Reply
 
Thread Tools Display Modes
 
Old 09-26-2006, 12:35 AM   #1
Skoolie
 
Join Date: Sep 2006
Posts: 105
Year: 92
Coachwork: ward flat nose
Chassis: international
Engine: dt466 mt643 air ride
Rated Cap: 84
axle ratio change

Hi guys and gals, I'm new here on posting, but have been enjoying your site
for awhile now. I finally got myself a 92 FC International w/ a Ward 14
window. It has a dt466 and a MT643r trans. The air ride axle is a 4:44 on
295x75-22.5 tires. I drove it 900 miles to get her home at 60 mph.
It may have run a little faster but I didn't like pushing her over 2250 rpm. And THAT
may have been pushing too hard, I'm not sure.

Anyhow, I been doing some figuring? My idea is to replace the 4:44 w/
a rebuilt ratio of 3:42. This will give me a 65 mph cruise speed of 1886 rpm.
Has anyone tried a ratio this fast? And IF I ever find myself needing to
REALLY GET SOMEWHERE FAST, I can go 70 mph at 2031 RPM. Though
most of my driving will be at 60 mph which is 1741 rpm. I'm thinking that
dt466 at 210 hp shouldn't have any trouble working this axle ratio. Your
thoughts, please. [/b]
kotflb is offline   Reply With Quote
Old 09-26-2006, 04:01 AM   #2
Bus Nut
 
oldog12's Avatar
 
Join Date: Aug 2006
Location: Illinois
Posts: 381
How do you think it will handle a long uphill pull?
oldog12 is offline   Reply With Quote
Old 09-26-2006, 01:52 PM   #3
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
http://www.internationaldelivers.com...NGLE.pdf?src=1

Ignoring the fact that that is a new DT466 versus your older one (I don't htink the specs are all the different other than power output), you will see that maximum governed speed is 2600 RPM, the same as my 6.6L Ford. Please remember that is a governed top speed, not a mechanical redline. Sure, semis might be turning 1500-1700 RPM going down the highway, but they have well in excess of 1500 ft lbs available to them right at about that speed and enough gears to always have the "correct" ratio. You're limited by the fact that you have just over 500 ft lbs of torque and 4 gears (5 if you factor in torque converter lock up).

Basically, I think that you have a good deal going on paper, but in reality, you'd be MIGHTY sorry with that ratio. If you can even find a ring and pinion set in that ratio, you will have an amazingly difficult time achieving those speeds you have listed, especially with any sort of load like a hill. If and when your tranny shifts into 4th gear, you will be cooking that poor converter I think. Your tranny is going to think it's pulling twice as much weight around due to the lack of mechanical advantage.

Basically, my suggestion is this...keep the ratio you have. You aren't spinning the engine too fast as it is. If you really want to run it slower or go faster on the highway, swap to a true class 8 manual tranny. I know an RT6613 Road Ranger 13 speed was an option in my bus and might be something to look at if it's really that important to you.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 09-26-2006, 04:32 PM   #4
Bus Geek
 
lapeer20m's Avatar
 
Join Date: Nov 2003
Location: near flint michigan
Posts: 2,653
redline for the DT360 is 3,100 rpm, i would assume it is the same for the 466
__________________
Quis custodiet ipsos custodes (who will watch the watchmen?)
lapeer20m is offline   Reply With Quote
Old 09-26-2006, 05:24 PM   #5
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
If the redline varies like the governor does, the higher the output, the lower the rated redline for obvious reasons. I think it would be safe to assume his DT466 is in the lower output tier and thus would have one of the higher redlines. 3000 doesn't sound out of the question.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 09-26-2006, 06:36 PM   #6
Skoolie
 
Join Date: Sep 2006
Posts: 105
Year: 92
Coachwork: ward flat nose
Chassis: international
Engine: dt466 mt643 air ride
Rated Cap: 84
Thank you gentlemen for the feedback. I gauss I assumed wrong, I was thinking the redline for the dt466 was 2600 rpm, but maybe that is the standard governor setting.

Therefore are you saying I can run this engine at 2250 rpm all day and not hurt the longevity of this engine. I had read on an earlier post that 1800 rpm is the ideal cruising rpm for this motor, and looking at the link you posted, it is at a good torque point, though at a slightly lower then max horsepower point.

