whats the hp ratings for a 396 high output engine?

upalnight
0

Asked by Dec 20, 2006 at 02:45 AM about the 1966 Chevrolet Chevelle

Question type: General

27 Answers

carGrrl
15,985

The standard 1966 Chevelle engine (RPO L35) was rated at 325 horsepower at 4800 rpm and 410 lb-ft of torque at 3200 rpm. The RPO L34 was rated at 360 horsepower at 5200 rpm, and 420 lb-ft of torque at 3600 rpm. Ready for the top-of-the-line? It was an RPO L78, rated 375 horsepower and 415 lb-ft of torque at 3800 rpm. 0-60 in 6.5 seconds, man. Woooooah. =) CarGrrl

6 out of 6 people think this is helpful.
wonder
60

1965 z16 425hrspwr which in fact could have been much more

6 out of 6 people think this is helpful.
ChevelleGuru
170

The L78 was usually rated at 375 HP... There were "supposedly" some "listed" as "425 HP"... However, these were the EXACT same engines (375HP vs. 425HP), same cam, same heads, same carb, same distributor, etc... Only the "rating" (on paper) changed...

10 out of 10 people think this is helpful.
18TandSVT
4,635

As far as I know, the highest "rating" was 375. That's a joke though.

15 out of 15 people think this is helpful.
John Tenore
85

The L34 produced 360hp, 415ft/lbs of torque. It was possible to get the 375hp motor option but few were made.

2 out of 2 people think this is helpful.
John Tenore
85

The 375hp motor was "underrated" in chevelles for insurance purposes! The likely output of the L78 motor was in the neighborhood of 425-450hp. The car reported 0-60mph at 6.5 seconds, on 1966 hard rubber tires. My 1967 ss396, L34 stock except for a solid cam/lifter setup, modern wide radial tires and a tighter suspension was hitting 0-60mph in under 5 seconds, you get rid of wheel hop and wheel spin and when you can shift at 6800 rpm's instead of 5500 rpm's time improves greatly!

1 out of 1 people think this is helpful.
Robbie Pate
75

the LS5 396 which was in the '70 SS was advertised at 390 horses.

4 out of 4 people think this is helpful.
Travis Moore
45

the LS5 is a 454

4 out of 4 people think this is helpful.
Stephen Boland
205

There were four 396 engine options offered in 1969. (#1) The base 396 engine was rated at 325 HP for the basic SS package (in '69). This was also teamed up with the 3 speed transmission as standard issue, the four speed and automatic were an option. (#2) The 350 HP version was an option, as well as the (#3) 375 HP (Known as the L78). The original '69 brochure for the Chevelle did not list the L78, but the El Camino brochure did. If you had a knowledgeable sales person, he would have been able to order the L78 engine for you in a 1969 Chevelle SS. The other (4th) option was the L78 with Aluminum Heads. This was the rarest option. The HP was not rated higher, but the weight was a considerable improvement over the cast iron heads. Both versions of the heads on the L78 were big rect port heads and both the 350 HP and two 375 HP versions had an aluminum intake, which the 325 HP version did not come with. the 325 HP version and 350 HP versions had the smaller oval port heads as well. Later in the 1969 production year the bore of the 396 changed to a 402, however, the car was still called an SS 396, then the 454 arrived in 1970. All SS 396 Chevelles were 402 CI in 1970 with the SS 454 as an option.

9 out of 9 people think this is helpful.
Stephen Boland
205

The 396 in 1965 was rated at 375 HP in a Chevelle SS 396. 415 lbs of torque. ONLY 201 Chevelles in 1965 were SS 396 engine cars. The Corvette did offer the 396 engine for one year only 1965 and it was rated at 425 HP. This might be the engine that you were refering to, but it was not offered in a Chevelle.

4 out of 4 people think this is helpful.
Stephen Boland
205

5 versions of the big block was offered in 1970. 3 402's (still marketed as 396 engines). #1 was the L34@360 hp #2 was the L78@375 hp #3 was the 375 hp (with the additional option of RPO L89) This was Alumn Cyl heads. RPO Z15 the 454 options : #4 LS5 454 rated @ 360 hp #5 LS6 454 rated @ 450 hp

2 out of 2 people think this is helpful.
Stephen Boland
205

That is correct Travis. So was the LS7.

1 out of 1 people think this is helpful.

325, 350 & 375 but mine pushes about 425.

