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FULL DYNO RESULTS ON THE L78 396, OVERRATED AT 425 HP OR
FULL DYNO RESULTS ON THE L78 396, OVERRATED AT 425 HP OR UNDERRATED AT 375 HP? WHAT DID IT MAKE?
#FULL #DYNO #RESULTS #L78 #OVERRATED
“Richard Holdener”
HOW MUCH POWER DID THE L78 375-HP 396 REALLY MAKE? WAS THE 1965 L78 425-HP 396 CORVETTE OVERRATED? WAS THE 375-HP L78 396 CAMARO OR CHEVELLE UNDERRATED? HOW MUCH POWER DID CHEVY’S LITTLE BIG BLOCK REALLY MAKE? AFTER FINDING LEAKING HEADS IN PART 1, WE REPLACED THE HEADS FOR A SECOND TEST. I…
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So what your saying is just a +.090 over bore.., adds 50hp? I get unshrouding the valves .050 but I dunno. Thats alot. Those heads have to big valves to begin with. I trust you Rich and Westech but….somethings not right here. The LS6 is very similar so, add stroke and adds 75hp? I am unbiased as I'm Mopar.
I always thought the 396 in the 65 Corvette had much better exhaust manifolds then the same engine in a Chevelle, hence, the higher power rating in the Vette.
So everyone else on the planet can get one HP per cubic inch from this engine but you lol ,good tuners got closer to 450 HP you say it was more then likely 375 HP what CC heads are those closed chamber heads and what are the cam specs ?and why not a 780 you have to build it just like Chevy did and you didn't I've never seen real rectangular port heads that didn't come stock with guid plates
If you put he stock Mufflers Carb water pump and Fan with alternator it would be hard pressed to pull 375!
Did I miss something? What was the fuel used in the test ? Was it leaded 100 octane or pump 93 unleaded ?
Dyin to know, Richard, how we didnt see any oil applied to the pushrod cup in those rockers? Plus you didn't use 'Vette manifolds….
I recall the MkIV being introduced part way through the 65 model year, the first part of the year being the 409, but single 4 barrel only. For a very brief period, the L78 was rated at 450hp, before they dialed it back to 425. Chevrolet was in a difficult position, their new improved big block had to be seen as an improvement over the 425hp W engines of the year before, and the factory knew there was a 427 Mk IV being released in a short few months. If their 396 was already rated at 450 or 425, what would they have to rate their 427 at. That’s the problem when you play fast and loose with the numbers, it wasn’t the first time the Chevrolet division got themselves in this trap, and it wouldn’t be the last.
the 425 horse 4 speed had an 800 double pumper I own one
I know how badly you wanted to get this project done. I believe your findings are spot on , especially when one factors in the necessary factory accessories, carburetor and exhaust manifolds. Thank you for building the engine as close to stock specifications as possible. What were the camshaft's specifications? Well done Richard!
Drive one you will understand 😊
This just shows how impressive the ls motors are built
Really enjoyed that? Get your hands on a zl1
There is NOTHING like a big block chevy at full song.
My uncle has several L98 swap vehicles, with a turbo 400 and 3.08 gears in a 89 camaro with Holley 750 in a pretty much stock L98 on 93 octane. Full assesories without ac. Put down right at 330 whp. Runs low 12s @110 mph. He has a L98 swapped in his 92 Silverado drag truck runs mid 11s 112-115mph. My uncle has at least 3 L98 engines sitting on stands. Mention LS swap around him and be prepared to get into a heated battle.
0:32 you inaccurately stated it had a 3.75 inch stroke. it should read 3.76 instead.
Disappointed in the torque.
thats awesome i have a mildy built 396 with ported head and intake and holley 770 street avenger long tubes msd dizzy and roller rockers and a summit racing came and was wondering what kinda power it make.
Yes! Thank you, Richard. Made 390 hp with manifolds and over 425 hp with headers and a tune on day 2!
Did the '65 L78 Rev to 6400 per Chevy specs or Not ?? …….Theres More HP at 6400 than 5600…..'65 L78 owners would Stay at Dealer until it Did !!
it's a 396,, and did you hear it,,,,, it has all the horse powers it needs,,,
I love this test. We have a sleeper version of this engine in our Chevelle. 509cid bowtie block dressed as an L79, (291 heads / 569 intake/ exhaust manifolds 396 badging) It's interesting to see just how much I could uncork if I added some long tubes.
To bad you didn't have the Corvette manifold. Still might not have made the 425hp or would it?
Somethin's Not right here….The 1st year production 1965 L78 was Factory rated 425 HP @ 6400 Rpm…..Next yrs 1966 & Later Chevy specs it at 375 HP @ 5600 Rpm……Despite Chevy specs Both engine Internals are Identical ?? …..Somethin besides "Exhaust Manifolds " are Different !! …..Not Likely to Lose 800 Rpm (And 50 HP) with Different exhaust Manifold ……That extra 800 Rpm naturally makes More HP…..Probably 50 HP More !!…….Your "Reproduction" Cam's probably got Less Actual Duration timing than the '65 Factory L78 did !!
I think you got it right. As installed (mostly) 375 sounds about right, 425 hp optimized. Now lets step up the intake and the cam a little bit, and see whats she does. I have a couple of 402's at my disposal, and I am looking for ideas.
Thank you for the follow up video Richard I was disappointed in the first one when it started leaking water. I’d like to see you do another video like you have in the past with other engines were you optimize with modern cylinder heads and modern roller cam and intake manifold. maybe this is too much to ask but the 396 is probably one of my favorite big blocks and I was happy to see you do a video on it. thank you for the content. I very much appreciate it.
1 hp per cube respectable
Put a Turbo on it and let it eat
The corvette used a better exhausr manifold