FULL DYNO RESULTS ON THE L78 396, OVERRATED AT 425 HP OR UNDERRATED AT 375 HP? WHAT DID IT MAKE?

[@rogerharris907]

Have experience with those engines in the 70,s, I agree with the engine builder. We didn't have the carb and ignition technology back then I would like to see a set of 350 horse oval port heads dynoed on that engine.

[@buzzwaldron6195]

Carb. and ignition tech was fine in 1970...

[@eflanagan1921]

@@buzzwaldron6195 you may have my share of points and solid lifters 1

[@kpadalldotablet1009]

Why oval? I had a 396 back in the day and we used the L68 Tripower and ported the heads, intake, exactly to the tripower manifold, which was square port. We got more horsepower than two 4 barrels on tunneler. No joke. For some reason, that Tripower system was magic.

[@georgeperillo6421]

Back in the day (1971-72) I owned a L78 396 Corvette Sting Ray Coupe. My engine upgrades were Hooker headers, A set of Crower racing valve springs and a Mallory dual point distributor, which was more trouble than it was worth, as I spent alot time at Reath Automotive getting the points calibrated on their Sun distributor machine. But that engine was very stout. That throaty idle sounds familiar. Thanks for the memories.

[@h2oskiaddict]

Reath Automotive in Long Beach? Is it still there?

[@georgeperillo6421]

@@h2oskiaddict Nope, it's gone along with Lion's Drag Strip.

[@garywilson7992]

@@georgeperillo6421 I think 1965 was the only year that Chevrolet offered the 396 L-78 425 hp in the Corvette. In 1967 & 68 I had the same factory 396 L-78 in a SS Impala. And I assume you already know what that Vett would run in the qtr, and you obviously would’ve been faster than my full size Impala, being lighter, and Vetts were known to hook up better than most with a good pair of slicks. But I could turn consistently in the mid 13s in the qtr with slicks and a 4:88 rear end.

[@michaelfercik3691]

@@garywilson7992 Yes, 1965 was the only year the L78 396ci was put into the Corvette. I had a March built 1965 Corvette L-78 396ci / 425hp engine (only) that was rebuilt with what we called a full race cam and the compression ratio was bumped from 11 to 1 to a 13 to 1 compression ration and stock heads, intake, carbarator. It was put into my Slit Bumper -1972 Camaro RS/SS (Sun-flour Yellow) with a stock turbo 350 transmission, and 373 ratio rear end. Never made the Drag Strips that were long distances away, but our County Sheriffs Office held street racing down by allowing us to race using two way radios for shutting down all traffic on the seldom used roads, with letting any traffic go through between races. Sometimes we talked a couple of Sheriff Deputies into sitting at the end of our measured off quarter-mile for giving accurate trap speeds, along with stop watches used at starting and ending lines, which were visually and radio communicated starting of the stop watches. We we crazy, so there was no pretty ladies flag starting the races, instead it was men with big brass balls and were usually intoxicated, and yes all of us drank beer while racing with everyone policing each other for someone being "too intoxicated could not race". "How stupid and young immature we were". I used to power brake the transmission while popping wheelies coming off the line with ETs in the mid-tens at over 135mph. Back in the 1960's and 1970's, the cops would always tell us to take our drinking and parting off main street. We were told to either "take your drinking out of town, or go home". Most of us were underage drinkers, but, back then most people figured if you was near the age of being drafted into the Vietnam War, you are old enough to drink, especially if your life was to be taken in Vietnam.

[@garywilson7992]

@@michaelfercik3691 Quite an upgrade to the L-78 with a higher lift cam & the 13:1 compression, but to be honest, I wonder how accurate whoever it was that was doing the 1/4 mile timing claiming mid 10s, seems just a little faster than I would’ve guessed. I did something similar in 1969 with my 67 Chevelle factory L-78 engine. Had it rebuilt with the L-88 cam, 12.5:1 compression pistons, etc, along with the 4:88 ring & pinion I had taken out of the 65 Impala before I sold it. Anyway, with 10” slicks, I was around 2 seconds faster in the 1/4 than the L-78 Impala. Of course to a layman that doesn’t sound like much difference, going from mid 13s to mid 11s, but that translates to a huge difference at the end of the 1/4, when every 1/10 of a second is around one car length give or take. And so if you ran mid 10s and I ran mid 11s, I’d of lost by around 10 car lengths. And yet it sounds like we had fairly comparable engines, and so that’s why I question the accuracy of the timer?

[@clevlandblock]

Nicely done. This video addressed one of the Chevy BB mysteries of that era in no-nonsense fashion.

[@williamstel9330]

Pretty awesome. In 1971, I knew a fellow that had a 66 Chevell with a 325 hp 396 4 speed. It would be a neat car to own today.

[@impalaSS65]

Thanks, the first video, and this one together are the reality for anyone doing the hands on themselves. Also great to see an L78 perform as intended. Love any big block that is this close to stock. Those OEM style chrome valve covers are the best looking ones. Even though I'm not crazy about the ad hoc solution with the dent for the vacuum reservoir.

[@harleysgarage327]

Glad to finally see this, impressive for a stock engine, no matter how you rate it. Keep in mind your testing done on the L79, LT1, DZ were all run with headers, so I think this is a great comparison to those engines. Thanks for doing it with manifolds and headers!

[@MultiHotrod74]

Glad to see this finally completed. Thank you Richard!

[@dclug1]

Nice to finally see the finished product. I have a 1969 396 in a corvette. Has 215 oval port heads, 10.25:1 compression. Only changes from stock are a comp cams 268 and a chevy performance dual plane intake with a 750 vacuum secondary carb. With headers and running the manual water pump it made 435HP and 465TQ on the engine dyno. Your 396 above with a simple cam swap would make high 400's in power.

