6.0L LS Head Test-Who Wins-799 vs 823?

I compared a set of stock 799/243 cathedral-port heads vs the 823 LY6 rec-port heads on an LY6 short lbock. The motor was equipped with a healthy Comp cam and run with the Dorman LS2 intake on the 799 heads and stock LS3 intake on the LY6 heads. Both heads had 26918 springs.

[@SloppyMechanics]

rich, i feel like you rush these things, take your time and give me more.

[@richardholdener1727]

Sloppy Mechanics thnx-these were all done long ago -I’m working on new stuff

[@masoncampos7043]

Maybe that's why it's "Speed" secrets... 🤔

[@richardholdener1727]

@Struinzu Vaffencullo They r great guys! I've helped out on engine masters a few times!

[@ratman5727]

@@masoncampos7043 LMAO! -you got something there!

[@milojanis4901]

It would be very interesting to see the AFR 245 Cathedral against the best aftermarket LS3 rec port head. Seems I remember this test (245 vs LS3 aftermarket?) from somewhere, and if I remember right the Cath put out close to same peak, but a lot more under the curve.....

[@soundslikealot]

I’ve never thought about cathedral port heads to win actually, that’s pretty impressive! Thanks for your videos!

[@richardholdener1727]

noname_RU it was closer than I thought -especially if you run a fast intake on the cath heads

[@bigdaddylovesyou8814]

What fast Intake manifold number do I get I have 799 heads thinking about running them on a cammed 6.0 ?

[@tsigoloiborcim]

"799 HP" graphic at 1:08 threw me for a second. LOL

[@romero.4089]

Me too I was like well time to find one

[@thegrumpyoldmillennial328]

Ask and ye shall receive! Man, you can't argue with that! The internet has made it sound like as cast 823s were better than cnc ported cathedrals, and I believed it for years. It's pretty amazing how tight all the gm castings are! Really just goes to show that our money is best spent elsewhere in the quest for cheap power!

[@richardholdener1727]

Tommy Presson the stock ls3 heads will support a lot of power -we made nearly 700 hp with a stock set on a big stroker

[@flatbrokemodsquad4241]

I milled my 823 heads and had them ported. they are flowing 40cfm more on intake and 50 cfm more on exhaust. I'll be using an almost identical cam, but with 61mm turbos, bosch 210 injectors and e85 controlled by the holley terminator x max. cant wait to see what that will do in my bronco.

[@richardholdener1727]

sounds like a good combo

[@milojanis4901]

Keep the 4 wheel drive-Youre gonna need it!!!

[@flatbrokemodsquad4241]

@@milojanis4901 most definitely! got some 37" paddles for the sand runs.

[@richardwimmer6846]

Can't wait for your video al,,, sounds like a bad a$s combo

[@raulburgos6083]

Very informative, just the information i wanted

[@matthewbailey5921]

An overlay of the maps would have been awesome

[@The_forgotton_one]

I'm going to run 823 heads CNC ported, they are going to make more HP and torque on boosted 413 stroker

[@traynice9633]

I got 100 question for you. I been checking out your channel for the last few days I must say you have good advice👍👍👍

[@richardholdener1727]

WELCOME AND THNX

[@shannonsisk]

Would be neat to run it with the fast, might have more torque down low and the same up top due to the compression increase of the 799 heads. Good info thank you for sharing this. Very useful indeed.

[@MrPoeta69]

thanks very good info !

[@richardholdener1727]

thnx

[@SPAZTICCYTOPLASM]

I don't know if you've done this, but in my experience and I'm nowhere near a veteran, ported, polished and reworked 243/799 heads seem to outperform 823 with the same work done. I always imagined the bigger valve advantage would help the 823s come out on top at the end of the day, but that might not be the case? Idk if anyone's empirically tested this. Most of my porting work is done by Katech so i imagine different guys will get different results.

[@richardholdener1727]

You likely don't have enough motor for the bigger heads to shine-the cath ports also have higher compression and since they will support over 600 na hp, most guys don't have a motor to tax ported rec port heads

[@TheTexican05]

The oversized 2.165” intake valves of the LS3 heads are poorly shrouded on a 4.00” bore. It takes a 4.030” bore or larger, ideally 4.065”+ to truly let the LS3 heads shine N/A. If you’re boosted, however, the compressor shoves in the air and can overcome this deficit. For the 4.030” bores and smaller, I strongly recommend a quality set of Cathedrals and a Fast. I made 640bhp/575lb/Ft with a squared 402ci LS2 using gently massaged TFS 235 heads and an off the shelf Fast 102 intake. 12:1 SCR on 93-octane pump gas and 24-27* timing. Ran 10.90s at 128mph, all motor on a 3450lb car with a built 6-spd T-56. Cathedrals WORK harder than their dyno numbers often indicate. Port velocity is a huge component of this.

