Hello,

I have an 1981 corvette that I am looking at placing a bigger engine in. What im confused about is how to determine what will fit. Currently I have an L81 350 cu in V8. I am thinking a new LS1, LS2, or LS3 would be bad ***.

Does this mean any 350 cu in engine will fit?

How big can I go?

How do you determine engine size?

I imagine once I have found what engine I want then everything else will fall in place i.e. transmission, bigger radiator?, differential, etc.

thanks,
George

 

The LSx engines are all about the same size.

The Big Block engines are of course wider and taller and they fit as well.

Cubic inches inside though can be very different across the different blocks.

http://www.superchevy.com/how-to/090...ngine-history/

 

Are you saying that pretty much any chevy engine will fit in my 81 vette? More specifically, any LSX engine will fit in my exisiting mounts?

If I can put pretty much any engine in my vette, do I have any other major restrictions that I could possibly encounter when swapping out engines?

 

I would also like to put a blower on my engine intake. From what I have read the L81 that is currently in my vette would not be able to take the added strain? Can i add a blower to any LSX engine that i choose?

 

Hi George,
Any gen 1 sbc chevy will fit in the engine bay. The LS engine series are nice, but take a lot of work and extra money to swap. They make kit's for all the parts you'd need and you can buy crate LS engines that come with the computer and gas pedal. I believe Scroggin Dickey Performance has the crate called the erod at 425 horse. You'd still need a ket for mounts and other part's not to mention that you will also need new exhaust headers. There are multiple threads on transplanting a LS into a C3 right here on the forum and that would Probably give you the names of vendors for the Parts kit needed to do the swap. I believe Texas Speed has transplant kit's available. Good luck. As far as determining engine size on which engine type are you talking about, gen! or LS series? as D said, unless you got a build sheet, they can vary greatly.

 

Thank you for the reply. But Im still curious how I can technically derive what engine will fit in my vehicle (and any vehicle for that matter). Is it just the transplant kit with new bushings or whatever that allows the engine to fit?

Thank you for the site and part suggestions I will check them out. Also going to look over the transplant threads here. Have a good day!

 

In order of easiest to most difficult that will fit...
1) Small block chevy gen1 263" to 400". This is Most likely what you vette has in it now and I believe that it ran with a few variations up to up 92(?) in vettes and a little later in some passenger cars or trucks.
2) Big block Chevy. Will require changing parts, is demensionaly larger than a small block so the engine bay will be a little tighter, I Think that they can be shoe horned into your 1980, but I've never done it. Again the search function will help alot in this area, it would require exhaust and accesory mount's ect.
3)Lt & Ls engine series's, will require a complete parts kit along with exhaust's, accessories ect.

So in trying to help you, Let me ask a couple of questions.
1)what is your goal here? I take it that your engine is worn out and you want to replace it. What kind of goals are you looking to hit with a new engine? Are you after power or ecconomy or maybe stock replacement?
2) what kind of budget do you have?
3)Are any of the drive train parts upgraded or are they all stock?
4) What will your intended use be? IE daily driver? Spirited street cruising? Hot street and or strip? Ect...

The forum has about every type of corvette owner from stock to twin turbo ls to big block and these questions should help you indetermining what route you want to go.

 

there is no easy answer for this. vehicles were designed with certain engine options. if you change that, you are re-designing on your own. there is no real formula, it's just what guys have been doing for the last 100 years on their own. find an engine, and figure out what it takes to make it work.

Every hot rod magazine has done dozens of engine swap articles over the years, from simple small block swap outs, to engines never intended for the vehicle (like putting in a hemi). you need to decide where to mount, how to make the mounts, what kind of transmission adapter, wiring, cutting firewall, making new crossmembers, etc. that's all up to you, unless you are lucky and find a kit someone sells (used to be more common).

it was easy back in the day, as many GM vehicles had all the various mounting locations pre-drilled in the corporate frames to use darn near any engine in any chassis, just by replacing the motor mounts and getting the right bellhousing...

If you want to know how to take any engine and put it in any car, you'd best start reading automotive engineering books and mechanical design to determine all the critical geometry, cooling requirements, weight distribution, etc.

easiest thing to do is copy what someone else already did...check the LS forums...

 

First off, thank you for taking the time to respond to my questions. Very kind of you. Answers below in red...



I really like your E-rod suggestion. My complaints with the 81 vette is the CCC sucks - It adjusts slowly but in reality all it can do is throttle air valves to the engine intake. I live in CO and if i go over a mountain pass I lose so much power. So i want to go to fuel injection and a blower so i have everything I need for combustion.


thank you for your time!

 

Welcome to the forum. Take your time and do a lot of reading of posts on this forum. Most all of your questions have been answered at some time. Then get out your wallet.

