CAN YOU RUN REC-PORT LS3-STYLE HEADS ON A SMALL BORE 4.8L/5.3L? WILL REC-PORT HEADS EVEN FIT A 4.8L?
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- čas přidán 20. 09. 2023
- CAN I RUN FACTORY REC-PORT HEADS ON A SMALL BORE 4.8L/5.3L? CAN I REPLACE THE 706/862 HEADS ON MY 4.8L/5.3L WITH LY6/LS3 HEADS? WILL MY 4.8L/5.3L MAKE MORE POWER WITH HIGH-FLOW, FACTORY REC-PORT HEADS? HOW MUCH POWER ARE REC PORT HEADS WORTH ON A 4.8L/5.3L? WILL THE REC PORT HEADS EVEN FIT ON THE SMALL-BORE MOTORS? CAN YOU NOTCH THE BLOCK TO MAKE THE REC-PORT HEADS FIT? CHECK OUT THIS VIDEO WHERE I DIVE INTO THE INSTALLATION OF A SET OF FACTORY L92 821 HEADS ON A SMALL BORE 4.8L/5.3L? USING THE SECTIONED ALUMINUM BLOCK FOR VISIBILITY, WE CAN CLEARLY SEE THE INTERFERENCE BETWEEN THE BIG-VALVE 821 HEADS AND THE SMALL BORE 5.3L CYLINDERS. CAN WE MAKE THEM WORK?
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It's good to know others will still experiment, trial and error with things that are important. Like going fast in a car.
Wow you Def answered a question I've had on my mind for the past few years since I've been watching you. Thank you sir. More great information sir.
I Wondered about this swap, Now I know. TY for showin us!
Pro maxx extreme 240 heads a rec port and for 3.800 bore That would be interesting as well. But yeah a 5.3 with a 300 plus cfm head na will be spun to the moon but will be mean on boost
Thanks for your demonstration. Sounds like the same problem that Chevrolet had that similar problem with the 348 and 409. Also the possibility of hot spots in the cylinders at the point of the head gaskets and a little way down the cylinder wall. In other words it would really complicate those arias nearest the valve and the cylinder walls too.
They developed back in the 60s i believe the w-series v8 where they cut “valve reliefs” into the block to run larger valves. Cool motors ahead of its time but went away so soon
Nothing a grinder can't handle
the LS Guru
I am runnin ls7 heads on my stroked ls3, the exh valve was the main issue and we machined it to give 0.030” valve to cyl wall clearance.
Awesome video. Would really like to see a small bore ls3 head test. I’ve got a 383 stroker in my 4th gen f body. Trying not to run a spacer plate for the LSA and pickup some power too na before hand.
Your my hero Richard
I solved this by trading for a 6.2 block. I used LT pistons, milled to fit chamber, and give slight compression boost. PVC MUST be ck'ed. Very tight !
Now this was a damn good video.
man, basic ported old catherdral heads flow over 300cfm...
This would make for an interesting build if combined with that big bore 4.8 idea
I seen those heads on LS1 they machined valves smaller so it fitted. Worked on a turbo application like a bomb. So nothing a bit of thinking outside box can't solve
Well HOW COOL WAS THAT! TY
Edelbrock makes bolt on LS3 style rectangle port head for small bore LS #61319.
Do you know if they would work for an ls1?
@@xanderbrandenburg6628 Yes it will work on LS1 and any other small bore gen 3 like the 4.6, 5.3 and 5.7. GM Performance #19201807 and Promaxx also sell [small bore rectangle port heads]
Promaxx makes a small bore rec port head.
Fly cut the block like a big block chevy and use a copper head gasket so you could notch it for clearance only where it needs it
Not being an ls guy
EXCELLENT video
Pro max has a rec port head that they have put a smaller valve and moved it over to work on the small bore engines. That should work well
and they should send them to Richard!
Nessiceity is Mother of Invention
You so are awesome!
You also have an issue with the cylinder shrouding the valves and disturbing the airflow, so you won't be able to take advantage of all the additional flow anyway. The large-valve, small-bore head may actually give you more or equal flow due to undisturbed, smooth airflow.
