it has Alusil cylinders and the crank will be no good. in that case I would get a 66mm counterweighted crank and rods and then must decide what P/C's to use.

Robert

You might be surprised. The last Euro Carrera 3.0L I bought in pieces had Nikasil cylinders. Also, these cranks are usually okay, unless the motor was severely abused...

-Wayne

Would be great if you are right Wayne, should know in about a weeks time. Counted the cooling fins last time I saw the motor and I am sure there were 11 so I could well be wrong.

Robert

That is not an accurate method of determing Nikasil or Alusil...

-Wayne

I believe all the 3.0 Carreras had Nickasil cylinders. Mine did. And I've read that they all did in a couple books, including Paul Frere's Porsche 911 Story. Unless someone swapped 'em, you very likely have Nicksil.

Sorry, sent before I was finished typing, try again ---

As I recall, the earlier 3.0 case has smaller mains than the later. If so, then Wayne's proposed short stroke 3.2 is dimensionally equivalent to the traditional short stroke 3.2 (as outlined in his book) but would have less friction due to smaller mains which may add to higher end output?

Nikasil or Alusil, that is the question
 

Hey guys, the easiest way to tell Nikasil from Alusil is with a magnet. Nikasil is magnetic.
As for piston pin location for short stroke (66 mm) crank, the pin location is the same for 2.0, 2.2, 2.4, 2.7, 3.0. and 98 mm 3.2. All these engines use a 32 mm wrist pin center to deck measurement . The difference will be the compression generated by similar domes. For example if you run a 3.0 RSR piston 10.4 to 1 on a 66 stroke crank the deck will be right but the compression will now be closer to 9.8 to 1. If you run a 10.4 to 1, 98 mm with 22 mm wrist pin on a 66 mm crank you will have a similar reduction on compression but the deck will be fine. Quick note: when building a custom engine like we're talking about, dimensioning the engine becomes all important.

REVVVVVVVVVV IT UP
 

Another thought:
If you run a 2.4/2.7 crank (70.4) you effectively limit your RPM to something like 7400-7600. Constantly revving a 2.4/2.7 crank over that is asking for trouble. That is why Porsche made the RSR crank. Too many failures from the stock crank. On the other hand the 66 mm crank loves 8000+.
and we all know how that sounds!!!
http://enginesounds.free.fr/porsche/911%202.0l%20-%20a%20bord.mp3

The difference between 2.2 and 2.4 pistons is the dome hieght not wrist pin location. In the early engines they shortened the connecting rod to make up the difference in stroke. I believe the measurement we are talking about is called compression distance and the compression distance on 2.0, 2.2, 2.4, 2.7, and 3.0 are all 1.335 in. or about 32 mm as I stated in the earlier response.
One of the problems with Porsche engine is that they keep changing the rod length to stroke ratio.
In the early cars it was almost 2 to 1. As the stroke grew the ratio got smaller causing some very bad rod angularity. I believe in the later engines the ratio is down to around 1.63 to 1.

Ummm, yes, I see your point. My proposed 3.2 is the same as a 911SC with 98mm pistons, but with a smaller crank journal.

I don't think it works like this. My guess is the frictional drag from smaller or larger main bearings would be negligible. It might even be higher on the smaller journal, because it's a smaller surface area? (think of the analogy of a woman wearing high heels - small surface area on the heel = harder to drag than than the same amount of weight in a big, flat box.

Again, I think the frictional forces between the two would be virtually the same, but that's just a guess.

-Wayne

Journal size counts
 

When talking about journal size there seem to be three factors.
Drag, load distribution and weight.
Small journal, less drag ( small surface area) , reduced load distribution, less weight.
Large journal, more drag ( larger surface area), better load distribution, more weight.
There is also an issue of strength but I believe that strength can be manipulated by corner radii of a given journal.
Given some of this is true:
Small journal with large radii should be, low drag, reduced load distribution (increase clearance, and oil pressure to correct) weigh less for easier rotation.
In the case Porsche engines, drag produces friction (heat) and in an oil cooled engine, heat is bad.

Can anyone confirm the viability of a set-up using the early turbo/3.0 Carrera case? I'm trying to build a CIS motor using these parts.

I am assuming the crank is same/similar in size as an SC crank, other than the small journals?

What about the rods that came with that engine? Same as SC's too?

Assuming I put in a 98mm MaxMoritz set, with a CIS-friendly cam, are there any benefits to be gained using 3.2 heads instead of the big port early SC heads?

thanks.

Re: REVVVVVVVVVV IT UP
 

WOW! I got chills listening to that sound clip! That's a high revving 2.0 with open tail pipes, yes?

No doubt, that clip is sweet!!

I think it's better to compare journal size with 'drilling'. I did a lot of drilling a few years ago and noticed that when using a large drill bit, the drill machine has to set at slow speed, otherwise the bit will overheat. With a small drill bit, it can be run at high speed. So, Henry's quote below is probably right.


Yoda, you kept saying that you're not an engineer, so where did you get that info from and how do you know if it's true?

25+ years of engine building and a life time of racing puts you in a place to pick up some knowledge.
Add that to a pretty good automotive library and then surround yourself with the best people and that's where my experience lies.

I don't necessarily state anything as the truth. If you read what I stated, you will find that almost everything is qualified.
Most of my conclusions are based in reason and observation.

Re: Journal size counts
 

This has been quantified by ford on their Windsor(351),429,460 engines. They all have a massive 3 inch main journal. The increased drag from such a large journal promotes severe local oil temps at higher rpms. Most of the Nascar Fords run with something less, around 2.75 inches so that they do not experience this problem.