From: tedhils (tedhils@cyber-south.com)
Date: Tue Nov 19 2002 - 08:48:07 PST
J.D.-
First, your math is pretty good, as far as it went. My friend's chart
for RPM differences (used for monster truck tires) shows right at the same
RPM at 65 MPH as you had. However, it also said reduce it by 1-300 RPM for
an automatic transmission. This gets it down to the 31-3300 RPM range.
And, if you have the correct tire pressure in the tires and full tread, they
should be about 31 inches in diameter (I just measured 10 or so). This gets
your RPM down to 2900-3100. Any 6.2 diesel engine that can't sustain
running about 3000 RPM already has serious problems.
6.2s are governed at 3800 RPM. It does not hurt the engine any more to
run it at 3795 RPM than it does at 1800 RPM. Detroit diesels actually use
less oil at high RPM than they do at low RPM. The mail drawbacks to running
the 6.2 at high RPM are noise and fuel economy. The same is true of any
sound diesel engine when run within the manufacturer's governor and
injection pump settings. High RPMs (again, within the mfg's guidelines) do
not harm an engine that in is good condition.
So you owners of CUCV pickups.... go for it. Running fast isn't going
to hurt your engine. I can't say the same about your ears, though. :~}
Ted
Ted Hils
Ted's Trucks 'N Stuff
Rural Route 2 Box 66H
Midland City, AL 36350
334-983-1092
Mon-Fri, 8-5 CST
----- Original Message -----
From: "J. D. Bowen" <oreuc@yahoo.com>
To: "tedhils" <tedhils@cyber-south.com>; <mil-veh@mil-veh.org>
Sent: Monday, November 18, 2002 9:18 PM
Subject: [MV] M1008, M1028, M1031 and M1010s at speed
> Let's put a little math on the 4.56 geared CUCV and
> draw your own conclusions (assuming my math is good).
>
> Using a stock 235/R7516 @ 29 inch diameter for
> calculations.
>
> Speed RPM's
>
> 45 2380
> 55 2908
> 60 3173
> 65 3437
> 70 3702
> 75 3966
>
> Can you run the 6.2 at 70 mph all the time? Probably.
> Would I want to run it at that RPM with stock
> gearing/tires? Probably not. At 2380 rpm you can see
> why 45 mph is where the military preferred it be run.
>
> J. D.
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