Originally Posted by cobalt327
I had thought the whole "only one good Vortec head" bs had been laid to rest a LONG time ago. For those who don't know, some wag at CHP magazine (IIRC) started this myth shortly after the Vortec heads came out (and before much was actually known about them, presumably). This myth has been rebuked many
times by dyno and flow bench tests, track testing, etc. etc. but still surfaces every so often.
Here are the FACTS: The ONLY significant difference in c/n 906 and 062 L31 production Vortec heads is the 906 head MIGHT have a hardened exhaust seat insert as opposed to an induction hardened seat. The insert MAY cause there to be a slight lip where the insert and head meet. And there might be a single angle seat instead of the three angle seat used on the induction hardened seats (this has to be verified). These differences certainly do NOT make the 906 w/insert a "bad" or "poor flowing" head. In fact, there are boat builders who prefer
the insert seat heads.
If the Vortec head as used on production vehicles has a problem, it's cracking- NOT flow. Some cracking isn't because of the heads per se
; they cracked because of other shortcomings of the engine.
IMO anyone who cannot get better performance from a Vortec head than a fuelie head- all else being equal
- needs to work on their engine building skills.
• Vortec heads
The 031 and the 906 are pretty much the same head and it is also the only vortech head that will out perform the 461. So yeah only one good vortech head. All the others are just as average as many of the regular casting heads. Some are much worse!
The humps can be ported out much bigger than the vortech can. So yes they can out perform them. With the 461 heads you can also reangle the ports a little to allow for better flow. This is one mod that does not need to be done on the vortechs. vortech already benifit from a better angle. With ports you have volume and angle if you have the best then your engine will flow. No magic or secret spells.
Small exhuast ports can be helped with a split pattern cam but when going for borke you may already be using the max exhuast duration or you may not want to use a bad cam to make up for the heads short comings.
I would be interested to see dyno results of stock cast vortech heads pulling more than 350 hp n/a and not using the 031 or 906 or any other gm performance products heads.
Both heads will make an easy 350 hp and both have been used to make 400 hp many times over.