Turbo Surprise! 1975 Oldsmobile Delta 88 Royale
Nothings says “pile in the convertible; we’re going for ice cream!” like a full-sized American two-door drop-top from the ’50s to ’70s, and this white whale in Attleboro, Massachusetts certainly looks ready for a leisurely cruise to the ice cream stand… until you pop the hood! Only the aftermarket wheels and blackwall tires on this 1975 Oldsmobile Delta 88 Royale convertible suggest any sporting intentions, but the turbocharged LS V8 under the hood certainly spices things up. Check out more pictures and a brief description here at Craigslist, where $8000 puts it in your driveway just in time for cruising season. Thanks to reader Pat L. for spotting this interesting turbo drop top.
The smallest of GM’s popular LS-series V8s, the 4.8L (293 cid) can make over 600 HP with a single turbo, according to MotorTrend. Based on the abbreviated description, the seller either did not build the car themselves or has done so many LS swaps that they no longer geek out on the details. A Holley Terminator system handles engine management, according to the listing. The Terminator can be made boost-aware. Properly configured, it should deliver the sort of quick startup and adjustments for temperature, load, and elevation that we expect from modern EFI (Electronic Fuel Injection). Some super-rough calculations would estimate a stock 4.8 LS makes about 275 HP, and a single turbo around half an atmosphere should bring at least another 80 HP for a total of 355, without over-stressing the stock components. Tweak it to one bar and you might see +50% for 413 HP, but not for long. The good news is that the engineering is (theoretically) done, and you *could* periodically replace the 4.8 far more cheaply than building a high-boost version, not that I recommend it!
The two-tone vinyl interior has seen better days, but you can imagine what a stylish ride this would have been in ’75, the final year of the convertible in this body style. Thanks to Wikipedia for some details.
I’d have sprayed any color but white on this classic Olds, but the brutal white paint certainly highlights the enormous size of the 88. That trunk should have no problem accommodating luggage for four… four households that is. A host of never-installed “performance” suspension parts is included, not with the Solo Nationals in mind, but more for tightening the pillowy road manners by one marshmallow on the cloud-o-meter. While that may seem silly, I’ve cornered a 455-powered ’74 LeSabre sedan (and others) with zeal, and reducing body roll 10% from “OMG we’re going to die” to “Whoa, Nelly” can make a big difference in whether your passengers need fresh britches. Can you picture driving your crew to the custard stand in this turbocharged Delta 88?
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Comments
Someone liked it the listing has been deleted. The builder had more into the fuel management system than the rest of the swap. Those little engines sell quite cheap. Surprisingly the turbos can come with a low price tag also. I am sure it runs much better than it did new.
If it really is a 4.8L, the builder could have chosen a more powerful, stock 6.2L for far less money. Gotta respect someone who builds a car to fulfill his vision, regardless of cost.
Actually, if you’re going for boost, the smaller bore (and resulting extra metal cast around each cylinder) is a huge reliability advantage over going with a 6.2 LS3-ish engine. Even in racing categories where you could use more displacement, you’ll find that competitors go for the 4.8/5.3 LS engines (same bore; different strokes, so to speak) for reliability and lower cost reasons.
And with the sturdier block, it’s easy to make an effective replacement for displacement by turning up the boost. Plus, as someone who’s currently looking for a 6.2 to do a naturally-aspirated buildup — that’s where the 6.2 DOES have it all over the 4.8/5.3 twins — I can personally tell you that 5.3s are priced all day, every day, at far less than half any good 6.2 is going to run you.
This guy made the right choice here for a boosted sleeper.
You wouldn’t need boost with the 6.2.
You’d never get enough out of the 6.2 to catch up with the boost.
You’re kidding yourself. Let’s get real here.
I have a 6.2 Silverado with a tuner, there’s no way I would ever go back to those two 5.3 Silverados, those 5.3’s are nothing but “dead sleds.”
I guess it sold quickly. The outside of the Olds is sweet looking. Under the hood it won’t make a prom date! All business and the new owner is going to have fun. 🐻🇺🇸
Fresh britches…MEOW!!
I like it a lot.I think the bright white makes it pop with the white top.8k was a steal if the swap was done professionally or at least somewhat.The interior repair was no biggie. I’d love to drive it just to check out the performance it has now compared to a smogged out 350 or 455.Definetly will pick up some mpg depending on the trans it had.
I hope the brakes were upgraded too. Hauling that beast down from speed..
Im sure at a stoplight to stoplight race this big beauty would be a real surprise cause you would probably only see taillights.im about to start work on a 73 delta 88,installing a fresh 455 rebuild with a turbo 400 trans.probably wouldnt even be able to hang with this delta.A real “sleeper” for sure
Hey i have 1972 olds delta royale convertible has 350 2-barrel power seat cruise a/c tilt wheel car needs alot but a great restoration project or daily driver
The stock bottom end on a 4.8 will handle 1000 hp with boost all day as long as it’s tuned properly. I had a 4.8 with a single turbo in a 86 GMC Sierra & it made 478 to the wheels on only 7 pounds of boost. It would have easily made over 700 if I had added another spring in the wastegate & tuned for E85. Can’t see any details since the add is gone, but I bet this car is making at least 500 to the wheels. Not gonna do that with a LS3 without some power adders like boost or nitrous. Someone is really going to enjoy this car.
My driver’s ed car was a 4 door Delta 88. Had plenty of power for beginner high school drivers.