| Author |
Message |
Steve (130.245.220.188)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 6:46 pm: | |
At 70 MPH cruising the tech hovers on redline (2100) RPM. Is there a way to lower the revs without killing speed? I have a allison world B400 5 speed. Or must the tranny be replaced.Also is operating in this condition bad for the engine? |
Johnny (67.241.166.66)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 8:05 pm: | |
Larger tires would help a bit, but they can be pricey. I'll leave the rest to those more experienced than I (like, everyone here) with Allisons & DD's. |
Henry R. Bergman, Jr. (Henryofcj) (65.194.145.42)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 8:27 pm: | |
Assuming your Allision has an overdrive high gear or fifth. Do not know what kind of mill you have except that it revs 2100 at 70, which if it....
.... is max'ed out means the gearing may be a little short. About the only way you could increase the road speed to a reasonable....
....level would be to change out the rear end/case for a higher road speed like 85 or soosss. Rather $spendy$. Good luck. Henry |
Henry R. Bergman, Jr. (Henryofcj) (65.194.145.42)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, February 10, 2003 - 8:31 pm: | |
Forgot also to says that it is POSSIBLE that fifth or high gear is electronically locked out. This happens when the factory put the wrong axle gears in the coach....
....because that is what they had and they were to cheap to do it correctly. Easy to find out if this is the situation and to have your tranny reprogrammed to give all 5 gears. Good luck. Henry. |
Jojo Colina (Du1jec) (68.8.173.2)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 12:05 am: | |
Running at 2100 will not hurt a Detroit. These engines were designed to run at 2100 all day long.
Jojo |
Jason windecker (198.81.18.161)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 4:09 am: | |
Just a thought, i think he said he was running a Allison world trans, arent these trans only for the 4 strokes, and doesnt the 4 stroke like to stay a bit slower than 2100 for long periods anyway? just a thought. and also thoguth u caould have the worlds reprogrammed into a 6 speed if necesarry am i wrong only used to older engine trans packages the 4 strokes are not that common yet in the used market, thanks for info u guys might have |
Tom Caffrey (Pvcces) (64.114.233.17)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 7:23 pm: | |
Steve, the governor will limit the speed to a safe value if running on the flat. The main effect that running right against the governor will have is engine wear will increase very slightly and fuel consumption will increase a bit more.
The actual numbers will depend on the exact engine configuration. For example, while peak torque for a coach 8V71 with N60 injectors has been reported to be at something like 1200 RPM, the best economy at wide open throttle has been reported to be at 1800-1900 RPM.
In the cases that I saw, fuel economy at peak torque looked like it was 10% lower than at 1900 RPM. I would have expected peak economy a lot nearer peak torque, but these coach DDs don't like to be turned very slow.
For a small change in speed, tires may be the best shot you've got. I expect you already know if you have all your gears.
You didn't say what kind of rig you are running. If it is like our two strokes, many of these are set at 2100 for full stroke on the injectors and 2250 for no stroke. In other words, there is around 150 RPM droop built into the governor.
This means that you won't cut off fuel entirely until you reach about 75 mph. If you drive about 64, you will be turning about 1900 RPM. Depending on the tire size you are already running, you might be able to achieve most of what you have in droop by going to a larger tire.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
Hal StClair (Hal) (208.13.129.225)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, February 11, 2003 - 9:20 pm: | |
Your world trans can be programed as a 4,5 or 6 speed, its all in the ECU-same hardware,same trans. You will have to pay Allison to re-program the ECU and you should be on your way.BTW, the 6th speed will be a .64 overdrive.Good luck with Allison!
Hal |