L31 Vortec Heads

For a very good, professional write-up on the Vortec heads, go to this Chevy High Performance article.

When GM Performance Parts released the L31 Vortec heads for small-block Chevy engines in 1996, they were an instant hit with the hot-rodding crowd due to the great flow numbers (outflowing the venerable Bow Tie heads), efficient 64cc chambers, and great price (under $500/pair, assembled).

I bolted a pair onto my Nova's 350 engine in 1999 and really enjoyed the performance and efficiency of the castings. I ran a 13.49 ET with my mild setup and it was as reliable as the sunrise. However, installing Vortecs on a basic small-block Chevy engine isn't a simple, bolt-on proposition. Also, there are additional costs involved that are not immediately apparent when you plunk down $500 at the Chevy dealer and walk away with two heavy boxes.

I've been asked many, many times what's required and recommended to install the L31 Vortec heads on a small-block Chevy engine. The following was written in 2001 and reflects prices and parts availability from that year. Be sure to look at current prices and parts before making your decision. Also, if you do get used Vortec heads, be sure to avoid casting number of 10239906. These come from heavier-duty trucks and have a flow-limiting exhaust seat installed.

Limits/Disadvantages of stock Vortec heads:

Parts and supplies required for basic installation:

Additional parts and machine work recommended for performance use:


If you've read this far you may be wondering if these heads are really that good to warrant the expense and hassle of setting them up to work properly. It depends on your goals and the intended use and expected performance from this engine.

These heads are capable of supporting 400 hp on a relatively mild 350 engine and they work great on the street and actually can help provide some acceptable fuel economy. Chevy High Performance magazine did a series of articles based on a Goodwrench 350 and Vortecs and made some good power (just over 400 hp with some mild port work). They really are great street heads.

The down side? These heads are pretty much maxed out right out of the box. CHP only gained a few horses by doing the port work and proclaimed that GM apparently did their homework when they designed these heads because they're nearly perfect as is. In other words, you won't likely be able to do anything to them later on for increased performance.

To summarize, if you're looking for a very streetable small-block Chevy engine capable of producing nearly 400 hp for street use and occasional drag racing, Vortecs are a great choice. If you ever plan to go for more power or add a blower, however, you'd likely be better off with one of several other head choices. Some choices worth considering (among others) are Trick Flow Specialties 23-Degree aluminum heads, World Products Sportsman heads, and RHS Pro Action heads. When considering bang-for-the-buck, the Trick Flows appear the most attractive of the bunch, so I'll compare them below to the Vortecs.

Price Comparison:

If you've got a fairly solid, typical setup (350, Edelbrock Performer intake, Comp XE268 cam, headers, performance carb, etc.), let's look at the cost involved in going from stock #882 heads to Vortecs or TFS heads on your engine:

Compare that to swapping to a set of Trick Flow Specialties 23-degree aluminum small-block Chevy heads:

So as you can see, if you low-ball it, Vortecs can be cheaper. If you go all out, the prices for Vortecs and Trick Flow's aluminum heads are very comparable. Which should you buy?


VALVE SIZE: 1.94 / 1.50
FLOW@.100: 70 / 48
FLOW@.200: 139 / 101
FLOW@.300: 190 / 129
FLOW@.400: 227 / 140
FLOW@.500: 239 / 147

VALVE SIZE: 2.02 / 1.60
FLOW@.100: 65 / 70
FLOW@.200: 133 / 102
FLOW@.300: 188 / 140
FLOW@.400: 226 / 164
FLOW@.500: 250 / 183

Decision Time:

If I were to buy something right now, it'd be the Trick Flows. That said, I do miss my Vortecs! I hope you take the information I've given and do further research and make a well-informed decision.

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Copyright 2009 Bruce Johnson and Craig Watson