Delicate Question (Mag Case Durability)

[afterburn 549]

#1-To start if you have "no idea" ,,, Please refrain from posting .
#2- If you are just a knocker please refer to step one.

The delicate Question is this -
Mag Case 2.7 with ALL updates....(Shuffle pins and the works)
How far can it go B4 the studs and stuff pull from the rubber Case {anyway} ?? ?
So, What has been the experience of the Borg here ?
I mean Torq. and HP. of course .
What is the limits with margin of durability and safety ? ? ?
And to keep on target dont say JUST go get a AL. Case.
Keep it to the Mag one.
For parameters lets talk about at least a 100,000 miles B4 TBO (Tear Dwn)
Or unusable.
Thanx for the hopeful discussion

[Steve@Rennsport]

Originally Posted by afterburn 549

#1-To start if you have "no idea" ,,, Please refrain from posting .
#2- If you are just a knocker please refer to step one.

The delicate Question is this -
Mag Case 2.7 with ALL updates....(Shuffle pins and the works)
How far can it go B4 the studs and stuff pull from the rubber Case {anyway} ?? ?
So, What has been the experience of the Borg here ?
I mean Torq. and HP. of course .
What is the limits with margin of durability and safety ? ? ?
And to keep on target dont say JUST go get a AL. Case.
Keep it to the Mag one.
For parameters lets talk about at least a 100,000 miles B4 TBO (Tear Dwn)
Or unusable.
Thanx for the hopeful discussion

JMHO,.......

The studs won't pull if they are have properly prepared (case savers) and oil temps are strictly controlled.

These cases crack around the #3 spigot and the #1 main bearing bore due to extended higher RPM operation. Keep the revs below 7300 and you'll be fine; it will outlast you.

Preparation is everything. These things are ALL old and tired and need a lot of rehabilitation to get the reliability.

[dipso]

I have a mag case. Bought it at 175,000. It was rebuilt at 135,000 by previous owner.
I just had it rebuilt last month at 245,000.
Didn't even split the case, no leaks except from cylinder matings. Everything is brand new from rod bearings out, but the case itself was in fine shape.
Don't know exactly what was done to it internally from previous rebuild, but it does have the head stud inserts from previous rebuild.

My understanding is that a mag case with upgrades is just fine. Mine has been.
I have about 250,000 miles on mine.

[afterburn 549]

Thus is better news then i thought.....but I am still wondering what max torq and Hp one could safely do?

[Steve@Rennsport]

Originally Posted by afterburn 549

I am still wondering what max torq and Hp one could safely do?

There are too many variables to give you a hard number; TQ or BHP. Sustained engine RPM, CR, and things like that make this almost impossible.

To be safe, keep the CR below 10:1 and the max RPM below 7300, keep the peak oil temps below 210 deg F no matter what the conditions and you'll not have a problem.

Naturally, racing engines are a whole different subject and those are the ones that suffer cracking.

If you have a specific configuration in mind, post that up here and I can tell you more.

[afterburn 549]

Thanx Steve,
I realize it is a Hand grande of equations . (LOL)
That is why i used a 100,000 sort of as the Base line....
In Vague terms at least..what are the limits of a Mag case as far as Torq and HP.?
I realize if it is in a 24 hour race that equates to a eng. that is probably "done" .
So in the "real " world With once in awhile reaches to the "red Zone" of limits...Could a guess be made as far ..........
DO not exceed this number __________________________?

[Eagledriver]

You can figure this out based on displacement and RPM. If you keep your RPM limit to 7300 and your displacement to 2.8 litres, you'll be hard pressed to exceed 240 HP. The torque can also be found from displacement and assumed volumetric efficiency of 1.0 max. I don't have that equation but I'll bet it's around 200 ft/lbs.

-Andy

[afterburn 549]

SO, Maybe after the 1st rebuild with linebore and all, these things have settled in as to where they are going to stay?
After such a bad rap for SO many yrs.............not so bad?

[Jimmy18E]

Built right and throwing some money at the build you can easily surpass 240 RWHP. My 2.5SS on two differnt dynos exceeds 240 rwhp and my friend with a 2.7SS hit 266 RWHP, both street cars and both built on 7R cases. Yes all the mods are done to the cases.

Good luck with the build, should be fun.

Jimmy

[afterburn 549]

This going way different then I thought........Years ago when i did mine, with every conceivable update.........I was hoping at best an other 100000 miles...B4 for the ritual again LOL
Now.........This thread is giving me some ideas..like 5 lbs of boost ideas...Now where does this denigrate too ?
I know i would not be the 1st
I have toyed with the idea in the past.....Bu everyone said it was just a handgranade .
Rich Clewit said it would work even with CIS pistons if there was not a nut behind the wheel
He was basing that on something to do with 964 engine C/R figures.
So now years latter....what is the thoughts?

[Steve@Rennsport]

JMHO, but I would not use a mag case for a forced-induction application due to heat related issues.

The aluminum cases are FAR more durable.

[afterburn 549]

PS, Dipso, Nice to see you up here out of the darkness.
And i think we have all leraned a lot here -
Thanx to the Borg of thought.
Thanx!

[Eagledriver]

Boosted engines are a whole other story.

-Andy

[KTL]

Can I ask what's the reasoning for choosing a mag case?

Light weight = big difference between Mg and Al. I can see why Porsche initially chose Mg because what a difference in weight.

Cheap price of admission = dirt cheap if you can score one for a song. But you make up for initial cheapness on the back end with all the case prep work.

Cool factor? I agree that a Mg case is just cool to have. So long as it's been properly gone thru to check spigots, mains, parting line, head stud thread inserts, etc., I think a Mg case is a great choice for a fairly stout non-turbo engine.

I agree throwing a turbo on there is asking for difficulties. Aside from the strength issue, I would heed Steve's warning that temperatures are a major consideration in keeping a Mg case from going crooked on you....

[afterburn 549]

My car has matching numbers.......and I have had the engine in awhile (I think 5 years)...Back then everyone said the mag case was not worth bothering with.
Back to the matching numbers.
So-
After much much thought,..I did every up date that was thought of ....
No problems.
But I would like to "cheaply' (LOL) raise the HP from 156 at the rear wheels to 200
But...up to now have been too concerned....
According the the Borg here I can...!
Of course HP comes with cost and several ways of doing it.
The turbo route is enticing sense I have dual plugs all ready and most the turbo stuff.
If I go an other direction it has to come back apart
Raise the C/R for one
Maybe carbs
ECT

[Eagledriver]

So you think that putting on a turbo won't affect the value of a "numbers matching car"? I would build your motor on a new block and store your old block for future restoration to stock.

-Andy

[afterburn 549]

I had not even thought of it till yesterday when everyone said it is a great platform...with in parameters...
And to own two engines is kind of costly.
and the numbers still would match LOL
I am just thinking with pixels......coffee at the lap top so to speak.

[afterburn 549]

SO,,,, I guess even if it is a cheaper way for me to go NOW,..5 lbs of boost will cost me more in a short run.......?
shucks.
darn.
But dad so and so did it ! !
crap.
Charlie Brown eyes** ^^