Richard Holdener is a gift! This man is doing gods work!

I'm a Ford guy and I still spend my time here.

My takeaway is, if you have an LSanything, put in a cam, add turbo & fuel, and be happy.

Love the work, can't get enough of this stuff

Killer video and test. This is great information seeing my ‘14 caprice came with a 6.0 and 823 heads.

These videos are pure gold. thanks

Doing Gods work here. Thank you Richard

This video answers a lot of my questions, thank you.

I definitely think the added compression had a good bit to do with the low speed power difference. I’ve never really done any high comp LS builds, but back in my Honda days when everyone was building 8-9:1 comp B series to boost I liked to keep mine in the stock VTEC B series compression range and my builds always had more power outside of boost and got better fuel mileage on the street than most everyone else’s builds around me. The added compression helped me get my Turbo online sooner also, but for street cars the difference between a 9:1 and 11-12:1 engine down low was night and day. This is especially noticeable with the B series which make no TQ to speak of so when you can actually drive around shifting at 3500-4500 while still accelerating nicely up to cruising speed it’s a blessing lol.

Richard is the man with all the dyno knowledge!

Stay who you are richard your awesome man so informational and so humble

Awesome information I'm wanting to do a mild 6.0 in my 92 s10 my aim is to make it fun, and in memory of my grandpa who passed away January 4th 2021 to kidney failure. When I was 7 him and my uncle built a Datsun mini truck with a Datsun 510 front clip with a Toyota 296 (hemi v8) this was hopsing featured in a issue of mini trucking magazine. All of your information is really helping me draw out a plan on what I want to build I'll more then likely start it with a junkyard 6.0 from something like a ss trailblazer or wrecked 2005-2006 pontiac gto

Ok so from what I've gathered from lots of people the original cathedral port design was implemented to promote low speed velocity and chamber filling while also out performing previous sbc heads. As designs changed and volumes increased a need arose for more upper rpm flow, hence the change and evolution of gm cylinder heads. Now we've all seen good ported heads(stock and aftermarket) keep up with and even beat quite a few square port heads. Now really good ported factory heads from gm back to back generally the square port are just superior....except in the lower lift numbers, not always but mostly and often not by much. However you can get factory gm ls3 style heads above 370 cfm with the right porting job, repeatable all day long amd that's something the ls1 style castings can't do, at least stock heads. Really though Richard obviously is right, if you're boosting any of these heads within reasonable boundaries, are perfect. Yes the curves might be rather different and one will probably promote more high rpm power nut like he said a 750hp turbo(etc) is still limited by how much power it can make and response is a matter of choosing the right setup/size and a/r. Similar to a blower of any design, though in this instance you may notice a bigger variance in power curves but not necessarily peak power. Rung what ya brung boys!

I have a set of 317 heads in my garage right now thanks Richard

Thanks Richard.

Hi Richard, thank you for all of the great videos. I know this may not be too popular anyway you could do something on the 3.3 lambda platform

So here’s my experience with this similar setup. I have a 6.0 lq4 with a 228r TSP cam. I had 243 heads and an ls6 intake. I recently installed 823 heads and an LSA blower. Obviously the blower adds airflow as soon as the vacuum drops and the bypass valve closes, but I noticed that I needed to add about 20% to the lower rpm, high vacuum area of my VE table. To me that means there is roughly 20% more airflow even down low and not at WOT. I definitely think the compression bump is the only reason that the small chamber, cathedral port heads keep up with the rec port heads below 4,000 rpm.

Comparing the port volumes would be interesting but I think it is static compression that is the difference and what that means is the 6.2 needs more compression. I don't think the cam is too big for an Enginemasters type build but it's close.

Thanks Richard!!!!

I had 317 heads on my 6.0, I thought of going Rec port heads but decided on ported and polished 243 heads. One of the reasons was the cam I decided to run probably wouldn’t take advantage of the extra flow if any on the rec port head vs a ported 243 head and a mid 220s cam. The bump in compression was another reason, that and in 2012 it was harder to track down a manifold.

It's the compression. That's my statement on the issue and test. Rec ports are race level stuff. Cool test.

great stuff - but I am more interested in 2K to 4K as almost all (non-race) vehicles will operate in this range. I am thinking with what I am seeing a real stump puller is there also.

So I was thinking about using the last few years of port-injected truck intakes. They have similar designs and the only real difference comes down to the port since some are for the cathedral and some for rec ports. What about doing a head test on the smaller 4.8 and 5.3 to see what the extra compression and/or airflow will do for them. Maybe try the long-stroke 5.3 and the short-stroke 5.3 to see what that does for power with the different combinations. Another good video. Keep up the good work.

