Author Topic: 455 build  (Read 922 times)


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455 build
« on: October 28, 2018, 08:21:41 PM »
Planning a .30 over with forged pistons/rods and would like a estimate of torque/HP diff between 6x8 heads and 6x4 heads ? All other input is appreciated ! Thanks.


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Re: 455 build
« Reply #1 on: November 03, 2018, 11:37:41 AM »
Not a big difference, and if this is a street driven car, I'd go with the 6x-8 heads, to be a little safer with low quality pump gas.

If most hp & torque are your goal, then, of course, the most compression has the best power potential.

So it just depends on how pump gas friendly you want it to be.

With either heads, a decent 455 should make near 400 hp & 500 torque, assuming it has a decent cam. Smaller cams might have little more torque at a lower rpm. Bigger cams will produce more top end hp.

A 6x-4 head 455 with a bigger cam would obviously make more top end hp than a similar 6x-8 head 455 with a smaller cam.

The cam can make a big difference in any 455. If you go with less compression, you can make up some of the loss, by using a Voodoo cam, or another cam that closes the intake valve sooner, to build more cyl pressure. 

If you go with more compression, you can bleed off some of that pressure by using a cam with more adv duration. On opposite ends of the cam selection might be something like a 262 Voodoo & an 041 clone. The little Voodoo might produce too much cyl pressure, and the 041 might not give the low end everybody would want, for a street driven car. I like the 041, IF you also run Rhoads lifters.

I just bought a Summit 2802 for my Super LOW budget 455 bracket build. It has unported 6x-8 heads. If I'd had more to spend I'd have gone with an 041/Rhoads. But, the Summit cam & Jegs lifters saved quite a bit, which I used to buy other needed stuff.
« Last Edit: November 03, 2018, 12:04:33 PM by oldskool »


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Re: 455 build
« Reply #2 on: November 23, 2018, 04:56:49 PM »
 Sounds about right. Stock D-ports flow in the 200-205 cfm range. Porting either will add about 30-60 hp, a little more if the porter knows how to port Pontiac heads. It's not thesame as porting Chevy heads.

1977 SE T/A (sold :( )
1974 455 T/A (sold :( )
1972 Esprit restomod
1976 T/A restomod
1975 Formula 400 4-speed donor car
1978 Martinique blue W72 4-speed T/A, hurst tops

Re: 455 build
« Reply #2 on: November 23, 2018, 04:56:49 PM »
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