427 BBC CHEVY EXHAUST TEST-STOCK L72 VETTE MANIFOLDS VS LONG TUBE HEADERS. BONUS TEST-600-HP 427!!!

[@johnb7430]

I was NOT expecting that big of a drop with factory manifolds. Wow, headers rule

[@christophermix6845]

Every gas v8 I buy gets headers. Absolutely insane how much better the drivability is!

[@madmod]

Stock manifolds + turbo for the win!

[@robertwest3093]

Yet the late model LS gains just a little switching to headers. Go figure!!!

[@charlesturner5195]

​@@robertwest3093 heads/cam full bolt on ls engines gain ALOT with headers.

[@lollipop84858]

How do you think the power was underrated at the factory back then?? And why do you think everyone knows they were under rated??

[@ford-oz3vs]

Wish someone would do a comparison with stock vs. extrude honed iron manifolds. I mean the F.A.S.T. guys have figured some way of making huge power with iron manifolds.

[@Dayandcounting]

Look at the engine rules and you will know why. Even the more stricter, closer to factory classes make those cars often a second or more quicker than any showroom stock would have likely been.

[@TheInsaneShecklador]

Back in 69 one of the first things (less than a week) my father did to his new L71 was put headers on. It looks like that was a wise move on his part. It also shows how impressive the 1/4 mile times Horsepower Depot is currently running with their F.A.S.T. Corvettes, equipped with stock exhaust manifolds, are.

[@piper5177]

“Stock” exhaust manifolds…

[@TheInsaneShecklador]

@@piper5177 You're right. I should have said stock appearing exhaust manifolds. Still impressive that they get the engines to run like that through manifolds and not headers.

[@crawford323]

I am a nothing hobby person seeking knowledge and lurking where ever I can to better understand big block Chevy and the maze of combinations available and Richard took the time to answer a simple question. His momma raised him right! He is the real deal and here to share with all of us what he knows and what he discovers.

[@richardholdener1727]

THNX

[@y5mgisi]

I appreciate all you do for the hot rod community.

[@edwardwood3622]

Ahhhh, what happened to the 600 hp graphs?

[@chucksgarage7165]

I noticed that too.

[@brad3139]

I'd love to see more of these exhaust manifold tests! Interesting stuff

[@edwardwood3622]

Absolutely, and with cams to optimize the stock manifolds or ported stock manifolds.👍

[@cedricwilson2055]

@@edwardwood3622not just flow he speaks of wave tuning and scavenging often

[@vrm86gt]

50+ hp gain from long tubes! Nice!

[@mojo3008]

I used to build these to restore vettes. This is one of my favorite muscle car era engines. Particularly the L88 and L89 variants. If you’ve ever driven one you know what I’m talking about. Absolute beasts!

[@joshgessinger4509]

Love big bocks but small blocks to lol!!! Want then all rich

[@randyphillips559]

YES!! An over-the-counter LS-7 in a 69 C-3 was an absolute beast!

[@charlesweadley8897]

I had a 69 Corvette with an L.S7. 454 With M22 rock crusher and 456 gears. What a street light brawler.

[@Aegis43]

Thanks for doing this test, Richard. Months ago I had asked you to perform this test on your 396 build because I am (was, it's done now) also building a 396, and you agreed to do it. This 427 is close enough. Like the guys below, I was NOT expecting this big of a drop off with Corvette manifolds.

[@scottbennett3119]

These are the greatest videos! Thanks Richard

[@richardholdener1727]

Glad you like them!

[@autophile-cv621]

Richard, thanks for these tests, it confirms what I did. I'm a small block guy. I built a 400 SBC with 10:1 compression, mild hyd flat tappet cam, full roller rockers, 1989 factory alum heads, Performer intake and 1850 Holley carb. On the dyno we ran with stock exhaust & with dyno headers. The loss was -21 hp & -19 lb/ft torque. A/F was 13.0 We were impressed with the 423 lb/ft torque at 4000rpm.