 

I'm not all that familiar with the ccc carbs and I want to say there is a way eliminate computer controled carb, maybe I've remebered that wrong, but someone will chime in shortly about it.
So the options are vast, now you need to decide how much power you want and if your willing to upgrade drive train to both compliment and withstand the power you decide on, check out vortecperformance.com and cncmotorsports.com for well built crate engines with power from mild to wild, if youre set on a blower and are having an engine built, I'd have it built to specs that will with stand boost and allow you to run a fair amount of it. The transmission and differential would last longer if built with a blower or decent levels of power in mind especially if you decide to run wide sticky tires, a lot of guys use the tires for the week link and some go a 4-link rear. I get pretty fair traction and am waiting for something to give.
There are several members running fuel injection on their sbc and there are companies that sell blowers with injection systems on them and I don't have much experience with blowers, I've got one setting in my garage for when I get bored with the power that my 400" is making, but no real experience and I'm sure that the members with that experience will chime in soon enough and be able to help you out if that is the direction you head. Were in Colorado are you, Dr. Lars lives in Colorado and builds engines as a side business I think, or atleast he did and Mark Jones with vortecperformance.com I think is in Colorado as well.
If you only want the blower for power, you can have a 550 to 600 horse injected small block that will pull through the mountains with out issue and have pretty fair manners being fuel injected, Diehard just did a write up about his 427" small block that is 600ish horse power and how well the manners are for being a street beast. I'm not trying to talk you out of a blower, but you don't have to have one for combustion in the mountains, blowers do have a cool and wow factor that most of us drool over. Check out those sites talk with them via email and figure out what exactly you want, with the erod you could add a blower later or buy a crate lsa with a blower on it already. Sdparts.com has a vast selection of ls crate engines and mast motorsports does as well.
Another thing to keep in mind is in order to make use of the power that a lot of those engines put out you'll probably want to upgrade the suspension and brakes as well.
When it comes down to it, restomodding a corvette with your son will cost some money but would be a really rewarding and worth while project with your son and would promote the automobile to the younger generation.

 

computer command control carbs need to be replaced entirely due to the design, the idle mix solenoid is controlled by the computer. they were problematic when they came out and tough to tune (IMO). but any quadrajet will bolt on in it's place. it's been quite a while since I worked on a CCC setup so I don't recall off hand if timing is controlled or it was just the mix, but on a SB, you can always drop in an HEI dizzy...

 

first and foremost: do you have to deal with the emissions inspections or not? if yes leave the car alone. if no, get a set of headers and dual exhaust, a performance cam and carb and intake. maybe even aluminum heads. from the block deck down, a 350 is a 350, for the most part. forged crank and pistons don't mean much at the rpm's you run at.

 

George you are getting way over your head if your intentions are to do this yourself. Money can put any engine you can dream of in that car. If you want a supercharge the hood has to be changed. Cut, replaced or a raised center. If this isn't a problem, slap a Holley 144 right on top of your stock 81 engine. Very few mods are needed and you'll have a very fast car. Passing emissions test shouldn't be a problem if the carb is adjusted right but some states do have an issue with a raised hold but 2 inches is all you need to fit this blower.
Big Chevy bolts in to almost everything but the accessory brackets are a head ache. You either go with a very expensive March system or you piece together original style brackets . Some are repo others you have to hunt for.
LSX engine I think you are expecting massive power, you'll be disappointed unless you swap gears and throw a lot of money at it. Including an overdrive tran and almost every part that the engine touches needs to be modified. Mounts, flywheel, AC compressor, entire fuel system, gas pedal, exhaust, and the list goes on.....
Just a dose of reality that keeps you from pulling apart your car and then walking away from it.

 

The engine 'size' that will fit in a C3 has little to do with cubic inches. It has everything to do with the external dimensions of the engine WITH ALL ACCESSORIES AND MANIFOLDS ATTACHED. Fit has to do with physical dimensions; power has to do with cubic inches and revs [and internal component choices].

I've seen 540 cu. in. engines in C3's; but that engine's physical shape is not that much different from the stock Chevy big block.

 

There's a LOT of information available here. Having said that, you'd be further ahead if you provided us with a little more information, as to what you're trying to accomplish, how much money you have to spend, and how easy you want a swap to be.

Yes, your '81 is a little sluggish, as the smog equipment in that era really bogged down the cars. However, you might have to comply with it, so your options will be limited. If meeting a smog inspection isn't required in your area, due to the age of your car, then you have a LOT of options.

Bottom line, however, is you can buy a "crate" small block, which will easily generate 400 HP (with the proper exhaust system), and bolt right into your car, in place of the stock engine.