BOOST VS HEAD FLOW-WHAT STOCK HEAD SHOULD YOU PICK FOR A TURBO LS? 706 VS 317-DOES MORE FLOW MATTER?
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- เผยแพร่เมื่อ 15 ก.ย. 2024
- DOES MORE FLOW EQUAL MORE GO? SHOULD YOU RUN 317 HEADS ON YOUR TURBO LS MOTOR? WHICH HEAD SHOULD I RUN ON MY TURBO LS? IS MORE FLOW BETTER THAN MORE COMPRESSION? WHICH HEAD MAKES MORE POWER NA? WHICH HEADS MAKES MORE POWER UNDER BOOST? CAN THE 317 HEADS COMPETE WITH THE 706 HEADS? CHECK OUT THIS VIDEO WHERE I COMPARED 706 AND 317 HEADS TO ANSWER THE FOLLOWING QUESTION-IF THE 706 HEADS MAKE MORE POWER NA AND AT ANY GIVEN EQUAL BOOST LEVEL, CAN THE 317 HEADS EVER MAKE MORE THAN THE 706 HEADS? LET ME KNOW WHAT YOU THINK!
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I love these statement/ questions!
Personally, I think the only bonus to the 317 head is the possibility of running a bigger boost number on pump gas before the fuel becomes a problem.
Run the test on 91 or 93 octane and run the boost/timing up to the octane limit. On race gas its pretty clear the 706 will win hands down, but on the street running pump gas i think the extra volume of air/fuel charge (same as more cubic inches) will probably show a big enough change to give the 317 the advantage.
the problem with most dyno data is that the testing us usually done on race gas, E85, or straight alcohol. Most people run pump gas powered hot rods, and mostly on the street. I know I cant afford to drive around on the street burning C16, and E85 is nearly impossible to find where I live, and i suspect I'm not the only one.
Anyhow, i just think the fuel type needs to be a much bigger part of the test criteria, rather than a minor mention at the end.
no race fuel in wich place do you living sir
@@francisbeaudry8598 We have race gas, Oregon isnt the moon, but last time I looked at a 5 gallon can of C16 it was well over a hundred bucks. Thats fine for a track car, but for most people thats not going to be something you can run on the street without a really fat wallet.
For the drag-n-drive project Im building Im running an EFI dual fuel system with pump gas in the main tank and e85 in a small tank on a second set of injectors that switch over at around 90kpa. and i think a lot of drag-n-drive people are starting to do something similar.
E85 prices aren't too bad for street driving, but ironically the availability of this "eco-friendly" fuel here in the land of rainbow haired greenie's is very hard to find. especially if you are away from home and need to find a station nearby. But anyhow, this is going off the rails, my comment was about testing the heads on pump gas instead of race gas. And while im at it, maybe test it on a turbo'd 6.0, since thats the engine 317's came on anyhow.
I think it comes down to the balance of peak cylinder pressure and Volume of air/fuel charge, vs combustion chamber shape difference. when you hit the wall on octane with 317's you'll have a higher volume of air/fuel to push that piston down, but will that advantage overcome the less powerfull combustion chamber shape? testing both heads on race gas and the same boost pressures does not answer that question.
@@senseimarvin454 tank for feed back here in quebec 210 /250 $ for C16 BUT WE HAVE 3OR 4 PLACE TO CHOOSE
Theoretically, the lower compression heads with better airflow will allow more boost on pump gas before detonation. However, that's theoretical and would need to be tested empirically.
It’s been tested 20 dozen times. It’s true for crap gas. e85, not so much- but 91, yes definitely. The reason Richard is unaware of this is because he’s too goofy to find a way to run knock sensors so he runs the same timing and all similar setups rather than pushing each combination to its limit. Dude’s getting silly in his old age
Just put a 317 on one side, and 706 on the other side! Send it!!
Like a dual plane intake manifold. 😂
It would run and drive and 90% of people wouldn’t know
best of both worlds. 😆
Whatever comes with the engine lol.
