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Old 01-11-2008, 03:18 PM   #11
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Re: Get my bus moving!

well said elliot.

my former bus i think came at rpm about 2200 rpm, redline is around 3K rpm fr the dt360. I "turned up" the govenor to around 2700 rpm. Changed things from about 57mph stock to 64 mph after i fixed it. Made cruising at or just a little above 60 mph very easy. Also improves acceleration, and possibly helps fuel economy. It seems to me that engines use more fuel when they are fighting the govenor all day long.

to answer the original posters question...stolen from this website:

http://www.freewebs.com/nevrenufhp/index.htm


Cummins 4BT,6BT, 6CT(3.9,5.9, 8.3)

For the 89-93's (Bosch rotary "VE" pump)there's a screw behind a tin access cover about the size of a nickel. Shown in this article: http://www.dodgeram.org/tech/dsl/more_p ... wer_ve.htm . It takes a 1/2"(13mm) to break the jamb nut loose, then take the screw out. It'll have a metal band welded on it that needs to come off. Once that's off you can run the jamb nut farther out(towards the outside of the pump, about 2 turns). Then put it back in and test, some smoke more than others(especially with Lucas POD injectors!). The pre boost power adjustment is under a cover that looks like a vacuum diaphragm, and it is one. It has a torx bit with a jamb nut. Loosen the torx for more low end & tighten for higher. The governor spring is different than in the later 12 valves, and not adjustable, but reasonably priced. The other adjustment is to rotate the diaphram, under the top cover with 4 screws. Turn the diaphram clockwise 90-120 degrees, this is like sliding the fuel plate on a 94-98. Now put it back in & test.
The best bang for the buck, is to get a gov spring, most of the time they are under $20, and let it rev up to 3200 rpm. If you plan on a gov spring, hold off on doing the fuel screw shown above, it needs to be close to stock setting. Great instructions are here:
http://www.dens-site.net/Dodge_CTD/Governor_Spring/


The 94-98 12valve:
Easy instructions at http://www.tstproducts.com/INSRUCT98.pdf They are instructions to replace the fuel plate, but instead of replacing you just slide it forward. I also have another article with a couple pictures here: http://www.thedieselgarage.com/forums/s ... php?t=6815 . Not that I'm getting to the troubleshooting part here, but often overlooked is the overflow valve. It's basically the fuel pressure regulator and should be replaced every 100k miles.
and for the Governor springs:
http://www.thedieselgarage.com/forums/s ... post165523

This uses a washer to shim the governor springs for more rpm, usually about 3200. It's the low buck alternative to a 3k gov spring kit(GSK). Although, you cant go wrong with the real thing. A real 3k GSK is usually $150 or less, and you need heavier valve springs if you start pushing past 3400 rpm(if you go with the 4k GSK). They also come with decent instructions, and can usually be done in just under 2 hrs for a first timer.



Tools needed-screwdriver and I think it's a 9/16" wrench. On top-middle of the pump on the right side there's an all-thread looking screw with a jamb nut. Loosen the jamb nut and take the screw out. There's a spring inside it, so be cautious. Run the jamb nut so there's about 4-5 threads left and re-install the screw. Run it up to the jamb nut, then tighten the nut up and it's done. Not much, but it's free.
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Old 01-11-2008, 04:03 PM   #12
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Re: Get my bus moving!


Thanks!

Quote:
...possibly helps fuel economy...
About improving fuel economy by increasing speed... we now get into the next two realms of Engine Mysticism.

These days, engines are being built with variable valve timing and other goodies that allow the engine to produce impressive power with modest fuel consumption at a wide range of engine speeds. But prior to such magic, every engine had one ideal speed where it ran the most efficiently -- that is, got the most power out of each drop of fuel. The shape of the camshaft lobes is probably the most important factor. The trick was/is to drive the vehicle at that optimum engine speed. If your engine's most efficient speed was 2400, and you were driving around at 2200, then it is indeed possible that an increase in speed (57 to 60, as you report) would bring the engine closer to 2400 RPM, and the improved efficiency might outweigh the increased wind resistance.

The second thing is about running against the governor. About that, I know nothing!... except what my gut tells me. And that is, that an engine might be "happier" running a bit below the governor, yes. Pure witchcraft, but I like it. Maybe it's just the driver who is happier.

Jimmy, about the fuel screw, and the "plate" and injector size and so forth... That is to increase power by allowing more fuel into the engine, regardless of speed. The engine speed governor is a different gadget which simply keeps the engine from reving any higher than the set speed. No, I'm no expert. We're all learning the same stuff! The Dodge-Cummins forum is a good source for the Cummins 5.9 -- just remember that our engines are not entirely identical to theirs.
http://www.cumminsforum.com/forum/
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Old 01-11-2008, 05:39 PM   #13
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Re: Get my bus moving!

Quote:
Originally Posted by Elliot Naess

Thanks!

Quote:
...possibly helps fuel economy...

i didn't do a good job explaining what i meant, my brain is foggy today. What i wanted to say is that if your bus is running against the governor at 60 mph, and you increase the engines governed speed to say 65 mph, but still keep the bus at 60 mph fuel economy may be improved....maybe it just makes the driver feel better to not have the pedal all the way to the floor.

i do find that many times my bus would cruise about the same speed with the pedal to the floor as it would if i backed off the throttle just a bit, and the bus definitely got better mileage with just this small change in pedal position without noticeably affecting top speed.
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Old 01-11-2008, 06:28 PM   #14
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Re: Get my bus moving!

