vortec confusion!

[razorbaq]

I was checking out the engine in my 94 5.7L z71 that I just bought. Then I got confused as I have always heard In 96 chevy introduced the vortec line of engines.
I have a Edelbrock intake I took off off a 81 sb, So I was looking under the bay to see how easy of a hook up this would be and started to get confused. The truck was a single owner (my good friend) and I knew it was all original, This intake had straight down bolts into the heads unlike the older engines I always played with, and I knew this was a characteristic of vortec heads.
Could somebody enlighting me on what this is, or offer a link to a site strictly about early to mid k1500 trucks, I looked everywhere and couldnt really find one. Thanks!

[MrPbody]

error...

[MrPbody]

The Vortec engine was installed in Chevy trucks from around '87 or '88. It includes the "191" (heavy duty) or "193" (light duty) cylinder head (last three digits of the casting number). This is NOT the same head advertised in catelogs as "Vortec". The truck heads have a "wing" in the intake runner, causing the mixture to swirl as it enters the cylinder, creating a "vortex" (where the name came from). In effect, the mixture "cork-screws" into the cylinder, providing superior cylinder packing at lower engine speed. Unfortunately, this advantage on the low-end comes at the price of poor higher rev flow. These heads DO NOT have a "high swirl combustion" chamber. NOTE: "HSC" does not mean "heart shaped chamber", it means "high swirl combustion."

The heads that came installed on '93 or so and newer 350s in F-bodies and Caprice are what the aftermarket calls "Vortec". Chevrolet compounded the confusion by adopting the name when they began selling those heads "over the counter" and through other aftermarket outlets. The performance "Vortec" head is pretty good once the exhaust seat and port is "fixed" (woeful in "as delivered" form). They do NOT have the "wing" in the intake runner, but they DO have an HSC chamber. The result is a head that flows much better on the high-end, without MUCH loss of low-end. All in all, maybe one of the better performance BUYS. There ARE much better iron heads for small block (Dart Iron Eagle for one, ProTopline for another), but they are more expensive than the "Vortec".

Helpful? I know, clear as mud...

Jim

[razorbaq]

Thanks alot I learned something new, But chevy sure did a good job in creating confusment.

[silicon212]

Actually, what are known as 'Vortec' heads, with the angled intake bolts (vertical), were used in trucks from 1996-end of SB Gen I. The heads on F-bodies and Caprices (and Roadmasters and Fleetwoods) were LT1 heads, because they had LT1 engines. The Vortec head was designed for OBDII-compliant small block Gen I engines, and is based upon the Caprice iron LT1 head.

The difference between the LT1 and Vortec heads are that the LT1 is reverse-cooled, and only fits the LT1 block, while the Vortec will retrofit on to any small block Chevy engine that's not reverse cooled.

[MrPbody]

silicon212,

Details... Details... Seriously, good job. I was not aware of those subtle differences.

Jim