(I vividly remember reading this at the time, as it made a lasting impression)
The Chevy small block V8 has found itself in just about every vehicle imaginable, and there were of course gobs of them that had found their way into hot rods and such by 1968. But this transplant into a Porsche 912 was well outside of that typical scope. The whole notion of a cast-iron water-cooled V8 in the rear of a (formerly) air-cooled Porsche may sound a bit heretical at best, but it actually worked better than expected. The reason for doing it in the first place was pretty pragmatic: the owner bought a 912 at an insurance company auction, minus its stolen engine. New and used Porsche engines were expensive; Chevy V8s not, even a brand new one.
There were a few challenges, but one serious problem: the 350 hp 327 made way too much torque for the Porsche transmission, and the solution was a bit unorthodox. It quite surprised me at the time.
The solution was to destroke the 327, down to a minuscule 2.375″ stroke, resulting in 239 cubic inches. Lest you think doing so would grossly emasculate the V8, keep in mind that an engine’s maximum hp is determined primarily by the breathing of its heads, not its displacement. The reduced stroke lowered maximum torque to around 250 lb.ft, but raised the engine’s top power peak rpm, ironically making it more typically Porsche-like. Its peak power was estimated at about 300 hp
Surprisingly, weight distribution was not affected that much, at 37/63 front/rear, compared to 44/56 for stock (43/57 for a 911). Well, that was undoubtedly enough to affect its handling at the limit more than a wee bit, but maybe the owner hadn’t fully explored that yet. Given the car’s 2485 lb weight and its 300hp, it was undoubtedly a rocket in the straights.
That’s supported by its quarter mile time of 13.8 seconds @106 mph. That’s right there with the best stock hemi Mopars, and the starting technique was “very gentle” to protect the Porsche transmission. Like most engine conversions it had its limitations, but the owner did enjoy blowing off Corvettes.
Interesting. I think this conversion predates one using the Olds Toronado transaxle, and had the engine in the back seat. From memory the builder used hollowed out suitcases to disguise the engine cover.
The claim was made that the improved layout meant that some factory ballast in the front of the car could be removed.
Too long ago to remember where I saw the article, or what V8 was used.
A more modern conversion here:https://grassrootsmotorsports.com/articles/how-ls-engine-turned-broken-911-true-budget-superc/
I remember that swap. It was in Peterson’s engine swapping book circa 1975. I still have it. The engine was a 425 Oldsmobile.
Thanks. I knew I didn’t dream it!
Pardon my ignorance, but wouldn’t it be far easier to install a VW engine? If it were modified it may get up Porsche power. Of course, it would still sound like a VW engine.
Just asking.
He was clearly looking for some serious power. Back then a seriously hopped-up VW engine might be able to make 100-125 hp in semi-streetable tune, but this makes 300 hp. A big difference.
But yes, a VW engine would have been a very easy swap.
The later 912s actually used a VW engine, a 2.0 type 4 as seen in bigger engined bay windows…. And the porsche 914.. though the heads etc in the Porsche were improved
Earlier ones like that used a 356 engine though, and the type 4 was barely in production at that point, and tuning a VW to that level was probably rather expensive… Even if that was the beginning of the hot aircooled VW’s heyday
Still seems nuts, all that work to make the engine less powerful. Could they have swapped in a Corvair motor, or waited a few years for a turbo Subaru?
I would be quite content with the 4 cyl unit in a 912.
The article states that the engine still made around 300. A Corvair motor is an interesting idea, if it would work.
He’d be waiting more than “a few” years for a turbo Subaru. The original WRX of 1992 was JDM only, and the 1.8 turbos of the mid 80s made like 115 hp.
Given the obvious issues with rear weight bias, perhaps a lightly-used Buick 215 would have been a better choice. I can’t imagine they would have been hard to find, or all that expensive in 1968.
I have seen a 215 in a Vanagon last year, and being already water cooled the plumbing didn’t appear terribly difficult.
The Buick and Oldsmobile 215 is larger than the Chevy according to the article. I think the 4.3 liter 90 degree V6 would have been a better choice from a handling and space perspective. Aluminum heads would have lightened the engine but were rather hard to come by, and an aluminum block in the Chevy small block was almost impossible. How much did the custom crankshaft cost? I assume the pistons were taller than normal, and I suspect heavier. I guess longer rods were too expensive. Very interesting! I think the 37% front and 63% rear is a bit too tail heavy for pleasant driving.
There is a company Renegade Hybrids who used to offer a kit to do this to vintage 912/911s back in the 90s maybe. I suspect with values up there is little uptake on those anymore but they seem to offer kits for other Porsches now as well.
https://www.renegadehybrids.com/
Very good work, decent weight distribution, I seem to recall 40/60 to be the balance to shoot for with a mid-engine car so this is really good when having that cast iron lump hanging out the back. Of course today it would be a LS and some new trans parts made from uber material.
I like the idea but would rather have the engine in the back seat.
That’s bad weight distribution. 1968 was an important year for these cars, Porsche launched the 911 and it had problems. The engine weight in the rear was causing handling issues so they cobbled together fixes. Lead weights in the bumper, too 6V batteries wired in series for 12V but more weight. And then in 1969 they modified the rear end of the car by moving the rear wheel arches back and using longer swing arms to begin the long wheelbase LWB cars. All to address a rear bias issue with their aluminum 6 cylinder. Now drop a steel SBC v8 on the back??? In a SWB car????
What an amazing world we live in, 55 years later. This engine was guesstimated at 300 hp, and given the time, we’re probably talking gross HP, so let’s say 230 net HP, maybe 250 if we’re being generous. That’s well within the realm of several small, lightweight 4-cylinder engines I could think of. Turbocharged Subaru flat-4 is a common and obvious choice, and the water-cooled Vanagon bits make swapping any VW or Audi I-4 turbo engines an easy option. But of course, a decent 912, even with a broken engine, is serious dough these days.
I saw a Porsche equipped with a Chevy V8 at a Cars &Coffee in Fremont last month. Wonder if it might be the same one. I like the idea of the Toronado power unit better, it made for a mid engined design. I’ve got the Petersen engine swap special too.
I had neighbor across the street from me who did one of these conversions, It was an amazing experience…
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