Another a460 vs P51 deal - 460 Ford Forum
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post #1 of 45 (permalink) Old 04-29-2017, 12:51 AM Thread Starter
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Another a460 vs P51 deal

This has been beaten to death I know, but please indulge me as I need an answer as to which would work best in my specific application. I currently have a deposit down on P51s, but as I sit and wait, I can't help but wonder if I'm making a mistake by not just going with a460s right now. I'm working on a 598, a460 block, under 12:1 pump gas, for my 71 f250 4x4, which will be used for sand drags, drag strip, sled pulling, and tame enough to actually drive without beating itself to death on weekends every now and again. Shooting for 850+ and 800ish torque with a streetable roller cam. C6, 4.10 gears with 35/36 inch tire. I have headers and intake already for the cobra jet style heads, but I think my headers could have different flanges put on easily enough, they are individual primary tubes with slip on collectors, so I'd just need to switch intakes. torque is as important to me as a big hp number, and I need help determining which head would give the best overall. I've read the P51s actually outflow the a through the midlifts, but then I read that flow isn't everything and a heads will outperform everywhere on an engine this size. Thanks in advance for the insight
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post #2 of 45 (permalink) Old 04-29-2017, 07:37 AM
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What header do you have. I'm sure they would work in my 71 ford.

Sorry, I'm no use to you about what head to use.
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post #3 of 45 (permalink) Old 04-29-2017, 07:45 AM
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Are you required to pull vacuum in any of those race classes you're in or do you plan on using vacuum brakes? Is there any part of the rules that say you have to be able to bolt a stock intake manifold or exhaust manifold to your heads, not that you'd use them? Oakley built a 598 using P-51 heads that pulled 15" of vacuum and made @900 horse for a mud drag truck.

Joey

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post #4 of 45 (permalink) Old 04-29-2017, 08:51 AM Thread Starter
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The only class I would be in would be the pulling, which would be super stock, and engine mods can be unlimited. The drags would just be for fun. My headers are a custom 3 step I got from 598broncobeast from this site. I would still use these. I know the P51s can make the power, but I'm thinking the As could do more with less compression and cam. Maybe not enough to make much of a difference. The P51s would require the bigger intake and some work.
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post #5 of 45 (permalink) Old 04-29-2017, 08:58 AM Thread Starter
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I plan to use vacuum brakes
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post #6 of 45 (permalink) Old 04-29-2017, 09:47 AM
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Originally Posted by MikeJC View Post
pump gas.....850+HP and 800ish torque....streetable roller cam....vacuum brakes
Never gonna happen, with any head.


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post #7 of 45 (permalink) Old 04-29-2017, 10:34 AM Thread Starter
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Which part carl? I've seen very close to what I just said at 557 ci... why couldn't it be done at 600 ci?
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post #8 of 45 (permalink) Old 04-29-2017, 11:29 AM
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Which part carl? I've seen very close to what I just said at 557 ci... why couldn't it be done at 600 ci?
pump gas.....850+HP and 800ish torque....streetable roller cam....vacuum brakes

There are compromises in each of those variables that disqualify at least one of the others. Easiest path will be to get an electric vacuum pump for the brakes and focus on the other three.

As for which head, AFR 315's would be my first choice.


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post #9 of 45 (permalink) Old 04-29-2017, 01:57 PM Thread Starter
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I understand about the compromising part.. i never meant to sound like my demands were in stone.. just a ballpark. I am focused on the other three things primarily, which is why I was asking which cylinder head would be the best start. I may even step up compression a little and run better fuel. The afr heads seem great and all, but I can't see going with a head that requires a different intake, and not just stepping up to the a460. If the slate were clean, you would take the afr 315 over the tfs a460?
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post #10 of 45 (permalink) Old 04-29-2017, 02:50 PM
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I understand about the compromising part.. i never meant to sound like my demands were in stone.. just a ballpark. I am focused on the other three things primarily, which is why I was asking which cylinder head would be the best start. I may even step up compression a little and run better fuel. The afr heads seem great and all, but I can't see going with a head that requires a different intake, and not just stepping up to the a460. If the slate were clean, you would take the afr 315 over the tfs a460?
Your existing headers will bolt right up to the AFR's without modification. You didn't really define what you had for an intake, but any standard port intake will work, and can be port matched. If you have something that uses a CJ gasket, you could easily sell it and buy AFR's intake.