7 out of 7 people think this is helpful.
360HP
50

I HAVE HEARD PEOPLE ON OTHER SITES REGARD THE 325/396 AS JUST A GENERAL PURPOSE ENGINE! HOW STUPID CAN ONE BE? OH YEA, GM CORPERATION IS GONNA PRODUCE A LIGHT WEIGHT 2- DOOR COUPE WITH A 4-BARRELED BIG BLOCK FOR JUST GENERAL PURPOSE. WHAT THE HECK WOULD IT BE FOR? PULLING THE POP-UP CAMPER TO THE HILLS? NO WAY!! I MEAN.... WHAT GENERAL PURPOSE ENGINE HAS TO HAVE HIGH TEST GASOLINE? THE ONLY THING THAT HAMPERED THIS ENGINE WAS A SINGLE POINTS IGNITION. PUT IN A DUAL POINT AND THE L-35 WAS A HELLCAT TO BE RECKONED WITH BETWEEN 4200-5000 RPM.

2 out of 2 people think this is helpful.
360HP
50

THE 360 HP L-34 WAS AN OPTION. SOME OF THESE PARTICULAR ENGINES SHOWED A STAMPING CODE THAT INDICATED IT WAS FOR A CHEVROLET OF NO PARTICULAR MODEL RATED 325 HP. IN QUITE A FEW INSTANCES, A CHEVY DEALER WOULD HAVE ONE OF THESE UPGRADED 325HP CODED ENGINES IN THE BACK OF THE SHOP AS A DROP-IN CRATE MOTOR. ESSENTIALLY, IT WAS THE SAME EXCEPT FOR A MID-RANGE CAMSHAFT ADDED. THE OVAL HEADS ARE VERY DESIRABLE THOUGH. THEY ARE SHOWN TO HAVE REMARKEBLY CLOSE TOP-END POTENTIAL TO THE RECTANGLE STYLE WITH BETTER ATOMIZING CHARACTERISTICS AT LOW SPEEDS. THE L-34,35 396 WOULD BE PERFECT WITH THE L-78 CARB AND CAM. PROBABLY BETTER THAN THE L-78 BECAUSE OF A MORE PRACTICAL 10:25-1 COMPRESSION AND MORE COMPATIBLE OVAL HEADS.

3 out of 3 people think this is helpful.
Denis Sagendorf
425

MY FRIEND HAS THE 396 FROM HIS '69 CAMARO SS. IT HAS 375 HORSES STOCK.

2 out of 2 people think this is helpful.
SQ07
100

I've always wondered about the 425 hp vs 375 hp difference of the 396. I remember, years ago in a Hot Rod Magazine, around 1979 or so, an article on GM replacement parts and stock specs of various engines. It listed the 65 Chevelle Z-16 Hydraulic cam for the 375 hp, that year only, and a separate cam for the the 425 hp 396 that had slightly less lift, but more duration and overlap than the later 396/427 engines of 66-69. I also remember going to see a mint 396 425 hp vette for sale in around 1979 or 80 with 30k on it, bone stock, and it had a very racy, lopy idle compared to the stock 396 375hp and 427 425hp motors I've heard. I later noted the same idle on other stock 396 425hp vettes. The book, Chevrolet Performance Guide 1955 - 1971 available on Google Books, shows a different cam timing for the 396 425hp as well. Slightly less lift at around .497 and .503 for intake and exhaust compared to the later .519 lift of the 427's and later 396's , but with more duration and overlap. It seems it was sort of a big block equivalent of the the 327 365hp with the 30 30 cam, very rough idle and a high rpm performer, perhaps a bit much. The horse power rating was 425 at 6400 rpm, while the 66 427 was initially 450hp at 6200 rpm which would suggest a milder cam timing. The 450 hp rating was later down graded to 425 a 5600 rpm which just quoted actual hp at that lowe engine speed, just like the later 396's which were 375hp at 5600 rpm, but which were more like 400 or 410 at 6200 rpm. The 65 396 425hp shows 415 ft/lb torque at 4000 rpm, while the later 425 hp 427's pbulished torque, which was never down graded, showed 460 ft/lbs at 3600 rpm. Again, another hint that these motors had milder cam timing, producing both max power and torque at a slightly lower rpm. The 396 375 hp motor are rated at 415 to 420 ft/lbs agian at a lower 3600 rpm. Judging from the cam specs shown in the book, the later 427 and 396 had a slightly higher lift, .519 in and less duration on overlap to create a better behaved street engine, much like the taming of the 30 30 cam for the larger 350 LT-1 later created a better behaved and better performing street motor. Anyways, it's just a theory, but it seems like there is some evidence for it. The book I quoted, does have a few errors in it, so it isn't gospel, but it is interesting to note the different cam specs shown. So I am making an educated guess that the 396 425hp had a slightly different cam for that year only which produced a bit more top end hp than the later 396 375hp motors which shared a cam with the 427 425hp. Corvettes often had a prestege bump in advertised hp, for example, the 390 hp 427 was 385hp in the Impalla, the 460 hp LS-6 was 450 hp in the Chevelle, the 370hp LT-1 was 360hp in the Z-28 and so on, but a "prestige bump" of 50 hp suggests something else, even when you adjust for the fact that the 375 hp 396 was under rated like the 427 425hp. My contention is that it had a higher performance cam that was later replaced by the stock spec 396/427 high performance cam that carried over to the 454.

