414TATA Posted February 12, 2013 Share Posted February 12, 2013 Re: 248 C.I. Straight eight. My question. How many R M P is this beast turning at 55-60 Miles per hours? I know this has been discussed many times but when I do a search using RPM nothing comes up for me. If you can stand the repetition I hope you will help me out.ThanksWayne 1941 Super 51 Link to comment Share on other sites More sharing options...
Guest Grant Magrath Posted February 12, 2013 Share Posted February 12, 2013 There are formulas out there that you can find, and web pages with handy calculators. If you know your wheel diameter, diff ratio and the speed you're wanting to know about, it should be able to tell you.CheersGrant Link to comment Share on other sites More sharing options...
Guest jules greenway Posted February 12, 2013 Share Posted February 12, 2013 For 1931 the "Specifications and Adjustments" Manual has a very good graph for road speed in relation to engine RPM showing exact figures which differ for each model, not just engine size-the more "sporty" open cars seeming to rev higher than the big saloons.It shows the largest car/engine (Series 90-344.8 CI) doing 3000RPM at 65MPH and the smaller (Series 50-220.7CI) doing 3500+at 65MPHI assume the manual for 1941 should have the same info?cheersJules Link to comment Share on other sites More sharing options...
jeff Posted February 12, 2013 Share Posted February 12, 2013 The '38 manual has such a graph. It's at home now, so I will just rely on memory. A '38 Special with 248 engine and 4.44 rear turns about 3200 rpm at 60 and the Century with 320 engine and 3.9 rear turns about 2800 rpm at 60. Again, just going with my memory (usually faulty).Jeff Link to comment Share on other sites More sharing options...
414TATA Posted February 12, 2013 Author Share Posted February 12, 2013 Thanks Gentlemen I was thinking in the range of 3,000 RPM at 55 - 60 mph. Seems that number came to mind from a prior post.Wayne B. Link to comment Share on other sites More sharing options...
Buicknutty Posted February 14, 2013 Share Posted February 14, 2013 I just looked in my '41 manual, and with the 4.4 axle, it shows dead on 3200 RPM at 60 MPH, if you have the optional 4.1 ratio, it shows just a tick under 3000.Keith Link to comment Share on other sites More sharing options...
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