It's an "h4" engine, as opposed to an "i4" (inline 4) or "v4". H, stands for horizontally opposed, aka, boxer. 

I am not a fan of those batteries, I just don't believe the juice is worth the squeeze. The quality has supposedly change when the manufacturing changed a few years ago. 

-craig

> On Mar 12, 2014, at 9:46 AM, Pete O <pnoceanwesty@GMAIL.COM> wrote:
> 
> Anyone using Odyssey batteries for their Vanagon?
> 
> They are a top end battery and cost about $250.  Supposed to be made with
> "virgin" lead, not alloy and provide a longer lasting more robust battery.
> 
> They list the waterboxer as:  2.1 Liters 2109 CC H4.
> 
> What does the "H4" stand for?
> 
> Located here:  http://odysseybattery.com/
> 
> 
> Pete
> '87 Westy "JoesVan
> '79 Westy "Aardvark"