I'd like to see ported cathedral heads against stock rec port heads for N/A. The low RPM torque numbers are better for street applications. Consequently, what would milled rec port heads (no porting) do to the low RPM torque values? -match or exceed the stock cathedral head torque #'s ?

I’m just using ported 799s on my 403. 330 cfm and cathedral port, with small chambers! With a 225/232 114 cam, I think my single cab will make a nice daily driver. I’m hoping it makes 575 at the fw with a nice torque curve!

I think it's all about static compression, obviously flow helps but not as much as compression until 4500+rpm. That's why I put 1.6"/2.0" valves into ported 862 heads so I can have my cake and eat it too. Ls3 heads are only good for boost, strokers, and guys with massive cams in lightweight vehicles.

Richard, can you do more Honda engine stuff? Like b16 vs b18 vs d series all with and without boost and various bolt ons and cam specs maybe throw in a low displacement k series for comparison like you do with the big blocks and ls

I'll start with, Awesome vid, I've been wondering the differences! and good info to know. with that being said, the best advice I could possibly tell anyone that is trying to decide what to do with their engine they have sitting on that engine stand is.... just put it together. the more time you waste trying to decide what is best, is less time you have to spend actually enjoying the engine in your project. I've seen far to many projects go unfinished because everyone is always chasing that oh mighty hp number. when they constantly battle themselves swapping out a set of stock heads with another set of stock heads. then they're changing this and that, and changing this and since I'm in here I might as well do this.... its a deep rabbit hole to go down. I too was in that rabbit hole with my nitrous 6.0. till my friends said... "just spray more and enjoy it" lol

A smaller port volume of air will get moving faster, right? Good for low end but chokes up top.

😊I love this guy!!!!

I am building a 5.3 for a 57 Chevy that is a quasi- daily driver built for longevity but the occasional "spirited" acceleration. I have stock rotating assembly and rebuilt 706 heads. Now to select a cam.

Thanks for the videos ! Question when is the vortec 4200 coming back ?

Right on

GM knows what works!

built a 5.3 from an ATK HP 97 longblock to replace my hydrolocked LS1..it came with a set of 243 heads....Score! runs like a scalded cat lol

I would GUESS port design because of only helping in the low rpm area. Once it reaches the limits of less total flow it loses it's advantage and leans toward just needing more volume.

Discharge coefficient is higher on the small valve 706s that’s the reason for more torque

Would be nice if you did this on the lq4, be nice to see what I could get from my basic set up, have 317s that were rebuild with springs, im sure im leaving n/a power on the table

cathedrals have a revision problem in the large displacement , the test on a 5.3 would be great as there's probably guys wondering if recs. would be worth it on the 5.3. your vids are great and like no other.

It’s pretty obvious the compression bump was responsible for most the low rpm power gains. It’s why the 706 (smallest chamber) had the biggest gains below 4k and the 799 (2nd smallest chamber) had the 2nd highest gain. The 317 flows similar to a 799 and there was minimal difference with the LS3 head down low.

Richard, get out of my head! I've been watching your head videos most of the day. 🤣 Hey what ever became of the slant 6?

I have a VortecMAX and from what I’ve gathered, the 6.0 L76 with the 823 heads, is a really good combination. If that’s the case, is a good tune/management system, headers, and a cam all that’s holding me back from a good 500-550hp engine? I remember the mentioning that the LS3 intake and the truck intake flow virtually the same. If so, I’m very excited to put some more power down in the truck.

I wonder what the Ly6 would make with flat top pistons and some milling

Low in tourqe definitely the smaller combustion size makes up the difference.

Sure hope the 823 heads do well for turbo since that's what I built for mine xD (from other tests it out performed)

What is a good setup for drag and 1/4 mile racing? Give up low end torque for higher hp at high rpm?

Hey Richard. Have you ever done a compression vs octane test? Like even 87 regular unleaded and say 11:1 compression. Or say a 9.5:1 motor vs higher compression with the same combo?

If your installing a cam on a 6.0 or 6.2 and are planning on revving it past 6000rpm the rectangle port heads are the way to go it will need a 3000rpm or more stall converter and 3.73-4.10 gears for it to shine but if your looking for more torque off idle to 3500rpm with a tighter converter and 3.20-3.42 gears in a heavy truck the cathedral ports heads will be good would be my take hard to beat rectangle port heads on a LS above 4000rpm unless your wanting to invest in something like AFR 260cc mongoose heads but look to spend 2600 dollars plus for a set complete

I want to see the gains from a set of ported 706/862 heads with bigger intake valves, from the results you have here.

I wonder if the cathedral port heads flow more at .200 to .400 lift range thus making and more bottoms end power or how much could be due to Intake runner design sense it’s impossible to a comparison of just the heads.