[@greenbassboosts8872]

I just bought a 1995 ford van with a 300 i6 in it... Header seems to be cracked, exhaust leak at the manifold. Ive been thinking of getting a $200 header and putting it on, running a couple modern catalytic converters and dumping true duals out the side. If nothing else id have the coolest industrial tractor sound haha

[@takeit2-11]

Nice, I love the old school stuff. turbo magnum! turbo magnum! turbo magnum!

[@jmflournoy386]

I did a matching number 454 Chevell that had to look stock big stroker, the Late Kay Sissell did the heads, Jones hyd cam (not big) high ratio rockers, did great with stock gears, we extrude honed the exhausts, ported the intake

[@richardholdener1727]

it all helps-just no scavenging from the short ex mans

[@jmflournoy386]

@@richardholdener1727 eXACTLY no pull from the exhaust so opening the intake early just gives reversion and also not to close the exhaust late. The piston has to do all the work we learned this running with stock manifolds in the early 60s cheers

[@duncanmacrae6384]

Sure would have been interesting to also test the Chevelle/Camaro exhaust manifolds along with the Vette ones. You would think maybe another 20 HP down the drain?

[@markr5132]

Nice well done test-& relative to BB Chev/headers supporting the close to 50 hp that has been proven in the past.I have had many 427's, 396's and back in 1980 I have driven a bone stock L78 w stock electronic ignition (stock 780 set up on rich side) 1965 Vette daily for a year. Their is zero drivable problems with this engine. It idles at 1050-1100 puts smooth etc... A plugs would fouled every 3-5K as it was an older engine, and used quart of oil every 500 miles or so. 427's have same cam heads and 11" vs 10.5" clutch/flywheel so they are even more tame.

[@rhekman]

11:39 I think we're missing the dyno graphs?

[@richardholdener1727]

600-hp graph is up the whole time

[@johnnikollaj496]

I have a 427 vette and I have been torn about headers. Thank you and keep up the great work.

[@1439of2000]

Clearly this would be a big bang for the buck.

[@gordocarbo]

THat is an upgrade you can feel everywhere! Defwould

[@johnnikollaj496]

@@gordocarbo I'm definitely leaning that way now

[@gordocarbo]

@@johnnikollaj496 Cool! Header quality has come a long ways. Even cheaper ones have nice thick flanges, Ive had 0 leaks for 10 yrs now.

[@ChrisLincolnHomes]

My dad's 427/425hp was built to stock specs at Reid's Automotive in Brockton MA back in the mid 90's when the car was being restored. It dynoed, with manifolds, at 449hp. Remember, these were originally rated at 450hp then were downgraded mid year.

[@jackash9951]

The 425 hp was nothing more than an administrative correction resulting in a different air cleaner decal beginning around October 1965, a month or so after the first 1966s rolled off the assembly line. There was no de-tuning the engine. The decal change was to appease the insurers and Ralph Nader who thought 450 horsepower was too much for a light car like the Corvette.

[@Dayandcounting]

@@jackash9951 That is true but Chevy was always messing with cams and heads sometimes twice a year for one or the other. The changes were subtle and likely targeted Chevy solid lifter stalling issue with auto trans cars. Example depending on when your L88 427 was made you might have the original L88 grind or the later ZL1 grind and I'm certain that will make a power difference that could be felt.

[@kevins5833]

Would love to see that same 427 with big compression and big cam, 276-284 @50 750 lift I'll bet it would make 700HP easy...

[@randykeeton5622]

Your videos are gold Richard. RW

[@robertwest3093]

Headers alone would drop quarter mile times by half a second or more. Definitely good bang for the buck here!

[@davidresar8256]

No chart for mild vs wild. Love the big blocks... BIG BANG BIG BLOCK CHEVY COMING SOON???

[@DillonAuto]

My grandfather bought a 427 from GM in Detroit in the late 60s. My dad graduated in 64, I wasn't there. Price, hold on to your butts, $750.

