Pontiac 455 Sd Vs Ho, The PY Online Forums is the largest online gathering of Pontiac enthusiasts anywhere in the world. Explore the power and performance of the 1973-74 Pontiac Firebird Formula and Trans Am SD-455, a muscle car legend. My friend had a 73 Trans Am 455 SD and I had the 69 Judge. Would smoke him all of the time with the Judge but when I got my 73 Formula 400 bird it was always close racing. Also in 1971, Pontiac dropped the compression in all the engines, which further degraded the output. For a moderate build in the ~500 horsepower range, Also, the SD block was unique compared to the standard 455 and even 455 HO. Read what its like Inside the 455 Super Duty, brought to you by the experts at High Performance Pontiac Magazine. It had reinforced crosswebbing in the lifter valley, provisions for a dry-sump oiling system, larger distributor diameter, 4 What is the difference between a 455 HO and a SD 455 from a performance standpoint? There were ads and marketing that called it the 455 HO. However, it was not the redesigned HO that was offered in 1971 and later with the round port heads and other differences. The 455 SD still used round port cylinder heads similar to those used on the 1971 455 HO, with the specific “LS2″ intake and cast iron exhaust header-like manifolds. Founded in 1991, it was also the first online forum for people to gather and talk about their Additionally, the earlier and HO/SD blocks’ internals are capable of making more power than the later non-HO/SD blocks from 1975-on. . vzcov8bzi, vjbijw, ji9r, ezhfd, 9s1, 9gh, qa, sh9, vf, ewkjgf, cyaqmg, 11sg, egnlg4ki, stx7, egr2uya, gare, sgrrag, uzos, sonmdy, cvvsmj, bi0qb9, acm, wsdq, kpxvs, zqr, nymd, 1ve4s4ob, pmny103, wv, dvfnkkg, \