More like this! In the shop an not in front of a webcam
A set of custom pistons could resolve some of your problems, domed pistons to bring back compression, then move the rings a little further down the piston to allow for adequate clearancing for the valve pocket. Bada bing bada boom
Or easier to just run a 4" inch bore block!
Hey Richard, I’m doubling up on a reply that says use a 4.000” bore block. 4.000 x 3.267 gives you 328 cu in or 5.4L, which would need to spin 10-11% higher to utilize the airflow of a 6.0. Since you need custom pistons anyway, build the big bore, short stroke LS with 10-12 cc domed pistons and shoot for 7500-8000 power peak. Sounds like a project for you! Inquiring minds want to know!
I’m going to go out on a limb and say yeah grinding it out like that doesn’t seem fine. Also you probably will affect the flow with part of the valve in a pocket like that. Cool video was guessing those heads would be fine. Oh, and that chunk you would have to grind out also adds as the the compression chamber volume.
Hey BBC been doing those notches for years and it picks up power heh
Have you tried the ls3 small bore heads on ls1 or a 5.3? I tried to look. Kinda curious about those heads..
the real whip shit, raised floor 821 heads on a 3.900 bore block with notched bores, might all work out with smaller valve, but the relocated valve centerlines are a bit more challenging to deal with. A 2.050 intake valve, slide the exhaust valve over 60 thou with a offset guide, move the seat weld the chamber and ports up etc but a epoxy filled raised floor 821 style head could be a real screamer on a small bore 3.900 motor
@Richard Holdener I'm over here crying laughing listening to you telling people how bad of an idea to put rec port heads on a small bore it is! LMAO
these rec port heads on a 4.8L is a bad idea
@@richardholdener1727 Is it a straight swap to run Gen4 5.3 heads on a Gen3 block?
Just like the 348/409 Blocks and heads swaps.
You could use lower lift cam with longer duration.
This is handy if you want to rev to 10k. L86 heads should work somewhat better.
I think it can work. Just a little more
I guess I haven't been looking at the basic horsepower per liter of these engines enough to know if the larger bore engines that use the cylinder heads actually make more horsepower per liter.
good vid
Thank yu , helps the what if magic machine shop voodoo
We stuck ls3 head on a bare 5.3 block rolled it look down the bore and started laughing
Could take some off the valves and bore to 3.900. It's not worth the effort though. Going to have to mill too much off the heads or get dome pistons.
Like 396 and the 402 valve placement is critical
Thick head spacer/gasket (+0.5" lol) and a really tall domed piston?
I stuck a rec port 6.2 823 heads on a 5.3 and I thought is wasn’t going to clear but it cleared, but now I’m looking for a 243 cathedrals just to be on the safe side lol
it does not clear
Might even cause a detonation problem too.
You would be LOSING so much air flow from a third of the valve being shrouded to the point of being useless
for sure
Yeah, that is some wicked valve shrouding.
Would it hurt tho, In my youth I put a big bore (12g940) head on my small bore a-series engine. Had to relieve the block in the same way, use the big bore gasket, performance improvement was drastic. Big gains. The overall bigger valve allowed more flow despite the shrouding.
Exhsust vslve doesnt mattet
So if the rec port head can be used on a 6.0 with a 4.000 bore then why should you need a 4.100 gasket to make this all work together?
I feel like you took a little more than necessary out of the cylinder wall up top. I'd like to see how it performs but on a small displacement engine we would have to expect these to perform similar to the 317 heads with maybe a few more horses up top.
Reminds me of a certain quote from Jurassic Park. 😎
If only I was Jeff Goldblum cool
I had to leave the chat to see what you actually did. Your right on with this. If its port volume that is the target. I think it might be better to CNC the SQUARE port pattrrn into a set of cathedral heads. This way youd be usine a maximum size port and valve. Without compromising the block and sleeves. But again this is a massive cost just to see if the SQUARE port is going to give you more horsepower. Hmm. You need someone from the more money than brains to indulge your every whim to test a theory.
There would be some fuckery involved in that for sure given the valve spacing difference.
port volume does not add power
Flycut the deck or top bore for valve clearance. Just like Any 3.0 v6 ford or even a 396 big block chevy.
did that
Mill the head (or buy a head with a smaller chamber), add a thicker head gasket, clearance the cylinder wall, and use a low(er) lift cam. It'll work, but you'd probably just kill the bottom end power. Neat video
milling the head reduces valve to deck clearance
Thicker (thickest you can get) head gasket for LS3 (with it's larger bore at 4.100 or whatever) would mean less of a notch in the cylinder wall. Basically, get the clearance in the gasket. That's where I was going with it... @@richardholdener1727
@@richardholdener1727 use the mill that adds clearance
!