Hi Richard, I think the more interesting question is what is the better head if all u use is pump gas? Remember the reason the compression was lowered on that BBC 540 (8-71 blower I think?), from a few years back down to 8.5 to 1 was because it was a "street rod". I don't think u can really push the "317 heads" to really gain from going up in boost to catch up on the "706" heads as there is insufficient difference on port flow. If you really go with the "pure street" angle, then you would see the 317 heads able to do something that the 706 cannot; live with boost and compression w/o the E85, methanol or race fuel's. Just a thought.....
So why not run the boost up to just under detonation and back off a little bit. The lower compression of 317 should allow more boost and maybe more power
Then the question is, does it have more potential for power on any given fuel? Or does it just handle more boost pressure?
@@crash5811 well we know the 317 can flow more but has less compression. with that said the 317 has more potential because you can run more boost and or timing.
This is common sense but Richard refuses to test this way
Because you'll arrive at the same power level with less boost because of the bump in compression.
@@Mastermindyoung14 I would love to see it.
The tuning window is the key with higher boost .
I think an easy answer is to spend slightly/no more up front on an 08+ 6.0 with the square port heads, which is like getting a 99-07 6.0 with aftermarket heads and intake from the factory. Then this conversation becomes more academic.
I like the quick spool up of the 706 heads, but I like the high rpm flow of the 317 heads
Honestly, it really doesn’t matter whether it’s a 706 or 949 head if it can flow a certain amount of grams per second you’re going to end up with a certain given amount of air and that can be combined with a very certain amount of fuel and you’ll get a very certain amount of combustion. All things considered if the smaller head can only push for example 109 g of air but the slightly bigger head can flow 118 g of air if they’re at the same level the one that has more grams per air will make that much more power. It kind of goes back to the old saying there’s no replacement for displacement and a turbo charger or head design just displaces more air. That’s a fact. This is why some of the four-cylinder engines run in 25 pounds of boost are able to make the same horsepower as a V8 with only six or 7 pounds of boost.
Luckily both of my motors came with the best factory cathedral port heads… 243 Mafia represent! 😂
Only way to test is same
Boost say 20psi , add timing until mbt mbhp are acheived. If the 317 doesn’t handle more timing than the 706. Then the chamber shape regardless of cc is the determination. Or port and modify the 706 for the same flow and then flow is out of the formula.
Bore shrouding , real world flow might be an issue also. Back in the old days we would offset head dowels to make more power on a max effort head because 315cfm did not make more power than 292cfm. But shifting the head .040” made hp more on both heads.
If you wanted to compare 317 heads to 706 then I’d want them to be stock for stock.
By throwing out the “stock” rules you could also deck the 317 until the chamber CC was the same as 706 and it would also be an irrelevant test
Well yeah adding more atmospheric pressure you just add corresponding power since a motor is just an air pump.
The real question is will you get less detonation with reduced compression and better cfm? Meaning can I run more boost on the 317 prior to detonation and will I get less of a diminished return at higher levels of boost?
I have a great idea for heads for your upcoming 4" bore 4.8L that you mentioned......
I would love to see a set of 706/862 heads with both intake and exhaust valves completely UNSHROUDED in the chamber with a bit (alot) of grinding work to see if they can maintain their crazy low end response and then still have the flow to feed up high in the RPM range.
Don't worry, Richard. I listened. I have a built 6.0L with 317 heads, and I plan on adding twin turbos. Thanks
points for listening
Read every comment best i could. I would want to see the heads on an engine with equal compression. Not sure of bore size, cubes should be as equal as well. Tough test. Unicorn test
Sounds like a simple answer to me, add more boost to the 317 heads than you do to 706. Then the answer is always yes 😂😂😂😂😂
I really would like to see the test where the two were tuned to detonation with timing and boost to see which one makes more power. Of course within the timing and boost limits if the 706 it wins on a 4.8 or 5.3
I have 317 heads on my Chevelle, so the obvious fact here is they make more power than 706’s after 10psi of boost!!
FACTS…
I wish that was so, but seems it’s not
fax!
I would think that back pressure will be a problem before the air flow could make a difference, and there's no way you're going to hold a headgasket to get to that point anyways.
Waiting on the 3800 Big Bang video my dude
Liked, commented, and subscribed!
