That aspect of the total picture is one size fits all. The part that isn't covered on the chart is determining where the engine's peak torque RPM is. <span style="text-decoration: underline;">That</span> is what will decide the gearing because that is the RPM you want the engine to run at while at cruising speed (be it 45 or 105 MPH).<br><br><br>FWIW, I can see the strength advantage in ditching the lock-up. It is not something that I would even contemplate doing. I would sooner have a 3 speed auto with a locking converter than a 4 speed OD auto with no locking converter. Then again my last off road trip saw 1249 miles of combined use. The one prior to that saw almost 1600 miles of combined use.<br><br><b><i>Brian Cooke <nvrstuk@elltel.net></i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> So you're stating that the table (from your post below-- <br>http://www.4lo.com/calc/geartable.htm)
takes into account all engine <br>combinations, meaning it's a "one size fits all" chart for all different <br>size or brands of engines, figuring in cam designs, head volume and <br>efficiencies, induction systems...everything that affects torque curves and <br>throttle response, driver style and needs? I didn't know the referenced <br>chart could factor all that in. I can't see where the chart might show the <br>difference in running a 4cyl with 4.88 gears and 35" tires compared to big <br>block running 4.88 gears and 35" tires. I have my rig dialed in for my <br>needs. Not perfect obviously, but for the $$ I have in it, it works for me.<br><br>I'm not arguing that 4.10's w/37" tires is a "good combo"... My post below <br>stated that my 351W was turning at 2200 rpm...and I had regeared last fall <br>with 4.56 gears.<br><br>So figuring 70mph (my reference) not 65mph (the chart), my 351W is turning <br>at appr 2200 rpm. Definitely acceptable rpms for optimum mileage
with the <br>gears I'm running. Yes, I might be losing optimum acceleration with this <br>gearing when I'm cruising, but if I shift into 4th, I've got it all back. <br>If I need to crawl slow, I just shift in my 203 box and my 5.72 first gear.<br><br><br><br><br>Brian<br><br><br><br><br>Brian @ Columbia River Broncos...20 forward gears & 4 reverse to choose <br>from.<br>----- Original Message ----- <br>From: "Quinn Dusenberry" <q.dusenberry@comcast.net><br>To: <mail@broncofix.com><br>Sent: Saturday, May 10, 2008 12:13 PM<br>Subject: RE: was Re: [BFix] Thinking outload gas <br>mileageandEB....nowwhyditchthe lock up<br><br><br>> The idea is to get the engine most efficiently. Take a look at this gear<br>> table and then try to argue the point that 4.10's and 37's is a good <br>> combo.<br>> At 65 mph, your engine would be turning 1770 rpm. The only way you were<br>> turning 2200 rpm would be when you were going 80 mph. Either that or your<br>>
"effective" diameter was much less than 37" which could be the case.<br>><br>> Your switch to 4.56's is much better, but still not ideal. Keep in mind <br>> that<br>> this chart is purely a mathematical table based on the circumference of a<br>> tire. It does not take into account the fact that with a larger<br>> circumference also come more inertia and more weight. You should be <br>> gearing<br>> more towards the red side of the chart the bigger your tires get to help<br>> offset the mass and inertia parts of the larger tires.<br>><br>> http://www.4lo.com/calc/geartable.htm<br>><br>> Keep in mind that this chart is just your 1:1 ratio, you need to multiply<br>> all values in the table by your OD ratio (0.73 in your case) to get the <br>> true<br>> rpm at 65 mph.<br>><br>><br>><br>> -----Original Message-----<br>> From: Brian Cooke [mailto:nvrstuk@elltel.net]<br>> Sent: Saturday, May 10, 2008 12:20
PM<br>> To: Mike Bowlin; Quinn Dusenberry; mail@broncofix.com<br>> Subject: Re: was Re: [BFix] Thinking outload gas mileage<br>> andEB....nowwhyditchthe lock up<br>><br>> Not sure why a 351W turning at 2200rpm is bad gearing. Not like it's<br>> lacking torque to adequately move me at 70mph except when climbing a long <br>> 5%<br>><br>> + grade in OD. Not sure why I'd need to spin the engine at another couple<br>> hundred rpm for extended freeway trips is worth it for wear or for mileage<br>> IMO. Guess that's how I got almost 185,000 miles on this engine I built <br>> 20<br>> years ago... I regeared to 4.56's last fall to help offset the taller <br>> tires.<br>><br>> If this was a dedicated trail rig or used 90% on trail that's a different<br>> story. Quite a few EB's are driven more miles off road than on-mine is. <br>> Even<br>><br>> if you tow your rig to Moab, you're usually putting more road miles on
it<br>> than trail miles in a typical day. 10 miles to the trail head, 10 miles<br>> back. Trail is 5-15 miles long...whatever...just an example.<br>><br>> Most of you know I also run a doubler off road, so "go slow" gearing isn't<br>> an issue at all.<br>><br>> You're right, heat is a drawback of more HP. For sand, heavy wet snow and<br>> mud, you can't go wrong with more HP tho. Crawling over rocks is totally<br>> different. Just like tires, there's a different drivetrain combination <br>> that<br>> would be best used for almost every terrain.<br>><br>><br>> BTW, ask Jack how much fun having that 408 is too! :)<br>><br>> Brian<br>><br>> Brian @ Columbia River Broncos...20 forward gears & 4 reverse to choose<br>> from.<br>><br>> _______________________________________________<br>> bfix mailing list<br>> bfix@broncofix.com<br>> http://broncofix.com/mailman/listinfo/bfix
<br><br>_______________________________________________<br>bfix mailing list<br>bfix@broncofix.com<br>http://broncofix.com/mailman/listinfo/bfix<br></mail@broncofix.com></q.dusenberry@comcast.net></blockquote><br><BR><BR><p> 
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