was Re: [BFix] Thinking outload gasmileageandEB....nowwhyditchthe lock up

Sat May 10 23:58:13 MST 2008

Obviously it isn't a one size fits all chart. It's a general guideline for
most gas powered engines. That's why it gives a range of suggested gear
ratios from the yellow to the red. Sure you should bias it one direction or
the other based on your engine. Like if you had a less powerful, smaller
displacement engine, you would want lower gears to help offset that. I was
just trying to point out that rather than build a bigger engine to improve
your vehicle's performance, which you've already admitted you want to do, I
would reconsider regearing it first. Gears will do the same thing as more
torque will. Gears are torque multipliers. If you want to see how you like
how it drives with lower gears, borrow a set of smaller tires and try it for
a while.

-----Original Message-----
From: bfix-bounces at broncofix.com [mailto:bfix-bounces at broncofix.com] On
Behalf Of Brian Cooke
Sent: Saturday, May 10, 2008 10:03 PM
To: mail at broncofix.com
Subject: Re: was Re: [BFix] Thinking outload
gasmileageandEB....nowwhyditchthe lock up

So you're stating that the table (from your post below--  
http://www.4lo.com/calc/geartable.htm)  takes into account all engine 
combinations, meaning it's a "one size fits all" chart for all different 
size or brands of engines, figuring in cam designs, head volume and 
efficiencies, induction systems...everything that affects torque curves and 
throttle response, driver style and needs?  I didn't know the referenced 
chart could factor all that in. I can't see where the chart might show the 
difference in running a 4cyl with 4.88 gears and 35" tires compared to big 
block running 4.88 gears and 35" tires.  I have my rig dialed in for my 
needs. Not perfect obviously, but for the $$ I have in it, it works for me.

I'm not arguing that 4.10's w/37" tires is a "good combo"...  My post below 
stated that my 351W was turning at 2200 rpm...and I had regeared last fall 
with 4.56 gears.

So figuring 70mph (my reference) not 65mph (the chart), my 351W is turning 
at appr 2200 rpm. Definitely acceptable rpms for optimum mileage with the 
gears I'm running. Yes, I might be losing optimum acceleration with this 
gearing when I'm cruising, but if I shift into 4th, I've got it all back. 
If I need to crawl slow, I just shift in my 203 box and my 5.72 first gear.

Brian

Brian @ Columbia River Broncos...20 forward gears & 4 reverse to choose 
from.
----- Original Message ----- 
From: "Quinn Dusenberry" <q.dusenberry at comcast.net>
To: <mail at broncofix.com>
Sent: Saturday, May 10, 2008 12:13 PM
Subject: RE: was Re: [BFix] Thinking outload gas 
mileageandEB....nowwhyditchthe lock up

> The idea is to get the engine most efficiently. Take a look at this gear
> table and then try to argue the point that 4.10's and 37's is a good 
> combo.
> At 65 mph, your engine would be turning 1770 rpm. The only way you were
> turning 2200 rpm would be when you were going 80 mph. Either that or your
> "effective" diameter was much less than 37" which could be the case.
>
> Your switch to 4.56's is much better, but still not ideal. Keep in mind 
> that
> this chart is purely a mathematical table based on the circumference of a
> tire. It does not take into account the fact that with a larger
> circumference also come more inertia and more weight. You should be 
> gearing
> more towards the red side of the chart the bigger your tires get to help
> offset the mass and inertia parts of the larger tires.
>
> http://www.4lo.com/calc/geartable.htm
>
> Keep in mind that this chart is just your 1:1 ratio, you need to multiply
> all values in the table by your OD ratio (0.73 in your case) to get the 
> true
> rpm at 65 mph.
>
>
>
> -----Original Message-----
> From: Brian Cooke [mailto:nvrstuk at elltel.net]
> Sent: Saturday, May 10, 2008 12:20 PM
> To: Mike Bowlin; Quinn Dusenberry; mail at broncofix.com
> Subject: Re: was Re: [BFix] Thinking outload gas mileage
> andEB....nowwhyditchthe lock up
>
> Not sure why a 351W turning at 2200rpm is bad gearing.  Not like it's
> lacking torque to adequately move me at 70mph except when climbing a long 
> 5%
>
> + grade in OD. Not sure why I'd need to spin the engine at another couple
> hundred rpm for extended freeway trips is worth it for wear or for mileage
> IMO.  Guess that's how I got almost 185,000 miles on this engine I built 
> 20
> years ago... I regeared to 4.56's last fall to help offset the taller 
> tires.
>
> If this was a dedicated trail rig or used 90% on trail that's a different
> story. Quite a few EB's are driven more miles off road than on-mine is. 
> Even
>
> if you tow your rig to Moab, you're usually putting more road miles on it
> than trail miles in a typical day. 10 miles to the trail head, 10 miles
> back. Trail is 5-15 miles long...whatever...just an example.
>
> Most of you know I also run a doubler off road, so "go slow" gearing isn't
> an issue at all.
>
> You're right, heat is a drawback of more HP. For sand, heavy wet snow and
> mud, you can't go wrong with more HP tho. Crawling over rocks is totally
> different. Just like tires, there's a different drivetrain combination 
> that
> would be best used for almost every terrain.
>
>
> BTW, ask Jack how much fun having that 408 is too!  :)
>
> Brian
>
> Brian @ Columbia River Broncos...20 forward gears & 4 reverse to choose
> from.
>
> _______________________________________________
> bfix mailing list
> bfix at broncofix.com
> http://broncofix.com/mailman/listinfo/bfix 

_______________________________________________
bfix mailing list
bfix at broncofix.com
http://broncofix.com/mailman/listinfo/bfix