Great channel great info but little to no info on the 5.7 … frustrating as I haven’t found another channel performing all the tests you do and yet rarely is the 5.7 ever in the mix. Yeah I get it junk yards are full of the motors you run but the guys with the 5.7 are left out or a maybe that will work. Would love to see more interest in LS1 & LS6… thx

Hey Richard do you think you could do a 2000 hp combination ?? I would like to see that 👍 and what engine would you choose to use for that test 🤔?

Gday from Australia,ive been an avid watcher of this awesome feed,this may sound odd or even damn strange,what about de-stroking these engines,from the 6.2 backwards,start from the 6.2 and to the 6.0,5.3,maybe the 4.8 block,just a simple question,have a great day today

@9:25 mark the appearance of this graph should forever settle the question whether the LS rec port heads are indeed superior to the LS cathedral port heads. Here you have the same LS3 test motor, same healthy Comp Cam, same valve spring upgrade and both with their respective optimized "street" intake manifolds (stock LS3 and FAST cathedral). From 3000 RPMs to 4100 RPMs the power and torque are identical and we can safely assume that this the case below 3000 RPMs. Then at 4100 RPMs the rec port just splits and decisively just RUNS AWAY from the cathedrals in both power and torque by a healthy margin and putting a massive increase in area under the curve. Why hasn't anybody pointed this out in the comments???

Yesssss….

Same difference between a dual plane intake compared to a short runner intake. Low speed torque compared to high end horsepower.

Do you have reviews on the ls3 Holley 300-679 intakes

Id like to 706 heads on the 6.2l just to see the torque and hp #s bc of the smaller combustion chamber

To me. If you got a truck that needs the torque for towing. 6.0 with a 706 and some valve work and send it all day long. It'll love 2000 rpm to 6500 and that's where it'll live. if you are like me and want to make a truck more useless (4/6 flip and stepside and 3200 stall) I think a full ls3 top end kit with some decked 823 heads would be the way to go. Near 10:1 compression on a 23x/23x cam and it'll make 450 horse all day on pump gas... Then we add nitrous! 10 second truck?

Is this a stock 706 head? 513 is lots of frolicking horses from a really basic build. In one intake shootout you did a 5.3l longblock made just under 480hp with a Dorman ls2 from memory.

Should the smaller combustion chamber heads be tested with a slightly thicker head gasket to equalize the compression ratio between the heads?

If you milled the 243/799 to the same cc as the 706, would you get that low end power back and make the same or better all thru the curve with the milled 799 than you would with stock 706?

I would have like to have seen 799 heads on the 6.2. And maybe even ported 799s

I'm running a l33 5.3 I bought from someone who wanted the factory 799 heads off of it I used a set of 706 heads with the BTR stage 1 truck cam it's in an 03 Silverado that I daily drive in the summer I have always wondered if it would have made more power with the factory 799 heads but for a truck that spends most of its time between 2 & 5k rpms I feel like the 706 heads were a better choice or atleast equal to the 799 heads but will the power levels between the heads hold true on a 5.3 vs the 6.0 obviously lower power numbers but will the 706 still make a little more power from 2k to 5k than the 799 head does?

I'm going to 383 my 5.3 and port my 706 heads and ad a torkey cam ,I believe that it would pull my Z71 and cartrailer quit well.

I don't know if you had a chance to cc them, but I read the 862 heads are larger than the 706 heads, just curious if you noticed that. I have the cast iron 6L heads with the 2" valve in them. I have some 862 heads, is it worth the machine shop money to open up the valve seats for the 2" valves? I plan to deshroud the valves on the 862 no matter what I do. The more I study the LS the more it seems that the best bang for the buck is to throw money at a turbo setup. Perhaps a cam/springs also. But everything else is arguing 20HP for what could be $500 or more in extra parts cost.

I believe the 317 and 799/243 heads share the same valves and ports and the only difference is the combustion chamber size? If that's the case then it has to be the static CR.

Ported 706/ 862 heads

I wish you would take a pair of 317 heads, have them milled to where the chambers are comparable to a 706/799 head and test them. 317 heads are dirt cheap but a mill job may wake them up. How about it Richard.......

There is still a lot of "mystery and confusion" surrounding the rec port heads. The port size isn't actually as big as listed. The ports are smaller toward the valve. If an intake is just an extension of the head, then the head port at the intake is just an extension of the port at the valve. They don't have the low speed turbulence issues that normal big port heads have. I would like to see some tricks performed to each head and see how they compare. Ported 243 vs some worked rec ports, bowl work, offset dowel, etc.

