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Want more power out of 427

7K views 14 replies 10 participants last post by  kwillymac 
#1 ·
Hey everybody I have a few questions in hoping you can help me with. A friend of mine currently has 427 bbc that ran 520hp on the dyno. Now after a few years he wants more power closer to 650hp. No nitrous. He is on a very strict budget. Now the motor has forged crank and forged domed pistons. Now I thought in my mind he could disassemble the motor have the pistons milled down to be flat tops giving it around 8.5:1. Put a weiand 177 blower ontop. Possible upgrade to a hydraulic roller.

Would this work? If not could I get input on what you guys would recommend? This is strictly a street motor in a 71 gmc half ton.

Thanks a bunch
 
#12 ·
I agree. I'm no engineer, but from what I've been able to put together over the years, good engineering practice dictates that the crown thickness will equal about 7% of the diameter for a naturally-aspirated piston. The crowns on dedicated blower pistons will be thicker than those on naturally-aspirated pistons, so you would want to be adding material, not cutting material away. I don't know what the percentage of crown thickness to diameter would be with a dedicated blower piston, but common sense tells me 8% to 9%.
 
#6 ·
He has the 781 oval port heads. They have been ported with 2.19/1.88 valves.

I can't see it being very expensive to do that's all. Because all he needs is to lower the compression change cam and stick the little weaind 177 on there? Or am I missing something?

Is there a way to tell if the done is hollow or not??
 
#9 ·
^^^^^X2

the reason most people are saying that going the blower route will be expensive is for 1 the blower is going to cost 2500+ to get it delivered. Then I would say that it would be a little dumb to run a blower on facotry heads (just my opinion) and I'm not sure those heads in the shape they are in can even support 650hp. So there is a set of aftermarket heads, 1800-2500. To do this he is looking at 5,000 easy, and that doesn't include the machine work to the pistons (i'd just buy new pistons).

Since this is a 427 BBC which is basically the same block as the 454 BBC just with a 396 crank, I would say go after building a 496, he'll have about 2500 into the rotating assy and the machine work. Then go after the aftermarket heads, and probably another cam. It isn't too hard to make 600-650hp out of a 496 (with the tq to match). Then later on if he decides he wants even more then he could toss a blower on it and be in the 750hp range (suposing the block and other parts hold up).
 
#10 ·
my87z is correct
what I said,heads = 60 plus hp.50 cubes will add 60 plus hp,torque would go up.

or like I said 60hp for better heads and maybe 20 more with a roller cam,thats 600,,,
blower or 496 will both need new pistons.
do the math on the cost of parts and see what works best for the situation? a 496 can use bigger heads than a 427 so more power potential there
 
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#13 ·
I would swap out the camshaft for something like this one from Lunati Street Strip Hyd Cam - Chevrolet Big Block 285/295 - Lunati Power then buy you a 100-150 shot cheater nitrous system, good street motor then nos if you go to the strip.. 100-150 is pretty mild shot for bbc.. this setup may cost you less than $500-$600 you get the power you want and have fun for lot less than a 2 grand blower adder not blower wouldnt be cool, but i think you dont have the right SCR or the right setup for it, NOS just bolt on and go once you learn a few detail before you run it, not hard, just common sense
 
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