[@nytronorm]

Good test. Half a point of compression in favour of the 799 keep in mind.

[@richardholdener1727]

Garrett B just stock head against stock head-that’s how they come from the factory

[@nytronorm]

Yes that’s the best way to test it. Do you think If you milled the 823 down to 64cc chambers, it would pick up some numbers down low?

[@djzomb1]

@@nytronorm yes higher compression will lead to horsepower but your heads also flow less when milled

[@andrewdavis3166]

I want to see the dyno run of the 823s with the req port truck intake for a torque comparison. There's a fair gap in the application of the intake manifold used.

[@richardholdener1727]

Andrew Davis I compared the Ly6 intake to the ls3 intake-they r the same

[@thomasgjonovich5524]

Great video but I feel that the compression was the deciding factor here. The 823 heads have a bigger cc and at least one 1/2 point lower compression over the 799. I’m willing to bet if you deck the 823 heads to match compression they will make the same if not more torque down low and even more peak hp. I wouldn’t do a 823 swap on a 6.0 without raising compression.

[@richardholdener1727]

stock vs stock...not stock vs modified

[@thomasgjonovich5524]

@@richardholdener1727 I understand I was just giving my real world scenario for myself. I really do love watching your videos and appreciate all of the detailer work you put. I look forward to more of your content. Thank you for responding.

[@johnedwards2498]

I have a holley sniper intake with cathedral ports and was wondering how well it would work on an 823 rec port head

[@dariogonzalez6249]

Hello,first I want to thank you,awesome channel ,recomendation ls3w/823 heads,now on stand should I consider putting a turbo? if so wich? Thanks

[@richardholdener1727]

I have ls3 turbo videos up-it works well-turbo chose will depend on how much power you want-the S475 or VS racing 7875 can do near 1000 hp

[@vettsmoker2000]

Richard. The rectangular port heads require cam with more duration then the one tested. I think if tested with optimum cam for each style head you would have had a big difference between the two. Your thoughts? Thanks for all you do….

[@richardholdener1727]

THAT IS NOT TRUE-PLEASE SEE THE REC PORT VS CATH PORT CAM AND HEAD TEST VIDEO (THE HEADS REACT THE SAME TO THE CAMS AND VICE VERSA)

[@genepatrick]

so maybe this is a stupid question, bbuuuttt . . . i have a set of heads with a 5364 casting number and one of them is damaged so i planned on just buying a used one to match it, but then i noticed some of the heads with 5364 /364 / 716 / 823 casting numbers had difference Chamber sizes listed . . . this got me confused. recently Engine Masters did a similar shoot out to this one and they said the chamber size was 70cc but different places have 68cc listed . . . so my question is, is it possible for the chambers to ACTUALLY be different ? OR do half of these people (ether half) have the wrong info? As always LOVE your content! i share it regularly!

[@richardholdener1727]

there is a production tolerance- 1-2 cc isn't going to make much of a difference

[@genepatrick]

@@richardholdener1727 thanks man, you're the best!

[@3800TURBO]

We have 6sec 1/4 cathedral cars in Aus. They ain't as bad as people think. Richard do you have a single plane manifold test on the catheral heads?

[@richardholdener1727]

Track Days. Yes-lots

[@JamesStover-gr3hw]

Richard, When you post the specs or results, could you PLEASE the numbers on the screen for more than 1 millisecond. Thanks

[@richardholdener1727]

my video editing doesn't work in milliseconds

[@richardscarlett7942]

Id like to see this comparison with single and twin turbos

[@leepederson5254]

I wonder if with the cathedral port and a fast you retain the low torque? Then you would be beating the rec everywhere?

[@sailshane]

with stock LQ9 and stock 823 heads with comp 54-469-11 cam will I have valve clearance issues???

[@richardholdener1727]

CHECK

[@sailshane]

thx for your reply Rich Im glad you let me know because if I went off your videos where you say this cam head block combo works can be perceived as a workable combo.

[@chesspiece81]

Richard what do you think this motor would make with some ported 243s and ported Fast LSXRT 102 truck intake? Do you think it with ported 243s it would improve the bottom end of the stock 799s in this test but match the LS3 heads in the top end?

[@richardholdener1727]

I see you got your answer on the 225 TFS head video

[@user-ee4rw1es5f]

Which size cam did u run with the with the 799 heads?

[@richardholdener1727]

same cam for both

[@dalechenoweth915]

I would like to know why you disable/remove the VCT. Does it not help fatten the torque curve with a bigger cam?

[@richardholdener1727]

we can't control it

[@jareddeitch9121]

Hey Richard, love your channel. Learning a lot. My 06 C6 LS2 has some 0821 heads on it, what's your impressions on those? I can't seem to find any info on them.

