BF AUCTION: 1981 BMW 633 CSi Ending Soon!

We featured this BMW a while back as an Exclusive, but with some new information in hand, the owner has decided to run it as a BF Auction! So here is the story of how we came across this 633 CSi in the first place. A few days back while running business errands, we stopped at a small shop that has some interesting classics parked out front. We typically try not to pester people we don’t know, but with this BMW, an Alfa Romeo GTV6, a Merkur XR4Ti, and a BMW 2002 parked out front we couldn’t resist. The garage’s main door was open, so we thought we might as well see what the story was.

In the shop, we met Mike and David, who use this shop to work on their own projects. They aren’t running a dealership or a mechanics shop, just building cool cars to play with. They seem rather used to strangers dropping by and were extremely friendly. As the conversation went on, we told them about Barn Finds and the projects we are currently working on. Since we needed to get back to writing posts and they needed to get back to rebuilding a turbocharged V8, we exchanged contact info in case they ever wanted to talk cars. I sent Mike a link to the site and before long he was asking me about listing the BMW for sale as an Exclusive. Since they are just down the road from BF HQ and we wanted to take a closer look at this 633 CSi anyways, I told him we could come to take photos and video of it to use in his ad.

When we showed up a few days later, David had the car up on their lift so that we could get a good look underneath. As we were looking at the suspension, they both started pointing out interesting features that this car wouldn’t have left the factory with, such as the upgraded suspension. Once we got to the motor, David pointed out something really unique, oil ports in the block for a turbo. Well, two turbos to be exact. Mike directed our attention to the hand-painted pinstriping, which contains the text “twin turbo” over the rear wheels.

Once the car was back down on the ground, I took a look at the engine which currently doesn’t have any turbo components. It looks clean and original from the top, so we started discussing what the car’s story was. It’s a 5-speed, runs and drives nicely, and has signs of having had a turbo setup, so there has to be an interesting story! As it turns out, Mike actually found this car at a local donation center that runs a car lot. It had been donated and Mike happened to see it as soon as they listed it for sale. Since it’s a 5-speed, there was a lot of interest in it, so he went and bought it right then without knowing anything about it.

Once he got it to his shop, he discovered the Twin Turbo script and the oil return lines for the turbos. It’s quite odd to find features like this, so he started doing some research. There were a few companies that offered turbo kits for these cars, including Dinan and Callaway. He contacted Callaway but unfortunately, they don’t have any records going back that far. A reader that happens to know Reeves Callaway contacted him to see if they ever built a Twin Turbo kit for BMWs and sadly they didn’t. So, the mystery of the Twin Turbo script and oil returns continues.

I did some research of my own and discovered an interesting coincidence. A number of years back, there was another Twin Turbo 633 CSi sold here in Boise. It was equipped with an automatic and had been converted to Twin Turbos just prior to them selling it, but the seller claimed the parts were from a Callaway built car. I’ve yet to hear back from the seller, but what are the odds that there were two Twin Turbo 633 CSis running around Boise, Idaho? It’s hard to know for sure if that’s really what happened and it still doesn’t explain who built the car in the first place. It’s really too bad that they didn’t leave this car alone. With upgrades like the performance suspension and painted BBS wheels, there’s a good chance this car was converted by the dealer or a professional. Can you imagine the value if it still retained its turbo system?

There are a couple of small rust spots, the paint is showing its age, the seats aren’t perfect, and the odometer is showing 167k miles – which is probably why someone would have swapped the turbos. It runs great, check out the video below to hear it start and run. These cars were very well built and will just keep going as long as they are serviced and there aren’t any electrical gremlins. David has gone over the car closely to make sure it’s in good driving condition. The oil pan gasket had a leak, so he installed a new gasket. They did a brake job and checked out the suspension to make sure everything is safe.

I’ve seen a few of these cars over the years and have always been impressed with their styling and build quality. Typically though, I’ve not been so impressed with the transmissions that most are equipped with. For daily driving, an automatic is fantastic, but when it comes to European sports cars you really need a manual. Yes, these were meant to be a comfortable grand touring car, but that doesn’t mean they don’t handle well. And, when you get in the twisties, it’s just more fun rowing the gears yourself. This one goes into gear nicely and it doesn’t seem to have any issues. We didn’t have a chance to drive it, but hopefully, we’ll get a chance to do so and will report back!

Valuing this car is really quite a challenge. There’s a small following for 633s, but these cars don’t typically command crazy money unless they are ultra-low mileage or equipped with go-fast parts. And that’s what makes this one a challenge. It was definitely tricked out at some point in time, but it’s now missing the most valuable part – the turbo system. It is a 5-speed car, which adds value, has an upgraded suspension and it runs and drives without any issues. Given that we now know for sure that it isn’t a Callaway car, Mike has decided to offer it as a BF Auction.