[@dclug1]

@@kevinseybert5795 I’m not comparing my motor to his. I know they aren’t the same. I was just putting out there what my motor did on the dyno. I’ve done my research. I know these 396 motors quite well.

[@dclug1]

@@kevinseybert5795 I’ve only got the numbers I have to go by. Didn’t run on any other dynos to verify. And that would have been a pain. The shop that broke my engine in and tuned it for me builds high end BBC for race boats and such. Still working to get the car fully driving. Seat of the pants will really tell the story. It no doubt will have a lot more power than the crappy small block it did have. Nothing made HP in 1980.

[@psybersaber]

Thanks for sharing! I am doing a 454 build in a truck using 215 heads. I was curious as to what others have managed to get out of the 215 heads. I’m running a Lunati Voodoo 262/268 camshaft so I could possibly see similar results.

[@johnfarabee9234]

Good Job! This makes me have more appreciation for my C7 LT1 Corvette running 460 horsepower and 465 # TQ...NET!! I figure on a dyno with no parasitic losses these engines are easily over 500 HP Gross!!

[@barbarycoast3972]

I guess I was born at the right time. I was looking to buy a new Chevy when the 375/425 L87 became an option on the Chevelle. Unfortunately I didn't know much about it, except it was more HP. A 66 396 SS Cevelle. The car was beautiful. Now I consider it Chevy's 1st big block muscle car. Only had a couple of years with it when I had to go into the USAF. Never saw it again. Still think about it all the time

[@buzzwaldron6195]

The 396 was actually in late '65 Chevelle...

[@barbarycoast3972]

@@buzzwaldron6195 The L78 425hp only came out at the end of the 66 production. Thats why I said. I was born at the right time

[@buzzwaldron6195]

@@barbarycoast3972 - L78 started in '65 Corvette and L37 in '65 Chevelle had about the same power...

[@barbarycoast3972]

@@buzzwaldron6195 The L78 in the corvette and the late 66 Chevelle 396 were the same L78 engine. I owned that Chevelle. Solids, aluminum hi rise 750 Holley, 11.to 1 compression, equals 425hp

[@michaelangelo8001]

I test drove a 69 Chevelle back in 71, that had a 396/375 w/a three speed manual floor shift transmission. It was *very* strong. Made a lasting impression on me.

[@eflanagan1921]

If built that way , very rare package !

[@mrho4speed]

Great video and this takes me back to 1978 where "Popular Hot Rodding" magazine did several articles on a 396 rebuild = called "Project Engine" and what happens to torque and horsepower when different speed parts are used on an engine. The most significant part is of course the camshaft selection and to make a long story short = these guys coaxed 502 horsepower out of this 2 bolt engine. The last test was in the volume 18, number 9, September 1978 issue = truly great stuff!!

[@williamhaynie4229]

There is NOTHING like a big block chevy at full song.

[@holeshot1721]

Gives real meaning to chevy thunder!

[@lollipop84858]

Prove it

[@antilaw9911]

Hemi at full song 😃

[@antilaw9911]

440 at full song

[@OxBlitzkriegxO]

Except, literally any other big block engine. 🙄 All big blocks are awesome.

[@hugieflhr03]

Love the Carb Camera!

[@laughton57]

Great - Thanks Richard. I've been waiting for this. Make sure the kids at Engine Masters as well as Steve Brule know this! LOL.

[@mattrohr1266]

The corvette also used a 14lb steel 10.5 inch clutch and it had the same cam and heads as later 427 cars, but it felt just as strong, I have owned them all. Corvette 396 cars had 4.11 gears standard with an m21, and were rippers.

[@kevinvannoy]

awesome Richard.. so cool to see these factory deals on the dyno.. i think you nailed the factory numbers with factory exhaust..in my opinion there’s no way that factory carb will make more power. like you said the venturis and over all sizing are damn close.

[@noahdunaway]

I had a close friend back in 1966 that bought a 66 Chevelle 396-375 that was special ordered by a guy who backed out of the deal. It didn’t have a radio or heater. The car was fast compared to the muscle cars back in that day. One thing I will never forget is that the Chevelle came with a 3 barrel Holley from the factory, we pulled the air cleaner off and I saw with my own eyes. I’ve seen 3 barrel Holley carburetors but this Chevelle 396-375 is the only one I ever saw that came from the factory with it. The guy who special ordered the car was going to race it and I’ve often wondered if the 3 barrel was used because of the special order that made it evident that the car was intended for drag racing.

[@richardholdener1727]

the 3-barrel was not a factory option

[@noahdunaway]

@@richardholdener1727 I can tell you this that I saw the car straight from the dealership and It had the three barrel Holley on it, I am 100% sure it was the three barrel Holley. I don’t know how it came about but like I said I’m 100% sure that when he picked up the car the carburetor was on it.

[@dannyfritts9706]

My “L-78” has “HIGH PERF TRUCK” on the back of the block it’s a 4 bolt main with factory aluminum heads and intake bored .60 over with 12.5:1 pop top pistons, what would the displacement be now? This engine was in a 1969 Camaro I bought, I bought the engine rebuild parts for it. Also the engine number on the back of the block comes back to a 1968 Chevelle.

