abnormal_vetter

Hi guys,

Curiousity has gotten the better of me and have to ask...
What is the difference between a 1980 Corvettes L48 & L82 engines?
I know that there are slight athestic differences between the two, but what is different internally that gives the L82 that extra 40hp? Cam? Pistons?

7t9l82

forged crank forged flat top pistons better rods better cam bigger valves .

jb78L-82

There are many differences between the L-82 and the L-48 which is essentially just a GM passenger car engine. The L-82 from 73 to 80 is basically a LT-1 engine with the lower compression pistons like the 1971 LT-1 with 9:1 pistons rated at 330 GROSS HP, not net like all engines were rated in 1972, NOT RHWP on a dyno. The same exact LT-1 rated at 330 Gross HP in 1971 is rated at 255 NET HP in 1972. The 73 to 80 L-82 are essentially the same exact engine internally with the differences mostly exhaust and emissions equipment. So what are the differences between an L-82 and L-48 through all those years?

L-82 VERSUS L-48:

1. Forged pistons/crank versus cast Pistons/ Crank
2. 4 bolt main bearings versus 2 bolt main bearings
3. 9:1 compression pistons versus 8.5:1 pistons
4. Bigger valves on the L-82 versus the smaller valves on the L-48
5. Aluminum GM performance intake versus cast iron standard passenger car intake
5. Bigger exhaust pipe diameter 2.5 in L-82 versus 2.25 in exhaust on L-48 on 75-80 cars.
6. Freeflowing mufflers on L-82 versus L-48 on mid to late 70's cars
7. Higher lift cam on the L-82 versus the standard passenger car cam on L-48
8. Dual snorkel cold air air intake on L-82 versus single snorkel air intake on L-48 in later years.

The HP ratings on the 73-80 L-82's are as follows:All NET HP, NOT Gross HP as prior to 1972.

73-255 HP (True Dual Exhaust)
74-250 HP (True Dual Exhaust)
75-205 HP (first year of cat/Y pipe exhaust)
76-205 HP
77-210 HP
78-220 HP
79-225 HP
80- 230HP

The difference in HP between the years is mostly due to exhaust modifications. Note that a 71 330 Gross HP rating is reduced to 255 NET HP in 1972, a difference of 75 HP just by rating them differently, Gross versus Net!!

The 1980 L-82 was only EPA certified by GM and built with the Turbo 350 Automatic, no 4 speeds.Approximately 5,000 L-82's were sold that year.

Hope that helps!

81pilot

But, the L-48 had very good torque numbers, the disparity in torque was not there. Just sayin. :O)

jb78L-82

You are correct! The L-48 has better bottom end torque and is often thought to be better suited for the automatic with the L-82 better suited to the 4 speed due to its HP/Torque peaks at mid-high RPM per my comments above.

For example, the 78 L-82 is rated at 220 HP at 5,250 and 260 ft-lbs at 3,600 RPM versus the L-48 ratings of 180 (or 185 can't remember) @ 4,400 RPM and 270/280 ft-lbs @2,400 RPM.

Road and Track confirmed that the 4 speed 78/79 L-82's were faster 0-60 MPH back in the day with the 78 L-82 4 speed (220 HP) doing 6.5 sec and the 79 L-82 Automatic (225 HP) doing 6.6 secs.

I have driven 78-80 L-82's with an automatic versus my 78 4 speed and the difference is startling between the L-82 4 speed and automatic. The automatic "feels" much more sluggish than the 4 speed since the engine revs tend to stay low in the RPM range where the power is not.