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Discussion Starter · #1 ·
I want to change the heads on my motor from a basically cleaned up set (exhausts etc) to a ported set. The aim is 300cfm at .6".

I have a set of hyper eutectic pistons in it already which were chosen for their durability with a straight propane motor.

I am hoping to up the power considerably with the "new" heads. Will my hypers be OK at around 500HP??
 

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You will have no problem with the KB's, The new heads will give you what? 10-1 static CR????????, Even so,with propane having a high octane rating, no carbon, and none of the gasoline issues,you have no worries mate! I had a 460 propane powered F150 it had 10-1 CR 218/218 cam,ran super strong,towed as if nothing was back there, Ran smooth strong and long, until some scum of the Earth stole that Bad Boy!!!
 

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Discussion Starter · #6 ·
gregaust... not sure. I didnt assemble motor a friend did. They were very good quality according to him with a high silicone content, and I really dont have a reason to doubt it. All the other components on the motor were as he said they were going to be.
I remember him telling me a brand name, but I cant remember.

460 Tom.. I am aiming at a comp of 10-10.5 but no more. Propane has great octane but a bit poor in BTU so no point in going higher really.
Keeping the 90cc chamber of the D3VE head should net at 10:1, thats what I have now.

I want to build up the heads to 300cfm at .6" intake. The exhausts probably wont go better than 200-210 though which is poor.
I want to keep to standard valves as I have a set of stainless valves for the propane use.
My cam is a Crane 298 hyd flat. 598 lift 230 duration from memory. Induction is twin ported IMPCO 425 units flowing total of about 950cfm. Intake is very ported Port-O-Sonic. Headers are pacemakers (The only ones that fit in my engine bay but they have big primaries and are tri-wire).

The heads should be good for 600 or so.
I would be happy with 500 but the more the better right
.
The IMPCO is probably not enough but I am looking into some other EFI style gear.
Exhausts will have to go up to 3" twins I think too.
 

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On 2002-06-04 23:13, kid vishus wrote:
This guy found out the hard way the limits on hyper pistons in a 460.

http://www.dragraceresults.com/ubbcgi/ultimatebb.cgi?ubb=get_topic&f=2&t=004801

Personally, I dont like them in any kind of high performance application. They are not forgiving like a good forged piston. But, thats just my opinion.
Kid, As I read the postings at that site the guy states that the piston hit the valve. I am not sure that is a piston problem. Further back to this post, This guy will have no problem with hypers on a 10-1 Propane motor, I know I put over 100k on my propane truck. This is not smoke ,it is fact.
 
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