Besides the CCM, what is the difference between an L-81 & L-82? Are L-81's as easy to upgrade for better perfomance? Any information would be appreciated.

Thank you,
John

 

I think that L81 is more like the L48 than anything else. It's simply a GM engine designation, not really an option per se. For instance, in 1981 the engines were L81s but there was no other engine option available.

As far as upgrading it goes, it probably isn't any harder to upgrade than any other 350. Depending on where you live, your limitation will be smog rules rather than the ability to improve the engine. Oh and your budget too.

I don't know how many years the L81 was available, but I do know that the 81 heads were particularly poorly suited for performance. Changing these is probably a good start. The way that I've been improving my 81 is by starting with the weakest link (heads) and working from there.

 

'81 was the last year with a carb, which was computer controlled.
'82 was the first attempt at the crossfire engine.
Depending on smog requirements, changing the headers is the second thing I would do, after changing to true dual exhausts. Exhaust is a big restriction.
My '81 has true duals, the smog equipment fell off and mild headers from a previous owner. Being a ultra conservative old goat, I figure these added about 30 hp. Enough to bark the tires as the auto trans shifts to second with heavy pedal.

 

My 81 has a VIN that indicates 230hp L82, 8th digit is a 6. There are however no L82 designations on the car

 

Is the L-81 just a detuned L-82? I know that an L-82 was a heavier duty motor than the L-48 and therefore would handle mods better.

 

The L-81 is the L-48 with the computer controlled crap and the L-82 valve covers. That's it. Notice how it has the exact same power output as the 1980 L-48.

The smog equipment falling off, open exhaust, a cam, and heads turns it in to a good engine.

 

There were no optional engines for the '81 model year. All the VINs have a 6 for the eighth character. Last year for the L-82 option was 1980.

 

L-81, L48 or L82 doesn't make much differnce these days. While the L82 has a 4 bolt block and forged crank these don't offer much unless you turn serious RPM. The heads and cam for any of these engines are old tech. I pulled my L82 from my 80 and went ZZ4 with the roller cam.

With either of the engines the best bet is my recommentation:

Cam and heads - This would be my first change if the block has good compression and consitency across cylinders. I would go hydraulic roller cam and just recently I couple of folks posted using 60 degree v6 lifters that are a much less expensive retrofit. For heads I'd find some vortecs than are not too expensive but flow much better than the old designs. Note that aluminum version surpress detonation a bit better. You will lose EGR (ports not in new heads) unless you go with an edelbrock perfomer or other emissions type head if required.

Exhaust Manifolds - don't change until later in the project since vette manifolds do flow very well. I run manifolds on my ZZ4!

I would go with a high flow cat first then duals. I run a 3 inch cat on my 80 dual 2.5" into 3 inch pipe then back to dual 2.5". Looks stock but flows very well. Flowmaster makes some good dual 2.5 to 3 inch Y manifolds.

You may need to reprogram the carb controller or go with a an older HEI distributor and rochester carb without computer control.

Down the road go EFI.

 

One problem with the stock manifolds, AIR tubes. They're ugly and I don't think they help the flow much. For less than $100 you can get headers that flow even better.

 

Hmmm

ok

 

Thanks for the info.