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Old 10-15-2010, 05:30 PM
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Vortec head horsepower

How much horsepower can you really expect to get out of Vortec Heads that have been touched up a bit. Got a set on a 355 now. Getting ready to build a 406. Was thinking about using my vortec heads on them. It will be on a street ride.
Thanks Lee

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Old 10-15-2010, 06:00 PM
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In my opinion, the intake runners are too small to feed a larger motor. The heads do a fine job on a 355, but a larger motor needs more head. When I do DynoSims, I see them running out of steam on a 383. There will be fellows who will post following this, that they made XXX horsepower with the heads on a 408, but the question is, how much horsepower could they have made with a head that was sized for the motor?

The L31's are 170cc runners. A 408 will need 200cc runners.
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Old 10-15-2010, 06:44 PM
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I am not a mechanic. But the guy in my neck of the woods that is the "Head Guru" has had sucess porting these heads, then putting 205 valves in them. I don't know all the tech. details. What do yall think
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Old 10-15-2010, 07:20 PM
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I have stock Vortec's on my 406. I don't have any numbers, but it goes pretty good for a 4K lb truck.

I only went with these because I had them. Some day I will get some nice aluminum heads, but the Vortecs are hard to beat when I compare them in my Dynosim program using the parts I have. Of course, I hardly know what I am doing compared to techinspector1.

Hey techinspector, when you say "running out of steam", are you referring to the low RPM range that they seem to peak at?
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Old 10-15-2010, 07:35 PM
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I have a set of 062 Vortecs on a 406, 9.2 compression, 5.7 rods, etc. I did the bowls a bit, screw in studs, good springs, etc. Edelbrock RPM and an Edelbrock 750 carb.

I would have to agree with Techinspector. My engine flattens out between 5000-5500, after that there is nothing there.

My dynosim says 375HP, 435lb/ft torque. For the street it is a hoot to drive. Throttle response anywhere before 5000 RPM is awesome.

With the small runners, I'm not sure you could get a whole lot more from them with bigger valves. That is just an opinion though.
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Old 10-15-2010, 09:15 PM
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