Well good to know my 706 heads are truly worth keeping and better than the 317's. Dyno sheet dont lie. All in all, its part of the chamber of secrets.
Every head is a turbo head 😉
The 317 head came on a high output 6.0L truck motor with flat top pistons the LQ9 LS motor. A 5.3 came with negative 10 cc dish pistons. The LQ9 with 317 and flat top pistons had 10.5 to 1 compression. I have 317s on a NA LQ9 with long tubes, fuel injection 3/4 race lumpy cam and 350 gears. It just seems to rip the tires off on my vehicle.
I can’t believe Richard said my baby is ugly 😭 Lol
and wears overalls
Don’t stress the head. Stress the fuel and tune.
Back in my dynojet honda tuning days, a 11:1CR rsx type-s with greddy turbo kit 6psi would make 260whp. On 93 octane, ignition timing was down around 10-12 degrees to avoid spark knock. Hondata had very good knock detection. Exhaust gas temps were approaching the surface of the sun, but the combination was safe to beat on non-stop. Had stainless downpipes cracking and breaking tho. Had one rsxs customer bring good rods and 9:1 pistons to install. Made the same 6psi, same 93 octane, same hp/tq curves, with 6-8 degrees more ignition timing. Was no longer knock limited, and the egt gauge was no longer pegged.
61cc 706 vs 70cc 317? I will assume any gains from lowering the compression will stem from being spark knock limited on a particular fuel. Your results may vary.
the above comment is a timing test
@@richardholdener1727 timing / gaz octane= boost
@@richardholdener1727 it was very much a timing test. However I learned much from a knock limited 11:1 k20 to a 9:1 k20 on the same 93 octane fuel. My dynojet graphs overlaid because the 9:1 would take more timing. When you get into pump gas compression ratio vs boost, you should spend some time on knock detection that really works
Chamber design can affect power production. Facts...
;)
points
Just making sure you're aware of weingartner's cam challenge. Sounds like it's right up your alley, to at least see the results.
it will be interesting-I suspect a lot of guys making the same power
My guess would be the only way the 317's beat them is in an octane limited scenario. For instance, Alaska only has 90 octane as their highest grade of fuel. Also maybe if you're on the max end of a smaller turbo when heat becomes an issue. Would be cool to compare them in that situation.
I would submit that Alaska has a cooling advantage over, well, anywhere south of there.
@@wheelbasemedia5814 it can be 90s in certain areas in the summer up there. Not always THAT cold.
Figure out how much air your engine is moving on the cam and at Peak RPM..
Correlate that with head flow capabilities..
Then add boost pressure accordingly
If combining big cubes, big boost, pump gas, and an intake and cam suitable for high RPM, I'd run the 317s.
LOL at the people still arguing Compression and Flow in the comments, even though you were told in the video that chamber design matters, port size matters, You were told that even if you mill the 317 to match the chamber volume of the 706, the 706 still makes more power. But you're still arguing compression and flow.
Hmm I'm interested to see how this plays out for me. I have a stroked l33 with the 799 heads, forged rotating assembly with a final compression ratio of a tad over 9.5:1. I know cam specs also play a big role in power and needed octane. It'll get boasted eventually, gonna start off driving the car N/A before i aim for 650+rwhp with less than 10lbs of boost(hopefully) i did have it gapped for over 15...just to be safe 😅. Should be fun either way, less than 2900lbs with ....probably more than 400whp...should be spicy even before i go to kill me mode
Every head is a turbo head !
Seems like a displacement problem, but really you need to think why does the higher flow make less power, there's plenty of reasons it could, once you figure that out then you can decide if any change to the rest of the engine will fix it. A bad combustion chamber will effect flow and overall engine power very differently for example, if it's that this combo might work better with a bigger bore, maybe on a ls7 they'd out perform
It really comes down to valve seat diameter on 317 vs 706 I believe milling is less of a power adder
4:30 no, the point was when using pump 91 fuel the lower compression ratio allowing more boost making more power. I dont think the statement had much to do with flow difference
10:23 again, no, he probably is talking about the 317 working better when fuel octane limited and reaching for peak power
he specifically said the greater flow in the 317-his statement wasn't about octane limited situations
@@richardholdener1727 hmmmm, i see. Shucks man next time include a screenshot cut of the comment on screen.