[@Ecoblu1972]

Love the video 2024 probably pulling the 427 out of my father’s Copo Camaro. Looking to maybe put a roller cam aluminum heads and electric fans nothing that can’t be changed back he’s owned it since 71 and it’s going nowhere. I know cars make more power and run better. BUT there’s a difference in the experience

[@Dayandcounting]

If it's legit, put the stock motor in storage and use a 454 block no one will notice and a 427 crank will make it a 427.

[@Ecoblu1972]

@ it’s a legit matching numbers car he’s the 2nd owner he’s got the Protecto Plate the card with the engine, trans, and reared codes, gotta drop the tank to fix the gas gauge kinda hoping there’s a build sheet there as well. His cousin in Virginia bought a COPO Chevelle Hugger Orange brand new off the lot but he eventually sold it. AMAZING what were just regular cars that an AVERAGE working person could buy. My father originally was gonna buy a 66 L-72 corvette but the insurance was as high as the car payment, then it came down to a 69 L-78 SS Nova and that Camaro both were $1900

[@craigchiddo2794]

The afr 265 heads and comp cam from the 454 oval ports shootout would have been better the rectangles and crane set-up is better on a 496 I'm pissed nobody did a build on a 396/427 with afr 265 heads

[@gordocarbo]

id have liked to see the 265s on this one.

[@brysons7525]

Thank you for the informative content as always Richard! Side note, it appears you left out the dyno graphs at 11:50 and onward, no torque curve displayed and no mild to wild comparison. 😅

[@tyger13us]

i had an L72 driving around wasnt no big deal,, even had a tri power 435 hp,, drove fine in traffic, but it would get hot. All stock factory stuff back in those daze.. all wreaking yard mix and match parts back then..

[@kimmorrison9169]

My 402 big block has 595 lift solid flat tappet cam, ported L89 heads, single plane and 850 double pump. Drives nice, idles nice, screams when opened up in my light weight Nova. Nobody envies my gas mileage thou😮‍💨

[@randyphillips559]

I had a 427 vette, & yes they would get hot in traffic but I found by simply flipping headlights up temps would drop considerably!

[@Dayandcounting]

Where, any stock solid lifter Chevy is hard to keep running until warm on a cold day. If you have a pre '70 auto forget about it. It's either jack the idle up or will stall a lot.

[@Dayandcounting]

@@kimmorrison9169 There are some milder hydraulic rollers that would broaden the curve and improve power up top. A buddy used one in his LS6 clone and it sounds really close to factory at idle but make over 100hp more with 9:1 engine.

[@kimmorrison9169]

@@Dayandcounting yeah I know but I’m happy with the present set up with choppy idle and I really don’t need more power.

[@AustinRBa]

Gotta send this to my 454SS friend. He's running manifolds. Im curious how my 402 in a Chevelle will compare with a cam similar to the first 427 in this video, plus headers. Both of us saddled with peanut port heads.

[@MultiHotrod74]

It's my personal conundrum, but I'd like to see the stocker run with a 4 inch air filter in a Corvette drop housing versus an aftermarket intake that's an inch taller with a 3 inch filter.

[@jmflournoy386]

Duntov preferred a Big block Automatic

[@chucksgarage7165]

The dyno curves for the wild combo were not showing in the video. Just pics of the engine.

[@richardholdener1727]

the 600 hp dyno was shown for the whole section

[@DustinBaerwolf-kv9jx]

Try looking for a L66 396cid 265 HP to run some test, I had one once, very torqie !!

[@russelljackson7034]

Right on

[@gordocarbo]

Argued with vette guys for yrs esp with BB there IS a difference in normal/moderate driving Compare a 2/5" under car exhaust with the vette sidepipes, typical baffels, those are power robbers also .Look neat an all but.. Id have a hard time lowering compression, 350hp 396ish cam etc from the L72 vette.. For a few bux more per fillup using 91 pump and what 1/2 can or a small can of Torco, VP would be worth it to me. Will that engine ever see 5k where the top really picks up? On a serious note sure the first one idles awful close to a stocker..i just can do it...go backwards

[@karlmoltzan6196]

richard I love your videos. I just wish you would show the dyno graphs longer. On the 600 version you showed the dyno graph for just a few secondsand than only pictures of the engine while youwere giving the power levels. please look at this video to see what I meant.

