The internet tells us the smaller head with higher flow will make more power. In my limited experiences my personal engines have made more power when they are bigger. For years I never looked at or cared about flow numbers, i always focused on cylinder seal, clearances, compression and mostly making sure its all as close to "blueprinted" as I could with my limited knowledge. Personally i hope the 312cc heads make more power, if they dont they dont and I learn something new . The thing Ive learned the most over the years is Dyno's a nice tools and help you get close to your desired outcome but the rest of the combo and the Dragstrip is usually the heartbreaker. The Dragstrip is the land of disappointment for a lot of people .

Hell, I don't know, thats why I watched all your videos, to see what the empirical results are. Thanks for the videos!

Great content I really enjoy all the information thank you

Know idea. Too many factors to keep straight in my head lol! But will be exciting to hear.

Great video Eric, I can't wait to see the results. I am going to have to side with Richard Holdner who tested the AFR 265s on a 496. I believe 290 heads with the AFR dual plane make much more torque and had a better overall torque curve than the 317s with the either the dual plane or single plane. I also believe, based on your other testing, the 290s with the AFR dual plane made slightly more HP than the 317s with either intake and the 290s with the single plane. That's my humble opinion. Keep up the great videos!

My guess, The 317cc head will make more power and torque than the 290cc head. Intake, the AFR Dual Plane will make more power and torque. I’m running a 496 on the Dyno tomorrow and it’s very similar to Mr. Weingartners test engine, 236/242 .600/.600, 10:2 compression AFR 290 heads, AFR Dual Plane intake. I saw the difference between the Edelbrock RPM air gap and AFR, the AFR is bigger. I chose to run the AFR, we will see what happens tomorrow! Eric, great job with your work sir! Absolutely great!

CFM increase within the cam lift range means power will increase, even if CR drops (less than 1 pt). Alternatively, a CFM increase above max cam lift will increase power only beyond peak HP RPM.

i wonder what would happen .if you designed an intake manifold that used the tesla valve design to minimize the pulse/surge back up the intake from the combustion chamber?

317’s probably did the best peak power wise while the 290’s may have made more power below peak torque I haven’t seen a dual plane intake beat the rpm air gap yet but AFR has had 20 years to figure it out, lets hope they did! Im positive both heads gained at least 15-25hp over they’re stock condition

K wish I knew enough to make anaducated guess, but I'll get the news soon enough. Thanks Eric.

Eric, My guess is 852Hp,and 635ft.torque

The dual plan looks like a pretty good size dual plane. I'm guessing it makes the best average power.

I’m gonna say it makes more Horse power because of the smaller chamber and more compression

M y pick is the 290 heads.both hp/tq.i like to see what happen with the afr intake ,the intake with the around opening. The turtle will help. Thanks for all your hard work Eric.Take Care. Hows your Son doing.

I really think that older Brodix intake is cool

The 496 dyno mule needs to start off with a hot street car easy on parts solid roller camshaft, not a race roller camshaft mind you, and 18cc pump gas pistons around 750 hp. At that point you can test hydraulic roller camshafts and lesser intakes. In other words start off with a relatively high volumetric efficient street friendly combo and work backwards to establish relatively low volumetric efficient street friendly combos. Then the differences can be established observably.

290s made more torque and lost on hp by 5-15 hp to the 317s though i think the 317s got witin 10 ft-lbs of the 290s on peak. As for the intakes, i believe the afr outperformed the air gap and the brodix outperformed the 454r. Both heads made more power then before but i think the 317s power curve moves outward from the stock set where the 290s just outperforms its stock numbers.

I have a 496 with flotek 315 heads (same casting as promaxx 317) my heads are milled to 112 cc chambers. Factory valve job and no porting. About 10.75-1 compression. 255/255 @.050 .680 .680, 107 lobe sep. 454r intake, 850 carb. My pipemaxx computer software says about 640 hp 610 torque. I have no dyno data but I know it runs really good in a pro street 68 camaro.