👍💪

Richard there are a few videos of this guy putting ls heads on a 351 w can you try that .

The moment I learned ls3 heads could be run on a cathedral 6.0 was the moment I said f cathedral vs rec heads. Lol cams are cams. Brings in the intake. Now one of ems obsolete. (In my understanding

Whats the best heads and intake for 6.0 to get about 500hp...I have a 6.2 camshaft. And could I run a 96 4l60e behind it?

Port Cross sectional area will greatly affect where in the rpm range torque is made. Static Compression ratio will also affect torque and where its made. Valve size / valve curtain area will also weigh in on how well an engine makes torque at low rpm. The 706 head has a small combustion chamber, small port cross section and small valves. The port reaches an effective velocity at a low engine rpm for good cylinder filling. The small valves create an efficient curtain area for the airflow at lower engine rpm. Combined with small combustion chamber to make use of the low rpm cylinder filling where dynamic compression from cam timing isn’t really in affect torque torque production is high but power will suffer at high rpm. That the exact difference between the 706 head and the 823 head.

Has to be the compression.. send out a set of 706 heads for porting. It will be a better head than the rec port.. 😃

I wonder about these on a 4.8 im currently building since I'm new to the LS game.

How much boost/timing would you run on a turbo 5.3 93oct no meth gapped rings .026-.028 just a general area, im shooting for 14psi 14* maximum maybe 16psi 12*.

But Richard what if you mill the LS3 head to 59cc

So what's the compression ratio of a 6.0 with 706 heads? Too much to run with a "torque" cam on the street with 89 octane I'm guessing?

Give me Compression over Flow, But I'll also take Compression and flow.

I have 243s and a fast 102 intake on my LS2. Will swapping out to a factory LS3 rec port head and LS3 intake make more power?

Would I be correct in thinking the more NA power the quicker the turbo spool up time?

I have a LQ4 6.0 Suburban 2500. I use it to tow a 8000lb trailer. I was thinking about adding a pair of 862 heads (already own) with a cam and exhaust. How big (or small) of a cam can I run? Every two years I would have to put stock exhaust back on to Smog the vehicle. I like the BTR Stage 2 V2 or the BTR Truck Norris cam. Will those pass CA smog with Stock exhaust?

I say it's static compression to answer ur question. But here's a question, on a 5.3 and 6.0, what head would be best for N20? And how much of a power gain on a 300 shot? Be interested to see.

Is there any graphs that show lower rpm more suited for towing 1500-4000 rpm

Promaxx do a rectangle head for 4.8 to 5.7 i wanna see if there legit

Super off topic but I found out today JLP offers a 4.415 in stroke modular crank to stroke a 5.4L v8 into a 5.7. Combine that with a 3.605 big bore sleeve kit from darton, you can effectively stretch the 5.4 a 6.0L dohc mod motor. With the ability to bolt coyote manifolds onto a 5.4 4v via adapters, we now have the ability to compete in displacement with the LS crowd all while boasting 4 cams and tons of airflow! Thats a test I want to see, 6.0 ls vs 6.0 4v mod motor

Trying to upgrade my shop truck, pull trailers. I have a 6.2 engine. The truck was originally 5.3. Does anyone know if using the 317 on the 6.2 will make the torque ALOT better for my application than the rec port head? How much would I lose at the top with a stock stall cam?

If I am using my 317 heads that came on my LQ4 can mill the heads and run flat tops to get compression up without changing rod length?

Where’s the 706 heads on a ls3 vs 317 heads on ls3 ? Did I over look it or was I’m not tested ?

I’d like to point something out. If a fast intake makes the same as the ls3, why not use a fast intake on the cathedral setup instead of the dorman? It’ll close the gap because the ls3 intake is superior to the ls2 dorman.

hey richard i want to buy a 6.0l short block from the dealer which year should i go after

if not because of compression then I'm going to say port volume.

Time to do a 4 litre Jeep on boost!!

So, I commented on LQ4 in a past video that made 524hp, but you managed to get 584 outta this. Is it possible to do the ly6 Pistons or ls3 Pistons, do the 5.3 heads and get this same horsepower with the same cam and all. I know 600hp is hard to get with lq4 but is Pistons a way to go also?

I have a 2004 lq4 6L in a three-quarter ton van. Any of you guys can recommend any performance mods without tearing the motor apart or changing the cam? He mentions the Trailblazer SS manifold, do you think that would make any difference on a stock lq4 especially without hurting the bottom and? Or anything else that could be done?

Hey Richard, what about 821 heads?

There’s a Reason why they call cathedral heads “torque ports.” Port velocity.

Also the whole “rec port cam/cath port cam” thing is so silly; valve events are valve events lol.