# DIESEL MATH

## UN­DER­STAND­ING THE NUM­BERS BE­HIND COM­PRES­SION IG­NI­TION

Diesel World - - Feature -

Diesel guys are num­bers guys whether they know it or not. You’ll see the Big Three tout­ing num­bers in all their ad cam­paigns—best-in-class tow­ing, most torque, high­est horse­power. In a day of small-turbo econ­omy cars, diesel num­bers are al­most al­ways big. For many af­ter­mar­ket en­thu­si­asts, 500 rear-wheel horse­power and 1,000 lb-ft of torque are sort of the start­ing per­for­mance bench­marks. Whether you’re good at math or not, num­bers in­fil­trate vir­tu­ally ev­ery as­pect of the diesel mar­ket—so let’s have a look at them! We prom­ise to try and keep it ba­sic.

En­gine Dis­place­ment

Al­most all the diesel en­gines we work with in the per­for­mance in­dus­try are large, but if there’s a dis­place­ment you can’t place (or if you’re talk­ing to an old hot rod guy) you can mix liters and cu­bic inches by tak­ing the size in cu­bic cen­time­ters (5.9L for in­stance = 5,900cc) and di­vid­ing it by 16.38. This gives us 360.2 cu­bic inches. That means an 8.3L (8,300cc) is 506 cid, and a 1.9L TDI is a tiny 116 cu­bic inches. It may be off by a dec­i­mal place or two, but com­par­ing cu­bic inches to cu­bic cen­time­ters can be help­ful in ev­ery­thing from cal­cu­lat­ing air­flow to siz­ing tur­bos, since most Amer­i­can hot rod math is non-met­ric.