LT1-LT4 Modifications 1993-97 Gen II Small Block V8

AFR Heads on a 396

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Old Mar 23, 2004 | 05:32 PM
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Default AFR Heads on a 396

Right now im in the planning stages of my new rebuild, and im hoping for any help.

What im sure i want to do is go with a 396 stroker on a solid roller cam hoping to run up to 10k rpm (maybe 8-9).

What im unsure of is what kinda heads to get. Im thinking about getting Bare 227 AFR LT4 heads for $940 and doing basic porting myself.

Bare 227 AFR LT4 heads

Im also thinking about getting a good set of LT1 or LT4 heads with a good race port job.

My instincts tell me that the the stock castings wont flow enough (even with the best porting) to handle 10k rpm on a 396 motor.

THX for your help guys.
STU
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Old Mar 23, 2004 | 09:00 PM
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i'd like to see the 396 get to 10k rpm first,rod ratio's arent exactly condusive to major rpm.

as far as the heads go,the $940 heads will need a lot more then basic porting. they are rough as cast heads,basically they need everything done to get close to running. and yes,you will need those or the RR215's to flow the air for a setup like that.
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Old Mar 23, 2004 | 11:28 PM
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I wouldnt go any less that the 227s. Send them to a good porter and let them get to work. Dont know why you'd want to spin to 10k though? With the right heads and cam all the power that you could want can be made while spinning under 7k RPM. Besides I've never heard of an LTx motor spinning that high, even so it would be VERY expensive for the components that could handle it.
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Old Mar 24, 2004 | 12:52 AM
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Yea, the rod ratio is what kinda worries me too, with a 6" rod on a 3.875 stroke its only a 1.548 ratio, which isnt exactly the best setup for 10k RPM. I was also toying with the idea of a stock stroke on 6.2 rods, making a much happier 1.781 R/S ratio.
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Old Mar 24, 2004 | 12:58 AM
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Im thinkin Eagle forged crank and rods and diamond pistons. The rotating assembly and the block could handle it with 4 bolt mains. The only thing that i can forsee would be a problem would be the ignition and possibly the computer. The valvetrain should be able to handle it with a solid roller setup and rediculious springs.

Im not sure what the computer would do, but im thinking about goin with a delteq ignition to get rid of the opti for a stronger ignition setup (along with MSD's help).

Any other problems you can think of?
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Old Mar 24, 2004 | 01:33 AM
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10k? Forget maybe, you'll definitely want an aftermarket computer. Opti only handles up to like 8500 RPM, i think. Maybe not even that much.
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Old Mar 24, 2004 | 05:31 AM
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i wouldnt even consider eagle for a possible 10k rpm setup,too heavy. and whats the deal with 10k rpm? rpm's hurt parts. a 396 isnt meant to be a high rpm screamer.
you are gonna need LIGHT parts for big rpm,and that translates into BIG money.

Stock pcm calls it a day around 7k rpm,opti,well i have seen them go to 7800,but thats it.you may want to consider a complete aftermarket ignition setup,as in trash the opti all together,and convert to a distributer.
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