Chevy V8-Powered? 1974 Porsche 911

Over the years there has been a continual debate of Corvette vs. Porsche. While not similar in architecture, there has been a linkage in concept with both manufacturers pursuing different paths over the years to achieve their desired outcome. Don’t know which way to go? Here’s a solution, put the heartbeat of a ‘Vette under the boot of a 1974 Porsche 911 and voila, a Porvette, or maybe a Corsche, or a  – well let’s take a look and you can decide what’s what. This Porsche “hybrid” is located in Plaistow, New Hampshire, and is available, here on craigslist for $27,000. Thanks to Ian C for this most unusual discovery.

Similar in goal but very different in approach

By 1974, both Porsche and Chevrolet labored under the same U.S regulations regarding bumper impact standards, potential rollover standards, and clean air mitigation. Porsche offered the Targa, such as this example, and actually had it in their 911 line-up since 1967, but the idea was an open passenger compartment with a built-in rollbar. Chevrolet followed a similar path with removable T-Tops though they still offered a full convertible; time, however, was running out for that option. Chevrolet’s circa 1969 fire-breathing V8 power had been reduced to more of a warm burp with a 1974 standard HP of 195 net, emanating from a 5.7 liter V8. Over at Porsche, the standard 911 generated 150 net HP from its 2.7-liter flat-six, an engine half the size, and two cylinders less than that of the Corvette. As for bumpers, Chevy ditched the chrome-plated steel units for body incorporated plastic-covered steel beams while Porsche tacked on a front park bench and rear battering rams. And of course, Porsche still maintained an air-cooled, rear-mounted engine layout while the Corvette continued with its water-cooled, front-engine, rear-wheel-drive traditional domestic car arrangement.

Smash the ’74 Porsche and the ’74 ‘Vette into each other and you’ll end up with this Chevrolet powered, Porsche 911 Targa. The engine is a traditional small-block Chevy but it has been “stretched” to a 427 CI displacement – it is not a big-block Mark IV that famously displaced that same size. So, you may be asking, “How’d he do dat? Well, the seller apparently purchased this 911 already converted. It’s a standard water-cooled V8 powerplant with, I guess, a radiator mounted up front. The engine’s valve train appears to be rather sophisticated but there is no mention made as to the specific engine componentry or how all of this goodness came together, much less how this Porsche performs. The V8 is attached to a Porsche 930, four-speed transaxle and unfortunately, needs a clutch – the car is non-operative as it sits. This mashup is known as a Porsche GT8RS; its appearance has changed a bit since 2014.

The body of this 911 mimics that of a Carrera wide-body that has been further modified with skirts, fairings, an outsized whale-tail, and vents in the fenders and hood – ostensibly for engine cooling. The images aren’t very clear but from what can be seen, the bodywork and finish look damage-free. Unfortunately, there are no pictures of the interior but the seller does mention that a roll cage has been installed.

One could make the case that a Porsche 911 is a Porsche and a Chevrolet Corvette is a Corvette and never the twain should meet. I think I would subscribe to that position but for the sake of outrageous fun, this Porscholet is a serious attention-getter and you have to admire the idea and the skills that made it a reality. And having an all-aluminum V8, this 911 may possess some pretty outrageous road manners don’t you think?

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  1. James West

    Why no clutch replacement ? Sounds a bit fishy to me…

    Like 5
  2. JudoJohn

    Definitely NOT a fan. Just because you can, doesn’t mean you should.

    Like 16
  3. Curt Lemay

    Regular 911s handle crappy, imagine this. If this is so much fun, why don’t they keep it?

    Like 11
  4. leiniedude leiniedude Member

    I think I know why it needs a clutch. I met a couple at an outside seating saloon last weekend. They were checking out my old BMW & I was checking out there sweet 55 Handyman. We got together and he told me he put a SBC in a 914. You meet the nicest people driving in an old car.

    Like 3
    • Bmac777 Member

      You didn’t get to the part where you explain why it needs a clutch.

      Like 4
      • leiniedude leiniedude Member

        Dropping the hammer on a built sbc.

      • JMB#7

        Dropping the clutch will tear up the transmission and half shafts. Slipping the clutch will wear the clutch disk prematurely.
        With the SBC there are only two (three) reasons to slip the clutch.
        1. They flywheel weighs 10 lbs or less.
        2. The clutch is a multi disk high power (good luck slipping it)
        3. The driver is clueless and has no idea what he/she is doing.

        Like 4
  5. Steve R

    I had a friend right out of high school in the early-80’s that bought a 930 turbo with a blown up engine. He installed a 302 out of a 69 Z28 and drove the car for years. Last time I saw him was in the early-2000’s he still had and drove it. Nobody gave him a bad time, he loved it and took good care of it. At the time, it was the only way he could afford a car like that, he did what he needed to do in order to put his butt in the seat of his dream car. It didn’t matter what the engine was, nor what anyone thought about the conversion, he loved the body style, the power train was secondary.

    Steve R

    Like 15
  6. T

    Destroying a piece of art. I don’t understand.

    Like 4
  7. alphasud Member

    I think the cost of a Porsche rebuild is what drives people to do a swap such as this. By the time your done you end up close to the cost of a rebuild. Early 911’s need to be driven with respect to their trail throttle oversteer. The additional weight behind the rear axle compounds this. This is not a car to text and drive in.)

    Like 6
  8. Jeffro

    Kennedy Engineering Adapter. Had a 1968 VW Bug that had a Mazda 12A rotary in back. Fun car.

    Like 4
    • JMB#7

      There are videos of drag racing in New Zealand with rotaries hanging off the back of VW Bugs. Sure seems like they have a lot of fun!!!

