Has anyone noticed the size of race engines lately, particularly the naturally aspirated and nitrous oxide equipped engines?  Has anyone seen the size of the cylinder heads out there now, or the size of the intake ports?  Look around, it’s not uncommon to see Small Block engines these days over 460 cubic inches.  A 650 to 700 cubic inch Big Block engine today considered only average.  850-inch and 900+ cubic inch engines are out there among us.  

It’s Accufab’s contention that in race applications, the available intake air on naturally aspirated or nitrous equipped engines is too restricted.  It takes about twelve times as much air as it does gasoline to create fuel.  A 4500 style race carburetor may be good for anywhere from about 1,200 to 1,500 cubic feet per minute (CFM) of air.  But recent tests have shown significant horsepower gains with inlet air supply’s way above what had been previously thought to be “enough”.  

Accufab’s recently released dual-bore throttle body, a replacement for the “split Dominator style” carbs used on many naturally aspirated and nitrous oxide equipped race engines has proven that.  The flow ratings for four of these 2.75-inch dual-bore units is an unbelievable 7,396 CFM.
 
The old school of thought told us that no engine can benefit from that much incoming air, but the dyno says differently and the results on the dyno are now visible on the drag strips.  Ask Pat Musi.  Ask Sonny Leonard.  Ask racers like Dennis Radford and others who have switched to this new Accufab dual-bore set-up.  Naturally aspirated or nitrous race engines need air and lots of it.
 
With those results in hand, Accufab decided to put that thinking into a replacement for the 4-Barrel Throttle Body.  In many race classes, racers are limited to a single 4-Barrel carburetor or a single Throttle Body.  Accufab used a clean sheet of paper for this one and came to the conclusion that the standard intake manifold opening for the largest carbs available (the 4500 series) was just not adequate.  Accufab’s goal was to design a better 4-Barrel Throttle Body, not to try and fit it onto the existing 22-square inch 4500 series intake manifold inlet opening, an inlet opening that was originally developed in 1969.  Accufab’s concept was to develop a new 4-Barrel Throttle Body, with a 33- square inch area, a 50% increase, and let the racers (or the intake manifold manufacturers) come up with better intakes to match the increase in air flow.  Racers are creative, they will figure out how to modify their existing 4500 series intakes to accept the 8500 Throttle Body (the bolt pattern is slightly larger) or better yet, use a sheet metal plenum style intake manifold.
 
The Accufab 8500 Series 4-Barrel Throttle Body uses the same 2.75-inch bores as their dual-bore “split Dominator style” units and flows 3,600+ CFM at 28-inches.  There are no 4-barrel carburetors that can come close to matching that flow rating.  And if that’s not enough, racers can mount two of them together for double the volume.
 
These units, machined from billet aluminum and highly polished, can be used with either electronic fuel injection (EFI) or mechanical fuel injection.  For EFI application, there is a provision for either a Ford or GM style throttle position sensor (TPS).  Center-dump type throttle linkage is included.  Each throttle body weighs 3.5-pounds, compared to up to 13-pounds for a big 4500 series carburetor.

More air flow, more horsepower, less cost, less weight, what’s not to like?  

For more info and pricing, call Accufab, Inc., (909) 930-1751.

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