The Real Reason I Bought My Project Corvette
The 1985 Corvette I purchased this fall was always going to be a project car.
It had needs from day one: When I bought the car, I had to winch it onto the trailer. Because of how it was cared for and brought back to life, it is likely always going to have some issues. The only real solution is a full mechanical restoration, and that makes exactly zero rational sense given the amount of work and mountain of cash required. My car is worth keeping on the road, but even a total restoration would result in a stock C4 that would still be a consolation prize compared to an original, unmolested version. Even then, there are plenty such survivors.
This C4 Corvette is a gateway, an opportunity to step into territory that I have never charted.
Of all the gearhead projects I’ve wanted to execute, an engine swap is high on the list. For years, I’ve been daydreaming and planning a mid-engine V-8 Corvair build. It would be a ballsy first swap, since it requires completely reengineering the car and lots of fabrication. I’ve wanted to dip my toe in the fabrication swimming pool for a while, but I also knew that V-8-swapping a Corvair was a cannonball off the high dive when I barely knew how to swim. I had fallen back on purchasing an abandoned V-8 ‘Vair project and finishing it. Some of the heavy lifting would be done, but I would still have my hands in the project like I wanted. That plan left me waiting for a car that may never come up for sale, let alone near me or at a fair price.
What to do? I have motivation. I have tools. As of September, I have a 1985 Corvette that just fell in my lap. I guess it might be time to start doing some serious thinking and gathering of parts. Wait. That sounds like planning…
After I bought the Vette, and my engine-swap dreams began anew, my first phone call was to a friend whose father has a few engines just hanging around, from a date-coded 427 coated in oil and wrapped in plastic to a grimy, crusty V-8 unceremoniously extracted from a 2003 GMC Yukon. That 427 is a dream, but the 160,000-mile LQ4 from the Yukon was both in my budget and more appropriate for my plan.
That plan is obvious by now, I hope: Swapping an LS into my Corvette. I can hear the pitchforks rattling, and the voices accusing me of cutting up a good Corvette, but if you’re familiar with the history of this car, we all agreed earlier that this car is neither sacred nor special. What is it if not the perfect blank canvas to do just about anything I want with it? And what I want is something I built with my own hands, that makes 400 hp, is fun to drive, and can be taken to the track. Do I need to yank the current engine to check all those boxes? Certainly not, but removing the L98 certainly creates fun opportunities.
Furthermore, pulling the engine is potentially the most cost-effective option. This “pulled running” LQ4 is an iron-block, aluminum-head Gen-IV small-block, and that single generational shift is a big one. To pull realistic gains out of the L98 currently under the Corvette’s hood, I would need to invest similar money and time as I would in doing the engine swap, because the LS platform is so well supported in comparison.
I’m not the first, the only, or even the most interesting person to attempt this swap and I consider that a good thing. I have my doubts that any hot rodder who pulled up to the drive-in during the 1960s with a Model T and an early small-block under the hood was told how their swap was unoriginal or boring. The relative ages of car and engine in that last sentence are the same as in my project: 40-year-old car, 15-year-old engine.
The L98 in the car is in decent health too. Just like last year, jokes in one shop turned into dynamometer runs in another. While mild, the L98 pulled strong on the rollers even if the numbers are not impressive by modern standards: 172 hp and 267 lb-ft. That’s great. Now is the perfect time to pull it and let it find a new home in a Square-Body pickup or third-generation Camaro. The L98 would be a riot to drive in either of those vehicles, and right now, I can let a buyer not only hear the engine run but drive it, too. That holds a decent amount of value, and selling the old engine would certainly help offset the price of the new one.
Another thing that puts those dyno numbers in perspective is that the middle-aged Yukon engine is rated from the factory at 300 hp and 360 lb-ft. So even if those ponies aren’t the thoroughbreds they once were, I still stand a chance at a good power bump even running the factory engine computer and tune. This says nothing of the aftermarket potential, and if you think I’m going to have an engine in my shop on a stand and not do something to it, you are mistaken.
