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What kind of HP numbers do you think you will end up with?
Hopefully about 50 more than it’s making now. But it’s not just the power. I want more life and feel in the engine and power delivery. Revvyness, eagerness. Hard to explain :-)
Car is pretty quick as it is now.
I wouldn’t want any more than 50 more for the chassis. I’m running skinny 185 and won’t be running wider.
The other thing im considering while it’s all out is a regear. Stack up 2-5 a little better. Longer 2 then tighter up the stack
So this is an interesting dilemma. The "smart" thing to do in building my little sleeper (i literally got 3 "cute" comments yesterday alone, perfect platform for it) would be get a 3L or 3.2L case and go from there. Likely less expensive, more power out the box. But, there are 2 things interesting to me: the character of the smaller engines + keeping the spirit of the mag case from this generation of the car. Ok if i could find a turbo 3l case for less than 5 figures maybe i'd do that... Idiocy? Probably. And likely will recover 20% of spend on a resale. It was likely not a great idea to buy a full, complete, everything included motor in good running condition. Or maybe it was? Definitely paying a premium vs. getting something that's already torn down or in parts or partial. But we don't do this for financial well being do we? :-)
My initial thought was swap it in as is (change tins, carbs, heat bits, etc from CIS) and run it, and build the motor in my car. You know, keep it with, it's been there since '92, that sort of deal, but, that's kinda stupid. Not original is not original. But, I think i'm leaning to just driving the motor in the car and building the one I am picking up next week to save on swap costs. My initial logic was: the one I'm buying is likely in better condition than one in car, so I could just flip it on resale. But doing the math, with the extra swap step likely it's a wash. What to do with motor in the car once it's out? Sell it. I think the carbs along are worth about $3k. Or maybe I build another motor for some other "to be" landed project...
I've talked to several builders. The luxury of living here in porsche central in SoCal, and they are generally a friendly bunch. The reality is these things have been around for 50 years. Call after call similar formulas shared. The builder I'm going to use, well, maybe not the most 'conventional' in the sense of the classic air cooled world. More on that later. But, I am interested in blending the 'old' with the 'new ideas' for this engine build. Could some of the tech or ideas or materials being used on 911 GT car motors with turbos spinning to 9.5k+ be relevant? Of course, totally different world, but, the materials, techniques, and technology are all relevant even in the old.
So I'll be using those well known formulas and sprinkling in some of the less often seen things on these old motors (Like full EFI with wide band O2, dual coil-on plug ignition, etc).
Competition Engineering i've heard of too. I was talking to a builder a few weeks ago (you'd know the name) who prefers Ollies for consistency and knowledge. They've had good luck with a few others too.
This is a typical list of standard services to a mag case:
1.Align main bore back to STD.
2.Spot face through bolt holes.
3. Head stud Case Inserts
4. Deep inserts
5. Tranny inserts
6. Shuffle pin whole case
7. Clean oil sq.
8. Media tumble
9. R and R oil plugs
10. Hot tank
11. Oil by pass mod
12. plus misc parts...
Well, I have a 3.2L case - hot-rodded with PMO carbs, cam, SSi, dual plugged etc. (1975 915 in a '73 unit body) - DO like all the torque, it will even pull form 2k rpm when I am lazy...
If I had it to do over again I'd go with a Mg case (despite the cost), saving the 40 lbs. or so off the butt end; bump up the displ. to 2.8L (can ya get 2.9L and be happy??) maybe EFI; and a typ 911 trans. in a '72 body (more wt. savings and momentum...)
Buddy of mine is doing similar build on his ‘73. Almost exact situation you are in, driving car now with great stocker motor in it and is building a spare 2.8 RS Spec motor, believe he is doing EFI. Had his machine work done at Ollie’s, and your estimate is spot on.
Well, I have a 3.2L case - hot-rodded with PMO carbs, cam, SSi, dual plugged etc. (1975 915 in a '73 unit body) - DO like all the torque, it will even pull form 2k rpm when I am lazy...
If I had it to do over again I'd go with a Mg case (despite the cost), saving the 40 lbs. or so off the butt end; bump up the displ. to 2.8L (can ya get 2.9L and be happy??) maybe EFI; and a typ 911 trans. in a '72 body (more wt. savings and momentum...)
So...
Its where my head is at. I don't know, really, on 2.9, but supposedly it puts more stress on the case than is desirable. I believe Andial made 2.9 P/C from Mahle back in the day and clearly they knew what they were doing. I'd sacrifice that last bit of displacement for reliability, though.
Originally Posted by CBA
Buddy of mine is doing similar build on his ‘73. Almost exact situation you are in, driving car now with great stocker motor in it and is building a spare 2.8 RS Spec motor, believe he is doing EFI. Had his machine work done at Ollie’s, and your estimate is spot on.
Yeah RS spec is often quoted, and a good foundation. Technology has moved a lot in 50 years!
And so it begins. It was probably idiotic to buy a full, lower mile running engine. Who knows what I'll really use off of it :-) But, will sell off what I don't need. The full induction and exhaust system will be first listed on Pelican. And it was definitely idiotic to buy a mag case motor vs. a 3L. Ah, the stupid things we do.
It has a documented rebuild 20k miles about 10 years ago, the case was split, new piston/cylinders, bearings, valves, and a very complete parts list. Will need to tear it apart and HOPEFULLY the work was done well at that time, but case will need to be reworked i'm sure. The engine drove very strong and ran super smooth/well. So I pulled the trigger vs. rolling dice with a removed motor or just a case.
Will pick it up this week and bring it to the shop.
They've started a build list on ideas for the major components.
08-10-2019, 10:01 PM