As you talk of putting more air in.
Let's see a stroker
With 317 vs the 706 on a stroker application. Your moving more air.
Air compressor right?
I would think the 706 heads with the small bore would be less shrouded and flow more than enough to feed the small motor the large bore may benefit from the higher flow some. Probably wouldn't make up the differences in the compression. I can see the bigger heads making more power under boost at the same boost level. Being boost is a measurement of restrictions the smaller head should hit the boost level and be flowing less cfm. But not sure if it would even come into play on a 5.3. As there's not a huge flow difference. If it was like 50 cfm less something like the 706 flow 275 and the 317 flow 325 and still Probably only noticed on a large bore.
Lets see on pump gas where the boost timing and power limits are on both
I think he covered that in the video
What happens when your base fuels knock limit is reached with the 706. But not with the 317. Then the 317 makes more power.
To say a higher compression setup will always make more power is wrong too. Even if you are not knock limited. You are eventually cylinder pressure limited. If you were to monitor actual cyl pressure. With a 706 VS 317 head. Run both motors up to say 600hp. (yes you will need more boost with the 317 head to reach the same power) At like HP, the lower compression setup will have less peak cyl pressure at the same power. Meaning the lower compression setup has more "power potential" than a higher compression setup. Same reason they run low compression on top fuel motors. If they ran high compression they would have such peaky cyl pressures that they wouldn't ever keep heads sealed. You are trading response for peak power potential with less compression. That and the tuning window on low compression stuff is MUCH wider. Great for entry level folks.
the test was 706 vs 317-not compression always wins
@@richardholdener1727 Compression is the main difference between the 706 and the 317 head though.
Hell now I’ve got the wrong cam, the wrong heads and wrong wheel drive on the gxp lol
I've made some good not massive power from old school sb chevrolet and 455 buick and Pontiac of wich I only bolted together the 455 s as each were bought by someone that lost the vehicle. However I only know what little I do from your channel, Travis Black I think is his name and power Nation. I have avoided these super heavy small blocks like the plague until last year. But what I want to know is what head is equal to the Iron Angel plug heads on chevy 302 and the 400. May not have been factory on the 400 I found them on. But my Goodness it was a beast till a conecting rod crashed the cam.
Could you do a fuel test for example tune pump gas kind of rich maybe 11.0-10.5 then see what percent of methanol you could add to your fuel to get the air fuel back to a more typical ratio then see if it picked up power
But with 87 Octane fuel... FAX~
exactly
The only way it will make a difference is when cylinder pressure is too much for the fuel you are using the 317 may let you run an extra pound of boost or a couple more degrees of timing … I’m going to guess that the hp might top out the same at that point
why would anyone, on a street driven car, ever want to trade more power all through the RPM range to gain a little at the top? Even if it were possible, I think it is counterproductive.
Definitely maybe
sometimes.
It’s a compression limitation question, not air flow. Does the higher compression of the 706 limit the max boost compared to the 317
The turbo(s) dont care what heads are your engine.
The 317 has lower compression so under boost I assume it would reduce pinging and allow more timing at the same boost level. So wouldn't that make it possible to get the power back? Would that only be better assuming fuel is the limiting factor?
Richard, isn’t this the now classic myth that lower compression for boost makes somehow more power, um…er with pump gas? lol
I’ve heard you say for years that low compression motors show gains from boost but high compression motors with boost do better. (Higher Hp/Ci)
And still this argument lingers around.
What my question that is still out there is if more top end torque makes higher Hp N/A before boost then why not dyno and rev test up to 9k or 9800, and why wouldn’t you build a motor to last up higher then if it makes more power N/A before boost would make it sky high?
RPMs make winners.
By the time you spend the money to get into the 4 digit levels to make the 317 win. Just buy some aftermarket heads and save some money
...So... if the milled 317 still make less power than a 706...why do better flowing aftermarket heads make more power without making additional changes (other than those AM heads)?