The engine choice is not the end all, be all of a project. But even when doing a common swap like this, there are a lot of opportunities to leave my fingerprints on the project and make it my own. With car and engine in hand, it’s time to get down to business and start planning out the rest of the powertrain. The Corvette currently has a manual gearbox. While I don’t plan on changing that, only a fool rules out other options without at least some consideration, so some research and internal debate are on the horizon.
I welcomed this project car into my garage on a relative whim, and after living with it for only a few weeks, the opportunity it presents has become clear. The process likely will not be quick, easy, or fun all the time, but there may never be a better time to take on a project I’ve always wanted to tackle. Why wait?
I think you’re on the right track here, Kyle. Looking forward to seeing occasional project reports!
Thanks! I’m excited to dive in.
If a project is what you want, this sounds like a good one. I’d find a good ZF 6-speed from a later C4 to pair with the LS.
For most other people, buying a clean ’96 manual with the factory 330 hp/340 lb-ft LT4 is the cheaper, easier path. A little patience will find you one for $10k-$12k these days.
Good idea on the ZF transmission. I have to admit I do want six forward gears for both logical and illogical reasons. The adapter support for putting an LS in front of one is good, let’s see how easy finding one will be…
And I totally agree on your point comparing this swap to a later car. Now that I’ve spent time with a C4 I know a later car would likely be perfect for me, but somehow I can’t find the $$$ to buy a ready to go late C4 but will happily scrounge the couch cushions to buy parts for a swap. The right late car would be a delight.
“I do want six forward gears for . . . illogical reasons.” LOL Kyle. I love it!
A ZF 5-speed transaxle is a good idea on the V8-Vair, too. The small end of the 2-ft-long clutch input shaft is the main weak spot if power exceeds about 300 bhp with sticky tires. Can’t count the number of Corvair input shafts I’ve changed in stock Saginaw transaxles over the years.
Sounds like a happy choice to power up the car. My ’95 had all the power I could handle, but I do enjoy the upside of my ’07. I am in the minority who likes the looks of the C4, but their real selling point will always be the suspension. Still a bargain after all these years. Keep us updated on your progress.
The looks have really been growing on me, and the handling sold me on keeping this car during the first few drives. Getting in and out is interesting, but I’m still young enough that it’s not too big of deal. Once in the car is quite comfortable. I look forward to really putting miles on this one.
Kyle you may want to do some Forum reading. Like many web sites there is useless chat but there are guys who already have done what you plan. It can save you time and aggravation.
Absolutely. Read a fair number of forum threads before making the decision. There is impressive support for these and a number of build threads that range from way more than I plan to way less than I plan. Learned something from each.
Having a Corvair, you probably already know the name Steve Goodman. If you don’t, you need to. He runs a little 1 bay shop in the western suburbs of Denver called Rear Engine Specialists, and he is THE Corvair Yoda. He knows more about Corvairs than anyone alive on the planet, and can tell you 5 different ways to put a V8 into one. Last time I saw him, years ago, I mused that it would be nice to be able to swap a 5 speed into a Corvair without the extra work involved in using a Porsche transaxle. He rummaged through the organized chaos behind his desk and handed me a photocopy of a news article about a man who built a prototype 5 speed for a Corvair. He said only about 15 were built, but they’re out there if you want one. When I remember that, it makes my head explode all over again. Amazing!
I’m 70 and can still get in and out of my C3 okay. It just takes a bit longer than when I was in my 20’s, but like you said, once your in it’s fine. A C4 might be more of a challenge for me now.
I’m 66 Ken and I can still get into & out of my C4 fine. Both feet out the door 1st & push my ass up using the door pillar. If there’s a will there’s a way. Arthritis be dammed.
you simply fall in and out of it;
not to the ground, of course, but think of it as a slightly higher Lola T70 or Lola GT40 (no, Ford didn’t design it);
Hi Kyle,
I have a 92 C4 that was the 1st year of the LT1 engine with reverse cooling. I did a rear end swap & went with 3:54 gears from the old 2:79 (granny) gears. Really breathed new life into the engine running at higher rpm’s. Also did a high performance auto trans rebuild with a 2500 rpm stall converter & shift kit. Great acceleration off the line & she cruises at 80 mph at 3,000 rpm. Added some Magnaflow SS mirror finish wide open mufflers to the stock exhaust which deliver a nice, mean tone & killer dual exhaust looks. The color is Quasar Blue – the coolest car color I’ve ever seen. The chrome rims really make the color pop. It’s a real beauty. I also reupholstered the seats with custom leather covers. Comfortable & fast. I’ve owned the car for 24 years & it currently has 125,000 miles on it.
