Question: L81 horsepower

[LRose26]

I have an 1981 corvette engine, L81, and I was wondering what the maximum horsepower is for the crate. I'm wanting to put a 671 supercharger on and I'm not sure what the horsepower rating is.

 

[6880 Mike]

The L-81 was rated at 190hp net. I don't think you want a 671 sitting on top of it. Pull it, store it for future resale, and start your project from there

 

[JohnZ]

Put a 6-71 on that engine, and it'll be in pieces under the car before you get to the end of your street. Blower motors are a whole different ball game; you'll have to build one or buy one. A nice (unblown) 383 crate motor is a LOT better solution, will be reliable, and about 1/3 the cost of a blower motor.

 

[LRose26]

Well ok then. Where could I get a 383 at a good price?

 

[Peer81]

Doesn't a blower need a low compression engine? I think most aftermarket 350's or 383's are already to high with 9:1 or higher?

Groeten Peter

 

[DeeVeeEight]

Well ok then. Where could I get a 383 at a good price?

GM Performance Parts or Blueprint Engines are a good place to start.

STAY AWAY FROM EBAY AND LONG DISTANCE (motor) PURCHASES. THE WARRANTIES ARE WORTHLESS ON EBAY.

If you do not go with a GM or Blueprint product then find a local engine builder and do business there, close to home. If you ever have any issues you can resolve them a lot easier if it is local rather than long distance.

Do you have a budget in mind?

 

[tcxd40]

Doesn't a blower need a low compression engine? I think most aftermarket 350's or 383's are already to high with 9:1 or higher?

Groeten Peter

Yes they do. Even though the L81 is a low compression engine the stress generated by a supercharger on unprepared factory parts would destroy them quickly. There is a possibility that the use of a B&M or low boost style supercharger could work.

tcxd40

 

[coffeejolts]

I agree with what the previous posters have said. Putting a blower on an L81 is a horrible idea. These motors were not built with big power in mind. Modding the original L81 is not worth the time or money. Buy a GM performance crate motor and a built transmission, then bag up the originals and pack them away. If you want power and modern technology, and money isn't an object, then you can consider going this route:

http://www.crateenginedepot.com/store/LS3-62L-CrateEngine-19211709-P1897C53.aspxLS3 Crate Engine



Huge discussion thread about C3 LS* swap on another site.

 

[LRose26]

Money isn't an issue, but i don't understand what to look for in a new engine. i got this car as a gift from my parents, and this stuff is new to me. i want something with horsepower but also somewhat decent on gas. i know the LS series are good that this, but i was wondering if there would be other engines that accomplish this too. i want to know my options if i have any.

 

[Peer81]

Begin with reading about the car and it's components. Like said the L81 is a nice engine but not for forced induction. Also keep in mind the original TH350 isn't made for super high performance but before the transmission gives way the alu diff will go first so also check that. Problem with these cars is that the quality of the different components are the same so upgrading one the weakest point will shift to the next weakest thing.

Also thing what you want to do with the car, stoplight springs, cruising with highway high speeds etc etc?

Groeten Peter

 

[damoroso]

Money isn't an issue, but i don't understand what to look for in a new engine. i got this car as a gift from my parents, and this stuff is new to me. i want something with horsepower but also somewhat decent on gas. i know the LS series are good that this, but i was wondering if there would be other engines that accomplish this too. i want to know my options if i have any.

You have all kinds of options. I suggest you start with what you want from the car. Daily driver, street/strip, pro-touring, long trips, fuel economy etc.. That's where you start, then work back from there. You can do some modifications to the current engine, pull it for a new crate engine, build (or have built) something specific for your application or do a swap to something else. You can swap to another small block, an LS engine or even a big block. People have done all of the above, but the engine is just one piece of the puzzle. And each engine option brings it's own set of questions. For instance, you should also consider the tranmission. Will the current trans work well with what you want to do? Does it need to be re-built, re-placed with something else or modified? Then the rear-end, suspension, brakes.

Again, start what do you want the car to do and work back from there. You'll find lots of help here!