[@williambeekman2527]

Someone has Installed LS3 Heads On You're LS2.

[@wersty4927]

I have a gen 4 5.3 my plans are to run the summit pro ls cam stage 4 with the lsxrt intake manifold on my 799 heads of course with dod/afm/vvt delete. Was planning on switching heads but I think I'll keep the 799 and do that cam and intake what do ya think?

[@richardholdener1727]

that will work

[@bigdaddylovesyou8814]

Need help I have a pair of stock 799 heads & a lq9 6.0 v8 engine. How much do I milled the heads. & what cam do I use ?

[@richardholdener1727]

most mill .030 for higher comp, then comp cams 54-469-11 cam

[@louisvelazco9565]

What gaskets do I use for same set up and also push rods

[@scottbarrera6860]

Would the fast intake work good with 823 heads?

[@richardholdener1727]

they make a FAST for those rec-port heads, but it adds almost no power compared to a stock LS3 intake

[@Moparbarnett88]

What would be better for lq4 with holley sniper efi and single plane intake, 799 heads or the factory LS3 heads

[@richardholdener1727]

ls3

[@Moparbarnett88]

@@richardholdener1727 Thank you,

[@Moparbarnett88]

@@richardholdener1727 Would the valve train, springs and valve from 799 heads fit the LS3 heads

[@characterdevelopment2361]

823 heads have lower compression? Compared to 799? What were numbers on compression s

[@richardholdener1727]

Marshall Lyons 64 vs 69 cc about 1/2 point difference

[@characterdevelopment2361]

@@richardholdener1727 in the test what did you change tune wise. I trying to put a little build list together.

[@richardholdener1727]

Marshall Lyons what do you mean-each combo ran the same AF and tuning to keep it consistent-both ran best at 30 degrees total and 12.8:1 though neither was sensitive to AF

[@characterdevelopment2361]

@@richardholdener1727 well I've heard that 799 heads didn't like alot of timing. I was working on an ls swapp for a gbody. Was wondering how it head worked.

[@richardholdener1727]

Marshall Lyons we adjust the timing til they stop making power-the dyno tells us what they want

[@scutchnuts]

What is the compression of both motors?

[@cowill8674]

@richard which push rods, and springs part numbers i should use with the the ly6

[@stephanouellet3673]

But 799 get more compression maybe .5 more then 823... Almost 9HP there

[@codycleveland2853]

the split on the cam is not ideal for a rectangular port head

[@kilacali916]

Im doing a ly6 swap in my 1972 blazer with a 4 speed its a weekend warrior, pulling a boat and playing in the mud and hills when camping which heads and cam would u recommend

[@jonycard1]

Honestly with a set of 799 heads with ss2 cam you'll enjoy yourself.

[@hassanabas1549]

For a quarter mile setup with a 6.0 stock engine fbo cam which one would you suggest 823 or 799 +which intake manifold holley or fast?

[@richardholdener1727]

823 and stock ls3 intake

[@hassanabas1549]

@@richardholdener1727 thanks helped alot

[@hassanabas1549]

One last thing if I sprayed 100-150 wet shot of nitrous(fogger) does that have any direct effect at both heads and intake manifold +which gear ratio would be best for a 6.0 with a 6l80 for 1/4mile alot of questions here sorry .

[@popsicle33]

So what is the difference between 823s and 821s?

[@richardholdener1727]

valve weight

[@paisa96ss]

Do we just witness a crime?

[@Walrus50]

Opinions on 862 heads for built motor

[@mrmidnight32]

What about the 862 heads? I was told those are underrated heads. I have those on my truck but never thought about them being good.

[@lp_rc523]

CK_32 run of the mill low cc head good for stock application but when you want power 799 or 821 will be better

[@mrmidnight32]

BlacZ/28 I’ve heard they had high compression which is good for NA builds

[@lp_rc523]

CK_32 true more compression is better for n/a but with those truck heads you can only take them so far which at that point of porting then 799 can out perform the 862 on every level so it’s really at preference I say for a street car the 862 (61cc)will do fine but so will the 799 (64cc) as for the ls3 heads the bigger pistons make up for the cc of the 823(70/69cc) ls3 compression is 10.7.1 and 5.3 with flat top pistons and 862 is at 9.9.1

[@AnglinTexas]

kzbin.info/www/bejne/sJeuZWh4pqqiZ7M (706) / 862 are good heads

[@dnvr12]

Any info with the fast intake?