My son was thinking about LS swapping his 69 C3 Vette, but I am trying to talk him into going BBC for the easy grunt, I have been researching a build using a World Mk IV Merlin Block and using a Scat 4.250 crank and stock length rods, thats the easy part, what I am trying to build is a square 600HP 600TQ efficient engine for street use with max revs @ 6000, and now I'm stumped on cam, Heads and pistons to suit a combo like this. We are going to swap out the Muncie for a TKX 5 speed with the stock 3.36 rear. The current motor is a 1970 LT-1 350HP block stretched to 383 with Brodix 200 IK heads and Howards roller cam kit 232.6 in 240.6 ex 114 LSA goes pretty hard but not as hard as a nice BBC.

You lost a bit of flow in areas with the 317’s, but I’d still say due to the efficiency of the port. Between the 290 & the 317, I’d say they both did very similar up to around 5500rpm, then the 317 made slightly more hp. I’d also say the 317 made very slightly more tq, but a couple hundred rpm higher than the 290’s made peak tq. I’d still say the RPM air-gap made better power. Edelbrock seriously seems as though they got that (rpm) intake dead right. I am interested to see if the roval port design on the AFR, matching with the 290, did. Being the Brodix fan that I am, I’d love to see the BM2000 outperform the Vic Jr, but I’m not sure it did. Hopefully it’s very close.

Curious about the manifold with turtle…seems like a good idea to add an angle to plenum floor…but who knows.

Permatex 85249 hylomar sealer might help you with swapping intakes etc. When dyno testing

My thoughts? The 290(295) made more area under the curve than the 317s. On the 290s I'd run a single plane intake sized to keep the velocity up in the runners. While dual planes make more low end grunt, it seems that when the flow dtops off, it happens quickly, while the single planes seem to taper off more gradually. Ultimately, the 317s w/a large runner, large plenum intake, probably made the highest absolute Hp and possibly Torque, but again, I think the 290s made more area under the curve - And a flatter curve, both torque and Hp. I'm not big on dual planes except for big inch towing applications. Incidentally, I've had to coerce an intake off as well, same reasons except it was an iron head engine & the ledge on the head didn't go much higher, bit the aluminum intake sure got wider! Multiple cans of brake cleaner helped - latent heat of evaporation!

Do you want to test an old Torker 2-O intake (for oval ports)? I've got one I can send to you if you do.

I'm 6 minutes in the vid & I'm going with the larger heads, single plane intake with the 4500 adaptor & the 1050 Dominator. Making more power & torque from the getgo... That single plane looks nice, decent length runners & far more direct to the valve etc. You have added some more valve spring for the RPM👍 With the channel membership do we get bought up to date with the testing you have done to date or from sign up forward. Also what is the go with the books as I'm only interested in the PDF versions? Great work & Thanks Eric👌

Better low lift flow numbers suggest the 290 makes more torque at low rpm, while the 317 should excel at upper rpm

I'm guessing the smaller head will make more torque at lower RPM. I never had a dyno but I always thought smaller head creates more torque at lower RPM. As far as manifold I don't have a vote but maybe shorter runner equals more torque at low rpm as well??

Hey Eric, Tim here, my gut says the 290 cc makes more tq, and the 315 makes more HP.....that is conventional protocol.....ur vid suggests to not hold to yer gut......but I have personal proof (albeit its a Pontiac motor).....that a smaller runner makes more Tq, and a big runner makes more Hp, but at a smaller window of curve......I like fat curves on both, and the flatter the tq curve, and holding it, shows volumetric efficiency......so, my gut says smaller head made more tq, bigger head made more Hp.....that's my take......BTW, I am PROUDLY wearing one of my Weingartner Racing t-shirts today.....love the tech!!!.....

I say the bigger head did better. Looking forward to the results. I can wait. Lol, I'm busy building engines.

I think 317’s are the rectangular heads made more on both. 715HP, 640 lbs trq. I’m not a channel member but have book number 48.

Turtles usually make the pressure waves bounce back and forth

With the cid bigger heads will make more power.

290 cc head more torque more HP. AFR intake should be about close to the Edelbrock. Single plane probably less torque down low, but better torque at a bit higher RPM and more HP.

If I were forced to bet money, I'd always take the Edelbrock RPM air gap over other dual planes. It seems to win most dyno side by side videos.

I forget what is the rpm you are running up to now that the valve control is better? And what are the cross sectional areas? I think just because the head flowed worse on the bench doesn't mean it actually flows worse because depression differences. And what shape were you trying? Hard to guess but I'd imagine both performed better than last go around. I'd assume the best results would be taking the 317, raising the runner, using some epoxy... would create the best results but that's a lot of work for this kinda application.

