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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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Richard Holdener

Richard Holdener

11 ай бұрын

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?

Пікірлер: 236
@DillonAuto
@DillonAuto 11 ай бұрын
It's good to know others will still experiment, trial and error with things that are important. Like going fast in a car.
@SnowAmbassodors
@SnowAmbassodors Ай бұрын
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
@loundclear9279
@loundclear9279 11 ай бұрын
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
@bishop94z
@bishop94z 12 минут бұрын
That’s a tough one. After machining the top of the cylinders, a custom low lift grind, maybe a replica of the ramjet 350 cam specs but for an LS (431/.451 196/206 @ .050 109LSA). Might be good for a high boost setup with an HO 5.3 🐌
@davidreed6070
@davidreed6070 11 ай бұрын
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
@yepyep340
@yepyep340 11 ай бұрын
and they should send them to Richard!
@peted5217
@peted5217 11 ай бұрын
Nessiceity is Mother of Invention
@Sir.VicsMasher
@Sir.VicsMasher 11 ай бұрын
Edelbrock makes bolt on LS3 style rectangle port head for small bore LS #61319.
@xanderbrandenburg6628
@xanderbrandenburg6628 2 ай бұрын
Do you know if they would work for an ls1?
@Sir.VicsMasher
@Sir.VicsMasher 2 ай бұрын
@@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]
@stellingbanjodude
@stellingbanjodude 11 ай бұрын
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
@horsefly1020
@horsefly1020 11 ай бұрын
Or easier to just run a 4" inch bore block!
@bdugle1
@bdugle1 11 ай бұрын
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!
@Nafskie
@Nafskie 3 ай бұрын
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.
@mikeruthen6236
@mikeruthen6236 2 ай бұрын
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
@peted5217
@peted5217 11 ай бұрын
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 !
@GrandPitoVic
@GrandPitoVic 10 ай бұрын
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.
@lynndragoman2454
@lynndragoman2454 11 ай бұрын
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
@kimmorrison9169
@kimmorrison9169 11 ай бұрын
I Wondered about this swap, Now I know. TY for showin us!
@Airman..
@Airman.. 11 ай бұрын
the LS Guru
@mariotillery8459
@mariotillery8459 3 ай бұрын
Just like the 348/409 Blocks and heads swaps.
@realazliving
@realazliving 11 ай бұрын
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.
@ShawnGilbert1967
@ShawnGilbert1967 7 ай бұрын
Hey BBC been doing those notches for years and it picks up power heh
@youritake8618
@youritake8618 11 ай бұрын
This would make for an interesting build if combined with that big bore 4.8 idea
@natricjol
@natricjol 10 ай бұрын
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.
@jarrusjenkins
@jarrusjenkins 10 ай бұрын
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!
@seancollins9745
@seancollins9745 11 ай бұрын
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
@bobjensen7136
@bobjensen7136 10 ай бұрын
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.
@SentinelPrime13
@SentinelPrime13 11 ай бұрын
Promaxx makes a small bore rec port head.
@Stevesbe
@Stevesbe 10 ай бұрын
Nothing a grinder can't handle
@anthonyrowland9072
@anthonyrowland9072 11 ай бұрын
man, basic ported old catherdral heads flow over 300cfm...
@SDPP992
@SDPP992 3 ай бұрын
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
@richardholdener1727
@richardholdener1727 3 ай бұрын
it does not clear
@sstevocamaro
@sstevocamaro 10 ай бұрын
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.
@shaadydog1
@shaadydog1 10 ай бұрын
They are meant for min 3.898 bore though
@Turbogto_guy
@Turbogto_guy 11 ай бұрын
Now this was a damn good video.
@lelandlewis7207
@lelandlewis7207 10 ай бұрын
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.
@brunothinkshecan7305
@brunothinkshecan7305 11 ай бұрын
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?
@taylorscott9785
@taylorscott9785 5 ай бұрын
You know if that cut in the cylinder bore is retained you’re just going to blow a motor instantly right?
@josiahpaynter6890
@josiahpaynter6890 11 ай бұрын
More like this! In the shop an not in front of a webcam
@Einimas
@Einimas 11 ай бұрын
You could use lower lift cam with longer duration.