[@richardholdener1727]

yes-it makes more

[@perry_cuts7533]

Which head gaskets did you use

[@richardholdener1727]

Fel pro

[@perry_cuts7533]

@@richardholdener1727for the heads or for the 6.0 block

[@perry_cuts7533]

@@richardholdener1727and what lifters did you use

[@86boostdcapri]

I assume the results would be the same using an lq4 6.0 bottom end?

[@richardholdener1727]

yep

[@nathanielmackinnon6738]

What about the fact that the lq4 has dished pistons and lower compression. Wouldn’t that equal less power!

[@Brayan-rm6ti]

@@nathanielmackinnon6738 its a ly6

[@crw3673]

Begs to ask the question. Can you have a f.a.s.t cathedral port, go up against a f.a.s.t rectangle port? Using the same throttle body, switch between each run. This should settle the debate!

[@richardholdener1727]

charles walkes the Fast rec port adds little if any power over the stock manifold at this power level

[@crw3673]

@@richardholdener1727 its not about the power, but equal playing field. That's why to even go as far as the actual same throttle body between each dyno pull. Cuts out different variable.

[@williambeekman2527]

The DLS2 and LS3 Both have a 92mm Opening.

[@offensivetomato2294]

Can I ask I just bought an Lq4 and want to know the best junkyard heads for boost and torque?

[@donniecahill5243]

The heads that come on it....317s

[@OutlawChevy2]

799s.

[@PROCOPO]

Hi Richard I have an L77 here in Australia on my 2014 Holden SS that has 823 heads from factory, so your saying that these are also LS3 heads?

[@williambeekman2527]

823s which is a L77 Head have a Standard Intake and Exhaust Valve, 821s which is a LS3 Head have a Hollow Stem Intake Valve and a Sodium Filled Exhaust Valve. Other than the Casting Numbers and Valves Their the Same Heads!

[@PROCOPO]

William Beekman thanks heaps for your reply

[@nathanstephenson7917]

Did Richard do this test in a boosted application?

[@swappedoutZ71]

Im in search of tq under peak. Would i be better off with ported 5.3 heads, or ported and MILLED ls3 heads? The 5.3 heads would have big valves installed. Cam is 224/230 so keep the split in mind as well, not sure if its more ideal for cath or rec. Ported ls6 heads can also be subbed for 5.3 heads, they will be milled and ported also. Which is my best choice? I see the small heads have better tq under curve but im unsure if milling ls3 heads can give me the same gains under curve due to compression increase.

[@richardholdener1727]

if you care most about torque below 5000 rpm, milled, ported and chamber work 706 heads and a different cam

[@swappedoutZ71]

@@richardholdener1727 curious to know if milling ls6 or ls3 heads could see the same tq gains as 5.3 heads

[@swappedoutZ71]

@@richardholdener1727 i went with ported 243s with a smaller 62cc chamber like the 706 head. Should give me good results

[@JesseJames-rg3jz]

Can u put 823 heads on a 5.3

[@richardholdener1727]

no-but the good news is that motor does not need those heads

[@andrewn.3660]

823 vs. 0821

[@VenegasTrucking]

Stock oil pump?

[@richardholdener1727]

yes

[@bryceeakle4509]

What length push rods you running on the 823 heads

[@richardholdener1727]

stock

[@buchohood]

Adapter plates an LS3 Intake on 799 heads?...

[@richardholdener1727]

i tried that-not great

[@mohammedalmamari6662]

Dear @Richard Holdener (Swap car)I have l98 engine Caprice SS 2009 with823 head /manual TR6060 I swap the intake manifold to Ls3 but I need ur suggestion. For DD I NEED CAM that tune as stock at ideal my goal is 500whp max

[@mohammedalmamari6662]

I learned a lot for ur healthy channel. 500 /400/600 lS challenge but still I need ur help to select the right can I'm interested for DD NOT TRUCK it's sleeper Gt86 2017

[@markusgarvey]

A motor refers to something powered by electricity. FYI...

[@richardholdener1727]

thnx-I'll call General Engines or the Ford Engine Company to ask what they think

[@markusgarvey]

@@richardholdener1727 They all fucked up.... 'motor ' Figure 1. An electric motor from an old vacuum cleaner.[1] Figure 2. An electric rotor.[2] An electric motor is a device used to convert electricity into mechanical energy-opposite to an electric generator. They operate using principles of electromagnetism, which shows that a force is applied when an electric current is present in a magnetic field. This force creates a torque on a loop of wire present in the magnetic field, which causes the motor to spin and perform useful work. Motors are used in a wide range of applications, such as fans, power tools, appliances, electric vehicles, and hybrid cars.

[@markusgarvey]

@@richardholdener1727 ...and you should.

[@512kjt]

@@richardholdener1727 BOOM

[@mikeeagle2653]

Love your video much respect. Please stop moving like a robot tho it takes away with what your saying. Thanks.