L82 DCR: The Ultimate Case for a New Cam in an L82?
11-06-2017, 08:35 AM
#21
Race Director
so the worst thing about this cam is it is retarded 4 degrees? get a double roller timing set. 44 teeth on upper gear. put chain on 1 tooth advanced. now it is 4 degrees advanced instead of 4 degrees retarded. get a multi-keyway lower gear set and you can put it straight up, or 2 or 6 degrees either way...
11-06-2017, 09:20 AM
#22
Le Mans Master
Just a touch of reality here:
The Base L-48 78 C3 was a dog especially the automatic....0-60 L-48 auto in 1978 was 7.8 sec with a compression ratio of 8.2:1 with a low lift passenger car cam which is what the L-48 essentially was.
The L-82 4 speed in 1978 was the fastest American production car that year with the L-82 4 speed bone stock with 0-60 MPH time of 6.5 seconds, which was pretty darn respectable back then! In fact the only cars faster in 1978 were the Porsche Turbo and the Ferrari 512. The 79 L-82 auto ran 6.6 sec 0-60 mph.
I drove my friends L-48 auto 1980 and it was a dog compared to my 78 L-82 4 speed..no comparison.
Headers, duals and timing adjustment on an L-82 and the car was even quicker...bone stock motor.
My 78 L-82 with no emissions, shorty headers and 2.5 duals did 233 RWHP with a weak #6 compression cylinder..fully healthy it would have done at least 240-245 RWHP...A base stock engine L-48 could NEVER achieve those types of numbers.
Sorry!
The Base L-48 78 C3 was a dog especially the automatic....0-60 L-48 auto in 1978 was 7.8 sec with a compression ratio of 8.2:1 with a low lift passenger car cam which is what the L-48 essentially was.
The L-82 4 speed in 1978 was the fastest American production car that year with the L-82 4 speed bone stock with 0-60 MPH time of 6.5 seconds, which was pretty darn respectable back then! In fact the only cars faster in 1978 were the Porsche Turbo and the Ferrari 512. The 79 L-82 auto ran 6.6 sec 0-60 mph.
I drove my friends L-48 auto 1980 and it was a dog compared to my 78 L-82 4 speed..no comparison.
Headers, duals and timing adjustment on an L-82 and the car was even quicker...bone stock motor.
My 78 L-82 with no emissions, shorty headers and 2.5 duals did 233 RWHP with a weak #6 compression cylinder..fully healthy it would have done at least 240-245 RWHP...A base stock engine L-48 could NEVER achieve those types of numbers.
Sorry!
11-06-2017, 09:35 AM
#23
Le Mans Master
I gave you the documented numbers for the L-48 and L-82 0-60 MPH for a 1978 corvette.....you do understand that those numbers are from a standing start?...That is the BEST those 2 engines could muster with a qualified driver at the helm....no theoretical there. I am sure what you experienced happened.....but too many variables to draw conclusions......I think you should let it go at that....
Last edited by jb78L-82; 11-06-2017 at 09:37 AM.
11-06-2017, 09:40 AM
#24
Race Director
In 1982 I had a 1978 Porsche 924, 4 cylinder 5 speed, stock, header, no cat. Raced a 1978 Corvette L48. Close but got him by a car. The Porsche was no speed demon by any means but it was red and the girls liked it. That is all that mattered then.
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NewbVetteGuy (11-06-2017)
11-06-2017, 10:01 AM
#26
Le Mans Master
I gave you the documented numbers for the L-48 and L-82 0-60 MPH for a 1978 corvette.....you do understand that those numbers are from a standing start?...That is the BEST those 2 engines could muster with a qualified driver at the helm....no theoretical there. I am sure what you experienced happened.....but too many variables to draw conclusions......I think you should let it go at that....
Like I said, twice now, mine not stock. It was also at an altitude of 5000 feet.
A long slow ramp engine with low DCR is going to suffer greater losses below peak torque with it's higher peak torque RPM at altitude vs one with higher DCR and a lower peak torque RPM.
I was only giving my experience, real life experience not manufacturer best possible performance numbers.
You chimed in with all your L-82 specs defending the cars performance. They were both turds by today's standard. That's the long and short of it.
Last edited by REELAV8R; 11-06-2017 at 10:07 AM.
11-06-2017, 10:47 AM
#27
Race Director
GM had 2 groups of people they had to make happy. EPA folks and their stockholders. they had to do what they had to do. 30 years of design engineering later, cams are worlds better. even the flat tappet ones. how hard is doing dog bone conversion on these 2 piece blocks? I think I remember seeing youtube videos on it. I know you cant with big blocks.
11-06-2017, 11:10 AM
#28
Le Mans Master
I suggest comparing cam specs of performance engines across the board between manufacturers and you will be surprised how similar many of them were
11-06-2017, 12:48 PM
#29
Melting Slicks
Thread Starter
The strong points of the L82 cam is it makes 350 HP in a higher compression engine with iron, crappy flowing heads. With better heads, intake, headers, exhaust and tune it has 400 HP potential in a 350 . With the late intake closing point and 114 LSA it allows you to run 10.5 to 1 compression or 11 to 1 with good quench and careful tune with IRON HEADS while getting decent fuel mileage. It has the mannerisms and RPM range of a 222 duration cam with extended RPM potential and a flat torque curve because of the 114 LSA. It is durable because the ramps are a little slower, less hydraulic intensity, good if your running flat tappet. It is an ideal cam for some builds. 
The L82s were between 1.6 and 2 CR points lower than that; the cam is a bad match for the compression ratio, especially with the low TC stalls in the automatics.
A modern cam grind would be a much, much better match. More torque off the line, more fuel economy, same or more max HP.