[@richardholdener1727]

the 600-hp graph is up through the whole discussion

[@takeit2-11]

hit that pause button

[@craigchiddo2794]

Holley made those nice cast iron ls headers how come no love for the big block

[@pmd7771969]

I have built a few

[@twgarage-terrywatson1672]

Awesome stuff, maybe a 70-LS-6 build next? There’s another channel running a supposedly stock 69 427 and on the Dyno it showed 500hp with stock manifolds. Lots of B.S out there. This is why I love your content. Correct realistic numbers, drives me nuts when others post a bunch of B.S. 👍

[@richardholdener1727]

the LS6 is going together

[@twgarage-terrywatson1672]

Awesome 👏

[@imtheonevanhalen1557]

What you see all the time are people with tube headers and no extensions......THAT is where to real benefits become real. The extensions create a venturi effect creating vacuum on the other cylinders to remove exhaust gases. Start with 12 inches and do incremental increases...........you will feel the gains

[@scottsigmon926]

Wow, that’s a lot!! I bet it got rich with the manifolds on it!!!

[@richardholdener1727]

NOPE

[@exploranator]

WHY did they go with such puny compression in the second motor? They wanted to run 40 degrees of timing?

[@markreibson7030]

how mild would the bbc have to be for the stock exhaust manifold not be a cork? 396/325hp? 366 with peanut ports and a 200° cam?

[@AustinRBa]

I'd be curious where the power curves start to get closer. I'd think it'd eventually hit a level that it just can't pass. But even ignoring the "cork" effect, it'll never catch up with headers. Headers are creating a scavenging effect using the pulses of exhaust to help pull one another along. Manifolds won't ever produce that effect.

[@ChurchAutoTest]

Rich I know you've tested AF variation from cylinder to cylinder a fair bit. Do you think cases like the first motor picking up power when running deep into the 11's AFR means that it's got some pretty big variation between cylinders?

[@richardholdener1727]

might be

[@rickuyeda4818]

Dude, all you need to say is "Headers is this much and stock is this much". Do you get paid per word??? BTW, the '69 Camaro ZL1 in the F.A.S.T. class runs cast iron exhaust manifolds that have been Extrude Honed with a full exhaust and it runs 9's on Polyglas tires.

[@benjamieson5626]

Charts didn’t come up at the end to compare but great video. Would the factory iron off modern be close with a bigger cam? For budget build

[@richardholdener1727]

stock manifolds don't do what long tube headers do, but you can still make power with them-look at the FAST racing vehicles

[@tomk4739]

Is the flat flat flat graph missing?

[@HioSSilver1999]

Vid is missing the graph towards the end

[@mojo3008]

What about porting the manifolds? Does anyone do extrude honing? Is it effective?

[@cedricwilson2055]

More than flow, wave pulse and scavenging comes into play

[@torqueytorque8861]

As an L72 owner, I can confirm your 10% reduction in HP and torque switching from headers to stock manifolds. What really baffles me is the claim the engine made more power with AFRs in the 11s versus 12s. Weird.

[@jackash9951]

Yeah, that mystified me too. Every article I've read over the past 30 years has said carbureted engines make the most power at an AFR around 12.5 to 13.

[@sanfordrhudy774]

Richard Holdener do you know what the specs were in the TwoLaneBlacktop 55 Chevy? Would you do a copycat of that engine, then put some modern touches to it, so we could see the differences are from way wayback to now?

[@richardholdener1727]

NO IDEA ON THAT BUILD

[@AlanRoehrich9651]

That was a Joe Reath 427, with a tunnel ram and two 660 center squirt Holley carburetors. Probably real close to an L-72 engine, other than the intake and carburetors.

[@buzzwaldron6195]

2 cars for that movie had BBC 454 with dual quads added for looks... 1 car had stock L88 427 rated "430 HP" (so rich kids wouldn't order it over the street 435 HP 427) which actually make 560 HP with headers for racing scenes...

