P51 Head HP gain after head port

So I am running a set of P51 heads on my T-bird, out of the box as cast. Also running a Mafia intake that is stock as well. A460 block 4.3 Callies crank 4.420 bore with Diamond pistons on GRP 6.7 rods. Cam 274 280 @.050 110 center line. I don't run it very hard, leave at 6500 and shift at 6800. Stick car . Called Kaase about porting heads and was not impressed of hp for money. Thanks Steve

bigblock t-bird wrote:So I am running a set of P51 heads on my T-bird, out of the box as cast. Also running a Mafia intake that is stock as well. A460 block 4.3 Callies crank 4.420 bore with Diamond pistons on GRP 6.7 rods. Cam 274 280 @.050 110 center line. I don't run it very hard, leave at 6500 and shift at 6800. Stick car . Called Kaase about porting heads and was not impressed of hp for money. Thanks Steve

55-65 hp Just a ball park if they get 30 more cfm out of them could be up to 70 hp.

Thanks Blake, that's about the HP gain I would like to see. May need to turn it more?

bigblock t-bird wrote:So I am running a set of P51 heads on my T-bird, out of the box as cast. Also running a Mafia intake that is stock as well. A460 block 4.3 Callies crank 4.420 bore with Diamond pistons on GRP 6.7 rods. Cam 274 280 @.050 110 center line. I don't run it very hard, leave at 6500 and shift at 6800. Stick car . Called Kaase about porting heads and was not impressed of hp for money. Thanks Steve

What ET's are you running?

Gary, so far my best run in the heat was a 5.21 @ 136. I think I may just run it harder? Steve

IDT-572 wrote:

bigblock t-bird wrote:So I am running a set of P51 heads on my T-bird, out of the box as cast. Also running a Mafia intake that is stock as well. A460 block 4.3 Callies crank 4.420 bore with Diamond pistons on GRP 6.7 rods. Cam 274 280 @.050 110 center line. I don't run it very hard, leave at 6500 and shift at 6800. Stick car . Called Kaase about porting heads and was not impressed of hp for money. Thanks Steve

55-65 hp   Just a ball park if they get 30 more cfm out of them could be up to 70 hp.

Just the heads being well ported with some good mid-lift flow remaining, on an 800 horsepower engine, I have seen 50 to 60 horsepower but, now that engine could also take more advantage of a better suited camshaft, ( which didn't help before), and make almost 80 more horsepower.

bigblock t-bird wrote:Gary, so far my best run in the heat was a 5.21 @ 136. I think I may just run it harder? Steve

It runs real good. What fuel and compression?

What's it weigh?

Gary,

I have done three 557's with flat tops and out of the box P-51's with a ported Victor intake, no vacuum pump or fancy ring package. Wet sump pan.

All three made between 900 and 905 hp 800-810 tq.

This was with off the shelf parts.

If he weighs 2400-2500 lb 900 hp will run close to his time.

IDT-572 wrote:Gary,

          I have done three 557's with flat tops and out of the box P-51's with a ported Victor intake, no vacuum pump or fancy ring package. Wet sump pan.

All three made between 900 and 905 hp  800-810 tq.

This was with off the shelf parts.  

If he weighs 2400-2500 lb 900 hp will run close to his time.

Blake, would you happen to have flow numbers for an as cast P-51 preferably on a 4.440 bore?

I have had them on 4.400 to a 4.600 and didn't affect the flow, I would suspect the valve moved so far of the cylinder wall is why.

I have seen them from 385 cfm too a little over 400. The three I had on the dyno were all around 400.

But it seems the lower cfm heads still made the same power.

IDT-572 wrote:I have had them on 4.400 to a 4.600 and didn't affect the flow, I would suspect the valve moved so far of the cylinder wall is why.

I have seen them from 385 cfm too a little over 400. The three I had on the dyno were all around 400.

But it seems the lower cfm heads still made the same power.

Thanks, typical cam like you told me about at Columbus awhile back, 285/296 112 Comp? Do you see a 532 at about 860 HP?

Yes probably close to that.

I think the cam was more in the 281 300 range on a 113

"But it seems the lower cfm heads still made the same power."

Especially if the short side was prostituted for numbers up high.

Gary I have 15 to 1 and run 110 Sunoco.  2550 with me.  I'm thinking it's got 925hp 950hp. Yep vacuum pump and fancy ring package. Right now I have a 5.00 gear and may switch to a 5.29, for the 1/8. Going to run my shift up to 7000 and see what I get. For what these heads are they do very well as cast. Steve

Thats a lot of gear for that weight car. Do you have a low neumerical gear in the first gear set?

1st gear is 3.14 2nd 2.11 3rd 1.54 4th 1.21 5th 1.1 Liberty. Yes it sounds like a lot of gear, I get 5th about 80' from end. 1st threw 3rd come fast real fast. I wish I had an in car of a run! A 5.29 would put me at 7000 or 7100 at the 1/8 Steve

Thats a 15 to 1 finaldrive ratio in first gear

Wow.

"I have had them on 4.400 to a 4.600 and didn't affect the flow, I would suspect the valve moved so far of the cylinder wall is why."

Yep, that SCJ/P51 intake valve is waay off the cyl. wall.....this is only a 4.400" bore:

bigblock t-bird wrote:Gary I have 15 to 1 and run 110 Sunoco.  2550 with me.  I'm thinking it's got 925hp 950hp. Yep vacuum pump and fancy ring package. Right now I have a 5.00 gear and may switch to a 5.29, for the 1/8. Going to run my shift up to 7000 and see what I get. For what these heads are they do very well as cast. Steve

Wew that is lot of gear. I would tend to put more cam in it. Somewhere on the net there is a 532 P-51 pump gas motor built by SAMS. Around 11-1 compression. If memory serves me correctly the cam was very similar to yours, 275/284 109. I think your combination with that compression could function very well with more duration.

Lem Evans wrote:"But it seems the lower cfm heads still made the same power."

Especially if the short side was prostituted for numbers up high.  

Sometimes you don't need more air.

That's not usual with a BIG racing engine with a CJ style head. A lower rpm street strip/pump gas deal would be another matter.

bigblock t-bird wrote:So I am running a set of P51 heads on my T-bird, out of the box as cast. Also running a Mafia intake that is stock as well. A460 block 4.3 Callies crank 4.420 bore with Diamond pistons on GRP 6.7 rods. Cam 274 280 @.050 110 center line. I don't run it very hard, leave at 6500 and shift at 6800. Stick car . Called Kaase about porting heads and was not impressed of hp for money. Thanks Steve

Free HP......tighten the lash on the exhaust down by .010". Leave the intake alone. It will pickup. If the cam is degreed in around 106 or so then there is more in it. Degree cam to a 103 ICL.

IDT-572 wrote:Gary,

          I have done three 557's with flat tops and out of the box P-51's with a ported Victor intake, no vacuum pump or fancy ring package. Wet sump pan.

All three made between 900 and 905 hp  800-810 tq.

This was with off the shelf parts.  

If he weighs 2400-2500 lb 900 hp will run close to his time.

Sorry to hi jack this but how does that compare to a60's out of the box.

The P-51's upper end porting lol (I have learned not to say max ported ! ! ! !) Are about where a good set of 2.300 A heads start to make power.

A 460 heads can and do go into the 470+ range with regularity nowadays. With some big valve heads going over 500 cfm.

The P-51's are the top of the SCJ line, with the AFR's coming that may change though.

Bottom line they are not A460 hp capable, and I still say the A 460's are the best hp per dollar head starting from scratch.

With the base A460 heads being $2,750, including ti retainers and shipping, they are the bang for the buck on a racing engine.