Adam
11-06-2017, 12:53 PM
#30
Melting Slicks
Thread Starter
so the worst thing about this cam is it is retarded 4 degrees? get a double roller timing set. 44 teeth on upper gear. put chain on 1 tooth advanced. now it is 4 degrees advanced instead of 4 degrees retarded. get a multi-keyway lower gear set and you can put it straight up, or 2 or 6 degrees either way...
No the worst thing about it is that it's designed for a 10.5:1 - 11:1 static compression iron motor. Put it in an L82 and you get a lazy bottom end with no torque and poor fuel economy and a terrible match with the L82 autos' 1800 stall TC.
The retard ground into the cam just makes this situation even worse. The stretchy timing chains even more so.
The lazy cam lobes designed for crappy 1960s valve springs also make the situation worse.
When you consider that late C3s could have options that bring the curb weight over 3,700 lbs, the cam choice is a near crime in a sports / "touring" car. (My 79 L82's curb weight with the aluminum wheel upgrade was 3,650 lbs...)
Adam
Last edited by NewbVetteGuy; 11-06-2017 at 12:55 PM.
11-06-2017, 12:55 PM
#31
11-06-2017, 02:29 PM
#32
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St. Jude Donor '05
^^^^
trick flow makes a 58cc aluminum head theres your compression, reasonable too. Replace with about any modernish 260ish-270 type cam the power difference will be major. I dont know why guys are married to old junk.
trick flow makes a 58cc aluminum head theres your compression, reasonable too. Replace with about any modernish 260ish-270 type cam the power difference will be major. I dont know why guys are married to old junk.
Last edited by cv67; 11-06-2017 at 02:30 PM.
11-06-2017, 02:47 PM
#33
I gave you the documented numbers for the L-48 and L-82 0-60 MPH for a 1978 corvette.....you do understand that those numbers are from a standing start?...That is the BEST those 2 engines could muster with a qualified driver at the helm....no theoretical there. I am sure what you experienced happened.....but too many variables to draw conclusions......I think you should let it go at that....
He wasn't comparing stock for stock. Yes, stock for stock the L-82 was marginally faster than the L48. At the end of the day though, they are both just small block chevys. They both had poorly flowing heads and fairly pathetic power stock. ANYBODY doing even a mild sbc build will make more power than the L-82 did. So ANYONE planning to make their C3 decently quick really shouldn't care whether it has an L-48 or L-82, the only part your keeping is the block, in which case the only advantage is that the L-82 had 4-bolt mains (which really is only coming in to play if you're getting over the 400+hp mark).
So I think REELAV8R race is completely believable, a mildly modded L-48 will definitely pull away from an L-82.
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REELAV8R (11-09-2017)
11-06-2017, 03:19 PM
#34
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St. Jude Donor '05
https://www.summitracing.com/parts/t...make/chevrolet
56cc they have another pn which uses 1.4x spring ;even an "old tech" Isky 264 cam headers would really wake it up
The 270 has somewhat similar duration but will be night/day difference they have very strong midrange
56cc they have another pn which uses 1.4x spring ;even an "old tech" Isky 264 cam headers would really wake it up
The 270 has somewhat similar duration but will be night/day difference they have very strong midrange
Last edited by cv67; 11-06-2017 at 03:21 PM.
11-06-2017, 04:18 PM
#35
Had a 1976 L-82, 4-sp
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Royal Canadian Navy
Lots of people use this type of reasoning comparing less powerful engines to more powerful. It doesn't make any sense because the counter to this is to modify the more powerful engine too which of course will be superior to the other.
11-06-2017, 04:24 PM
#36
Correct, but in the example that is being talked about here, it is a modified L-48 vs a Stock L-82. So it makes perfect sense that the L-48 was faster.
Let's be realistic here, we are talking about two smog era small block chevy's. As soon as you start modifying them, it really doesn't matter what they started out as.
11-07-2017, 07:28 AM
#37
Burning Brakes
An L-82 with an ignition recurve and a free breathing exhaust and some carb tuning was a low 14 second car with a manual transmission you would be high 13 second range. I have never I repeat never driven an L-82 with the timing adjusted that wouldn't burn the tires.
The lil red truck was indeed faster mainly because in 78 it lacked a catalytic converter, there was about 35 horsepower in a dual exhaust.
The cam in the L-82 is capable of 12 second quarter miles in a c3 Corvettes so I don't see it being that bad.
At some point I will run my L-82 stock cam short block down the track and I'd bet it will suprise alot of people
The lil red truck was indeed faster mainly because in 78 it lacked a catalytic converter, there was about 35 horsepower in a dual exhaust.
The cam in the L-82 is capable of 12 second quarter miles in a c3 Corvettes so I don't see it being that bad.
At some point I will run my L-82 stock cam short block down the track and I'd bet it will suprise alot of people
11-07-2017, 07:31 AM
#38
Burning Brakes
so the worst thing about this cam is it is retarded 4 degrees? get a double roller timing set. 44 teeth on upper gear. put chain on 1 tooth advanced. now it is 4 degrees advanced instead of 4 degrees retarded. get a multi-keyway lower gear set and you can put it straight up, or 2 or 6 degrees either way...
I have a Crane Blueprinter L82 Cam in mine. Anyway to know if this was machine with the 4 degree retard?
11-07-2017, 08:52 AM
#39
11-07-2017, 09:27 AM
#40
Melting Slicks
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St. Jude Donor '11-'12-'13,'19-'20
Correct, but in the example that is being talked about here, it is a modified L-48 vs a Stock L-82. So it makes perfect sense that the L-48 was faster.
Let's be realistic here, we are talking about two smog era small block chevy's. As soon as you start modifying them, it really doesn't matter what they started out as.
Let's be realistic here, we are talking about two smog era small block chevy's. As soon as you start modifying them, it really doesn't matter what they started out as.
