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Discussion Starter #1 (Edited)
Why do the Intakes on the P51 heads seam to outflow the A460 heads in the mid lift flow numbers when the A460 heads have a larger valve and a raised port?
 

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Theirs more to it than just the flow numbers.

Plus are you refering to out of the box numbers or ported numbers?
 

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In my oppinion, those heads weren't designed to use similar valve lifts at similar RPM levels. So, of course they have different shaped flow curves.
Apples vs. Oranges again...!
 

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Discussion Starter #4
In my oppinion, those heads weren't designed to use similar valve lifts at similar RPM levels. So, of course they have different shaped flow curves.
Apples vs. Oranges again...!
Yes but i thought a raised port head would have flowed better all round not just in the higher lifts. Does the P51 have a greater cross sectional area but tighter short turn so as the volume of air flow increases it has trouble getting around the turn and the A460 have a smaller cross sectional area but better short turn which helps the higher lift numbers.What are the features that make one better in the mid lifts and one better in the higher lifts? I Am just trying to understand the design features that make each head better in its particular area.
 

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The A460 head has a much larger crossection. If you change the short turn radius on ANY head you will change the flow characteristics.
Example; By increasing the high lift flow of a P-51 to try and match an A460 head you will LOSE that midlift flow and because of the port height you'll never get the high lift numbers of an A460 head; (especially above .750").
 

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I'm also interested in this question. For approximately 600 streetable cubes, mild, smallish cam, is the A460 the overall better head due to the large cubes, or will the P51 still feed it for approximately 700hp/tq?
Which head would use a smaller cam relative to the flow to acheive the numbers?
How different would the power curves be?

Sorry for all the variables and just tell me to pound sand if it's too unreasonable.
 

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my 521 is making somewhere in the mid to high 600s with a hydraulic cam and a 4150 carb and I think its quite streetable in a 6000lb truck with 39.5 tires. A roller cam would make 700 pretty easy with my setup.

Im not sure you need 600" to meet your goal or need 700hp in a 3000lb car. I can break my tires loose at 45mph.
 

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I am interested in this topic, also. In a previous post I tried to make the point that the flow charts posted on this forum show out of the box A460 intakes have less mid-lift flow, and the P-51 (412cfm) even out flows the A460 (387 cfm) at .700 lift. I have a 545 with Edelbrock heads that makes a little over 700 HP with a flat tappet cam. I am not racing for the rest of this season, and my engine is 3 years old; so I am considering an upgrade for next year. Charlie, who I know is right, advised that the A460s would be wrong for my combo, including the problem of the extra weight of the A460 valve, pistons, headers, intake, etc. I KNOW that Charlie is right, but is beyond my technical comprehension. Hope Charlie will give us another shot: why can’t I put out of the box A460s on now and have room for porting in the future. I think our Falcon could leave the earth with a little more HP.
 

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If one is gonna do a flat tappet which generally do not have huge lifts I suspect that the A460 heads are not the way to go...it's a matter of 'package'. The last set of TFS A460 heads we tested with the 2.350" intake valve option flowed 430ish around .800" lift....ported units with the same valve have been to 460ish....bigger dia. Ti. intake valves more yet . There is not one cyl head for all applications .
 

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P-51's will not out flow a well ported set of A460 Heads or make more power, No Way, Know How........ I have 2 sets of A460's Both worked and a very well worked over Set of P-51's for this years EMC with Charlie, and although they work very very well for a stock type heads, the will not hang with a set of A460s in an apples to apples compairson.

Typicaly in a typical max effort build the A460's will be in the rang of 50-100hp better and probably 2-3/10's faster on the track in a race preped car.

P-51s just don't have the port volumns and shapes that a full race type head has. Plus the Exhaust port isn't compromised on the A460's like the factory type ford heads are.

On the Flip Side a stroker street engine operating in typical Street/Strip type RPM Ranges would be better served with a set of P51's / SCJ's / Streets Rather than the A460....... They have better low speed useable power.
 

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You are gonna have to prove that 2-3 tenths to me Defree :D
Give me 2300# Chassis Car, 3 more points of compression and 34 more inches.....LOL

Build the same motor you have with A heads and it will be faster........
 

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I was just messing with ya , but I think there is a point to the weight issue. If you put my engine and an a head engine on the exact dragster chassis ,that a head deal will have to make several more ponies just to be at an equal playing field.

I am not bashing the A head either I wish I had a set of all of them :D
 

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Bellow is my present setup. What would happen if I substituted A-heads on thiis same combo, assuming I could get the right springs for the Intake valve? The reason I like this combo is because iit s on the fourth year without engine or trans freshening. All of my friends with roller cams and powerglides seem to break one of the other every year, despite good maintenance.

1967 Falcon, rectangular frame, 2800 lbs w/driver, Ron’s injection, C6, 4.88, 17 x 32 tire, 4 link, 4.5 bore A460 block, 4.3 stroke, Edel heads, 14-1 compression and flat tappet cam. 60' is 1.23, 1/8 is 5.82 @ 118
 

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Your buddies aint using the right pieces lol.

Aint nothin' wrong with a good solid lifter deal set up right.

So far so good with the glide..........;)
 

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There is no way of knowing what would happen to many variables , your converter would need to change, headers, etc.

I think you really want A heads and thats what you should get if that is what you want ,otherwise you will not be happy .

Lem , Charlie, defree and Randy are telling you like it is , they have been there and done that , they know what works and what does not.

Now this is my opinion :D

The main thing is the total combination , and if you change to A heads you are going to be replacing everything except crankshaft and rods and block . , you will gain weight, your a heads will not run optimum with a small cam , and your car will run faster with a glide as it is. Why would you want to spend all that $$$ and not buy optimum parts (roller cam, etc ) the first time ?
 

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yeah, i do feel like a huge pain in the hiney when I ask these questions, as well. But, I guess my current 'deployed' status (meaning I can't just call you up and ask) and just lack of overall experience puts the cart before the donkey and I end up asking anyhow.

So when do cubes become a hinderance to the P-51's? Or is this not a concern until the HP numbers get close to 900-ish?
 
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