[@richardholdener1727]

the aluminum heads are the l89 option and your displacement is 408

[@dannyfritts9706]

@@richardholdener1727 thank you Richard. I bought a 1969 Z-28 in 1978 the 302 had been blown up from racing it, the BB was in it when I bought the car

[@garywilson7992]

Very interesting, and I wish had a time machine, because I’m about 57 years too late to take advantage of anything. In 1967 I bought a very low mileage 1965 SS Impala 425 hp L-78. And I regret not putting headers on it, not realizing how much restriction there was with the factory exhaust manifold, although for what it’s worth, I did install exhaust cut outs at the manifold collectors, that I only opened if it was a serious enough race for enough money. And I don’t know how much it actually helped, bypassing the mufflers, but it was intimidating, and with a rev could sound like all hell was waiting to break loose. I also removed the 3:31 ring and pinion rear end, and installed a 4:88, that with the 7000 rpm shift point allowed me to approach around 6500 rpm in 4th gear near the end of the qtr mile. And of course I also would put on my good pair of slicks, or all I would’ve accomplish was destroying tires and creating a massive smoke screen. I was 19 years young and hadn’t yet had enough experience, and I won so many 1/4 mile street races with that car, that I didn’t think I’d ever come across anything on the street that could out run it. Until I finally did, and I was shocked, because it wasn’t even close, and I think I even suffered from PTSD for quite awhile. And I still remember 57 years later and counting, my best friend at the time, haunting words to me after the race was over, he looked at me and laughed, and said, “hell Willy, you might as well been on Hoover vacuum cleaner”.

[@michaelfercik3691]

That is a $300,000 car, or more when restored to factory specs. That car only had a few hundred produced compared to 2,200 Corvettes with the same 1965 L78 engine,

[@otisbailey5455]

Thanks Ritchard, I have been waiting impatiently. I will ride with the 425 rating on mine as it has the proven upgrades that work. The 67 SS best release of 612 units.

[@DanClayton-fo6wt]

I dynoed a 1969 L78 396 that had a hydraulic flat tappet 238°/242° @.050 cam and weiand stelth intake with 850 carb and on my dyno it barely made 400hp with dyno headers.

[@mikewillett5076]

Were you at high altitude or was the compression particularly low? Not trying to be smart, really asking because it just seems like it'd make more, even ground at less than optimal LSA.

[@DanClayton-fo6wt]

@mikewillett5076 Engine had been rebuild at some point quite some time before it came to me to dyno. Still had the std bore TRW forged 11:1 pistons. Cam had been switched to a hydraulic flat tappet as mentioned. Leak down test was fair at 16-24% it just didn't make any power. I played around with timing and a/f ratios but it just never really responded well. Think it made 405hp @ 6000 rpm. I got a chance to drive the restored 70 chevelle the engine went into and it ran well. I think there are so many inflated dyno numbers out there most people would be surprised what an honest 400hp actually feels like.

[@mikewillett5076]

@@DanClayton-fo6wt . Thanks for the reply. You know what? You are right about how powerful and honest 400 horsepower engine can feel. We tend to think of a 400 HP factory engine as powerful but not when we build one ourselves. But that is a good number!

[@JViello]

Engine dyno or chassis? That can make all the difference in the world! Same if you are using any correction factors - everything has to be SPOT ON for them to not skew the results. I used to develop turbo kits for my own company and then the company that purchased us for a couple/few years after. Everything from diesel side by sides to muscle cars to exotics. I've literally got thousands of hours of dyno time. I know people like to bag on results and whatnot, but 400hp to the tire is healthy in just about any car less than 3500lbs.

[@keithw372]

would that be a L78 with a hydraulic lifters?

[@N-Lee]

Always nice to see Richard not running out of ideas to test.

[@1967davethewave]

Thanks for another classic engine test Richard! People will argue and claim this and that but marketing was responsible for selling cars and embellishing a little helped to push that. It also helped to bring about the change to the "Net" rating that started in 1971. Cars seemingly lost 50hp or more overnight. I figured the 396 would be closer to the higher number as I always figured the 427 with the same heads was around it's 425 rating. Now build one of those and lets see. I know Pontiac 400/455's will make about the same horsepower if they use the same heads just like your 302/327/350 test. But of course different torque numbers and peak rpms. No matter what it's cool to see actual numbers and not just good campfire stories and hyperbole! An actual 375hp in the late 60's is nothing to be ashamed of. Those cars were very fast with minor mods in light cars like the Nova and with a set of slicks bolted on the back. They can still embarrass a lot of the new muscle that has the benefit of 50+ more years of technology.

[@recoilrob324]

I had a 350 horse 396 out of a Chevelle in a Camaro and it took no crap from 375 horse motors. They have 10.25:1 CR, oval port heads and Q-Jet spreadbore manifold and it was running a small 204/214 @ .050" with slightly less than .500 lift. On pump gas and properly tuned the heads flow enough to feed the displacement just fine and the larger heads actually take away torque below 5000 rpm where much of a race is run. We did lots of top end pulls against 375 horse motors and never had one keep up. Of course..I'll take a little credit for this due to tuning but if you look at the dyno graphs the 375 doesn't exceed the 350 until well over 5000 rpm...so on the street I don't think the 11:1 CR helps very much as they're detonation limited on pump gas today and actual power of the lower CR motor able to match or even exceed it due to better timing advance being used. Love the old Big Blocks! :)

[@gordocarbo]

@@recoilrob324 Ive always preferred ovals over rectangle ports on these With a little bowl work even 20 deg cam timing these really woke up!

[@1967davethewave]

@@recoilrob324 I bought a 70 Corvette in 1995. It had a 454/4speed of unknown vintage, definitely not the original engine. I pulled it apart after the summer cruising was over and it had rec port heads. I decoded it and turns out it was a 70 LS6 someone had ground the numbers off of, restamped and tried to pass off as the original engine (very poor work and very obvious it wasn't). After reading a couple of articles by John Lingenfelter about the superiority of the oval port heads I pulled the rec ports off, sold them in local classifieds (this was the 90's) and used the money to build a set of oval ports built to Lingenfelter's specs. I went from low 13's in the quarter with the rec ports to well into the 12's with a best of 12.51@110 and the car just felt like it had more torque. The oval port heads from what I have read over the years just superior on engines under 700hp or so. Of course if you have a 1200hp Pro Stock car I'm sure you want those rec ports!!

[@williepelzer384]

I street raced everything in those days, and I can tell you headers made a BIG difference on those big blocks. 😊

[@Wilson-cp4gx]

Thanks for coming back to complete this with the right cam. Nice test. These were hard to beat in a chevelle with headers and a 411 or 456 gear.