Header fitment, "street use", and quality of the head out of the box sway me towards the AFR's, but the A460's are certainly an option if you're willing to put in the extra time and money they'll require.



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post #11 of 45 (permalink) Old 04-29-2017, 02:54 PM
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Originally Posted by MikeJC View Post
I understand about the compromising part.. i never meant to sound like my demands were in stone.. just a ballpark. I am focused on the other three things primarily, which is why I was asking which cylinder head would be the best start. I may even step up compression a little and run better fuel. The afr heads seem great and all, but I can't see going with a head that requires a different intake, and not just stepping up to the a460. If the slate were clean, you would take the afr 315 over the tfs a460?
Out of the box TFS A heads 340 runner


Airfl ow Results
PowerPort A460 340 with Standard Bolt Pattern
Lift Value Intake Flow CFM Exhaust Flow CFM
.100" 76 67
.200" 160 120
.300" 246 162
.400" 312 204
.500" 357 237
.600" 392 264
.700" 418 286
.800" 428 303
Tests conducted at 28" of water (pressure).
Bore size: 4.500"; intake valve: 2.350"; exhaust with 2" pipe.



AFR 315 Bullit heads.


315cc Street Head Flow Chart
.200 .300 .400 .500 .600 .650 .700 .750
Int 162 241 309 360 405 415 423 427
Exh 127 172 218 252 274 279 284 284
Test conducted at 28" of water (pressure) on Superflow 600
Bore Size: 4.380", 3/4" radius plate exhaust, 2 1/8" curved pipe


From a raw airflow perspective the AFR heads are on par with the TFS A 340 runner castings excepting the high lift exhaust numbers.

I sold both pair of P-51's I had purchased for personal projects after the AFR 315's showed themselves to be a better choice. The AFR heads are no joke let me tell ya.

What it really boils down to here is intake port cross section. The AFR 315 heads are 3.44" square.

A 598 peaking at 6800 is better suited with about 3.72" square. The TFS heads on paper are better suited especially the CNC ported 360 cc version. The larger and better exhaust port would lend itself to better high rpm power in an all out application. The higher intake port entry relative to the valve has advantages that go above and beyond simple airflow.

Since your original question was TFS vs P-51 I feel the A heads are a better choice given your criteria.

From a clean sheet perspective it depends on how much room you want to be able to grow. Given the cam duration it will take to generate the power curve you are after putting some compression to it is not a bad idea. It would help the torque curve everywhere under peak (street use at light throttle) and make a bit of extra power as well. I see no reason that a large high compression stroker with a solid roller and the AFR 315's couldn't get close to 1000 hp.

Carl makes a good point in post #10


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post #12 of 45 (permalink) Old 04-29-2017, 03:58 PM Thread Starter
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Thanks guys. I think I have my answer. I should have specified that i do currently have a tfs mafia intake. So I'm changing intakes either way if I don't stay with the P51s. And when I say a460, I'm referring to the cnc 360cc versions. Yes, it does pretty much come down to having room to grow, because we all know how these things go and I may build something bigger yet, next time around
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post #13 of 45 (permalink) Old 04-29-2017, 04:01 PM
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Thanks guys. I think I have my answer. I should have specified that i do currently have a tfs mafia intake. So I'm changing intakes either way if I don't stay with the P51s. And when I say a460, I'm referring to the cnc 360cc versions. Yes, it does pretty much come down to having room to grow, because we all know how these things go and I may build something bigger yet, next time around
Then you have found your answer.




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post #14 of 45 (permalink) Old 04-29-2017, 08:08 PM
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When did AFR revise their head cc? I thought they were 270, 285 and 300 when they first came out? Now they are 280, 295 and 315?

'71 torino gt m-code
now- 460 w/roller cam
one day w/t56
anyone wanna donate to my cause?
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post #15 of 45 (permalink) Old 04-29-2017, 08:34 PM
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When did AFR revise their head cc? I thought they were 270, 285 and 300 when they first came out? Now they are 280, 295 and 315?

My rep explained to me that the original listed volumes were short and they revised after measuring intake ports recently.
No changes to the CNC programming.


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