1981 Corvette C3 Engine Ideas Needed

I am rebuilding my 1981 C3 to become a daily driver. I spend 210 miles a day in my commute mostly interstate and don't do anything crazy other than the occasional country road. I have the stock number matching SB 350 with TH350 automatic in it now. The AC, and all smog stuff have already been removed and has an Edelbrok carburetor so it runs as well as possible with out replacing cam and heads. What I was wondering is if I wanted to do an engine swap I was looking at some crazy ideas mostly just for fun. I really appreciate fuel economy and reliability more than anything. I wont go lower in horse power but I don't mind staying around the same. So would dropping to a v6 be an interesting idea? Do they produce V6 engines that are easy to get and make good power? I hate to say I know my V8 350 inside and out but other than it I have only worked on Mercedes. I even thought about a Mazda 20b rotary but got death threats from the RX guys ^_^. Any fun ideas out there that I could keep the project under 4K or 5K? No matter what engine I go to I want another gear in my transmission, looked at going to a TH 200 4R if I don't add to much HP. Thanks all!

A mild LS swap would be one way to go. Or get a used vortec engine and trans out of someting.

Given that you can easily make more power than the stock 350 internals with a modern LS engine, that would be where I would go with this. A 5.3 would give you an easy 300 + HP, better gas mileage and with 700R4/4L60  transmission you can get 4 gears. You can pick up both cheap and then spend your remaining budget on a wiring harness, engine controller, exhaust and have a nice, fuel injected ride when you are done.

Saber_Mike said:

 Any fun ideas out there that I could keep the project under 4K or 5K?

You can buy a lot of gas for that kind of money.  They don't get much more reliable than a small block Chevy, if it's in decent condition why mess with it.  You could possibly get a little better mileage with a V6, but I don't see where you would ever get your investment back.

LR4 and 4L65E from a 2wd truck. Done. The 4.8 makes 280+ and is small cubes to get good economy. If it can knock down 24mpg in a 5k lb truck with the aerodynamics of a building it should be amazing in a C3. 

Something blasphemous like an S2000 motor, rotary etc

+1 to the bobzilla suggestion.  

I suppose you really want a V6 a 4.3L from a Astro or something should bolt in. You gain fuel injection and power is likely a wash.

bobzilla said:

LR4 and 4L65E from a 2wd truck. Done. The 4.8 makes 280+ and is small cubes to get good economy. If it can knock down 24mpg in a 5k lb truck with the aerodynamics of a building it should be amazing in a C3. 

My immediate response to the title of this discussion

I realize its the gut reaction to grab the cheap truck versions to swap into a car, but with a Corvette you will probably need the lower profile bits to make it fit... Right? At least the G8/GTO/Camaro/TransAm LS instead of the truck versions.

 OR just for fun build a de stroker out of your 350, long rods  and a bump in compression , you really want a 200r4.   a 700r4 has a lower 1st gear -easy launch with smaller eng. the early model's won't need a computer to shift. MINIMAL PARTS FOR SWAP of the trans, a thousand in the engine . Eagle crank  rod kit KBpistons  a good valve job ask about a cam  with the right lift/overlap you could get great mileage have some money left for seat cushions.

In reply to Saber_Mike : I’d go the other way, ( big silly grin ) toss a Jag V12 in it.  Using a 1992 or newer version you’d have the GM 4 speed overdrive.  Now in a 4200 pound XJS it gets about 19-20 mpg. Driven gently.   So the smaller lighter Corvette should yield about 23-24 mpg. 

Plus since it has sooooooo much torque you could put taller tires on, still have really great acceleration and even better mileage.  

 Here’s the great part, you can convert all the Lucas stuff to GM Delco  very easily.  The GM Atlas engine used in SUVs like Chevy Trailblazer, GMC Envoy etc. is a modified version of the Jaguar in line Six  which was built off the V12 so fuel injection  rails etc could be adapted.   

Or if you want you can buy that dual 4 barrel manifold and toss 2  4 barrel carbs on it.  

It’s very narrow so you will have a lot of engine compartment room  but it’s a couple of inches longer than the Chevy V8 

RossD said:

I realize its the gut reaction to grab the cheap truck versions to swap into a car, but with a Corvette you will probably need the lower profile bits to make it fit... Right? At least the G8/GTO/Camaro/TransAm LS instead of the truck versions.

That's part of making an LR4 fun, Z06 intake, valve springs and a cam.