[@gordocarbo]

Had a fake 68 SS in the mags back in the early 90s..Loved that 396. Close ratio M21 tall fwy gear lumpy hft cam headers it never quit pulling. Was always surprised at how much torque it put out. No need for OD

[@davidkirkham6497]

Yes, I purchased new in 1969 Chevelle L78/ 396/375 HP, m22 rock crusher. I ordered it with 3:73 rear end bears which were not near low enough for street racing. These had lots of power & always regretted not getting at least 4:10 or 4:56 gears to unleash the true potential of these high reviving mills. I had a lot of valve spring peoblems, probably from over reviving the engine! I used to speed shift it @ 7000 rpm.

[@AlanRoehrich9651]

The 396/425 in the Corvette was rated with an 850 vacuum secondary carburetor. Chevrolet removed all of those any time one came to the dealer, and replaced it with a 750 vacuum secondary. The insurance companies went insane when the first big block Corvettes were released in 1965.

[@richardholdener1727]

this wasn't carb limited at 425 hp.

[@benkrom2737]

11 to 1 solid lifters, yeah 425 hp

[@thegdfp6447]

780 came on them. Any verification of the 850 used for ratings?

[@nmbr3fan]

Absolutely wrong…..every 396/425hp and 396/375hp came with a 780 vacuum secondary carb from the factory (Tonawanda). Only the 427/430hp L88/ZL1 came from the factory with an 850….and that was a double pumper.

[@richarddahmer4474]

The main resign that all engines of big block or small block for that matter is back in the 60's to early 70" insurance companies would not insure a car if it made more HP then cubic inches!! I lived through that time and Ford or Chevy the 427 ford and 427 chevy where 424 HP rated if you look at the old test results, they did dino testing at way low RPM! like if you're a Chevy guy you know what a DZ-302 made way more then 296 HP! For me it was Ford back then, I build and race both now days, but the 289 HP "K" Engine was rated at 271 HP Yeah right! LOL!!! if you had to buy a new car on time you had to have insurance to cover the loan so a 435 HP Corvett or a 308 HP GT 350 Shelbey Mustang had to be bought cash! or get your own loan!! Definitely not like today where HP sells cars and insurance companies don't care? I built plenty of L-88's back in the day and with all GM parts 12.5 to 1 and the off road only Cam "Snowflake Aluminum Heads" They all made really close to 600 HP! some over! 289's with the same setup from ford 12.5 to 1, La Mans cam! made over 400 HP! etc. On pump gas! But we had 105 to 110 octan pump gas with real lead in it back then! LOL! @@richardholdener1727

[@PeggyParrow]

I had 1 ,they actually came with a 780 vacuum seccondary carb. Everbody calls them 750s but measure the primarys verses the secondarys, the secondarys are noticably bigger, therefore , the 780 rating. The prim. And sec. In a 750 are the same size !

[@coreyshort9461]

I agree with the marketing being the reason for the difference in HP. In 1965 Chevy still offered the 375hp 327 and with it also having 11:1 advertised compression and a similar solid flat tappet cam I can see why chevy may not want two engine options rated at the same power especially since the small block was so much smaller in cubic inch.

[@DaveyHo69]

Back in the '70s, my friend had a built L78 in his stock car, sold it to me. In my '68 Camaro, it would peg the right turn indicator in L2, Drive WAS the Millenium Falcon!!!

[@Lagrange1186]

I think we need more carb cam! Awesome video Richard thanks again.

[@richardholdener1727]

agreed

[@thman6453]

Carb cam is pretty cool 😎 👌 👍

[@richardholdener1727]

agreed-the squirters are adding plenty of random fuel

[@derekmelyndadeckens2982]

Thanks for sharing this! I've been waiting for these results

[@NobilityandLoyalty]

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!

[@bdugle1]

I love the sound it makes! Looks to me like the peak hp was waiting for you at 6100-6200 with headers. Nice re-creation, thanks Richard!

[@SpringVinMoto]

That overhead carb shot makes me proud to be an American! Really great series of videos. I may have to get an ultra xp for mine

[@thomasalair5861]

Yeah but even while watching it on my phone I have an uneasy feeling anticipating the pop and a ball of fire in my face.

[@buzzwaldron6195]

Like to see the 2 1/4" rear barrels of a Q-Jet...

[@doctorcountersteer6580]

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....

[@richardholdener1727]

you weren't looking close enough

[@alexbrown4820]

I think we all kinda expected the results from what we saw with the sbc 302, 327 and 350lt1 testing. But now im curious what it does with a modern valvetrain and edelbrock rpm air gap.

[@peterwaroblak166]

Back in the day when they were new, a buddy bought a new '69 Camaro 396/375, for what ever reason it did not run strong, he had trouble keeping up with A 350 Camaro, It was a beautiful black on black 4speed, I still give him a hard time for not keeping that car.

[@Myriadconcepts-q9u]

On my 1970 L/78 I put a set of L88-L89 open chamber heads with the matching 12.5: 1 giant dome pistons with a bore at 402 cui Harrison mag pulse distributor. I had the Hemi 2.25 intake valves from Chrysler. 120cc chambers. Factory intake with a 1” Moroso spacer below an 8.50 DP Holley plus a set of Hooker 11:51 race car headers with 2 1/8” primary’s 533 hp at 7,k on the floor Dyno At MOTON Performance in Baldwin Long Island in my 1970.5 Z29 RS/SS Camaro. The car had a 4.33:1 posi 12 bolt rear and super T10.

[@scoutdogfsr]

That's a lot of go power for a alloy t10 to handle. My 70 AMC Jav runs a 518hp 401 and I had to go back to the Iron case t10. Super t10 cracked after a few hard road course laps. 2yrs later the 50yr old stock case t10 is still running strong.