[@scotthultin7769]

Thanks for sharing ☺️

[@jims2286]

Corvette Big Block exhaust Manifolds are less restrictive than Passenger car manifolds On a1970 450 Hp LS- 454 passenger car Exhaust Manifolds Are Minus 79 Hp over Headers

[@richardholdener1727]

80 hp from headers?

[@jims2286]

@richardholdener1727 The original how-to hot rod a big block chevy book over 40 years ago showed that passenger car exhaust manifolds lost 79 hp on a 1970 LS 6 454 450HP

[@DragonFireEngneering]

Even when running headers, there is often little or no room for collector extensions which seem to be a critical feature. And running straight through mufflers is not very practical as sanity is more important than horsepower (most of the time). Often the horse power difference between engine dyno testing and chassis dyno testing is blamed on drive train losses but portion of that has to be from the exhaust system. Looks like it could be significant part of the loss to me.

[@richardholdener1727]

very few vehicles run open headers and no exhaust (which has the extension)

[@anthonyrowland9072]

they did this on a built big block F.A.S.T car and the extrude honed manifolds and performance exhaust still lost like a 100 wheel hp.

[@antilaw9911]

Im building 454 to put in 1980 camaro. I want factory cast exhaust manifolds. Which ones might fit? Thanks!

[@richardholdener1727]

no idea

[@mediumjumbo7484]

After watching this video ,I can't imagine why anyone would. It certainly changed my mind 👍👍 ​@richardholdener1727

[@matthewdupuis232]

Is it youtube or just me: I can't see the dyno graphs at the end, just a close-up picture of the engine.

[@richardholdener1727]

It is me

[@garyhosier4765]

WAIT!!!! The 55 Chevy engine went behind the Doug Nash!!! That’s trick!!! Centering the engine in the car facing reverse!!! Must have run to a transfer case and back to the rearend. Or maybe it was front wheel drive!!! That’s original in a 55!!!!

[@AtomicDog58]

I have a question I have a 454 Engine And the suffix code starts with C6Z what is it Those are the only numbers on the pad Is it a 427 is it about 454 is it a 396 what

[@richardholdener1727]

production BBC block codes are avail on line

[@AtomicDog58]

I tried online C6ZI cannot find please help

[@thud9797]

​@@AtomicDog58 The C6Z is NOT a suffix code, from your stamp it appears to be a the partial VIN stamp from a mid 80's truck.

[@fppro1679]

I've been told that, without the muffler on a big block Chevy that, with Open headers versus stock manifolds and mufflers, it can be as much as 100 horsepower! Pumping losses are immense!

[@richardholdener1727]

we didn't see anywhere near that

[@fppro1679]

@@richardholdener1727 No, you did not. I read that in another book. Denny Hulme, New Zealand race car driver for Bruce McLaren said the 427 ZL1 aluminum block Chevrolet was the best engine he ever drove, really manageable power and it could really wind! With the kind of heads you can get now for these engines, I'm thinking the proper exhaust system could maybe start approaching that number.

[@richardholdener1727]

stock ZL1 power is very easy-but they used bigger motors in the Can Am cars

[@fppro1679]

@@richardholdener1727 home was commenting in that year about the 427. True, and later years they went out to I think 494 cubic inches but it was the 427 car he was so fond of. At the end of the series they had turbocharged big blocks so powerful that Mary andretti drove one and said he literally couldn't touch the throttle without breaking loose and he could pull the front wheels off the ground in any gear by just stabbing the throttle.

[@overcastfriday81]

Confused....3500# lb car with 7 big block liters and a dual plane intake? There should be no shortage of torque or driveability. I'm not suspecting it had bonneville gearing and camshaft...I suspect it was out of tune before the rebuild.

[@69johnjunior]

Should have used 3 inch exhaust for a better comparison.

[@jmflournoy386]

I'd think about reducing overlap with stock ex

[@edwardwood3622]

Ya? I have never heard that. Is that why stock cams have such large lobe separation angle? Richard can you please do a test? This is information I am and maybe many more would be interested in.

