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Posts: 7
Reply with quote  #1 
Within the last year have gotten into racing small engines and I love it.  There is one thing that I don't understand.  The WF engine seems to be briggs top of the line engine but it comes with a 7100 rpm limiting coil.  The animal has a 12k coil, why not the other way around?  The WF has also a billet rod and the animal the squeeze cast one but again it is "allowed" to rev higher.  Last but not least, the header.  The WF has a small dia exhaust compared to what most use on the animal.  Is the header another limiting factor or does it help with low end power?  Please explain, thanks


Posts: 1
Reply with quote  #2 
The reason why the world formula is limited to 7,100 RPM is because with the stock valve springs, the valves start float around 7,300. Briggs and Stratton is trying to prevent that so you don't have to change valve springs every race. If you want more RPM just switch the coil between the two motors. And with the animal they typically come with 6,000 coil since they come stock with softer valve springs. I race Quarter Midgets with the M series Animal and the World Formula classes. I have to run the 6000 coil in animal and 7100 in World, that is what they typically have stock unless its modified.

Posts: 198
Reply with quote  #3 
Another way to look at the two engines is the WF is designed and engineered specifically for a race class and by controlling the maximum RPM it levels the playing field (taking away the advantages of out RPM spinning your fellow racer), also reduces cost/maintenance while maintaining reliability.  The exhaust is really about durability verses ultimate performance.  With everyone running the same exhaust you have a level playing field and a system that will likely outlive most racers careers.  You can't find that in an after market exhaust. 

The Animal is a standard approach to racing.  From the factory it is spring limited well below the rev limiter but it allows for the flexibility to be modified for the type of racing and the rule set it will be raced under.  Think of it as a piece of clay, engineered for racing, to be molded to fit a rule set.

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