@steveyoutube1709
@steveyoutube1709 11 ай бұрын
Not being an ls guy EXCELLENT video
@jaydubb71
@jaydubb71 11 ай бұрын
@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
@richardholdener1727
@richardholdener1727 10 ай бұрын
these rec port heads on a 4.8L is a bad idea
@Projekt5.3
@Projekt5.3 6 ай бұрын
​@@richardholdener1727 Is it a straight swap to run Gen4 5.3 heads on a Gen3 block?
@Freedomishere-im6ug
@Freedomishere-im6ug 10 ай бұрын
We stuck ls3 head on a bare 5.3 block rolled it look down the bore and started laughing
@barryhuddlestun3098
@barryhuddlestun3098 11 ай бұрын
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.
@rustysausage69
@rustysausage69 11 ай бұрын
There would be some fuckery involved in that for sure given the valve spacing difference.
@richardholdener1727
@richardholdener1727 10 ай бұрын
port volume does not add power
@paulriceman3669
@paulriceman3669 9 ай бұрын
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.
@Whosurdaddy71
@Whosurdaddy71 11 ай бұрын
I think it can work. Just a little more
@Crysmatic
@Crysmatic 10 ай бұрын
This is handy if you want to rev to 10k. L86 heads should work somewhat better.
@scotttimpany2845
@scotttimpany2845 11 ай бұрын
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
@richardholdener1727
@richardholdener1727 10 ай бұрын
milling the head reduces valve to deck clearance
@scotttimpany2845
@scotttimpany2845 10 ай бұрын
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
@eflanagan1921
@eflanagan1921 10 ай бұрын
@@richardholdener1727 use the mill that adds clearance !
@Mike-xt2ot
@Mike-xt2ot 11 ай бұрын
Flycut the deck or top bore for valve clearance. Just like Any 3.0 v6 ford or even a 396 big block chevy.
@richardholdener1727
@richardholdener1727 10 ай бұрын
did that
@dreece2000
@dreece2000 4 ай бұрын
Your my hero Richard
@The_Cronan
@The_Cronan 10 ай бұрын
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.
@richardholdener1727
@richardholdener1727 10 ай бұрын
blend the bigger bowls to the smaller valves?
@yepyep340
@yepyep340 11 ай бұрын
Well HOW COOL WAS THAT! TY
@ShawnGilbert1967
@ShawnGilbert1967 7 ай бұрын
Thanks, just put smaller valves in the rec port head...
@richardholdener1727
@richardholdener1727 7 ай бұрын
that requires new seats too
@ShawnGilbert1967
@ShawnGilbert1967 7 ай бұрын
@richardholdener1727 we be cool to make your own small bore Rec port head though ;) then turn it up Have a happy new year richard
@scotthultin7769
@scotthultin7769 10 ай бұрын
Like 396 and the 402 valve placement is critical
@jamesanderson4515
@jamesanderson4515 9 ай бұрын
Have you tried the ls3 small bore heads on ls1 or a 5.3? I tried to look. Kinda curious about those heads..
@kumakaroshi117
@kumakaroshi117 8 ай бұрын
Thank yu , helps the what if magic machine shop voodoo
@jonadkins9339
@jonadkins9339 11 ай бұрын
Wonder how much closer a 3.9 bore gets to fitting.
@jonwaterbury3312
@jonwaterbury3312 11 ай бұрын
Will the airflow change so much so, that it makes any more power? That is the question!
@3800TURBO
@3800TURBO 11 ай бұрын
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.
@JudgeMeNotLeMans
@JudgeMeNotLeMans 11 ай бұрын
Might even cause a detonation problem too.
@michaelblacktree
@michaelblacktree 11 ай бұрын
Reminds me of a certain quote from Jurassic Park. 😎
@richardholdener1727
@richardholdener1727 11 ай бұрын
If only I was Jeff Goldblum cool
@jmflournoy386
@jmflournoy386 11 ай бұрын
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
@shawnbins203
@shawnbins203 11 ай бұрын
You would be LOSING so much air flow from a third of the valve being shrouded to the point of being useless
@vornice7604
@vornice7604 11 ай бұрын
for sure
@michaelblacktree
@michaelblacktree 11 ай бұрын
Yeah, that is some wicked valve shrouding.
