Two 427s

[Vortecpro]

Engine 1.

Blue printed .060 over L72 427, 12.2 compression, 242/242 520/520 solid lifter cam, stamped LS-6 rocker arms, stock GM 840 rectangle port heads, 2.190/1.720 valves, factory 163 intake, 4 quart factory oil pan.

Engine 2.

.060 over 427 10.3 compression, 264/264 560/560 solid lifter cam, roller rockers, ported GM oval port 781 heads, 2.190/1.880 valves, Performer RPM air gap intake, 1 inch open spacer, Moroso oil pan.


Both engines will be tested with the same Holley carb, 2 inch headers with mufflers, which one will make more power?
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[WILMASBOYL78]

I will vote for the oval port motor...wilma

[bugsy]

The one with the best VOLUMETRIC EFFICIENTCY. Probably square port engine. IMO

Engine 1

[KenMaisano]

Engine#2

Well the 870 Square port has two points more compression could add about 30HP.
The 781 Oval port has 20 degrees more duration could add about 30HP. But the oil pan is +10HP
If the 781 larger valves were machined correct. about 1.900 Bowl area and chambers deshrouded.
The Oval port Engine should take the win by about 30+ HP.

I built a 049 Oval port 454 8.5to1 compression Q jet Super Stock engine in the early 1990s and it make 660HP. The Ovals can really work, these were 2.08 1.7 255ccs.

[VintageMusclecar]

Engine #2 by 75+ HP

[Vortecpro]

Thanks for the replies. Engine number 1. has been tested and made 575 HP @ 6500 RPM, very impressive when you consider the factory cam specs, I could see the vacuum coming in at 16 inches at idle. I ran the the engine to 6600 and was down 1 HP, I really like the way the 427 carries the power out, this is very important to me. Engine number 2. will be tested this week, I will post the results. Its interesting todays 236 headed flattop piston Super Stock 454 makes right at 720 HP, with the 049 headed version making 740. Ken, I would be interested in where your S/S 454 peaked?

[Vortecpro]

Eric, you might be a little optimistic there.

[VintageMusclecar]

I was figuring on ~550 HP for engine #1 and 625+ for #2. Seeing engine #1 already made 575, I'll revise that to 50 HP. I still think #2 will make 625+. I know your 467" version makes 660+ HP and over 600 lb.ft. I'd think the 427 should be close to those HP figures with a little less torque.

[earntaz]

Idle to 6500 RPM ... #2
6500 RPM+ ... #1

SOOOOO ... #2 gets my vote for what its worth ... TAZ