254 Straight Eight

[Deleted User]

Hey folks, I know I have this somewhere in my books but cannot seem to find it. Can anyone tell me the compression and cruising RPM of the 254 cc eight cylinder?



Ok, found the compression: 6.5:1



But, anyone know what the RPM at cruising speed(s) are? I know this is kind of an ambiguous question with different gear ratios, etc. but if someone can get me an approximate. I'm thinking 2000-2500 RPM on the highway but not sure. Also, what's considered in the red? 3000-4000 RPM?



thanks for any input!



Rick

Park_W

Rick, the non overdrive cars turned almost exactly 3,000 rpm at 60 mph. Nowadays that seems (and sounds) uncomfortably high. The factory-equipped overdrive cars do much better ... about 2400 at 60 mph. Overdrive with the "non-overdrive" rear-end gears (4.11:1) bring it down to about 2160 at 60 mph. That's what I'm running in my '47 C8, and it's great. Still all kinds of hill-climbing power in 3rd gear with the OD.

[Deleted User]

Rarerodder wrote:

Hey folks, I know I have this somewhere in my books but cannot seem to find it. Can anyone tell me the compression and cruising RPM of the 254 cc eight cylinder?



Ok, found the compression: 6.5:1



But, anyone know what the RPM at cruising speed(s) are? I know this is kind of an ambiguous question with different gear ratios, etc. but if someone can get me an approximate. I'm thinking 2000-2500 RPM on the highway but not sure. Also, what's considered in the red? 3000-4000 RPM?



thanks for any input!



Rick

Hudson 8 engines are relined at 3800 RPM's. As far as cruising speeds that depends on tire size. A 1/2 inch difference can make the difference in RPM at 60 MPH. Like in my Hornet, std is 3:08 and I installed 2:73 which lowered my RPM by 400. No loss of power and 2 more miles per gallon. I sell 4,000 RPM tacks and that is what you need. This way is no guessing. Walt.