This feels like a dumb question to ask, and I'm not receiving a MacArthur Fellowship Grant any time soon but I'm also not bringing up the rear of the class either.
But, when the 706 heads max out because of compression, can the 317 head keep going cause of the lower compression and make a but more top end?? Just curious
I think the question is can the 317 heads handle more boost than the 706 with all things equal and does that translate to more power? Like 706 maxed out at say 12psi vs 317 maxed out at 17psi
What if we tried na with massive cubes? Like 450+ la short block with all the camshaft. You’d tax the heads pretty hard and maaaaaaaaaybe find out if the flow finally wins over the better chamber design? I’m still voting 706/862’s but it’s another one at to text
i would like to know what the difference is on pump gas. Can you use more boost and ignition timing on the 316 heads?
As a daily driver.
Are you running the same timing with both heads? You can run more timing with the 317.
If your doing that test might aswell combine water cooled vs air to air test in conjunction with the heads
that video is up
I think they might beat a 706 if the bore and stroke were maxed out.
Displacement needs to match air flow
317 head it seems to valves have less shrouding
👍great question, I wonder if a super-whiz-bang aggressive camshaft might help offset this, to recover some of the benefits of the greater flow 317 vs the better chamber 706?
they do the same thing with a different cam-they both gain power
That's true, you would have to take it into the 4 digit levels for it to matter. So why even try? Lol. Not worth it.
I agree.
Can we try a Test with a flat top piston 6.0 with 706/ 862 heads running pump gas
I am currently running a twin turbo build on a built bottom end LQ9 bored and stroked to 408 with CNC ported 317 heads. I would be curious to see how a set of equally ported 706 heads do under 25 30 plus psi of boost.
That’s the test that I want to see also. I believe the 317 heads with 2.05 valves or 2.08 valves will edge out the 706 heads. Need to test on an engine with large bore solid lifter, cam, high rpm, and big boost.
@@danielsullivan9865 I have the perfect engine for it lol running a summit stage 3 turbo cam.
TEA ported 706 heads vs TEA ported 317 heads
@@richardholdener1727 that would definitely be an interesting video to see!
you know what there is so much gibberish going on here that after listening to this and reading the comments nobody knows the answer to the post question,a short 3 minute post of yes the 706 made morte power with turbo boost,or yes the 317 made more power with turbo boost,this is because which had better flow
Req port for the win
How bout 706 heads vs Rec port heads ? Does compression gain beat air flow there? Rec ports have 70cc chambers
That video is up-706 vs ly6 heads (rec ports made more up top-lost down low)
The only way I am going 317 is if it’s a 400ci or bigger
Maybe on a big cube big cam high rpm n/a build. Would it come to the point where the 706 would be a big enough restriction to hurt performance enough for the 317 to pass and then boost. Like a max effort 600+ na build then boosting it?
The 317 heads won't support 600 na hp, nor would the 706 heads
No it will not. Not in the combination tested.
This comparison seems to take a 706 headed engine with its compression against a 317 headed engine with lower compression.
What if you had a 317 headed engine with the SAME compression as a 706 headed engine and then tested that way?
the heads don't provide the same compression. If you want to make the compression the same in a head comparison, let's then make the airflow the same.
@@richardholdener1727 ok how about doing this same test on just 93 octane?
It seems like the flow would help but it doesn't appear to
So, dumb question, the 317 flowing better, how does that affect the way the turbo spools? Could more exhaust flow cause a faster spool? More drivable in the low RPM range maybe?
the motor makes less power NA with the 317s, so it spools a turbo worse
Good video
Can the 317s outperform the 706 in an NA application? If they can't, they won't under boost.
@@wheelbasemedia5814 but you can add more boost and timing with a 317
I always miss the lives so I just came to a comment section. But I am building a 5.3 and I plan to sell it I want to know what rebuild kit and cam do you recommend(the pistons were rusted and my dad accidentally busted one of them beating it out). I would also like to know how much I should sell it for as a Long Block.
it is harder to sell a rebuilt LS long block since the junkyard is full of running LS motors for cheap
I would lay wager you'd lift a head before you get to the point where the 317 makes more HP (if it ever would get there).
