COMMON-RAILS ARE LUCKY TO CRACK THE TOP FIVE OR EVEN THE TOP 10 AT MOST BIG PULLING EVENTS.

COMMON-RAIL VS. MECHANICAL

Then, something interesting happened: Mechanical guys stepped up. In a world where a 13mm P-pump (12mm is stock) was as hot as it got, there were soon 14mm and 16mm pumps; plungers that varied timing; and huge International-based injectors in Cummins engines. These guys weren’t messing around.

As of 2019, the landscape is vastly different. Now, commonrails are lucky to crack the top five or even the top 10 at most big pulling events. In sled-pulling’s top pickup class, Super Stock diesel, there are usually only two or three brave souls who even enter computer-controlled trucks; the other 15 or 20 are all mechanical. This mechanical domination continues through Pro Stock and Limited Pro Stock classes, where eight out of the top 10 pullers are all mechanical.

DAILY DESTROYER

MECHANICAL: 1, COMMON-RAIL: 1

While brute power might dominate sled-pulling, there’s something to be said about having finesse in a daily driver. Thanks to nearly infinitely variable timing and fueling, one can have a 500 to 700 hp common-rail truck that’s virtually smokeless. We’ve even seen 1,000 hp pickups that have been nearly clean, save for maybe a little low-end smoke and idle haze.

On the other hand, a 1,000 hp mechanical truck can be quite the “smoke monster.” Even if you’re not one to care about smoke, low-end spooling suffers, as does general drivability. Mechanical trucks will usually require more air to make the same power, which makes the situation even worse.

However, common-rails can use tricks such as negative timing and carefully controlled fuel pulse widths to spool just about anything.

Now, we’re not saying that you can’t have a big-horsepower P-pumper; it just usually comes with sacrifices. Manual valve bodies, an immense amount of timing and a high-stall

Common-rail injection has come a long way in the past few years. Now, stand-alone computer systems and two or even three high-pressure pumps (such as this Industrial Injection triple fueler) are commonplace.

The driving force behind mechanical injection is the venerable Bosch P-pump. Both P7100 and P8600 models are popular in competition usage, and pumps such as this 16mm plunger Scheid Diesel unit can put out fuel for more than 3,000 hp.