June 24, 2018, 02:29:48 PM

Author Topic: revisiting engine and transmission change  (Read 1366 times)

Offline Tin Lizzy

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revisiting engine and transmission change
« on: April 02, 2007, 09:52:28 PM »
Well it looks like we are going to do some engine changes. After Dreamweavers troubles with clutches and transmissions etc I think we are both going to convert our coaches to 6v92t and go with a 9 speed or 13 speed roadranger tranny.
I have been told that installing a tranny like these means the shift pattern is reversed but that something can be changed on the tranny to make it shift in a regular gear pattern. Does anyone have any knowledge of what needs to be changed?
Now we are on the lookout for 2 6v92t's and two transmissions, anyone have any ideas of anything available in western Canada or western US?

I am also ready to change my original MC7 windows to RV windows and I need a quality source for windows out of an RV.

As Dave has several MC9 rads we are going to change the rads as well.

This should be the summer that I get everything done so that next year will be bussing time for me......after 4 years or so!!!

Any info would be appreciated
Tin Lizzy
1972 MC 7
Calgary, Alberta

Offline niles500

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Offline TomC

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Re: revisiting engine and transmission change
« Reply #2 on: April 02, 2007, 10:41:18 PM »
If you now have the 8V-71, why not rebuild them to turbo specs and do what I did and change it to turbo and air to air intercooled?  If you hop up a 6V-92TA and go to 100 injectors, that's 600mm injection per rev-and that would be putting alot of stress on the engine.  If you hop up a 8V-71 with turbo and air to air intercooler and go with a conservative 80mm injector, you get 640mm injection per rev, and that was a factory setting by Detroit that put out 400hp and 1200lb/ft of torque.  Go to 90 injectors and you're getting into 8V-92 performance country from a 8V-71, or 450hp and 1350lb/ft of torque-of which you'd have a very short lived 6V-92, if you tried, but the 8V-71 can take it.  Just saying you can get alot of power out of a 71 series as compared to the 92.  The 71 is just a more robust engine and alot more forgiving.  I took mine from 65mm injectors that were 300hp and 800lb/ft to the very conservative 75mm injectors with air to air intercooling (custom made to my design) and now have 375hp and 1125lb/ft of torque.  It changed my 6% long hill climbing from 30mph to 40mph pulling my car, don't hardly have to down shift, and actually have some passing power now.  With a good 13 spd, you'd be in hog heaven.  I personally don't like the 92 series since it has wet cylinder liners that can leak into the crankcase, whereas the 71 series has dry liners that are almost impossible to leak. 

On the Roadranger transmissions, they make reverse shifters for bus use, at the transmission.  Personally- I'd go with an Allison- no manual transmission can come close to the around town acceleration, and the pure enjoyment of not having to shift constantly-and this from a truck driver that drove nothing but 13 spds for 21 years and 1.3 million miles worth.  If anything, put in a 10 speed Autoselect transmission (Autoshift that works with mechanical engines-only difference is that you have to work the throttle between shifts).  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.