early Al case vs 7R, which is stronger?
 

Are the 7R cases as strong as or stronger than the early 2.0 Aluminum cases? Are there any limitations (configurations, extra machine work, etc) in using a early 2.0 Al case as a basis for a small displacement hotrod motor?

I actually tried to search on this and came up with Nil. I apologize ahead of time if its been covered before.

TIA

My understanding from talking to Ted Robinson at German Precision and from Rich Walton at Smart Racing is that the AL case is stronger than a Mag 7r. The AL case might need some mods to work in your particular application but it should be a better long term case than a 7r.

-Andy

Yes, the Alum case is stronger than the 7R case, but you need to install piston oil squirters and do the oil bypass. I've heard it is also NOT a good idea to shuffle pin the Alu case? Anyone know more?

Much stronger (Al case). Jerrry Woods or Bruce Anderson (can't remember which) has had some problems with shufflepinning the aluminum cases - seems they become very stiff then, and can actually break ribs? This is off the top of my head. Definitely shufflepin the mag cases if racing...

-Wayne

Thanks guys. I just re-read the section in BAs book where he says NOT to shuffle pin a Al case.

New question:
Assuming the oil bypass mod and the piston squirters are done to a early Al case, is there any reason at all to use a 7R case instead. Does using an early 2.0 Al case have any limitations or disadvantages in any way outside of needing these mods?

Obviously the spigots on an aluminum case, assuming its virgin, would be too small for anything but a 2.0 (80mm).

edit, I read that wrong.

I meant to include boring the spigots out in my previous post.

The early aluminum cases are the trick setup for racing. The downside is that they do require quite a bit of modification to get all of the upgrades. The cost of a good, modified, early case is often the same cost as a Carrera 3.0 or early Turbo case...

-Wayne

I can only think of three benefits of the mag cases:

1) They are lighter then the aluminum cases
2) There are a lot more of them around.
3) If the rules of your racing class require that the case be made of the same material as was originally standard on your year/model car, a Mag case may be your only choice.

Shut up....just shut up......you had me at "they are lighter".......:D

There are two reasons why you would select an early aluminum case over a 7R case; you have more money that you know what to do with (for appropriate modifications you would to make a 2 litre case reliable to larger engine specs and power) or you really like small displacement 911 engines.

Remember, the Porsche 911 engine was always more about design over matterial. I could see pursuing a 930 aluminum case for big power displacement reliability, but selecting a early aluminum over a 7R case doesn't make good sense considering all the design built into the 7R case, unless you are an ediot with a torque rench.

I disagree completely. The cost to properly recondition and machine a magnesium case often runs about $1500. See the chart in my Engine Book for more details. The cost to modify an early aluminum case is also about the same, including the cost of the case. They are both about $1500 for the finished product. The aluminum case is far stronger than the mag cases, as proved many times over by people who've worked on these engines.

The deficiencies with the 7R cases are well documented. The material of the case is too weak to support the additional heat and HP that the 2.7 engine demanded. That is why they went back to aluminum in 1976 with the introduction of the Turbo and Carrera 3.0 engines. It has nothing to do with anyone's ability to work a torque wrench.

-Wayne

The fact is, the 7R as is makes a suitable street engine up to 2.7 liters and a great case up to 2.4 liters. I do not agree that an early 2 liter case is stronger that a magnesium 7R at comparable displacements and power. Aluminum cases get line board just like magnesium cases do. I not arguing, that given the same design blocks, the aluminum is stronger in an absolute sense, but in a practical sense, aluminum is no better a choice for moderate power or displacement applications.

if you shopped around, you could get a 930 case for the modification cost of an early 2 litre case. Now, why would you want a early aluminum case considering all the needed modification? Even after the latest mods is not as good as a 930 case, Unless someone can present evidence to the contrary. Gosh, I wonder how the 917 held up like it did!

small displacement turbo :).