I gave a thumbs 👍 and it was taken off ??

The BM 2000 probably whipped all those intakes, and no way does the AFR dual plane beat the Performer RPM Air-Gap. The 290 heads beat the 317s up to about 5000, then the 317s should pull ahead.

290s for the win probably makes more peak power earlier with that small cam, I’m ready to find out though

I'm certain the smaller port heads out perfomed the 315,Richard Holdner did a similar test and the AFR 290 destroyed all the othe BBC square port heads

1.i think the big head made more power even though it lost low lift flow but i remember you mentioned that engine has more vacuum than the flow bench so since you gain more flow at higher lift i and the compression is now the same i think the bigger head won on power. 2nd. Torqure i think the oval port won on torqure it's smaller and you did soem work to it. 3rd. I think the elderbrock air gap won over AFR just because that manifold is known to do good. 4th. I think the bodix bm1000 did better than the 454

I think the Promaxx 290's would be superior, especially if the LSA is narrow 108°. I do like a tunnel ram 😅. The AFR intake probably was the best considering the cubic inch and the duration. I'd love to subscribe, however I am a Po boy from GA. 😂

I think the new Brodix intake is better than the 454R

565hp and 678ftlbs of torque. Pauls Karts has some pretty interesting flow facts regarding combustion chamber shape and flow bench vs real life.

Questions are flawed: Need more data about complete engine specs.

Smaller head = more torque start-to-mid curve Bigger head = more HP + torque mid curve and up Dual plane plenum = more torque start-to-mid curve Single plane plenum = HP + torque mid curve and up. Brodix = best #'s overall Just guessing...

I think HP will be in the vicinity of 700 and TQ around 610.

From what i remember from your last video, the Promax 290 are the winner because you milled the 317 heads to bring up the compression to match the 290's. But in the process you lost port stability with the 317's and cfm. A noisy port regardless of the cam max lift will lose power. Now i believe the new AFR makes more power than the Performer RPM and the Brodix versus the Edelbrock Victor 454 i can only guess; maybe the Edelbrock? In the end, a dyno only measures torque. Make more of it you will make more horsepower. Horsepower= torque x rpm divided by 5250, the dynomometer constant. As far as torque and horsepower the 496 made? 650 horsepower and 590 torque with the 290 heads and the Edelbrock intake.

Ok, because you asked. But I kinda think I know the results by the tone of your voice and how many times you brought up the torque compare. Heads: the 317 was best torque and best power despite less flow. But I would have guessed the 290 would be better. The intakes who knows what worked best on the dyno? But from my past experiance. The duel plane will be way way faster at the track. Probably the singleplain brodie is a little better peak. But the duelplane will crush it on the 1/4 mile with an automatic.

My prediction is 645 Hp across , lol thos dual planes seem to be be better ports for big blocks

I believe the 290's outperformed the 315-317's, I also believe the new AFR intake outperformed the performer rpm intake,and the new Brodix outperformed the Edelbrock 454 intake

317 heads, single plane, 730/650tq.

Do u do port e energy calculations Eric?

The smaller heads win due to the shorter duration & lower lift.

It make more hp. Because the vacuum is higher with 496 Then your bench

Well hopefully you will make videos on all of these combinations man because I cannot afford to become a channel member I have little kids and I work 80 hours a week to get by

I think the air gap is better than the AFR

I think the 290's made more tourque and power because of the size of the engine.

not much horsepower but fair torque.

Yes it made more hp

Does not make more power because it lost CFM. If any power was gained it would come from compression

I think 290 head is better did you molfy the block for the size of the valve

720 hp.?

I think theres myth that u cant use hydraulic lifters with 600 lift it wont loss control over valve train

I'm guessing the head that has the better coefficientcy of discharge wins.

290s all the way....hp&tq. Coefficient of discharge..

I think the bigger head did better every where. The single plan was probably the better one as well.

its gonna make about the same power if both of the heads flow about the same. rec vs oval port SOMETIMES doesnt make much of a difference. ive even see it on your channel and others

736hp and 675tq with the bigger heads

735 H P.

Big head and afr most powa

725 hp, big head works better too!

Biggest hole more powerful

Have ya been losing "NON MEMBERSHIP" subscribers?