      Like 2
  9. charlie Member

    Uncle had an early 911, it was the squirrelliest car I have ever driven. It required constant attention to the road and was always threatening to throw you around back end first. Much worse than my mother’s ’60 Corvair in that respect. If Nadar had driven an early 911, or a Renault Dauphine, they would have been in the book as well. (and if you kept the proper tire pressure in the Corvair it was OK, something like 15 in front and 32 in the rear). But this engine has to weigh more than the Porsche engine so it would be even trickier to drive safely.

    Like 2
    • Chester

      Why do all the Porsche guys insist these things handle well? I have driven a few and they were both bad in that regard. A even bigger question is why did the company itself continue to put out these death traps, and at a premium price? I bet they laughed all the way to the bank. You know, when the Devil temps you with a beautiful woman who is not your wife (that condemns your eternal soul to the underworld) he is going to make her the most beautiful creature you have ever seen that will be the envy of all your buddies, but eventually you will see that she has halitosis and is crummy in bed, but the damage has already been done.

      Like 3
      • Curt Lemay

        Chet buddy, that analogy seems a bit of a strech. What are you railing against, the unbalanced rear weight of the car, or the ignorance of the rich people who think of status more then common sense safety?

        Like 4
  10. Kim

    That oversteer would swing like a 600 pound pendulum around corners! They are pretty rear heavy with the original air cooled aluminum engine.

    Like 4
  11. JMB#7

    Lots of comments, but no data. He does say all aluminum SBC. That engine is most likely heavier that the flat 6, but how much heavier. The seller should put it on a scale, one end at a time and let people know what the weight distribution is. There are many items that can be removed or relocated to bring the balance closer to what is desired. And what is desired is a separate subject. I am confused as to why so many people on a “Car Forum” would react negative to the handling characteristic of a Porsche 911??? Seriously???

    Like 4
    • Chester

      So what exactly are people supposed to discuss here, zucchini bread? Your comment makes no sense, with all due respect.

      Like 5
      • JMB#7

        Please re-read. Many comments about the 911 being tail heavy and the SBC making it more tail heavy, and that tail heavy cars are squirrelly and poor handling. According to Grassroots Motorsports, the all aluminum SBC weighs less than the 911 flat six. I take that weight issue with a grain of salt. However I am citing a very credible source. Regarding the fine tuning of weight balance, things like moving were the battery is located can influence weight distribution.

        Like 5
      • JMB#7

        If you wish, please post you recipe for zucchini bread.

        Like 7
  12. Douglas Hunt

    Do these small block conversions use a reverse rotation camshaft?
    I recall reading a car magazine article years ago and they had done this swap and used a reversed camshaft
    I know the GasMonkey guys did a swap as well, do not remember the details though

    Like 2
    • alphasud Member

      I think you can swap the ring and pinion on the transaxle as well. The 915 transaxle has that provision like the early VW transaxle.

      Like 2
      • douglas hunt

        i knew that on mid engine use they could be turned over, i did not know they could swap the ring and pinion

  13. ACZ

    “Porsche hybrid”. I love that. He says that it needs a clutch. I wonder what else he broke when the clutch let loose, or if he cratered the entire transaxle? I wish there were some bottom pictures. What little you can see appears to be well thought out but who knows?

    Like 1
  14. John Klintz

    I strongly agree with T and JudoJohn! I have a one-word comment: DISGUSTING!

    Like 1
  15. Bruce

    You’d be surprised how much a stock flat six weighs

  16. Howard Ross

    Damn, what a bunch of whiney haters. I’d love to own it just to destroy all you late model corvette and mustang posers. The whole idea of hot rodding is putting big motors into small cars, but that requires more than writing a check at the dealership!

    Like 7
    • Curt Lemay

      But this isn’t 1978, writing that check to the dealership is going to get a whole lot more car. If you enjoy working on the car, great, many do not. The real issue here, as many here obviously see it, is one of safety related to too much unbalanced weight in the rear end.

      Like 2
      • JMB#7

        Why do we think there is too much weight hanging out back? Most sources indicate that an aluminum block & head SBC weighs less than the flat six. If the question were with respect raising the CG then there may be a small concern. Until someone arranges to put it on scale to determine weight distribution, the argument is acedemic.

        Like 4
  17. roland schoenke

    A lot of people on here are saying how bad 911s handle, they Clearly haven’t driven one in the last 20 years, They’re pretty amazing . That said the CaymanS might be one of the best but its mid engine .

    Like 4
    • JMB#7

      It appear that if a car does not handle like a 1960 Lincoln Continental, they they think it is dangerous and uncontrollable. Personally I prefer a neutral, or tail happy car over one that always goes straight including in the turns. Self driving cars are on horizon, maybe that will make them good drivers.

      Like 6
  18. Dbag

    I know this car.
    It used to have orange wheels & vinyl graphics, dubbed the “GT8RS”.
    Can probably still find pictures online.

    Was north of Austin for a very long time.
    Mainly used as a car show car, but the fit & finish wasn’t too great.

  19. Bmac777 Member

    I’m no expert on 911 handling statistics, but having driven a few, I find these “deathtraps” or “severe understeer……..” comments to be more opinion based than experience.
    There is an S turn on a road that I’ve driven on for years, I’ve taken it in many muscle cars / bikes
    My fastest (successful!) speed though it was in a mid 80’s 911 Cabriolet @ 65 mph.
    I don’t know how a car that could do that is considered “bad handling” by anyone

    Like 2
  20. DaveT

    So it gest more (or less interesting) 520 HP and fiberglass and carbon fiber bits!

    and even more info – this this is a hot mess!

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