10 out of 10 people think this is helpful.
Lonesomecowboy1948
40

Well let me tell you first hand. In 1969 I ordered a a red 1969 SS 396 ci-450 HP aluminum head chevelle . With tires,traction bars and a tune it ran 10.90's. I sold my race car and raced my chevelle

4 out of 4 people think this is helpful.
OldTed
20

In Oshawa at the start of 1966 production in the fall of 1965, the L72 427 got 450 hp stickers for a while before being replaced with the more common 425 hp stickers. Same engine. The 425 hp and 375 hp 396s may have had slight cam difference but were essentially the same engine. I've owned a COPO Chevelle and two L78 Chevelles. Both L78s ran about the same and the COPO car would have smoked either one. Not even close. If anything the L78s were over rated, especially as delivered from the factory. The lean jetting in the carb and the slow advance curve and retarded timing really killed them as delivered. A week after delivery of a '69 L78 Chevy Nova, a friend took his to the strip and could do no better than 15.1 in the quarter at about 92 mph. You can calculate with formulas roughly what that car was making for power and it will disappoint more than a few. GM was also probably correct in leaving the hp numbers the same for the L89. Rectangular port heads needed a lot more air flow than an L78 could pump with such a mild cam. With the L78 engines it is a case of the older I get, the faster I was. Hate to burst bubbles but I also rode in a few L78 cars back in the day and they didn't impress either.

2 out of 2 people think this is helpful.
moondog54
20

A long dead thread but what the hay. I had the 396/325 bone stock with a 3:73 rear end. I first added a Holley 800 spread bore and later a 650 spread bore. The 650 ran better overall but the car was the fastest with the 850. I never timed the car but in street races it ran equal to Chevy and Mopar big blocks. All of this depended on transmissions and gearing. Also, engine tuning made a big difference as well as gas. Amaco premium was 103 octane as I recall and the car ran as if you added 20-30 horsepower, very noticeable. Cars then were not like they are today. Tires, gas, air cleaners, tuning, ignition timing, whether you left on the emission stuff like air pumps - it all made a difference. I drove what the owner told me was a 1970 454, 360hp model. My 396/325 was stronger, to the point where I offered the guy a chance to drive mine to prove it and he turned it down. Then again one of my best friends had a 1969 Firebird 400, stock 350 with a 850 dbl pumper Holley with tall gearing (around 3:35 or taller). He absolutely slaughtered me on a 25 mph roll - not even a remotely close contest. Things were funny back then. Cars today run much more consistent. Still, which would you rather own:)?

2 out of 2 people think this is helpful.
Jamey Byers
10

I had a 396 325 hp 67 SS Chevelle and replaced the engine with a 396 425 from a wrecked Corvette. The 396 375 hp engine in 65 Chevelles is basically the same as the 396 425 Corvette, with solid lifters, but the Corvette came with a bigger Holley carb. I ran 11.7 @118 in the quarter on street tires. BTW I had the only 396 425 with factory air!