This year car is not going to see great value gains. C4 models are not in great demand and there are still a ton if them around. The LT4 models are of interest of anyone buying. For a little more the C5 is just a better car.
Dropping LS here is good but do a cam and heads. Push it just over 400 HP. Hook it to a better Tranny.
Document all the work so it will add value by showing all that was done and it was correctly done.
We did a C4 at work with over 600 HP. It was fun and supercharged. Just be aware these cars are a bit flexible. They can sag in the middle and in our case twist and break windshields.
Yes, I would recommend adding the X-brace from a convertible C4, at least.
Interesting. Hadn’t seen this yet. Only seen the tube-style braces that replace the targa roof. Looks like something worth tracking down.
Yes the X brace is a help. Some early cars could get so bad the targa will not line up.
The problem with the C4 was the car was going to be a TTop. At the last second going to production Loyd Reuss said to make it a Targa.
This is why the C5 is so stiff the new Corvette team wanted to make sure this never happened again.
If you drive a c5-7 they feel like a go cart as the chassis is that stiff.
BFG had a C4 test car and the Cage they had to install made a big difference. I got to drive it in town snd it was the stiffest C4 I ever experienced.
But it was hard to get in and out of.
Check out vette2vette instead of the x brace you have an adjustable bar on each side tying the front and back together. C 4 no flex frame stiffener bar system
Thanks for the tip!
I was initially skeptical about it being cheaper and easier to get 400 hp out of an LS than the original TPI, but doing a little internet research indicates that, as impressive as the TPI setup looks, it was known for being restrictive, as were the heads. A TPI Camaro/Corvette has always been on my target of opportunity list, but the HP numbers really aren’t that impressive.
It’s tough. I really thought an era-correct-ish performance build could be fun and felt cool to be even slightly “anti-LS,” but the performance per dollar just didn’t make sense, and the labor was roughly the same.
The benefits of the LS are everywhere. Weight, strength, ease of making power size etc.
The engineers literally took a Chevy small block and filled their wish list.
Jaguar engineer told a Corvette engineer he was envious of how low they got the weight of the engine.
TPI is great for a fat torque curve, but you are pretty much stuck with 300 horsepower (IIRC) if you use it on a small block. Edelbrock makes an aftermarket unit that does better, but it costs almost as much as a complete 5.3 from the junkyard.
You’re correct. TPI is prohibitively expensive to make power with compared to what we have today and that’s just to make power a stock LS based truck engine puts out. In fact there is a complete Edelbrock TPI for sale on eBay and they want $2,950 for it.
https://www.ebay.com/itm/276715218387?chn=ps&mkevt=1&mkcid=28&google_free_listing_action=view_item
I always knocked people who SBC or LS swapped every project they had. My experience with a 1988 Chevy truck was that the 5.7L made nice power, but the interior made the truck something that turned me away from the whole make. Now I’m mostly a Dodge guy, but as my boys say, “We aren’t make-ist.” If it rolls, we welcome it into the garage.
My oldest lucked unto a 1975 K10 when he was 13, and we have been building it together, getting it ready for when he is old enough to drive it on his own Now that we’ve worked on his engine, and seen how the rest of the truck is almost like LEGO, do I see the appeal of the compact V8. And yes, he found a great deal on a 2001 6.0 LS from a 2500HD that will probably be swapped into the truck with a manual by the time he gets to drive it on his first date. But he has to save some money or learn some more electrical for that to happen.
send him to LT1swap.com for all the wiring info he can cram into his young flexible brain. the rest can be bought for under 50 bucks for the harness. Use an 87 hanger in the stock tank with a walbro 255 for the fuel pump. Go to Tejas Steelworks.com for all the squarebody swap info your heart desires. If you’re in for the work and learning, they can be done crazy cheap still.