[@gordocarbo]

@@scoutdogfsr Had a 71 sst 401 .What did you do to yours to get that kind of power? Broke my share of the top left ear of a few muncies...all big blocks.

[@rotaxtwin]

Great objective testing, Richard. Some folk love to state that the numbers were understated but testing shows otherwise. 375 sounds legit.

[@simbanugz2906]

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.

[@richardholdener1727]

L98 TPI motor?

[@fireballsoutherner]

L78 was rated at 375hp iirc. And ran solid lifters and a cam with .500 thousands lift with special valve springs. Also a higher perf GM/Chevy aluminum intake made by Winters iirc

[@richardholdener1727]

we have all that

[@gordocarbo]

@@richardholdener1727 if only there was a dyno video he could have watched!

[@jeffwebb-eb5hg]

I bought a '70 SS, El Camino, years ago, it had 42k miles. I put an Edelbrock performer intake, 750 CFM , HEI headers. Dyno showed 412 HP , 422 # .

[@Thumper68]

My old man taught me to oil bath lifters overnight before installing.

[@anythinggoesgarage5943]

that's pretty much spot on... I saw them squirters having fuel pulled thru them.. looked like the primary may have been leaking at the gasket? I've got the 325 hp version in my 68 Chevelle SS 4 speed. It has oval port semi closed chambers that makes great torque. Crane 270 old school car. Its a tire fryer with 3.31 gears.

[@gordocarbo]

Saw that also

[@vinnievega197]

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.

[@kylemilligan752]

If we are talking apples to apples, i do recall that Mr Holdener's tests of the the L48, L82, L76, Lt1, and Dz302 all needed long-tube headers to be close to the factory "gross" Hp ratings assigned to them. No mention was made of manifolds

[@brianhicks9568]

i think you are really close on that but the original 1965 vette motor supposedly ran 425hp out at 6400 "according to book" and the 375 hp L78 supposedly got the rating at 5600. i guess 800 rpm might make a difference if it honestly went there from factory, but like said might just have been marketing on them to help sell corvettes can't have them making the same as normal joe blow sedans. love the dyno numbers they don't lie.

[@jesseduke694]

Nice test! Im glad u didnt run out & spend ur money to put aluminum heads on it right away! Good job Richard Holder!

[@scottmccoy4129]

Great Video- real world scenarios and BUL’s challenges! 👍

[@royrussell6335]

EXCELLENT ! BRING US MORE !!!

[@scottbennett3119]

Yes! Thank you, Richard. Made 390 hp with manifolds and over 425 hp with headers and a tune on day 2!

[@tonybuck5252]

U did an excellent job testing this engine

[@mikemorris4973]

These are my favorite videos. The OEM's could list whatever the marketing dept wanted and the general public never really knew. Its the exact reason why I kept my 454 LS-7 that I found in a crate, bone stock on the internals and then took to westec to see what it really made. Keep em coming! how about a 455 shoot out (B/O/P) - all to factory specs?

[@richardholdener1727]

that was cool-wish I knew you guys were running that-I would love a vid on it

[@duncanmacrae6384]

I would love to see the BOP shootout also. I'd even cough up some of the parts!@@richardholdener1727

[@mikemorris4973]

@@richardholdener1727 9 months later and I finally see this lol. email sent

[@gregcampbell3064]

Cloned one of these motors using a 2 bolt block, open chamber rectangle post heads with some mild port work. Borrowed it to a buddy to use for a bit in his 69 Chevelle. We raced a mutual friends 68 Chevelle with a 454 that ran 12 flat earlier that day at the test and tune night. Both cars were very similar. 68 had slicks, 69 had drag radials on our little late night street race. The 408 won with full exhaust on the 69 vs open headers on the 68 by about a 1/2 a car length. The 68 guy was very impressed by the 408 and so were we. I have always been impressed by what the smaller BBC was capable of on the street and the strip, Good video thanks!

[@gordocarbo]

Same here. Head wants a 454 but after an afternoon blasting around in a built 396 its just right. They dont like too much sustained rpm as I found testing the line lock too much. Wrist pin was crying lol

[@eflanagan1921]

Do you mean you loaned him the engine ?

[@franciscoceballos583]

I always polish the Beringer before installation

[@richardholdener1727]

Beringer?

[@craigchiddo2794]

I would like to see what it would make with ported 049 oval port heads l-88 cam and single plane manifold

[@Jim-g3s7m]

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.

[@richardholdener1727]

planned

[@Huntinghogs]

Been waiting for this one. Don’t forget the Corvette was rated at a higher RPM then the Chevelle. If I’m not mistaken they had different height intakes for hood clearance. The Corvette also ran a different exhaust manifold.

[@SpecialAgentJamesAki]

Probably different cam too. They do that a lot without saying they are doing it. Just like the 305 video, manual trans vs auto had different cams. Some weird random stuff like that. On the olds 455s they had slightly different cams for 2 and 4 barrel carb motors then there was different cams for what vehicle it was originally in. Engines and heads with the same casting identifier so not much of a way to tell without measuring the cam or knowing where it came from. Interesting stuff 👍👍

[@Huntinghogs]

@@SpecialAgentJamesAki yes, their is some variation in cam spec for various years.

[@gordocarbo]

Vette guys woulda been mad if the A or F bodys made the same power. LT1, same story

[@Huntinghogs]

@@gordocarbo I read somewhere that’s why they did it. Couldn’t have a family car making more power than the Vette. Marketing games at their finest.

[@richardholdener1727]

cam is the same

[@carywhatzizname4060]

So now we know! Thanks Richard! The 1969 advertised specs for the 396/375 had peak power coming in at 5600 rpm, which is a little below the 5900-6000 rpm result from the test. Of course, 1960s advertised power figures were not always very reliable.