I want to thank Mike and David for listing this BMW with us and for letting us come take a look! It really is a great looking car and could be a fun project whether you turbocharge it or not. Take a closer look at the photos and if you have any questions, message Mike. And if you would like us to check out anything specifically for you, let us know in the comments below!

  • Location: Boise, ID
  • Mileage: 167,053
  • Title Status: Clean

Do you own an interesting classic with a cool story? Does it need to go? Please consider selling it here on Barn Finds!

Bid On This Vehicle

High Bid: $1,633 (Reserve Not Met)
Make An Offer
Ended: May 7, 2019 4:00am MDT
Top Bidder: leiniedude
Buyer Premium: 5%
  • leiniedude
    leiniedude bid $1,633.00  2019-04-30 19:05:11


  1. Mountainwoodie

    Hmmm…how exactly do you remove a twin turbo from a block? Cap off the return lines?

    Like 1
    • Josh Mortensen Staff

      Correct. Someone removed the oil lines and threaded plugs into the block to seal the returns off.

      Like 2
  2. Mountainwoodie

    Thanks Josh.

    Like 0
  3. HMSpininfarina

    I remember the ALFA GTV with a Calloway twin turbo in the same year. My dad almost bought one from the local BMW dealership in the mid 80s but got scared off by the Alfa reputation. I have yet to see one again.

    This is tempting.

    Like 2
  4. Scott

    Great cars these owned a standard euro spec 5 speed 635csi the straight six was strong despite having over 230,000 miles … fuel economy was never its strong point but man it did it with style this was in the days before these where collectable here in Scotland

    Like 2
  5. local_sheriff

    Regardless of having the Twin Turbo setup or being a real Callaway his asking is indeed reasonable for a manual 6-series coupe. In the BMW world this should be regarded as the e21’s Cousin Anthony

    Like 3
  6. rod444

    Have always loved the style of this 6 series, especially the large canopy glass with elegantly narrow pillars. Even the c pillar.

    And BMW should be commended for spending design energy on the rear seats as well as the front. Instead of a cheap bench afterthought this is one of the few rear seats that say “yes, it’s still sporty back here too. C’mon in”

    Love this car.

    Like 5
  7. Mike Foil

    I actually sold these cars NEW in Chicago for Patrick Cadillac, BMW, Mitsubishi, and Saab!

    The 633csi was a very desirable vehicle when it was new, and the manual transmission was about as much fun as I could find on the lot giving that most of the Cadillacs were Big Tuna boats at that time!

    Nice BMW, hope it sells well! Good luck to all involved.

    Like 4
  8. CJinSD

    Do these auctions have reserves?

    Like 1
  9. leiniedude leiniedude Member

    Hey Josh, i tried to log in as a bidder 3 times with no luck. 2 are on me with a mistake on my card. Any help? thank you, Mike.

    Like 0
    • Jesse Mortensen Jesse Mortensen Staff

      Hi Mike, I just emailed you. We will take a look and see if we can help you.

      Like 1
      • leiniedude leiniedude Member

        Thanks Jesse!

        Like 0
  10. Steve Haygood

    Which picture exactly shows the plugged off oil return lines ? I see the boss on the block where ( if it were a 745 block ) the oil return line would go, but can’t find the actual picture other than that.

    Like 1
    • Josh Mortensen Staff

      Hi Steve,
      It was a bit tricky to get a good photo of the oil return line plug. You can sort of see it in the photo I attached. It’s up in the top left corner. I’ll see if Mike can get us a better photo of the plugs though!

      Like 0
  11. Neil Raden

    I had a 2000cs, a 630CSi and 86 735i. I may jump in on this one even if I do have two projects going now.

    Like 1
  12. giade FLIGHTNING

    Hi ~ i dont see an Option on your Site for being Informed just before this Auction is about to End. Is there some way ? Devotamente ~ gF NM/FL

    Like 0
    • Jesse Mortensen Jesse Mortensen Staff

      There’s “watch” link that you can click to get updates. You need to be registered as a bidder to see it though.

      Like 0
  13. Andrewnot a member

    Anyone old enough to think Hawk (Spencer for hire } ?

    Like 1
  14. Warren Allgood

    Just a thought. Maybe previous owner kept turbos fo other project and donated this car afterwards?

    Like 1
  15. leiniedude leiniedude Member

    I agree Warren, Just what I thought. As a motorhead I don’t blame them. Take care, Mike.

    Like 0
  16. Ryan king

    I would like to contact the owner to ask about his 2002s I’m somewhat near the area.

    Like 0

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