[@jmflournoy386]

@@edwardwood3622 lots of reasons for large separation angle including smog , helping a big cam idle etc etc I'm of the LCA is a result of the valve events not the cause school

[@richardholdener1727]

the overlap is not the issue

[@edwardwood3622]

@@jmflournoy386 you obviously have a way better understanding of camshafts than I do. For an engine with stock manifolds is it better to have a larger LSA, longer ex duration with a shorter in duration or both? I am very interested in making the biggest power possible with stock manifolds for a F.A.S.T type car. Thanks

[@edwardwood3622]

@@richardholdener1727 hi Richard, if you wanted to improve the power numbers of the stock manifolds, is there any change to the cam you could make to help?

[@carlzalesski2975]

I'm building a gen 6 427 bbc for my monte ss

[@daytradescottie7253]

Holy crap!

[@malamri424]

Will long tube headers with stock cats improve power?

[@richardholdener1727]

yes

[@JamesStover-gr3hw]

Hi Richard, Great video. I the a 396 or a 402 with AFR 265 oval port heads (full CNC version) would be a great build. This would show what a great set of heads would do on a 71-72 402 with smog heads. Just a thought. Keep up the great work

[@edwardwood3622]

Did the stock manifold test get timing and jetting redone? Would it have helped as the exhaust scavenging was changed?

[@richardholdener1727]

you mean lack of scavenging?

[@edwardwood3622]

@@richardholdener1727 yes

[@atheplummer]

I don't understand why the torque numbers are so low on these supposed 'wild' builds. I have a 468, with a flat tappet camshaft, 781 (ported) heads, Holley Strip dominator intake & a 500 Holley 2BBL that made 632 Lb/Ft at 3200, with a peak HP of 437 at 5700 RPM, before the carb left. I built this 20 years ago, used cast crank, "pink" style long rods & 13:5/1 compression, with 108 fuel. I wonder what kind of # it would have put up with a RPM Performer intake. I ran this engine in a sportsman dirt track car for 12 seasons, with zero freshening, a buddy got it really hot over 260 on a caution & it pulled the piston top off #8. This engine is currently being freshened up to it's former glory, but were going to fit it with a Tunnel Ram, with a Holley High Ram top hat & a Tick Performance Air/water intercooler & a procharger. Going to run a AC compressor to cool the recirculation/fuel loop water... because cold intake charge makes power & the Tick performance intercooler acts like a velocity stack, to straighten the air before it enters the intake runners. Plans are to fit this engine in a square body with a T6 manual, Cal track bars & a home brew QA1 front crossmember conversion. I hope the crank & rods can handle the build.

[@YourMom-ll6ku]

Lol because it was around 10:1 compression on pump gas 89 probably

[@atheplummer]

@@YourMom-ll6ku I know compression builds HP, but Torque? Isn't that a factor of rotating assembly weight? Maybe I'm asking the wrong question here. When we build this engine, concern was recriprocating weight, because I was dirt track racing, I wanted the lightest recrip. weight I could get (hence the cast crank, pink rods, & a full internal balance recrip. assembly. I ran a triple disc clutch and a ultra light harmonic balancer. The thought was, that I wanted the engine to act as a engine brake at the end of the straightaways, setting me up for the next corner. Heavy recrip. asssy's make more torque. For mine to make that much torque, is totatlly baffling to me. Unelsss it's the compression ratio that's making the torque, which I've never factored in. With the upcoming repurposing of this engine, I'm wondering if I shouldn't lower the compression ratio, since I want to run a Procharger on it. My plan is to run E85 escluslively on the street, & methonol on the track. I know E85 can be used up to a 13.7:1, if knock sensors are working properly.

[@richardholdener1727]

a motor that makes 1.35 lb-ft per inch yet makes less the 1 hp per inch? seems odd.

[@atheplummer]

@@richardholdener1727 It was restricted to a 500 Holley 2BBL, and they checked the bores, in order to be legal to race sportsman dirt class. When I put a 850 on it, things are way different. 5700 RPM was peak HP, and the carb was hurting it higher up than that.