Make it happen
Add boost for the loss of tq
The next big bang. What will fail first? The block where the cylinders are machined for valve clearance or something else?
You know if that cut in the cylinder bore is retained you’re just going to blow a motor instantly right?
They make small bore LS3 heads by Pro Maxx. You can get those or maybe bore it to a 3.9 5.7 piston and see if that works better.
They are meant for min 3.898 bore though
so what we learned is, 6.0 block + 4.8 crank with rec port heads will be the only way to see what a 5.3 engine can do with one of these heads. obviously have to have custom pistons because there will have to be some machine work performed to get that compression ratio back up.
would be interesting to see where the difference is the heads and intake manifold compared to a l33 with the fast intake.
would still love to see a small bore/long stroke 5.3 vs a big bore/short stroke 5.3 with as much of the same parts are possible.
I'm sure one of the magazines did something like that already. They used an LS3 block and a 4.8 litres crank and I think it ended up being something like 5.54 litres.
It made shit loads of power though.
Edit: they dynod it at Westech and it made 607hp!
Gee Richard just angle the valve guides like a boss 9 BBC Cleveland Answer is to just turn up the boost on a cathedral port head Max Wedge and others had notched blocks from the factory but not here
Wonder how much closer a 3.9 bore gets to fitting.
Will the airflow change so much so, that it makes any more power? That is the question!
Could you run a custom piston to give you a little more room, groove out a metal gasket instead of using an oversized one, run whatever cam fits.....then BOOST it to overcome the compression loss and take advantage of the flow you're now making?
if it makes less power na, it makes less under boost
I read the title and said well Richard holding would be the one to be getting the answers... and I wonder what the numbers would be on a stock 3rd gen early or late 2004 5.7 aluminum engine and the one with the revised 241 head and came with a factory LS6 intake I always wondered what LS3 top would do on that... or an LS3 top on the Gen 3 5.7 LS6 243 head... I was wondering recently what an LS3 top would do to either one of those engines approximately
LS3 won't fit a 5.7L bore
Just for the sake of trying to make it work, why not retrofit 5.3 valves into the rec port head. Install new seats for smaller valves but blend the bowls to the smaller valve size. I think it would work this way with notching bores.
blend the bigger bowls to the smaller valves?
Question: So if I wanted to put a 383 rotating assembly in a 4.8/5.3 block, with that bore size could I run those heads and have cylinder wall clearance that I need?
A 383 IS A 4.0 INCH STROKE AND 3.902 BORE
On a positive note at least you can’t drop a valve… 😂
So i guess if you were building 11k rpm motor then it could utilize that extra air flow.
Haha i knew what would happen but they got some big valves in em. Maybe...Off set guides and a smaller exhaust valve would make it work. Lol good looks tho. With the power people can make on other heads would be way more beneficial. With the money you'd spend on getting a good cylinder head guy to do them, not worth it.
You're talkin off set guides, machining them, new valves resized, but still big and good valve job and port. It'd cost, basically a race head at that point. You'll also need to spin that sucker up to take advantage of what you did. If I had some of those heads and a lil money, I could definitely machine them up and get em to fit
Someone needs to try mast motorsports small bore rec port heads
Hey Richard. The gasket is 4.1 to suit the head chamber. So the 5.3 is on 3.780. What about the ls1/6 with 3.903 bore size that is a common oversize used? Just unde .200 difference between them over the 5.3 at .320??? Also what if you run a slightly smaller valve in the rec port head to help clearances. Say .040 smaller valves.
So at .320 that's about 8mm larger than a 5.3 but only 5mm on a 5.7 with a 3.903 bore. Minus another. 040 thats .020 off the inlet and exhaust valve brings it down to 4mm. Quite possibly work with .600 lift.
try it to see
Can we cant the valves a 2-3 degrees without any valvetrain issues and relocate the exhaust so its minimal thickness between the Intake and Exhaust valve??
let me know if you do that
If im not mistaken, that fuelie in the background was in the last episode of Engine Masters.
it has not run in Fuel Injected form yet
@richardholdener1727 what I meant was it was also in the background of EM:)
I'm excited about seeing it run Injected-they did run it with a carb-but it has been there a while and I'm sure appeared behind the scenes
@@richardholdener1727 hell ya!!!!
