In addition to all the comments, the 426 Hemi Imperial would need a lower gear ratio. A 3.23 would probably be sufficient. These engines did not have a whole lot of torque at the low end, so they would need the help of the lower ratio for good driveablitiy. These engines also had a phenomenal high rpm performance (they could rev all the way to 6500 maintaining a high level of torque) so a super high speed Imperial would certainly be the result. For the record, 6000 rpm w/ a 3.23 and the 235/75 tires would correspond to a hair over 160 mph. I would bet that the Hemi would have enough torge at this rpm to acheive these speeds in an Imperial. Now, a "Magnum" Engined Imperial is certainly more practical, even if somewhat slower. All you need for that is a cam replacement since the rest of the stock 440 engine is virtually identical to the HP (well, at least the 68-71 440s, the 67'sand 66's had different heads, as far as I know). The larger camshaft (intake duration increased from 256 to 268 degrees and overlap from 30 to 45 degrees as I recall) is the main element that allows higher rpm performance that the HP 440 has. Sure, some HP 440s had bigger exhaust manifolds, but this is not going to make a significant change. The bigger cam will result to the loss of some low end torque, but that's fine w/ me. D^2, 2x68s with cam "upgrades". Quoting "ChiPieAlandPaula@xxxxxxx" <ChiPieAlandPaula@xxxxxxx>: > Hello All, > I do not want to wander from the the stated purpose of the site. But, > one > must remember that as originally produced the 426 Hemi was a thinly > disguised > racing engine. The "Street Hemi" was a barely streetable variant. Fast > as > they were -- they required a tremendous amount of care. That was one of > the > reasons that the 440 Magnum was introduced. It was actually faster than > the > Hemi to 70mph or so(depending on gearing) and required nowhere near the > > maintenence. Since the typical Imperial buyer was in their 40's - why > would > they want a tempermental racing engine? This sounds to me like someones > > fantasy. > Speaking of such -- imagine an Imperial with a 440 Magnum engine, heavy > duty > suspension, heavy duty cooling and an all leather bucket seat interior. > That > would be a truely unique high speed traveler. Of course, this would have > been > easier to do than the aforementioned Hemi. > One final point -- in a Motor Trend from 1971 there was an article > about > the state of Texas. The author described a Texas "sports car" as a 4 > door > Imperial with a heavy duty suspension and radial tires!!!!!! > > Allan From > > Billings, Montana >