Help Figuring Out my FrankenPorsche

[canyon.classics]

I was told that a car I recently acquired had all correct 930 parts. I knew it was a turbo clone so numbers matching was never an issue to me. Everything underneath looks correct, I can see the turbo, waste gate, all correct factory 930 exhaust and parts ect. But the engine number is puzzling. If I am decoding it correctly 64F03953 comes back as a 1985 regular Carrera motor. Its a 930/21 motor. Secondary my question is how much internal and external difference is there between a 1985 930/66 motor and a 930/21 motor if all the manifolds, turbo, and exhaust were bolted onto an original non-turbo motor? Would it be easy to do and make a 3.2L Turbo motor essentially. What would the HP difference be. Any expertise would be appreciated...Also assuming about 7,000 930/21 motors were built and mine is about 4,000 into production could it be the original engine to the car? My sequincial # is 170777 which would make it the 777th Cabriolet off the line in 1985 out of only 1050 built. I know without the COA there is no way to tell but im just trying to make light out of this.

[RSBob]

People on the turbo forum might be able to help you out quickly. 911 / 930 Turbo & Super Charging Forum - Pelican Parts Technical BBS

[javadog]

There's no easy way to tell what's inside. DO you have the original pistons and cylinders, or those of a turbo? Which cylinder heads? Cams? etc.

You can figure it out if you do a little digging and open up a few things. But you're going to have to learn what the differences were and how to spot them.

Whether or not that's important enought to do, I can't say.

JR

[spuggy]

Originally Posted by canyon.classics

Secondary my question is how much internal and external difference is there between a 1985 930/66 motor and a 930/21 motor if all the manifolds, turbo, and exhaust were bolted onto an original non-turbo motor?

What 3.2 parts you would retain usually depends on whether you want a hi-po 930 or to build a "stock" 930 on a 3.2 case.

What's the oil pressure? If you're getting ~20 PSI on a hot idle and ~5 bar over 3,000 RPM, that's not a 911 oil pump. Which would mean someone split the cases to fit a 930 pump, and the chances would be good a lot of other things would have been done "right" as well.

If you wanted to build a 3.3 930 factory "clone" from a 3.2 short block, you'd need to replace heads (wildly different Intake/exhaust ports and 930 heads are cast from RR350 alloy), turbo also uses sodium-filled exhaust valves, different bore/half-finned cylinders, low-compression pistons, 930 oil pump, softer cams, larger piston squirters IIRC - oh, and possibly an air injection system for smog on the 930, depending on era/market and your local requirements.

The 3.2 distributor rotates the wrong way compared to a 930 or SC, think the intermediate gear needs to get swapped to use a 930 dizzie.

The 3.2 crank is, strictly speaking, not a 930 part - different part #'s and, I believe oiling holes etc - but there's enough folks running 3.2 cranks significantly north of 600HP long-term without issues that that's not likely to be a problem - as long as you bin the stock rod bolts made from string cheese in favor of the ARP part. Which is a great idea even for stock 3.3 motors (and probably 3.2's as well, considering the carnage that results when they loosen off and let go).

Oil temp/pressure sensors might need attention - you usually match these to whatever gauges you're running.

What transmission/chassis? A 930 tub with a 4-speed 930 transmission? Or a 911 tub with a 915?