Stock P51s vs Ported P51s

Does anyone have any data on this? How much is port work worth on the P51? The intakes look really good, but I imagine some could be picked up on the exhaust side? Is it worth the money to have some P51s ported? Does anyone have any flow #'s on a set that was ported? Stock they are supposed to be very close to 400 on the intake side.

Combo:

572 cid 4.500 X 4.500
16:1 compression
Cam 284 @ .050 / .773 lift intake, 296 @ .050 / .749 lift exhaust on a 112 lobe center
1250 cfm dominator, TFS intake
With stock P51s 924 hp @ 6900. Over 900 from 6300 to 7400.

BOTH sides can be improved considerably at the higher valve lifts.
430 and 275 is a considerable improvement.

fabio has that data.... look in his build

psfracer wrote:Does anyone have any data on this? How much is port work worth on the P51? The intakes look really good, but I imagine some could be picked up on the exhaust side? Is it worth the money to have some P51s ported? Does anyone have any flow #'s on a set that was ported? Stock they are supposed to be very close to 400 on the intake side.

Combo:

572 cid 4.500 X 4.500
16:1 compression
Cam 284 @ .050 / .773 lift intake, 296 @ .050 / .749 lift exhaust on a 112 lobe center
1250 cfm dominator, TFS intake
With stock P51s 924 hp @ 6900. Over 900 from 6300 to 7400.

They don't flow 400 out of the box now. but it's easy to get them to.

You need more split and lift also..................

So what that would translate to hp wise? I know that would depend on many factors, but would it reasonable to assume I could pick up 30-40hp with port work?

The cam info you posted showed the intake lobe to be 282* @ .050"..........not 284*

What's you rocker ratio?

1.75 is the rocker ratio. Oh yea, 282 not 284.

1.75 X .455" = .796" lift. intake.

Yeah, so the exhaust would be at .771 because of the 1.75 ratio vs the 1.70--I forgot about that. Then take out the .018 clearance which would make it .753 exhaust, and .778 intake.

psfracer wrote:So what that would translate to hp wise? I know that would depend on many factors, but would it reasonable to assume I could pick up 30-40hp with port work?

Let's do the math.

1. You have had your engine dynoed and it made 924 Hp out of 572 cubic inches. 924/572 = 1.615 Hp/cu.in.

2. Randy Moore's (KY Mustang) is very similiar to yours, but not as much compresion. It has fully ported P-51 heads with titanium 2.300" intake valves. It made 951 Hp out of 562 cubic inches. 951/562 = 1.692 Hp/cu.in.

3. Bobby Shrewsberry's engine is very similiar to yours, but not as much compression. it had fully ported P-51 heads with stainless steel 2.300" valves. It made 942 Hp out of 559 cubic inches. 942/559 = 1.685 Hp/cu.in.

Both engines made more per CID than yours did. Using their higher Hp/cu.in values, your 572 CID engine should make between 963.8 to 967.8 Hp. Let's split the difference and say 965.8 Hp.

965.8 Hp minus your present 924 Hp equals an increase of 41.8 Hp. So 965.8 - 924 = 41.8 hp which you are asking for 30 to 40 hp more. Therefore I say yes, to answer your question and I highly recommend porting and flow testing your heads.

Charlie Evans

Great post. The math looks good to me.

The Snake made over 1000hp with his 570" deal............

richter69 wrote:The Snake made over 1000hp with his 570" deal............

580 inch 1003/580 = 1.73 hp per cid.

Porting the heads is more than worth the effort. Give Charlie a call................ And call Lem on the cam

They like something different in the cam department than your normal scj deals use.

my bad on the typo lol.

c.evans wrote:

psfracer wrote:So what that would translate to hp wise? I know that would depend on many factors, but would it reasonable to assume I could pick up 30-40hp with port work?

Let's do the math.

1. You have had your engine dynoed and it made 924 Hp out of 572 cubic inches. 924/572 = 1.615 Hp/cu.in.

2. Randy Moore's (KY Mustang) is very similiar to yours, but not as much compresion. It has fully ported P-51 heads with titanium 2.300" intake valves. It made 951 Hp out of 562 cubic inches. 951/562 = 1.692 Hp/cu.in.

3. Bobby Shrewsberry's engine is very similiar to yours, but not as much compression. it had fully ported P-51 heads with stainless steel 2.300" valves. It made 942 Hp out of 559 cubic inches. 942/559 = 1.685 Hp/cu.in.

Both engines made more per CID than yours did. Using their higher Hp/cu.in values, your 572 CID engine should make between 963.8 to 967.8 Hp. Let's split the difference and say 965.8 Hp.

965.8 Hp minus your present 924 Hp equals an increase of 41.8 Hp. So 965.8 - 924 = 41.8 hp which you are asking for 30 to 40 hp more. Therefore I say yes, to answer your question and I highly recommend porting and flow testing your heads.

Charlie Evans

Randy's and Bobby's engines were not dynoed without a vacuum pump. Paul's engine has a pump. Having said that, I'd think Paul's engine with ported heads could be 980ish for HP.