My '78 L82 4 speed is in need of some engine upgrades. The car has a tired 350 and will never be a show car or daily driver, but I would like more power for cruise nights. Looking for 350-400 hp. I'm really not concerned about keeping the numbers matching. Is there value in keeping the original 350 and have it rebuilt or just go with a crate engine. Any suggestions on good crate, maybe the ZZ4.
Appreciate or opinions.

 

I look at it two ways.
1.) building it yourself is a great way to get exactly what you want from the motor and knowing what it is capable of based on how you built it. Lots of work and time though.

2.) Crate motors are very reasonable if you can get one that will last and is well built.
I think you likely get what you pay for in that area. They still have to make a profit so some corners on quality may be cut to achieve this.
It's lots easier though, and you'll be up and running much sooner.

Here are a few crate companies that have come up here on CF.

http://www.blueprintengines.com/inde...ng/gm-355-main

http://www.vortecproperformance.com/...binations.html

http://www.enginefactory.com/375hp.htm

http://pacmachineco.com/index.php?ma...7kvonp6olb0qp6

http://www.ultrastreet.net/engines/350_realstreet.php

http://www.bigalstoybox.com/turnkey.htm

http://www.tristarengines.com/about/warranty.php

 

I am rebuilding my L-82 4 speed right now. Do search under my signature.KEEP THE L-82 if you go crate. My rebuild with me doing the top end and most of the assembly, engine pull etc, new clutch, motor mounts etc is 5k.

 

If you don't feel comfortable or have the means to do the 350 yourself to get the 350-400 hp, then I would go get a crate and be done with it.

 

Good point! I am having my bottom end rebuilt because I don't feel comfortable with that aspect of the build.

One thing to keep in mind is that a crate engine is rated in the yesteryear standard of GROSS HP which is not how engines are rated today in cars/trucks which is NET HP. A 350 - 400 Gross HP crate engine is actually about 300-340 NET HP, still considerable for a C3 but not what the numbers want you to think you have. Just want to make sure that the OP doesn't think that buying a crate rated engine at 400 HP is 180 more HP than his stock L-82-its not.

I am hoping with my rebuild of the L-82 to come right in that Net HP range-330 Net HP-100 HP over the Net rated 78 L-82 of 220 HP.

 

Voted best answer 3 times..........by me
Excellent advice. Pick a crate, store your engine and no stress

 

the only way you can rate horsepower on a crate or rebuilt engine is gross. to get a net rating you would have to hook up all the accessories air intake exhaust.thats why all the crate engines are rated that way.

 

Here's another crate engine builder that came up here: http://www.smedingperformance.com/chevy/

They use new blocks, which is a big plus in my opinion. But I'm just a rookie.

 

I vote for rebuild if you are comfortable. Good way to learn your car, make sure everything is done correctly, and very satisfying.

 

That is not quite true. It is actually fairly simple to hook up the accessories and and use standard exhaust manifolds and a real exhaust to rate the engines in NET HP. The reason it is not done that way is the same reason the car companies used Gross HP ratings until it was mandated to use Net HP ratings in 1972-higher numbers sound more impressive than lower HP numbers-marketing. 400 Gross HP sounds a lot more impressive than 330/340 Net HP on the same engine.

Back to the OP's question, since it is an L-82 4 speed-hey I'm biased-I would get the OEM engine rebuilt, if it was me-for the same money or less as an equivalent HP crate engine OR save the L-82 for posterity, and go with a crate engine. Remember that there were only somewhere south of 3,300 L-82's made in 78 with a 4 speed (no breakdown between wide ratio L-82 and L-48's versus close ratio 4 speeds-L-82 engine only, thus the ambiguity) out of roughly 50,000 78 C3's. How many of those 3,300 L-82 4 speeds are left? Just something to think about.

 

so, different air filters , air inlets, different A/C compressors, alternators ,v belt drives ,serpentine drives , pulley diameters,different exhaust manifolds , exhaust configurations , for different cars won't impact your net rating? net ratings are done with the full exhaust for the car hooked up on the dyno, not sure many engine builders want to go thru that hassle. net or gross its only a measurement.

 

Yes that is true. Easier way that would accomplish the same thing is to use a known correction factor going from Gross to NET HP to give the buyer a more realistic idea of the HP of a particular engine in today's standard and relevant to most cars on the road today. If my V6 everyday driver has 270 HP then my crate motor will make 50-60 HP more than that engine, as an example, not 130 HP more using a 400 Gross HP number. The problem I have with all of this rating discrepancy is that the average buyer has no idea that crate engines are not rated in net HP numbers, unless it is an engine that is/was installed in a production vehicle, then it is NET. That's it. I would be happy if crate engines were forced to list the the HP as "GROSS" or "NET" when advertising HP figures.

 

You can produce 350-400hp (gross) from rebuild of your engine with right combination of parts. No need for bottom-of-page cam grind.

I would find a good machine shop first. Then, pull the engine and perform the complete tear down yourself. Take the block, crank, rods to them. They can clean, machine, inspect and assemble the short block. OR you can reassemble if you want. Once they finish the block, crank and rod prep, you can order your engine rebuild kit with proper bearing, ring and piston sizes. They can prep the block, install all block plugs, cam bearings, hone cylinders, hang pistons, polish crank. I used Northern Auto Parts for the rebuild kit and they are still very reasonable today and use much of the same name brand parts. Summit, Jegs and even GM dealer (Scoggin-dickey) offer comparable kits that you can have them configure once you have measurements from the shop.

Back in '99, I had the help of a mechanic so all I had the shop do was clean the block, bore .020, turn crank .020 under, hang new pistons on rods and install cam bearings and block plugs. Machine shop bill ('99) was under $500. I would add $250 for today price estimate for same work.

For power with excellent street manners, consider a retro-roller cam kit. You will boost lift, yet similar duration of your flat tappet L82 cam and get better flow in the entire lift range. Add a nice set of aftermarket cast iron or aluminum heads (dual springs for the roller), blueprint your carb (Lars) for the new performance parts, intake, rebuild/recurve distributor, Good flat-top pistons, bearings, moly rings, headers, duals and you are easily in 350-400 gross hp territory.

 

In the case of my lightly modified '76 L48, I put it on a chassis dyno. I hope to be able to put the replacement 383 stroker on a chassis dyno this spring.

This will more accurately show how much power I really picked up.

It seems to me, that you have to have a reliable base line (like dyno RWHP) to compare. If just for bragging rights, use the engine builders numbers vs the factory numbers.