😂😂😂
Definitely NOT on an 87 octane build
For all those guys out running 87-octane turbo builds!
@@richardholdener1727 the simple question was will a 317 EVER make more power than a 706?
The answer (as we discussed in the live feed tonight) is a loud and proud YES once detonation threshold is met (which should be part of testing, because it is part of reality in a vehicle.) If you don’t utilize the additional timing and boost available with the use of 317’s then absolutely not, because we know 706’s are rowdy… but if you find a way to run knock sensors on the dyno and actually push these combinations to the point of knock, bet $1,000 that 317’s are capable of making more power than 706’s under normal boost conditions (15ish PSI) whether that’s on 87, 91, whatever floats your boat.
It’s a bummer all your tests are without this valuable data.
@@boost1728 fair
Was this taken from a stream I think I remember this discussion
yep
@richardholdener1727 good have not gon fully nuts yet.🤣
Please explain the L33 5.3L (Alum block 243 heads) vs the LM4 5.3L (Alum block, 706 heads). Better yet, The LC9 came out with both flat tops as well as 3cc dish, but both had 243 heads and the 243/799 head engines were always higher rated by GM.
He has videos of all the different small block heads. The 706 wins because coefficient of discharge and shrouding of the bigger valves. The 706 heads have 1.89 valves. The 2.02 valves are worse at shrouding. That's why the 706 heads win
The LC9 is flat top only, when you say 3cc dish you might be referring to the valve relief pistons for the VVT motors.
Could this cam profile be more optimized for 706 heads? Perhaps another profile could be better optimized for 317 heads? If so, utilizing the same engine, which H/C combo is top dog?
#wrongcam
At what lift were the 317’s better? Maybe its the camshaft thats holding back the hp and the 706 is more efficient at lower lift.
600 lift cam-it's not the wrong cam
Are there performances gains in installing large intake valve on the 706? Or is shrouding too much of an issue at that point.
It's unrealistic but I'd like to see the 317 chambers welded and reshaped with the swirl ramp.
thats when you find out its quicker and easier to buy a 243.
Hi Richard how and would the 706 heads work on 5.7.
Thank-you
Aaron
better than the stock 241s
Have you run a 6.0 with 317's and a Truck Norris cam?
Sweet spot is 1889.1-1889.2 😂😂
winning
Wrong cam... over cam to 706 and see the 317 shine
we could run the biggest cam that will fit the stock p-v-the 706 still wins
The sky is blue... facts
you might want to research that
@@richardholdener1727 🤣🤣🤣
243 vs 706 heads? Which one has more compression or what are the differences?
799 vs 706 vids are up
@@richardholdener1727 did some quick research. Didn't know 243 and 799 were almost the same. I'll check out those videos
SO YOURE SAYING THAT 317 ARE THE UGLY BABY???
So what head would you recommend on 5.3 turbo ? 317 is not worth putting on 5.3?
If it has heads on it already just use those that came with it it will make good power with any factory ls head with boost
run what ya got
Hey man I need some help with my 4.8 I just cammed it first start up started making a loud knocking noise like a rod knock gonna pull the pan and check the crank tomorrow what do u think the problem may be ?
was the cam installed properly?
@@richardholdener1727 yes everything was professionally done
@@richardholdener1727 we’re gonna change the cam thrust plate see if that makes a difference we tore it down and there was 10 mm bolts in it instead of the beveled screws that belong in there
I have a 6.0 with 706 heads on it thats on my airboat im fixing to put a torqstorm on it should i change heads for such low boost
what fuel
@@richardholdener1727 wanting to run 91 I have a set of 317 heads and springs to go on them but I'm limited to 5400 rpms so probably won't make crazy boost
As a 317 owner, I don't think the 317s would ever make more power, even with the 706s boosted to just short of detention, it think the boost level needed one the 317s would be so high you'd lose head gasket sealing.
@@ThomasTT496Vega even with studs?
Baseless hypothesis. People have run over 30psi on stock heads- the same point 706’s will reach detonation before a 317 will.
Not only that but even at low RPM full throttle in a street truck: can definitely get away with more boost and more timing with 317’s.
How dare you assume his gender 😂