1 out of 1 people think this is helpful.
ducatimatz28
40

Although Impressive Looking; those BHP numbers on the Air Cleaner and Sales Brochures; aren't what determine your real HP. Most of this is for impressing Potential Buyers and High School Hot Rodders. The Engine doesn't go down the Street or Strip by itself, so BHP doesn't mean Squat except to look impressive(Decal) on your Air Cleaner Top. You still have to have a Chassis, Transmission, and extended Drive Train (i.e.driveshaft, rearend) . When you put one of these Cars (i.e.) LT1, L78,L72,LS6,etc) on an in floor RWHP Dyno, then those Factory OEM HP numbers don't look so impressive. Our Shop had a 500hp in floor Clayton Dyno in the 70's and we Dynoed a lot of Muscle Cars including Ford and Chrysler as well. A lot of customers went home with frowns after seeing what their real RWHP was. You can expect to lose as much as 30+ % going through your Tranny/ Drivetrain on the Older 60/70's muscle cars. For example we did a Factory 1970 Chevelle LS6 454ci/450hp with around 2000 miles. We altitude jetted it (3300 fasl) reset the valve lash, curved the distributor and had all the advance in by 3000rpm and the best HP Reading we got after numerous 6000+ rpm runs was 323 RWHP. Don't fret at that number though; we had a few High performance 289ci / 271hp Mustangs that barely made 200 RWHP. Don't get caught up in Mfger HP Hype advertising. They are there to sell Cars. Just be prepared to see a lot different number than what your Air Cleaner or Sales Brochure tells you on older Muscle Cars. Now the new Engines (ie LS3,LS6,LS7,LT4,etc. are a lot closer to those OEM Numbers ! BTW: The poster that claimed his OEM L78 Chevelle did 10.90's.......I clearly doubt that ???

2 out of 2 people think this is helpful.
ducatimatz28
40

I forgot to include the descripency between the 1965 Corvette 396ci/425hp and all other Chevrolet L78 Models being rated at 375hp. First of all the Engine in the Corvette was rated at 6400rpm verses the Industry Standard 5600rpm. The Reason for the Rating Difference ;Chevy had a Dilema, The Corvette's top Small Block in 1965 ,The L84 327ci Rochester Fuel Injected was rated at 375hp ( still the highest rated production Gen 1 SB Today even 5hp higher than the 1970 LT1 Corvette (370hp) You certainly couldn't advertise a New Engine that was almost 70 cubic inches larger than your Top SB and have the same HP Reading. That wouldn't have been a good marketing decision; So the easiest way to solve this is to rate the Engine at a higher RPM. This was also done on the older L88 option. The rating of 430hp was accurate but they never told you the RPM that rating was taken at. Not even close to the 7000 rpm you could rev this engine to. Between Mfger's Cleverness and Hype on Engine HP it was a pretty comical affair...

1 out of 1 people think this is helpful.
Genie Kay
10

I just acquired a 3955272 HI PERF PASS block, built April 17,1969. It's in rough shape but anyone have any other info on it. What's the F5 mean?

1 out of 1 people think this is helpful.
ducatimatz28
40

Genie: According to my GM/Chevy records your 3955272 Block was indeed used in 69 production, both in 2 and 4 bolt main configuration. your 4-17-69 build date on the block would indicate it still having the 396 cylinder bore spec. 402 blocks started showing up towards the end of 69 production. Easiest way to tell what size your block is(OEM) is to put a Bore Gage in the Cylinders and observe the readings. If the Bore diameter reads 4.094" or close than it is a 396, if the Bore reads 4.124" or close than you have a 402. The F5 designation may be a Foundry desigination at the Tonawanda Plant where all these Blocks were originally cast. Could mean Foundry # 5. An employee of the Tonawanda Facility I'm sure would know this ...

1 out of 1 people think this is helpful.
Kngreen1
10

I believe the 1969 Chev Nova SS 396 , Yes there were 3, each had a little diff, horses or Horse Power, but the one that was a little over 400 , I believe it came with a Turbo Charger , given it that extra Umph.....

1 out of 1 people think this is helpful.
Gold_Guy_Rich
0

-I had a '66 BB Vette and it was magnificent! And it would corner and stop too! I drove it at a rock steady 135 mph @ 6000 RPM, I believe it had 3.70 gears! A complete sports car!!! -The '69 400 Pontiac Firebird mentioned above could be bought with all the way up to a Ram Air IV(four) performance engine that was way, way under-rated HP! The Pontiac engine does not rev like Chevies but has enormous torque! I have a '68 FB 400 now that I built myself. I like the GTO Tripower(3 2-barrels) as you CAN bring them on 1 at a time for most control and they are simple compared to 4 brls. I even opened up the back(3rd) one for more flow by taking out some of the venturi bulge! Have to have accelerater pumps though. The Bird starts to lift the front end at 120 so it needs a big strong lip spoiler! I am 78 years old and started with a hotted flat-head Ford, bought a dual carb manifold from a Sears catalog. Be safe everybody, like a friend who raced midgets and had the "Altitude" record at a track said,"They are awfully heavy when they are on your head!" Rich

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