This looks like an interesting project. I look forward to seeing where this goes.
Do it! It’s not like you’re tearing up a Bloomington Gold winner, it’s an old car getting a new engine (and who knows what else). Hot Rodding at it’s best.
I’m on the fence with this one. Yeah, LQ4 is LS based technology and reliable, but still it has an iron block, is fairly lo po, and will require a lot of complex wiring. If you’re going to go through all that, you’d be better off with a real LS from a C5 on up. Better yet, the L98 is no slouch and with some performance upgrades (H,C,I, and E) could match the performance of a mild LQ4 build without breaking the bank.
I have put time into researching TPI upgrades and I found that it is astonishingly expensive to make moderate power by today’s standards, and that was over 10 years ago. The L98’s heads do not flow nearly as well as even cheap aftermarket heads and to make LQ4 comparable power, the plenum, intake runners, injectors usually need upgrading to support more cubes or HP figures complimenting what a stock LQ4 makes. Then there’s programming on the very archaic OBD I platform.
Frankly, unless purity is the goal, an LS based swap makes a lot of sense both in ease of work and hp per dollar spent.
An L98 should be able to make 300hp (crank) with just bolt ons. If you start swapping heads and a cam, I see no reason you shouldn’t make good power with it. Of course a modded LS has more potential.
Oh yes, it should. Based on my research in the past it is really getting enough air and fuel to the engine to support the upgraded engine parts. Major problem is cost in my opinion.
Are you going to consider the brakes and suspension, or is this going to just be a wannabe dragster?
It would be a shame if a good sports car was used only for burnouts and making noise in front of the ice cream parlor.
It’ll start out as a wanna be dragster but I do plan on overhauling the suspension and brakes when the swap is complete. Just going step by step at first. Will be easiest to sort out the swap if I’m not sorting out everything else at the same time. Eventually I would love to have this be a fun track day car, but that is a long timeline.
2 L98’s, Red auto ragtop, Black coupe 6 spd with suspension upgrades and cammed motor. Both fun to drive, Black handles incredibly on the track.
But my 01 Yellow Z06 is so much faster and handles so incredibly, hard to compare.
07 Atomic Orange is a go to golf car, but strait line acceleration rocks, can’t get used to paddle shifters so very limited track time.
Please keep us updated, have seen a few LS swaps, lot of work but probably worth it. Updates on suspension with that many miles will make huge difference.
Good luck!!
I wonder what the DMV smog regulations are for swapping in a newer OBD2 engine into a OBD1 car? We’re in New York and you can’t swap backward. You have to swap newer and meet the smog regs of whatever you’re swapping in. A friend has done a number of LS and later Hemi swaps and the harness/computer adaption is not cheep.
Here in Michigan, it’s not a thing. We do not have smog checks or any sort of limitations on what can be swapped specified on a state level. Any regulations are the federal ones everyone has to conform to.
I put an LM4 5.3 aluminum LS in a Porsche 944 and it is a great car. The aluminum LS weighs the same as the four cylinder Porsche engine so handling is not affected but now the HP is doubled. I’m an LS believer.
That sounds like a really fun swap!
How is the transaxle holding up?
How do you plan to interface with the dashboard? Will the C-4 electrical system have the hooks needed for an LS ecm? I have a 1985 C-4 it seems that a lot of the stuff in the car is dependent on the ecm to function.
The dash is not connected to the engine control, it’s separate and the sensors can be adapted to fit the LS. I do intend to keep the factory digital dash working.
That LQ4 should be good for an easy 400 hp, at the crank anyway. You should be able to get 400 at the wheels if that is your goal, but it will be harder. I would suggest that you replace the piston rings, and rod bearings, inspect the pistons and wrist pins, and get a good look at the cam bearings. The cam bearings in pre 2013 ls engines are funny, they may have copper showing when brand new. That by itself is not an indication of wear. If you can measure the bearing id and compare to the cam od is best. With that many miles a valve job should be done, the exhaust is likely to show some wear. A more aggressive camshaft and an aftermarket tune should get you close to the desired 400hp. Good luck 🤞