[@Mst-bh9ti]

Yes, and the HP rating for the 65 Corvette 396 were taken at 6400rpm. That is the main source or reason for differences that many seem to scratch their heads about. Guaranteed if you take it up around redline, you'll be well over 400hp.

[@kimmorrison9169]

Thanks for finishing this baby off Richard. Been waitn for it.

[@street_wise_gamgee]

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.

[@nerradnosnhoj5122]

There was a test done on one of these that made 425 HP with manifolds and up to 450+ HP and 465 Torque with headers , might have been in HOT ROD awesome engines the 396/402 BBC

[@alanmeyers3957]

Awesome? They usually won’t go 100,000 miles and those are the ones that don’t throw rods, I’ll take a small block anyday.

[@nerradnosnhoj5122]

@@alanmeyers3957 You are correct , most performance engines do not make 100,000, a lot do not make 5,000 miles without wounds being repaired and I am talking about performance engines in cars that are being pushed hard , dragstrip etc . both small and big blocks.

[@hondatech5000]

Love the carb cam. Accel pump nozzles really flow a lot of fuel.

[@jamesblair9614]

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.

[@benjaminwatson7868]

No that was the 427 rated at 450 then derated to 425

[@jamesblair9614]

Kevinseybert5795 I was mistaken when I said the L78 was briefly rated at 450hp, it was 425hp, then reduced to 375hp. However, the L72 was rated at 450hp early in 1966, before being dropped to a 425hp rating. A Google search of early 1966 L72 horsepower ratings explains it, and you can see the air cleaner sticker on early 66 corvettes. Chevrolet just had too many variants of their engines with minor differences in the case of the small block. In the case of the MK IV, they seemed to be hung up on maintaining 25hp differences between the different variants, and since their early hp ratings were extremely optimistic to start with, it quickly got silly.

[@mattrohr1266]

The 1966 reduction to 425 hp was insurance and corporate related only.

[@billdedrick1914]

@@benjaminwatson7868 The 1966 427 L72 was initially rated at 450 hp but re-rated to 425 hp by Chevy to minimize scrutiny by the feds and insurers.

[@benjaminwatson7868]

@@billdedrick1914 that’s what I said

[@CalvinWenzel-ri2pt]

I seen Holley accelerator squirters do the same thing on a dyno a long time ago. The owner of the dyno pointed it out to us, said it was Holleys way of safeguarding against people leaning out the mixture. They put anti pullover squirters on our race car, no other changes and cleaned up the air fuel mix on the top end. Too bad they were illegal in our class!!

[@gordocarbo]

Never heard that before but makes sense.

[@CrankAddict]

I had to pause the video to say that the carb cam is freakin' awesome. Nice editing!

[@hotrodswoodshed7405]

I think you are spot on correct. 👍 Good info. Thx Richard

[@stevehei8035]

Great presentation, the 396 often gets overlooked in performance engines. Can you see what putting add ons would do to increase the torque and HP please 😊

[@nathandean6639]

The 3310-1 has the spivys on the boosters to help distribution with the stock intake manifold .

[@upptowne]

I had the 375 hp BB I bought new in 1969. The dynos do not lie. 375 was a lot of hp in those days. I would love to hear one more time what the idle sounded like though mufflers. Thanks for goin to the trouble of getting the stock like cam.

[@alanmeyers3957]

A realistic comment, some guys act like these were the holy grail, they were slugs, compared to what we have access to now.

[@ws1807]

In addition to my comment earlier, the L78 engine had a different cylinder head with 1.99 insted of 1.88 exhaust valves. Those heads are hard to find and extremely expensive. Those heads were on 1965 425 hp vetts and 375 hp z-16 chevelle. That would add even more hp to what i already mentioned.

[@playlist55]

Like to know where you got that info. No Factory Big Block heads came with bigger than 1.88". Not even ZL-1 heads.

[@alanmeyers3957]

@@playlist55some of these comments sound like fairy tales, the snowflake heads and duntov cams, etc.

[@playlist55]

@@alanmeyers3957LOL, it's like people that actually read the book vs the people that skimmed thru the cliff notes. Sometimes I look at a comment, and I think... should I correct him? Most of the time, I think... nah, I can't help him. Unless of course I think I can help someone else. Like I don't want anyone repeating the 1.99 thing.

[@ws1807]

3856208: ’65 rectangular port, closed chamber, 2.19- and 1.99-inch valves. Used on 396/425 hp, 396/375 hp Z-16 Chevelle... I copied that. Put it in your search bar. I'm not sure it's true. It was new to me when I read it. I have some books on BBC's but their buried in storage. I've also built a few and I still own one. No need to talk down to people just wanted to see equal comparisons to the original engine and equal dyno tuning time.

[@playlist55]

@@ws1807Yea, it's not true... I do have my books and I've built more than I can count. I didn't talk down to you. I did respond to someone else generically about posts. I hate having to argue with people that "read on a comment board" something that is untrue. Do your own research, I have done mine. Biggest factory Exhaust valve installed in a head, by the factory, was 1.88".

[@mikeb6555]

Thank you Richard! MAN I just love the way a big block looks... never owned one though

[@HioSSilver1999]

I would love to see what some general improvements would do to this engine. Stuff like a better balancer, better oil control, roller rockers, better intake, e85. Do that with the stock cam and heads!

[@robking9857]

I would like to see the same tests... and then add a rowdy street/strip cam... and then add NOS to see how you can take one on a "relative budget" and up it in stages. Or, do the upgrades and add NOS with a stock cam... or both. Keeping in mind a hot street driver to the dragstrip and toss on slicks type of sportsman deal.

[@ericreimer6627]

I like that you ran it with manifolds and headers. I'm a little surprised at how much it lost with manifolds. The guys at Horsepower Depot (red 67 L88 clone that runs FAST series) run 9.10s with stock manifolds, or should I say "stock" manifolds. I know better than to think they're truly stock, and even still, they admit they're a restriction, yet with as much power as they make (555ci engine running 7,500 rpm), I kind of expected less difference on an engine putting out so much less power.