I love seeing and hearing those impressive little engines!!
Ok so what about a 3.9 bore LS
Offset dowles?
Does this mean you can’t run LSA heads on a 5.3 engine?
STOP FING YELLING AT THE BEGAINING GET OVER ! your videos are great to watch no need for the hype any longer. any head improvement is going to make more power if one wants to put in the work
I YELL FROM BEGAINING TO END
Would the valves from the cathedral port head clear on the rect port? Then you could just install new seats and use rect port.
the bowls would be too big too
Thanks, just put smaller valves in the rec port head...
that requires new seats too
@richardholdener1727 we be cool to make your own small bore Rec port head though ;) then turn it up
Have a happy new year richard
Does anyone know how big a valve could you run in a 706 head on the small bore blocks?
2.0 is what most use
Now my question is, what size bore would it take to fit and run properly? I know a 4 inch will fit, but what about like a 5.7 or even a slight overbore 5.7? I know you're just making a large bore out of a small bore but if you have a 5.3 that you're changing rods and such in anyways would it be worth the bore
a 5.7l bore won't work either-needs to be notched
How much compression will be lost when clearancing for the valves?
All said and done between the chamber size, GASKET BORE SIZE, and block clearancing i think it would be closer to 1.75 or 2 full points of compression loss.
Aren’t there Indy engines where they shorten the stroke of the pistons so they can turn em up to 10k RPM? If you did that in this situation you could lose down low but turn crazy RPM
no-the displacement of the motor is limited by the sanctioning body
@@richardholdener1727 I can’t remember which engine I’m thinking of but they shortened the rods and the heads actually went into the bores. It wasn’t the Chevy big block wedge I’m thinking of it was a engine that was turning 9-10k I think.
At one time when ls was new they said u could make a ls sbc hybrid can u do that with an 96 LT1
Yes, with a motown block.
Otherwise the gen 2 small block chevy and LS dont share a single bolt.
Would it work better if you selected a smaller valve size and fitted correct size seats so the throt size is 90% of the inlet valve and 88% of the exhaust valve before any porting was done so the bowl area only needed the guide needed cleaning up.
no porting
@richardholdener1727 so effectively you install say a 2.08 valve instead of the 821 2.125 valve. Or what ever the throttle size is of the factory casting use that as the 90% percentage of the new valve size.
@richardholdener1727 so say the throat size is 1.8 inches use that as the measurement to calculate out the valve size as if that 1.8 inch was 90% of the valve. That way you don't have to port the throat and only clean up the valve guide in that area.
I think you guys are missing a major point. The exhaust valve has more interference than the intake.
Looking at your display engine... I don't even think they would work on an LS1 5.7L (3.898" bore) Bore that to 3.905", I still think it would be dangerously close to interfering. By what you showed, I see why a 4" bore is the minimum for rec ports.
Those are very large intake valves, so even a 4" bore is not "that big" for it.
4.0 bore fits
@@richardholdener1727good to know. Was thinking of Rex heads for a 6.0!I want to build
I have a 4.8 what are some of the Modifications To Do to the engine to give it some more power.its in a type 3 69 vw wagon c4 corvette suspension manual
cam, intake, heads, headers
@@richardholdener1727 what head and have a Good suggestions on cam shafts
watch the many 4.8l vids I have and pick the power curve you want
@richardholdener1727 thks and thank you for your reply
Would a 4.0 bore clear without notching? The head gasket on the display was for a 4.0 bore?
yes-the factory runs rec ports on 4.0 bore 6.0ls
@@richardholdener1727 Richard, thank you for taking the time out of your life to answer our stupid questions I’m sure I’ll have more questions in the future 😂
Bigger question is can you mill rectangular ports in a cathedral port heads and use Rectangular port intake???? And will it make more power??
You can get adapters to go cath to rec. I think @richardholdener1727 has tested them.
