Question: Daily Driver Engine

[LRose26]

I'm looking to take out my L81 and replace it with a more reliable engine for daily use. I don't need a billion horses under the hood, but I want something better than the L81. What are my options?

 

[Hib Halverson]

Your options are to decide what you want. Saying you don't need 1,000,000,000-hp but you want more than the stock engine's power isn't giving us much to go on.

Why do you feel the L81 is unreliable?

What is your budget.

Is 250-hp enough? If not...how about 350?

 

[LRose26]

I just want something with a little more get up and go and I feel that the L81 can't do it stock. Now is the L81 worth building up to about 250 horsepower?

 

[KANE]

I'm looking to take out my L81 and replace it with a more reliable engine for daily use. I don't need a billion horses under the hood, but I want something better than the L81. What are my options?

Why do you feel the L81 is unreliable?

What is your budget.

Is 250-hp enough? If not...how about 350?

I'm with Hib on this one.

What has been unreliable about your engine?

I'm wondering if the reliability aspect is more related to maintenance, systems, and components as opposed to the engine itself. Alternators, belts, starters, etc. all play into reliability.

The reason I ask is that if you replace the engine... this is likely all that will be addressed-

So... unless you have had problems exclusive to the parts in the picture above, reliability might not be from the engine.


What else is going on? What have been your reliability issues that make you question your motor?

As for building up the L81... decent heads, a cam, vacuum advance distributor (if you decide to get away from the electronic Qjet), and a good intake & carb will go a long way!


(BTW- Welcome to the CAC!)

 

[Rex S]

Quickest way would be a crate engine from one of the many rebuilders or a GM crate engine. Pick your horse power and write the check. A crate engine is also fastest to replace as there is no wating for the machine shop and none of the possible horror stories heard about some of them. Most crates also come with a 12/12,000 to 3/36,000 warranty. Check your local smog laws but the car should be exempt.

 

[LRose26]

Well my problem is that I'm getting 10mpg and different random things are going out on me. I would like to keep my engine, except most people are saying that its not worth keeping, but if I can fix the mileage problem and get the horsepower up to about 250, I'll be happy. So, if you all can put me in the right direction, it would be nice.

 

[Hib Halverson]

(snip) Now is the L81 worth building up to about 250 horsepower?

It depends on the condition it's in now.

Can an L81 make that much power?

With the right combination of changes, yes. It was 190-hp stock and a 30% increase in power is doable.

I would think a cylinder head change, a hyd. roller camshaft, headers, modern intake manifold, mods to the secondary side of the carb and a revised calibration would have you there.

Do you plan to keep the computer controls or not?

 

[LRose26]

I would like to. Would the computer be in the way? So, would getting my engine up to 230 be unreasonable?

 

[KANE]

I would like to. Would the computer be in the way? So, would getting my engine up to 230 be unreasonable?

With a set of heads, a new cam, perhaps a distributor and carb- 230 is more than reasonable!

 

[LRose26]

Are there any limitations on heads that I would have? I don't have that much knowledge on this type of stuff yet.

 

[KANE]

Are there any limitations on heads that I would have? I don't have that much knowledge on this type of stuff yet.

Well... yes. They are late 70's smog heads and they don't flow very well. However, a set of these Iron Vortecs can be purchased complete for around $620 for the pair. They flow as good as the aluminum Vortec heads- just a bit lower compression.

You'll also need a Vortec bolt pattern specific intake... which runs about $187.


Add a bigger cam... around $200...

Oh- a new carb- around $300...

Finally, a vacuum advance distributor- around $200.





... so, you could make a good amount of power for parts around $1,600.

 

[LRose26]

If I bought these parts for the L81, would I have to get a new set of pulleys also?? I wouldn't think so, but I don't know.

 

[Crimson Thunder]

You are the perfect canidate for the GM HT383(not the ZZ383) crate motor. Not very expensive, puts out gobs of low end torque,and with its small cam will be very reliable.

 

[LRose26]

I have another question. If the cylinder head has a max lift of .475", 1-what does that mean? and 2-does that stop me from using certain cams?

 

[Koop]

ZZ4 is a very nice motor for a Vette and I've heard they get decent MPG. After you buy all the goodies and pay someone to fix up your L81 you may as well just get a ready to go motor with all the cool toys and a warranty.

My 383 gets terrible MPG.

 

[6880 Mike]

I have another question. If the cylinder head has a max lift of .475", 1-what does that mean? and 2-does that stop me from using certain cams?

I think you are referring to valve lift, not "head" lift.

Why not purchase a couple of the How To Rebuild Your Smallblock Chevrolet books and get a better understanding of what you want to do?

 

[Crimson Thunder]

It means the valve springs installed on the heads cannot handle a camshaft having more than .475 lift. If you are looking at cams for a daily driver,don't consider anything with more than 220 duration at .050 lift.