[@tankthebear]

I had a L78 I bought and slightly modified for my 68 camaro back in the early 70s. I kept the heads cam and intake stock but changed to high compression pistons added headers and then a 3310 Holley. I put the car on a chassis dyno and they back calculated the ENGINE horsepower to 500-510 or so....

[@richardholdener1727]

back calculated a modified motor? That isn't really the same as an actual dyno test but still a cool combo

[@tankthebear]

Yeah - I know - but it was all I had back then. This was 73. Only chassis dyno, I was 19, what did I know back then? Enough to build a pretty stout motor though. It ended up in an offshore racing boat (not mine).

[@robking9857]

HioSSilver1999 said: "I would love to see what some general improvements would do to this engine. Stuff like a better balancer, better oil control, roller rockers, better intake, e85. Do that with the stock cam and heads!" I would like to see the same tests... and then add a rowdy street/strip cam... and then add NOS to see how you can take one on a "relative budget" and up it in stages. Or, do the upgrades HioSSIlver1999 suggested and add NOS with a stock cam... or both. Keeping in mind a hot street driver to the dragstrip and toss on slicks type of sportsman deal.

[@davebeckley2584]

It seems that I didn't have bragging rights back in 1971 when I bought a Black Chevy Impala that had what I was told was an L78 396 425 HP with a Muncie 4 speed. Compared to some other muscle cars I'd raced and some I'd owned I kind of had my doubts anyway. Money was tight and there was little left after a cam and intake manifold for a dyno test as well as all the broken parts. Regardless, the car was a sleeper. Like most of the rest of us, I wish I had that car now as well as all the years.

[@andrewmacdonald3674]

It would be nice to see if the Corvette/66 full size L-72 827 828 exhaust manifolds would have hurt it as much as the passenger car style manifolds. I've heard also the the 858 cyl head doesn't make as much power as the 291, due to the bathtub style combustion chamber compared to the semi open 291 chamber where the spark plug isn't as shrouded. I am building an L-72 Biscayne clone with a 66 L-72 engine that made 530 dyno hp with more cam and head work, some say I will loose 40hp with 827 828 manifolds over a header???

[@hannibalbarca8670]

This is eye opening. Thought it would make more torque

[@lostallmymoney2082]

My L34 396 with a 750 Holley, hydraulic roller camshaft, Edelbrock airgap and headers made 399.5 HP on the dyno. I think the numbers for the L78 were pretty accurate for the 375HP. 425 HP was marketing. Edit: MY 1970 so it was a 402. But it was bored 40 over which made it a 410 cid.

[@danmyers9372]

Wow, I would have expected a bit more than 400 with the upgrades you list. Guessing you weren’t thrilled with the result?

[@lostallmymoney2082]

@@danmyers9372 was happy with it.

[@brad3139]

I like that you keep bolting manifolds on with these tests 👍

[@danlaperuta6916]

Would you consider putting a 454 crank (4 inch stroke) in a 396 to create a square engine 4 inch bore, 4inch stroke ? Keith Black makes the pistons for this combo.

[@richardholdener1727]

NO SIR

[@mikef-gi2dg]

@@richardholdener1727 I am looking at those same KB 396/402/434 pistons. I am curious why you wouldn't consider it. If there is an unseen (by me) problem with this, I would like to know before dropping some cash down the drain. Very good test by the way.

[@richardholdener1727]

My point was that this 396 is staying a 396 (actually 402). If you are asking if you should do it, then the answer is yes-bigger is better. Or just go get a cheap 454 from the junkyard for less than the cost of those pistons.

[@mikef-gi2dg]

@@richardholdener1727 Thanks for the reply, it means a lot. I've had 2 402's for a long time, and in my area 454's have turned to gold $$$ lately. Time do do something with them. Thanks again.

[@bengagnon6947]

Yeah it's funny how it varied from engine to engine. This one possibility slightly overrated then look at the L88 for example which said it had 435HP but actually had roughly 580HP from all the dyno testing I've seen. So it just depends on marketing from the competitors it was built for or tricking insurance companies lol thanks for the video very cool!!!!

[@alertgasper]

another factor is the remainder of the exhaust system. Pontiac ran into issues plugging the GTO engines into the Firebird, due to all the 90 degree bends an F body demands of the exhaust system past the rear axle and around the fuel tank. And on some Chevy big blocks, there were different intake manifolds to clear different hood lines--I'm too lazy to look up the specs on different L78 placements, perhaps someone can chime in if the Chevelle, Corvette, and Camaro all got the same manifold or not. i think the NSRA or ISRA had an issue with LS6 intake manifold choice in the 1980's?

[@DPWPERFORMANCE]

This is the kind of builds I love! I'm posting a '70 396 (402) next.

[@DPWPERFORMANCE]

What is the pipe joint compound like to wipe off the excess?

[@davea5113]

How long before the stock exhaust manifolds where changed out for Doug's Headers? Back in the day.

[@DaveyHo69]

I've got THE carb for that: 3959164-GE List-4346 2872 1969 big block 396/375 & 427/425 high performance models. 780 CFM Original GM part # 3959164 Holley list number 4346 on air horn, original. Exact fit for all 69 , 396/375 & 427/425 models. PART NUMBER: ENC-844

[@Faolan161]

Cam timing could have been different as well, which would make for slightly altered figures... Better fuel, possibly different timing curve... I think they probably gave ratings without any accessories for highest numbers possible. Did the Vette have available cast headers? Or larger carb? Ford BBF had such available on a select few. I suppose there's still a couple variables that might push power to 425, but there was certainly some massaging of numbers for sales

[@richardholdener1727]

The timing was optimized on the dyno-they don't do that from the factory. Fuel has little or no effect unless detonation is present-it wasn't. The Vette had different manifolds, but still way less power than long tubes. The definitely ran the factory water pumps on the dyno.