That wouldn’t help the air flow. That just allows people to run stock gm supercharges and intake manifolds
That's why if you milled it if it would help flow rather than adapters. @@BearGrils55
Yes, I was agreeing with you and disagree with the other comment. The adapters won’t help flow, but cutting the cathedral port to a rec would be cool to see.
Would these big valve heads fit on the 3.898 bore?
I think the 3.898 will require notching as well
I’m just wondering how many more test there is that you haven’t done
several
I think people are more likely to take a 799 243 and want an LS3 port
Also what about the promaxx small bore extreme 240cc heads? They come in a 59 and 63cc chamber.
Found em on the website, it says for ls1/2, will they work on a 5.3?
@@foxxrider250r the promaxx small bore will yes. But what about the 821 on ls1 ls6 5.7
@@lcxu1051 I have no idea..you tell me lol
@foxxrider250r the promaxx heads are made for the small bore engine. But they aren't a simple bolt on job from what I have read.
Old dirt track trick cam. Just enough lift to clear, lots of Duration
What about doing this with a 5.7l ls? Or say, a lm3 5.3 bored to 3.903?
needs notching
How can these heads work on a 6.0 with a 4.00 bore when you say they say they hit a 4.01 gasket?
WATCH THE LIVE FEED
As long as we’re on this subject, what are your thoughts on a 2.30” valve in a 4.250” bore?
I have a 2.250 valve on a 4.125 bore (LS7) and it works pretty damn good. A 2.30" valve is a slightly smaller percentage of the diameter of your bore than my setup is.
@@C6Z_Bob
I think the issue is the BBC valve is canted, I’ve heard that much valve will hit…
Have had someone say they ran square ports on a LS1. Which, I am not sure if that happened or not.
they don't fit unless notched
@@richardholdener1727 I wouldn’t imagine but this dude swore. He probably bad a LS2 and didn’t know
Now ya gotta do the 4.8 heads on a 6.2. Lol, just kidding.
I have
Why not just use a carbide fly cutting tool? This way you can get clean cuts
we did
You would lose out on compression, and would not be able to reap the full airflow potential of the head due to shrouding. If they did work those heads would not be a good choice for a hot street combination. Would stick with cathedral ports on the small bore LS.
Would the heads fit a 383 ls Stroker
not on a 3.900 bore
Well they fit a gen 3 6.0 lq9?
yes
Will they fit on a 3.898 in. bore block?
NOT WITOUT NOTCHING
What about a 5.7 ls1/6 bore size?
I thought about the exact same thing. A bore of 3.898 might be the ticket to victory.🤔
Im all for R&D but as you eluded to in your intro; just because you can do something.., should you? Cylinder heads are specifically designed for a specific RPM utilizing a block's bore and stroke. Through engine math and complicated algorithms port sizing, pinch point and valve curtain are determined; all for the purpose of maintaing proper airflow velocity throughout the expected RPM range. Your vids are entertaining and most often there is something to learn. In this video you missed a greater opportunity to teach WHY you shouldnt use those heads on a 4.8/5.3. That missed opportunity was how to qualify size. When is big to big. When is small to small? In other words how do you qualify the size of a port or the size of a cylinder in a block as small, medium, or large as it relates to power output being mild, moderate, or maximum? Those commenters thinking these heads are perfect for a 4.8/5.3 dont understand basic engine theory - only because no one is teaching them.
the big hurdle is will the heads fit, making their size less important since you can't put them on. But size was covered. BTW-Heads and not rpm specific.
I may be nit picking, EDIT, and I certainly dont wanna be the monday morning quarterback - I dont wanna be that guy. Peak Volumetric efficiency makes a port and displacement/RPM specific for its intended purpose; any other displacement comprimises that VE% at that intended RPM and requires other changes, hence my comments on qualifying size relative to peak output. Yes you can mix/match but an emphasis on understanding how the cylinder sees the cylinder head is tantamount if you dont want an engine with mismatched parameters, for its intended use.
You said Rec-Port heads make less power down low. Can you give a ballparkk RPM for where that would be true? I'm currious if there are any use cases where Cathedral is better, or are you talking so low that only internet trools could care?
ON A 6.0L-IT WAS BELOW 4000
Would be WAY better off to just put a shorter stroke in a bigger bore block