Wilsons Sandbox

Thanks to Gene Gillam (anngene@bellsouth.net) for forwarding Bob Watts' (WattsWattsMG@aol.com) message. It was indeed of interest. I was particularly interested in Bob's statment that he had "run at 5200 to 5500 for 20 miles or so on occasion." I sometimes drive the freeway here in Los Angeles and to keep from getting run over I have to drive 65 MPH (about 3500-4000 RPM). I had been told not to exceed that, but now I am thinking that it might be OK to step it up to 4500 or 5000 RPM. What say guys - Is it OK to drive at 5000? Jim Shade West Covina CA

Not without a note from your mother Jim Jim Shade wrote... "I sometimes drive the freeway here in Los Angeles and to keep from getting run over I have to drive 65 MPH (about 3500-4000 RPM). I had been told not to exceed that, but now I am thinking that it might be OK to step it up to 4500 or 5000 RPM. What say guys - Is it OK to drive at 5000?"

At 09:51 PM 12/16/01 -0500, FDShade@aol.com wrote:

>What say guys - Is it OK to drive at 5000?

Jim: 4130 RPM is 2550 ft. per min. of piston speed. One should not exceed that except for short periods of time, if one wants engine to last over a long period. Other than that you can drive all day at or below that RPM. Skip Kelsey....................................................

Hi Skip, Thanks for associating a fact with my seat-of-the-pants impression that 4200 rpm was my engine's "sweet spot" for cruising. What is the derivation for this theoretical limit? A wear index? I rather suspect its a very deep subject, e.g. mass acceleration rates, stroke and rod length, etc. Cheers, Peter -----Original Message----- From: Skip Kelsey [mailto:kelsey@shadetreemotors.com] Sent: Monday, December 17, 2001 11:32 AM To: FDShade@aol.com; mg-tabc@yahoogroups.com Subject: Re: [mg-tabc] RPM At 09:51 PM 12/16/01 -0500, FDShade@aol.com wrote:

>What say guys - Is it OK to drive at 5000?

Jim: 4130 RPM is 2550 ft. per min. of piston speed. One should not exceed that except for short periods of time, if one wants engine to last over a long period. Other than that you can drive all day at or below that RPM. Skip Kelsey.................................................... Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

At 01:53 PM 12/17/01 -0500, Peter Pleitner wrote:

>Thanks for associating a fact with my seat-of-the-pants impression that 4200 >rpm was my engine's "sweet spot" for cruising.

Peter: There is some engineering formula that dictates this RPM as being the threshold of a high wear rate on the engine. Although Jaguars exceed this RPM with not problem in the wear dept. Skip........................................................................

.......the wear dept. Wear, schmear.... all I know is 4200 revs brings out the sweetest exhaust notes and that's what XPAG motoring is all about!! Bill Tantau EXU 7606 -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web.com/ .