L82 vs. L48
Thread Starter
Heel & Toe
Joined: Feb 2005
Posts: 18
Likes: 0
L82 vs. L48
What are the differences between the L82 and L48 engines? Specifically those from the late 70s Vettes. Obviously the L82 makes more power, but I'm wondering how it makes that extra power. More aggressive camshaft? Freer-flowing heads? Sorry if this is a dumb question, I'm new to C3s.
Also, what would it take to make an L48 put out equal power to an L82? Is there any particular modification that really wakes these engines up (headers, carb, etc)? How reliable is each motor?
Also, what would it take to make an L48 put out equal power to an L82? Is there any particular modification that really wakes these engines up (headers, carb, etc)? How reliable is each motor?
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
The L-82 has higher compression, a better camshaft and better heads.
You could more than equal the L-82 with headers, a street port job on the heads and an L-82 camshaft.
BigBlockk
Later.....
You could more than equal the L-82 with headers, a street port job on the heads and an L-82 camshaft.
BigBlockk
Later.....
Melting Slicks
Joined: Jul 2000
Posts: 2,848
Likes: 0
From: Beacon NY
The L-48 had a 2 bolt main
The L-82 had a 4 bolt main
Other than that, they also had a different airfilter.
As far as compression ratio, I believe they both have the same (8.2:1), or at least in 1979 they did.
The L-82 had a 4 bolt main
Other than that, they also had a different airfilter.
As far as compression ratio, I believe they both have the same (8.2:1), or at least in 1979 they did.
Burning Brakes
Joined: Mar 2002
Posts: 1,102
Likes: 0
From: Montreal QC
Originally Posted by Victor
The L-48 had a 2 bolt main
The L-82 had a 4 bolt main
Other than that, they also had a different airfilter.
As far as compression ratio, I believe they both have the same (8.2:1), or at least in 1979 they did.
The L-82 had a 4 bolt main
Other than that, they also had a different airfilter.
As far as compression ratio, I believe they both have the same (8.2:1), or at least in 1979 they did.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Originally Posted by bbfirebird
What are the differences between the L82 and L48 engines? Specifically those from the late 70s Vettes. ...
Also, what would it take to make an L48 put out equal power to an L82? Is there any particular modification that really wakes these engines up (headers, carb, etc)? How reliable is each motor?
Also, what would it take to make an L48 put out equal power to an L82? Is there any particular modification that really wakes these engines up (headers, carb, etc)? How reliable is each motor?
http://www.corvettefaq.com/c3/ganeyexhaust.htm
Both are very reliable.
Racer
Joined: Mar 2005
Posts: 294
Likes: 1
From: Racine Wisconsin
I am going to try and upgrade my L48 to something like the L82. I'm talking to all the engine guys I know and the plan is formulating. Corvette Fever March 1996 and April 1996 did a two-part article on raising the hp of the L48 from 190 to 326. I don't think I need all that HP. I plan to incorporate part of what they did. (1) Pistons rods and crank will stay the same. (2) Crane cam, probably the HMV272-2. Comp cams have a nasty tendency to wipe a lobe. (3) Dart cast-iron heads with 2.02/1.60 valves. (4) Aluminum high-torque intake manifold (that fits under my 1973 hood (I have not found many options here, I may need to go with the late C3 Aluminum intake), (5) the 2.5 inch ram-horn exhaust manifolds from the 1965 327 corvette. (6) Some type of improved distributor perhaps the HEI. I'm attempting to keep a stock-looking engine compartment for the autocross inspectors. A local engine guy runs a drag car with 500 hp in a two-bolt main. He claims the two-bolt is reliable enough for what I want to do. The 2-bolt and 4-bolt castings are the same. The bearing caps can be modified for 4 bolts if higher hp or stroker kit is anticipated. Just my $0.02. Appreciate hearing what others are doing to work around the L48.
Drifting
Joined: Sep 2004
Posts: 1,532
Likes: 4
From: Fairview Heights Illinois, near Saint Louis MO, STL C3 Shark
76 specs......
L48 8.5:1 comp ratio 180Net HP @ 4000 / 270ftlbs @ 2400
L82 9.0:1 comp ratio 210Net HP @ 5200 / 255ftlbs @ 3600
L48 - sump head pistions
L82 - flat head pistions
Connecting rods are lighter in the L48 (13.7 oz vs 20.80 oz)
L48 camshaft:
280*intake duration
288*exhaust duration
.39" lift
1.94" intake valve
1.5" exhaust valve
L82 camshaft
346*intake duration
340*exhaust duration
.45" lift
2.02" intake valve
1.6" exhaust valve
Not sure if it makes a difference, L48 t-stat is 195*, L82 was 180*
L48, 8* initial advance, 30* total timing advance at 4000rpm
L82, 12* initial advance, 28* total timing advance at 2000rpm
I called Chevrolet and received all this info from my "GM restoration kit" which is free - includes all specifications etc for your year of Corvette.
L82 9.0:1 comp ratio 210Net HP @ 5200 / 255ftlbs @ 3600
L48 - sump head pistions
L82 - flat head pistions
Connecting rods are lighter in the L48 (13.7 oz vs 20.80 oz)
L48 camshaft:
280*intake duration
288*exhaust duration
.39" lift
1.94" intake valve
1.5" exhaust valve
L82 camshaft
346*intake duration
340*exhaust duration
.45" lift
2.02" intake valve
1.6" exhaust valve
Not sure if it makes a difference, L48 t-stat is 195*, L82 was 180*
L48, 8* initial advance, 30* total timing advance at 4000rpm
L82, 12* initial advance, 28* total timing advance at 2000rpm
I called Chevrolet and received all this info from my "GM restoration kit" which is free - includes all specifications etc for your year of Corvette.
Last edited by ruby76; Aug 16, 2005 at 09:18 AM.
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