Isn't the best fuel ecomony acheived somewhere between max hp and max torque, and if so, wouldn't that put my cruise rpm somewhere around 1800 and 1900 rpm? Since max torque is 1500, and max hp is 2300 rpm, after which increasing rpm just reduces the hp, where is the SWEET SPOT, on these engines?

As far as mountain driving goes, maybe 1 or 2 percent may be mountain driving, therefore my main concern is the other 98% of mainly flat and slight rolling hills. If I can get over the moutains in 2nd or 3rd gear without overheating, I'll be happy. Of couse I plan to install a radiator mister to help keep things cool. My goal is 12+ mpg in "no wind" highway driving between 60 and 65 mph. You thoughts, please.
kotflb is offline   Reply With Quote
Old 09-27-2006, 12:41 PM   #7
Bus Geek
 
the_experience03's Avatar
 
Join Date: Feb 2006
Location: Saint James, MN
Posts: 2,669
Send a message via MSN to the_experience03 Send a message via Yahoo to the_experience03
Here is my way of looking at things...torque is most important as it is what gets things moving...but if you want them to move fast, you need the horsepower. The horsepower is what's going to give you that 70 mph top speed. Ok...so cruising you want top horsepower then because horsepoewr is a unit derived from torque. Torque can be altered via gearing, but not horsepower. Cruising obviously requires less torque than accleration so......gear for top horsepower at cruising RPM. You will then have extra torque on reserve for when you get loaded down such as a hill. In a bus, hill doesn't mean a mountain...it means any hill. I can feel so little as a 3% grade in the bus. Length, not steepness, is what seems to affect my bus more.

Long story short....I would just leave your gearing alone. If you can find a thirdmember with 4.10's in the boneyard, more power to you, but I wouldn't pay someone to replace them with new. It would take a LONG time to recover that cost at the benefit of a just a few miles per gallon. You're well withing the design tolerances of the motor with your foot on the floor all the time so no worries about longevity. That really just leaves you with speed. Even a 10 mph increase in top end isn't going to get you all that much farther in an 8 hour driving day. What's 80 miles? I'd rather just sit back and enjoy the view.
__________________
http://farm4.static.flickr.com/3024/...09f20d39_m.jpg
Skooling it...one state at a time...
the_experience03 is offline   Reply With Quote
Old 09-27-2006, 10:37 PM   #8
Bus Nut
 
oldog12's Avatar
 
Join Date: Aug 2006
Location: Illinois
Posts: 381
Don't fix it if it ain't broke
oldog12 is offline   Reply With Quote
Old 09-28-2006, 08:52 AM   #9
Bus Geek
 
lapeer20m's Avatar
 
Join Date: Nov 2003
Location: near flint michigan
Posts: 2,653
i think ia gree with old dog. A lot of us would kill for a 4.44 rear end.

not to mention you have the highly coveted dt466 coupled with the mt643.
__________________
Quis custodiet ipsos custodes (who will watch the watchmen?)
lapeer20m is offline   Reply With Quote
Old 10-12-2006, 09:48 PM   #10
Skoolie
 
Join Date: Sep 2006
Posts: 105
Year: 92
Coachwork: ward flat nose
Chassis: international
Engine: dt466 mt643 air ride
Rated Cap: 84
thanks guys for the replys.
I'll leave it as it is and enjoy the views since I can live with the current 10 mpg it now gets, and start working on the conversion and body painting. That by itself should keep me busy for the next six months.
kotflb is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Rear axle gear ratio. To change or not to change. slade Conversion General Discussions 15 04-24-2017 03:33 PM
rear end gear ratio change Atridox GM | Chevrolet Drivetrain 2 08-13-2012 10:24 AM
Passengers - length ratio Thomas MVP Conversion General Discussions 11 04-18-2009 02:22 AM
Rear axle or 2 speed axle hoser Everything Else | General Skoolie Discussions 7 09-10-2006 10:56 AM
Changing the Gear Ratio Mat7103 Conversion General Discussions 6 03-05-2004 08:10 AM

» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 10:48 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.