[@Faolan161]

@@richardholdener1727 excellent deduction. Carb size? I can't see an 850 being the cause for another 30 horse, but maybe it's possible....? Cam timing might account for a small amount, but it sounds to me you nailed down the variables.

[@richardholdener1727]

they came with 780s-a 425 hp motor doesn't need a bigger carb

[@gordocarbo]

@@Faolan161 A 650 double pumper can feed a 425hp BB just fine.

[@gordocarbo]

@@richardholdener1727 Sure you know mfrs shared large carb sizes just calibrated them for different engines Maybe explain this to these guys? Too many believe thier stock 455 needs a 850, lt1 needs a 780 etc Wish I coud get the funds to have you or Brule super tune my solid roller 383. I know theres more in it...

[@mikef-gi2dg]

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.

[@alanmeyers3957]

Would those be the 396, 30 over?

[@mikef-gi2dg]

@@alanmeyers3957 Yep they are factory 402's

[@mikef-gi2dg]

@@alanmeyers3957 Yep they are factory 402's.

[@mikef-gi2dg]

@@alanmeyers3957 Yep factory 402.

[@shadvan9494]

@RichardHoldner. I would agree with the 396 L78 being closer to 375 in most cars that used the factory log style manifolds. however, the Vette used a different exhaust manifold. it was closer to a header in design, and I am told they flow really well compared to the log manifolds. probably not as good as real headers, but probably closer to shorty headers, I would love to see this retested with Vette manifolds. but they are ridiculously expensive. a matching set of factory originals will set you back about $1500.

[@richardholdener1727]

flow is not the same as scavenging-Vette headers won't add much

[@jamesbosworth4191]

That's what I always thought - the Corvette had superior exhaust manifolds, and at first, a bigger carb. Wonder what Tri-power or dual quads would do for power?

[@GlassTopRX7]

It will make way more power with the hood up with tri power or duel quads. @@jamesbosworth4191

[@scottsigmon926]

We ran a 396/375 on the engine dyno with the stock 780, stock solid lifter cam and manifolds but it had an electric water pump and made 378 on 110 octane gas!

[@JViello]

If you don't NEED it, (I.E. optimal timing and A/F ratios on pump without knock) race gas will actually make less power. Slower burn rate and other factors.

[@scottsigmon926]

@@JViello a 396/375 has 12.5 compression!!! And it’s supposed to be ran on leaded fuel.

[@JViello]

​@@scottsigmon926 12.5!? For the L78? You mean 11:1 right? I don't know what any of what I wrote has to do with your comment. It was just a factual statement about fuel octane. We were talking about what the engine produced from the factory in 1969 and you were using an example using fuel that had a MUCH higher octane than what was available in 1969, higher specific gravity etc etc etc. If you are saying the engine YOU ran had 12.5:1...that might have been your problem right there. Race fuel isn't some magic bullet. Head design is much more complicated than "compression vs octane". There are designs that are optimised for a certain compression ratio and any attempt to raise it is met with less than great results. Again, just a stated fact, not saying your engine had this issue or that the L78 did.

[@playlist55]

@@scottsigmon926 LOL, no, L78 396/375 has 11/1 compression

[@Girl123_45]

Being blessed with family and friends that own Camaros and Novas with this engine and 428 CJ Mustangs. Seeing endless races between the two and knowing the results. Also being honored to witnessing several 428 CJ dyno runs. I can honestly say that the 396 was a match to the 428 CJ but only a match. All the 428 CJ dyno runs never topped 370 HP. All the FE runs were made with the factory full exhaust including water and electric being supplied by the engine, something around 350 hp for the CJ was the norm.

[@richardholdener1727]

The stock 428 Cobra Jets run at Westech didn't make this much power

[@Girl123_45]

I agree, it is a tussle between the two engines. The 428 doesn't always come out on top in terms of peak power.@@richardholdener1727

[@allankwiatkowski8217]

you are forgetting one thing,as a 66 chevelle owner with the 360 horse 396,i noticed that the horsepower rating for the chevelles was at 5200,corvettes 6200,and using your graph it is basically as gm said chevelle 5200 375,corvette at 6200 425,so if you wanted 425 horse in the chevelle just rev higher

[@richardholdener1727]

the 425 hp rating was only in 1965

[@garywilson7992]

It’s not that simple, to just raise the rpm’s, although that’s true many times for the factory manipulating horsepower ratings for the same engine. But for a 66 Chevelle 360 hp or a 67 Chevelle 350 hp or say a 69 Chevelle 325 hp, those engines had hydraulic lifters where the peak horsepower was typically under 5500 rpm; while the same CI engine with a solid lifter cam, higher compression and hi rise intake manifold, along with usually a bigger cfm carburetor, developed its peak horsepower around 6500 rpm, and they usually had 4 bolt main bearings instead of 2.

[@rickybailey7123]

Sounded like it wouldn't pull a greasy string out of a Lol im playing it sounded great thaks for the video!!!

[@larryharry7221]

Very informative video. Thank you.

[@shawnbins203]

The 396 425hp engine in the 1965 Chevelle Z16 had a Hydraulic cam. To confuse the 396/425 story even more. I’d be curious how the 1970 “Pancake” intake affects power output.

[@GlassTopRX7]

That was a L37, he's building it to L78 specs. the engine used in the 65 Corvette was top engine for Chevelles and Camaro throughout the 60's.

[@Myriadconcepts-q9u]

Oops forgot about the CAM, a factory ZL1 .600 on intake and exhaust, heads were port matched on both sides. Isky valve train with std rockers.

[@lancelanphier9509]

In addition; running the factory pulleys without the Meziere electric water pump would have reduced horsepower even more, so I would have to agree with you on the original rating of 375