@denisohbrien
@denisohbrien 11 ай бұрын
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.
@ryangulley2051
@ryangulley2051 8 ай бұрын
Exhsust vslve doesnt mattet
@OldDirtGuy
@OldDirtGuy 11 ай бұрын
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.
@Guns_N_Gears
@Guns_N_Gears 10 ай бұрын
If im not mistaken, that fuelie in the background was in the last episode of Engine Masters.
@richardholdener1727
@richardholdener1727 10 ай бұрын
it has not run in Fuel Injected form yet
@Guns_N_Gears
@Guns_N_Gears 10 ай бұрын
@richardholdener1727 what I meant was it was also in the background of EM:)
@richardholdener1727
@richardholdener1727 10 ай бұрын
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
@Guns_N_Gears
@Guns_N_Gears 10 ай бұрын
@@richardholdener1727 hell ya!!!! I love seeing and hearing those impressive little engines!!
@bluecollarhotrods9781
@bluecollarhotrods9781 11 ай бұрын
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.
@dennisrobinson8008
@dennisrobinson8008 11 ай бұрын
Those are very large intake valves, so even a 4" bore is not "that big" for it.
@richardholdener1727
@richardholdener1727 11 ай бұрын
4.0 bore fits
@theshark2804
@theshark2804 10 ай бұрын
@@richardholdener1727good to know. Was thinking of Rex heads for a 6.0!I want to build
@HotGritz910
@HotGritz910 9 ай бұрын
So i guess if you were building 11k rpm motor then it could utilize that extra air flow.
@billybadass411thefirst9
@billybadass411thefirst9 11 ай бұрын
You so are awesome!
@fredlogan3849
@fredlogan3849 11 ай бұрын
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
@richardholdener1727
@richardholdener1727 10 ай бұрын
I YELL FROM BEGAINING TO END
@jamesanderson4515
@jamesanderson4515 9 ай бұрын
On a positive note at least you can’t drop a valve… 😂
@christophershafer5615
@christophershafer5615 11 ай бұрын
Thick head spacer/gasket (+0.5" lol) and a really tall domed piston?
@Mike-yq7ce
@Mike-yq7ce 11 ай бұрын
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.
@larryw5429
@larryw5429 11 ай бұрын
Bigger question is can you mill rectangular ports in a cathedral port heads and use Rectangular port intake???? And will it make more power??
@jgilbert4756
@jgilbert4756 11 ай бұрын
You can get adapters to go cath to rec. I think @richardholdener1727 has tested them.
@BearGrils55
@BearGrils55 11 ай бұрын
That wouldn’t help the air flow. That just allows people to run stock gm supercharges and intake manifolds
@larryw5429
@larryw5429 11 ай бұрын
That's why if you milled it if it would help flow rather than adapters. @@BearGrils55
@BearGrils55
@BearGrils55 11 ай бұрын
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.
@kevinshasteen5682
@kevinshasteen5682 8 ай бұрын
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.
@richardholdener1727
@richardholdener1727 8 ай бұрын
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.
@kevinshasteen5682
@kevinshasteen5682 8 ай бұрын
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.
@BrockGrimes
@BrockGrimes 10 ай бұрын
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?
@richardholdener1727
@richardholdener1727 10 ай бұрын
if it makes less power na, it makes less under boost
@shawnlibby675
@shawnlibby675 10 ай бұрын
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
@richardholdener1727
@richardholdener1727 10 ай бұрын
LS3 won't fit a 5.7L bore
@slopoke22
@slopoke22 11 ай бұрын
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.
@slopoke22
@slopoke22 11 ай бұрын
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
@lcxu1051
@lcxu1051 11 ай бұрын
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.
@richardholdener1727
@richardholdener1727 11 ай бұрын
no porting
@lcxu1051
@lcxu1051 11 ай бұрын
@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.
@lcxu1051
@lcxu1051 11 ай бұрын
@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.
