2.2, 2.4 and 2.7 all need the same amount of case work?
 

Good morning gentleman.

Will a 2.2, 2.4 and 2.7 all need the same amount of case work since they are all magnesium cases or are he smaller displacement engine often in better shape due to less stress/heat?

Is there such a thing a “just” doing a top end ona. 2.2 or 2.4 or are you into the full thing once you remove the heads?

Thanks!

I've always heard that the 2.7 cases are the most beat up due to heat, and probably also the longer stroke which is known to have bad crank harmonics. The earlier cases need more updating (e.g. oil bypass, piston squirters depending on what you're building), but are reputed to often be in better condition.

Edit - you'd be fortunate to find an early 911 motor that is unopened and with good enough history to not have to split the case once you're in there. Possibly different story if it's been rebuilt of course.

Good morning, thanks for the response.

Good point on most early ones having already been re-worked, lot depends I suppose on the quality (or lack there of) of that work.

agreed with stownsen914.

I have a 2.7 7R that I tore down to do a "top end". once I put the P&C together and set to install (a few weeks) I noticed that the spigot deck surface had warped. previous to teardown the engine spun smooth as butter. after tear down there was up to .15mm differences throughout spigot deck. also the left and right piston to head measurements were different by about .15mm in Waynes book it mentions that when you split cases and leave it overnight the case will relax and warp beyond tolerances. then your only option is send to comp engineering for a line bore back to std and spigot deck operation, which is where I am today! from what I gather the warpage comes from heat cycles over the years and bad thermal reactor design adding extra heat to appease new emissions standards of that era. 2.2 and 2.4 from what I understand don't experience a lot of the same issues as they weren't fitted with those same emissions equip.

I have another question to add to yours. does this statement in Waynes book imply that if disassembled (edit:for a top end) and IMMEDIATELY put back together that the case will not have time to relax?

I love the 2.7RS era of Porsche and I find it a bummer that any time you want to tear one down to maybe check out P&C or something else fairly minor, you need to automatically account for doing open heart surgery on it too. oh well I guess thats just the way the cookie crumbles!

The case warping happens but not often.

You will need to do the oil bypass mod, case savers and all steel head studs. Should then be good to go for any application.

Optional but recommended are ARP rod bolts and ARP Flywheel bolts

Chris
73 E

I've worked on at least 10 magnesium engines in the last ten years , only 1 case was not warped , but the car only had 50,000 miles . I say there's no such thing as only a top end anymore , but do you like to gamble ? It's easy enough to check the cylinder top surfaces with a straight edge .

Pulled a 2.7 down, the crank spun freely, but the engine had a mild rattle or knock. Bolted the case back together with just the crank with new bearings, and it locked up. The case had become a bananna. Obviously the old bearings had worn in progressively as the case warped over time. I Machined the cylinder spigots, shuffle pinned and align bored it, 15 years later is still running strong.

Thanks for all of the responses. It sure appears that all the engines, even the smaller ones, end up costing about as much as the later bigger ones. Oh well.

this is true. maybe more really.