[@corystansbury]

I just have to ask-- Being frustrated with my free Internet content: Why are all the dyno curves the same color?

[@steveproctor1748]

Valve dropper

[@dubjay3779]

Wow. I was thinking 15 hp

[@Sweak22v1]

Big block powa!!!

[@SaneCayne]

Stock logs. Ouch!! 😳

[@richardholdener1727]

these were not logs-these are Vette perf manifolds.

[@SaneCayne]

10-4. I don't deal with engines anywhere near as much as you do to make that distinction. To me, there's headers and anything from the factory in cast iron, is logs. So if these were "high-perf" manifolds, I can only image how bad logs would've done! 😬@@richardholdener1727

[@shanerorko8076]

A richer total tune would indicate poor distribution. EFI could likely yield higher returns on this engine if port injected.

[@richardholdener1727]

a theory is always fun

[@cedricwilson2055]

Probably the vac secondary carb also

[@richardholdener1727]

dyno was not vac sec carb

[@AlanRoehrich9651]

Actually, the reason it wanted more fuel was probably a combination of the combustion chamber, piston dome, and camshaft. The factory dual plane intake doesn't have terrible mixture distribution. We stagger jet the carburetor, and it's fine, it's only a 6 jet stagger, even counting the two jet richer secondaries.

[@oct2274]

Graphs missing at the end

[@richardholdener1727]

the 600-hyp graph is up through the whole discussion-missing is the comparison

[@sleeeper88]

This engine would of been a beter combo with the 265 afr or 290.

[@newbomb327]

FAST racers are making 1000 plus horsepower through the cast iron exhaust manifolds...........

[@TheInsaneShecklador]

Jordan at Horsepower Depot said their engine picked up over 100 HP with headers.

[@Matt-e4x]

Can’t swap headers with manifolds without jet change, car was running WAY rich with the manifolds

[@james10739]

Was that paint good shit it looke like it was dipped in it i bet there were misfires because there was no ground for the spark plugs

[@regal105]

They talk about 427’a reviving high lol all in at 5900 and peak torque at under 3000

[@corvettejohn4507]

The hydraulic roller cam they installed was a smaller cam than the stock solid lifter L72 cam.

[@16vg60mikey]

first one in!

[@drbendaroo9610]

How yhe heck do the F.A.S.T guys run 9's with exhaust manifolds?

[@newbomb327]

We run camshafts that are designed for exhaust manifolds

[@Ghosts_and_Cars]

Would those cams work well with a turbo?@@newbomb327

[@socleanmx6]

​@@newbomb327explain more please🙏

[@cedricwilson2055]

Probably a big cam. Stock big block heads flow poorly anyway without chamber mods, manifolds just add to the problem

[@HioSSilver1999]

Lowering compression does nothing except let you use the regular unleaded gas....certainly nothing for drivability

[@richardholdener1727]

thus actual drivability

[@HioSSilver1999]

@@richardholdener1727 that's not drivability. That's cheapability. If anything lowering compression will make actual drivability dynamics, the traceability of the engine worse, along with mpg, emissions and power. That dude don't deserve that vette. He shoulda bought chevette so he could put cheap gas in it.

[@richardholdener1727]

only 91 here in Cali-and the motor drives perfectly as intended (data vs opinion is always 1 sided)

[@HioSSilver1999]

@@richardholdener1727 what i said wasn't opinion tho. Wanting to put cheap gas in a corvette and thinking it's good.....now that's a opinion.

[@roykrossin8343]

Long tubes !!!

[@396375a]

It's NOT a 427/425 motor!!!! It's a driver that's been de-tunded for the street!!!!

[@Imnotyourdoormat]

Nothing [with the exception of the Chrysler "HEMI"] responds to a set a pipes like a Rat Motor Chevy....

[@markreibson7030]

since zinc left the chat, i don't know why anyone's still using flat tappet of any kind

[@richardholdener1727]

they still work and zinc is still avail

[@EricErnst]

Exhaust mystifies me.

[@joe-hp4nk]

You ramble a lot.