@travisgilbertson9946
@travisgilbertson9946 8 ай бұрын
I think you guys are missing a major point. The exhaust valve has more interference than the intake.
@AndyR1982
@AndyR1982 11 ай бұрын
Old dirt track trick cam. Just enough lift to clear, lots of Duration
@DavieJones_Lockr
@DavieJones_Lockr 11 ай бұрын
I think people are more likely to take a 799 243 and want an LS3 port
@sethbaker5899
@sethbaker5899 10 ай бұрын
Someone needs to try mast motorsports small bore rec port heads
@freyja4954
@freyja4954 10 ай бұрын
Why not just use a carbide fly cutting tool? This way you can get clean cuts
@richardholdener1727
@richardholdener1727 10 ай бұрын
we did
@coboscustoms4342
@coboscustoms4342 11 ай бұрын
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.
@kyle8380
@kyle8380 10 ай бұрын
Would the valves from the cathedral port head clear on the rect port? Then you could just install new seats and use rect port.
@richardholdener1727
@richardholdener1727 10 ай бұрын
the bowls would be too big too
@mickmagnetta6264
@mickmagnetta6264 11 ай бұрын
good vid
@kylewest100
@kylewest100 10 ай бұрын
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
@richardholdener1727
@richardholdener1727 10 ай бұрын
no-the displacement of the motor is limited by the sanctioning body
@kylewest100
@kylewest100 10 ай бұрын
@@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.
@adanhuizar7219
@adanhuizar7219 8 күн бұрын
Hello Richard good morning,by any chance do you know if 799 heads are compatible with LR4 engine 4.8 stage 2 cam. thanks for your videos by the way
@richardholdener1727
@richardholdener1727 8 күн бұрын
yes-the factory used 799 heads on gen 4 4.8Ls-but I would pick 706/862 heads for a 4.8L
@dreece2000
@dreece2000 4 ай бұрын
I’m just wondering how many more test there is that you haven’t done
@richardholdener1727
@richardholdener1727 4 ай бұрын
several
@ericwilson2585
@ericwilson2585 11 ай бұрын
Yeah I wouldnt try something like that....
@mw2freak203
@mw2freak203 2 ай бұрын
Does this mean you can’t run LSA heads on a 5.3 engine?
@NateLarsonTheNetNinja
@NateLarsonTheNetNinja 11 ай бұрын
I'm weird. I did the opposite and I'm using cathedral port heads on a 4.065" bore. But... I got 12.6:1 compression, and over 600hp out of it NA... 🙂
@7000U9ZHIFT
@7000U9ZHIFT 10 ай бұрын
I was thinking about doing this on my 6.2 ls3 block aswell
@NateLarsonTheNetNinja
@NateLarsonTheNetNinja 10 ай бұрын
@@7000U9ZHIFT In my case, I wanted to maximize NA performance for drag racing. So as much compression and RPM as I could get. I had a set of 799 heads that had been CNC ported by PRC, so I had a machine shop shave them to 59cc and do a valve job (the guides were shot), and port matched a Hi-Ram intake. I don't have A to B results vs a similar rec port build, but I'm happy with the results. Runs 10.40's at 129mph at 3000' DA in a 3000lb car. Shifts at 7000rpm, and crosses the 1/4 mile mark at 7300 at that altitude. The 600+ number is admittedly an estimate based on ET since I've never bothered to put it on a dyno.
@ericwilson2585
@ericwilson2585 11 ай бұрын
Now ya gotta do the 4.8 heads on a 6.2. Lol, just kidding.
@richardholdener1727
@richardholdener1727 11 ай бұрын
I have
@lcxu1051
@lcxu1051 8 ай бұрын
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.
@lcxu1051
@lcxu1051 8 ай бұрын
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.
@richardholdener1727
@richardholdener1727 8 ай бұрын
try it to see
@bosqueboys
@bosqueboys 11 ай бұрын
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?
@richardholdener1727
@richardholdener1727 11 ай бұрын
WATCH THE LIVE FEED
@lcxu1051
@lcxu1051 11 ай бұрын
Also what about the promaxx small bore extreme 240cc heads? They come in a 59 and 63cc chamber.
