P51 Head HP gain after head port

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Re: P51 Head HP gain after head port

Post  bigblock t-bird on 28th November 2016, 22:05

Yep, A460's would have been the way to go. What Blake said of the p-51's is true and AFR's may be the new best CJ type head? My next engine may be a 598 with A460's. But for now the 528 with P-51's will haft to do. Thanks Steve

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Re: P51 Head HP gain after head port

Post  mudtrucker on 29th November 2016, 10:57

Lem Evans 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."

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


     What about the A460's will a 2.3" or a 2.35" valve clear a 4.390 or a 4.44 bore?
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Re: P51 Head HP gain after head port

Post  Lem Evans on 29th November 2016, 11:41

Yes sir.

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Re: P51 Head HP gain after head port

Post  99zx9r on 29th November 2016, 17:45

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

Sounds like you have a fun ride. Trapping 136 is impressive. How do you like the GRP rods? I run them as well in my 618 and hoping to get a second season out of them in 2017.
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Re: P51 Head HP gain after head port

Post  bigblock t-bird on 29th November 2016, 21:40

Before I went with the GRP's spoke with my engine builder about there life span. He called them and was told with my combo and rpm range, that 300 1/8 mile passes on there rod's. The motor turn's up fast with them. I do warm up the engine, shut off at the end of all run's. All this helps with engine life. I have only made 39 passes on them this hole year! So look's as if 3 years or so before I look at changing them. Steve

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Re: P51 Head HP gain after head port

Post  99zx9r on 30th November 2016, 00:28

bigblock t-bird wrote:Before I went with the GRP's spoke with my engine builder about there life span. He called them and was told with my combo and rpm range, that 300 1/8 mile passes on there rod's. The motor turn's up fast with them. I do warm up the engine, shut off at the end of all run's. All this helps with engine life. I have only made 39 passes on them this hole year! So look's as if 3 years or so before I look at changing them. Steve

Getting 300 passes wouldn't be bad at all. I'm hoping for 180-200...quarter mile, but on the throttle stop and going through at 7200.
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