Help building an L48

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Oct 26, 2007 | 10:24 AM

#21

thecorvette

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Joined: Apr 2007

Posts: 69

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There is more than one production vortec head. The most desirable is the "L31" head. Part number 12529093. Casting number 10239906.

Oct 26, 2007 | 11:43 AM

#22

desi

Melting Slicks

Joined: Sep 2002

Posts: 2,783

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From: Engineers do it better.

Quote:

Originally Posted by billla

Drop...from 8.5? Why?

I meant, increase. You know what I mean

Last edited by desi; Oct 26, 2007 at 02:02 PM.

Oct 26, 2007 | 03:21 PM

#23

billla

Le Mans Master

Joined: Jun 2004

Posts: 6,231

Likes: 65

From: Seattle WA

St. Jude Donor '14

Quote:

Originally Posted by yel76low

Performer heads flow less than vortecs? I thought Edelbrock 'guarantees' 400hp with their top end kit?

Not sure how this will display, but here are the numbers. The exhaust numbers aren't a straight comparison because of the way the port blends into the chamber. Look at the idle to mid-range flow up to .500 lift (the stock Vortecs are lift-limited to .475) - this is where every CFM counts.

I'm not discounting the Performer heads at all - I'm just noting that for a set of really cheap iron heads the Vortecs are an amazing deal!

Key:
EDL = Edelbrock Performer #60609
VTC = Vortec #12558060

Lift EDL VTC
I E I E
.1 67 58 70 48
.2 130 108 138 101
.3 183 144 190 129
.4 226 169 227 140
.5 229 175 239 147
.6 232 128 229 151
.7

Oct 26, 2007 | 03:36 PM

#24

billla

Le Mans Master

Joined: Jun 2004

Posts: 6,231

Likes: 65

From: Seattle WA

St. Jude Donor '14

Quote:

Originally Posted by thecorvette

There is more than one production vortec head. The most desirable is the "L31" head. Part number 12529093. Casting number 10239906.

P/N 12529093 is a bare head...

There are 3 GMPP heads; if you're going junking for heads it's a different story...and you're likely to spend more money than a NEW head:

12558060: production assembled head, 170cc runner, 64cc chamber, 1.94/1.50 valves, ,.475 lift (upgraded heads available to .525+ lift)
25534421: Bow Tie (aftermarket) "small port" assembled head, 185cc runner, 66cc chamber, 2.00/1.55 valves, .530 lift. Nice touches are dual pattern intake capability and center- or perimeter-bolt valve covers.
25534431: Bow Tie (aftermarket) "large port" assembled head, 215cc runner, 66cc chamber, 2.00/1.55 valves, .530 lift. Nice touches are dual pattern intake capability and center- or perimeter-bolt valve covers.

Last edited by billla; Oct 26, 2007 at 04:01 PM.

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