@foxxrider250r
@foxxrider250r 11 ай бұрын
Found em on the website, it says for ls1/2, will they work on a 5.3?
@lcxu1051
@lcxu1051 11 ай бұрын
@@foxxrider250r the promaxx small bore will yes. But what about the 821 on ls1 ls6 5.7
@foxxrider250r
@foxxrider250r 11 ай бұрын
@@lcxu1051 I have no idea..you tell me lol
@lcxu1051
@lcxu1051 10 ай бұрын
@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.
@lazylizard6532
@lazylizard6532 11 ай бұрын
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?
@richardholdener1727
@richardholdener1727 11 ай бұрын
ON A 6.0L-IT WAS BELOW 4000
@guntherdadson5046
@guntherdadson5046 11 ай бұрын
Ok so what about a 3.9 bore LS
@Wilson-kd2sl
@Wilson-kd2sl 11 ай бұрын
Would be WAY better off to just put a shorter stroke in a bigger bore block
@Ferretts89
@Ferretts89 10 ай бұрын
So, has anyone heard of L92 heads?
@richardholdener1727
@richardholdener1727 10 ай бұрын
yes
@jimlathrop8603
@jimlathrop8603 10 ай бұрын
Does anyone know how big a valve could you run in a 706 head on the small bore blocks?
@richardholdener1727
@richardholdener1727 10 ай бұрын
2.0 is what most use
@christopherhill-hn4kd
@christopherhill-hn4kd 9 ай бұрын
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?
@richardholdener1727
@richardholdener1727 9 ай бұрын
A 383 IS A 4.0 INCH STROKE AND 3.902 BORE
@tysonrojas5477
@tysonrojas5477 10 ай бұрын
Turbo it problem solved
@hondatech5000
@hondatech5000 11 ай бұрын
😢
@ZONES89RS
@ZONES89RS 11 ай бұрын
Have had someone say they ran square ports on a LS1. Which, I am not sure if that happened or not.
@richardholdener1727
@richardholdener1727 10 ай бұрын
they don't fit unless notched
@ZONES89RS
@ZONES89RS 10 ай бұрын
@@richardholdener1727 I wouldn’t imagine but this dude swore. He probably bad a LS2 and didn’t know
@The_Kman
@The_Kman 11 ай бұрын
How much compression will be lost when clearancing for the valves?
@rustysausage69
@rustysausage69 11 ай бұрын
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.
@shaadydog1
@shaadydog1 10 ай бұрын
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??
@richardholdener1727
@richardholdener1727 10 ай бұрын
let me know if you do that
@eewheeler29
@eewheeler29 11 ай бұрын
At one time when ls was new they said u could make a ls sbc hybrid can u do that with an 96 LT1
@rustysausage69
@rustysausage69 11 ай бұрын
Yes, with a motown block. Otherwise the gen 2 small block chevy and LS dont share a single bolt.
@aaronsitz5168
@aaronsitz5168 11 ай бұрын
Wts up with that sbc in the background all painted up
@richardholdener1727
@richardholdener1727 10 ай бұрын
Original 1957 Fuelie 283
@aaronsitz5168
@aaronsitz5168 10 ай бұрын
Cool stuff 😎
@aaronsitz5168
@aaronsitz5168 10 ай бұрын
Would love to see it dyno and mods see wat it is capable of
@jesusyeshuaelelyonelshadai6295
@jesusyeshuaelelyonelshadai6295 10 ай бұрын
Use normal heads big cam better.... Low vacuum low pressure.. no power.. loss more than gain
@TrentStover
@TrentStover 11 ай бұрын
What about doing this with a 5.7l ls? Or say, a lm3 5.3 bored to 3.903?
@richardholdener1727
@richardholdener1727 11 ай бұрын
needs notching
@shitbox82
@shitbox82 10 ай бұрын
As long as we’re on this subject, what are your thoughts on a 2.30” valve in a 4.250” bore?
@C6Z_Bob
@C6Z_Bob 10 ай бұрын
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.
@shitbox82
@shitbox82 10 ай бұрын
@@C6Z_Bob I think the issue is the BBC valve is canted, I’ve heard that much valve will hit…
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