I may be wrong but I think that sweet spot that Elliot is refering to for the most efficient rpm is where the horsepower and torque curve intersect.
My .02
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Old 01-11-2008, 07:11 PM   #15
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Re: Get my bus moving!

you are correct dave. that is the peak of your "power band." I have thought long and hard about the whole top speed/fuel economy issues that everyone comes up with on here. My take on the whole thing is this: the best way to increase top speed is to raise (numerically lower) the rear end gear ratio. and the only way to raise fuel economy is to decrease the amount of fuel consumed by the engine at normal operating rpm's. these are both very doable with a diesel engine (especially turbocharged). my plan (if i can ever afford it) is to use the cummins 6bt (5.9l) since there are so many documented performance modifications for this engine. it is very reasonable to expect, with the proper modifications, 300+ hp & 600lb ft of torque out of a 6bt with the inline pump used in second generation dodge pickups. if you increase the power output by increasing turbo boost you can actually get away with using only marginal increases in fuel consumption due to the fact that the fuel used burns more efficiently. now, if you combine the increased output (even if it means more fuel consumed) with the effects of re-gearing your rear end, you can expect a very much higher top speed (depending on ratio used) but also you could feasibly keep a consistent cruise speed on the highway EASIER at a lower rpm. the added benefit of the increased power output would be good hill climbing ability even with the higher end gear ratio.

the information used above should not be viewed as "the gospel," but simply my take on these two very related issues. furthermore i highly recommend doing the exact calculations on what would be needed for you particular setup to produce the desired gains, as well as the effects it could have on you drivetrain (obviously this varies based on engine, tranny, vehicle weight etc.)

chase
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Old 01-11-2008, 07:16 PM   #16
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Re: Get my bus moving!

sidenote: i have not seem anyone perform such modifications on a bus. but as an example i have personally seen a 1st generation dodge w250 cummins ext cab long bed with a suspension lift and 35" tires get mileage upwards of 25mpg on the highway without any real effect on it's ability to pull a load.
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Old 01-11-2008, 08:29 PM   #17
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Re: Get my bus moving!


I’m having trouble keeping up with you guys!

Jimmy:
Fuel is ooompf, and when you have more ooompf, you can accelerate from 0 to 50 in five minutes instead of six minutes, and you can climb Grapevine Grade at 30 MPH instead of 25 MPH. The governor is not directly involved with how quickly you get to 50, or how fast you pull the Grapevine.

Here’s what the governor does: When the fuel system is working correctly , you can push the foot feed (accelerator pedal) to the floor with the transmission in neutral, and nothing bad will happen. The engine will simply rev up to the governed speed and sit there and hum harmlessly.
This governor CAN be adjusted. Typically, this involves a spring or springs, which is replaced or tightened (or loosened?). So you need a tachometer to monitor engine speed, and then you need to learn how to adjust your governor. Once the governor is reset, you don’t really need the tach any longer -- except on down hills.
You MAY find that you have more power after adjusting the governor, but this would be a secondary effect -- the governor may have been activating gradually a bit below full governed speed, and the engine may simply have been governed below its peak-power speed.

Which brings us to Buster’s intersection of torque and HP....

Buster:
Yeah, that sounds right. I said “chart”, but I suppose I meant “graph”. Heck, I just drive with my foot and my butt.

Jason:
You explained it fine. But let me try yet another way, if only for fun: Question: Will an engine running down the road at 2200 RPM get better mileage if it has the freedom to climb to 2400 at the driver’s request, as opposed to being governed right there at 2200?
I think we may be operating in the realm of witchcraft.
If the engine is up against the governor at 2200, then the governor is acting as a cruise control. That’s good for mileage, avoiding unnecessary variations in speed. So if the governor is set to 2400 and the engine is spinning 2200 on cruise control, fuel mileage should be at least as good. But if the driver is holding the engine at 2200 with an itchy foot, then I would think that fuel mileage would suffer -- simply from the inevitable movements of the driver’s foot.
In other words, I suspect that the variables could easily cancel each other out. Just brainstorming!
You say you got better mileage without losing noticeable speed by just lifting your foot “off the governor” a little. I don’t doubt that at all. So many variables. Maybe the governor has an itchier foot than you do? Where I work, we/they spend a lot of time and brain power trying to convince drivers to ease up a little on the foot feed. I’m some sort of fuel mileage champion down there, and I’m not sure I could even explain it myself. Like buses, people have different personalities.

How’com’ so many of you have two names? I’m “Elliot” both at the top and at the bottom of the screen!

Chase, dear Child...
...I have about 40 bicycles in my yard that all need repair. Swing by Portland and pick up Sauce, and I’ll keep you both busy for a while.
...You are absolutely right about 300 HP from a 5.9. In fact, Cummins sold them that way for use in boats. 300 HP involves larger injectors, but a good power increase is supposed to be available with Injection Pump adjustment. Primarily, you modify or replace a part known as the “plate”. Those Dodge boys are all over that.

When fooling around with the fuel, you should have an Exhaust Temperature Gauge installed first. I read that it is easy to burn these things up with too much fuel.

When you two youngsters are done with my bicycles, you can install the Tach and the Exhaust Temp gauge that are still sitting on my kitchen table!

Now I really need to do something else for a couple of hours!
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Old 01-11-2008, 08:47 PM   #18
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Re: Get my bus moving!

elliot, i'd be more than happy to come help you with your bicycle troubles. that is, if you could pay to get me ther, then pay me atleast what i make at my job to do the work for you, lol. anyways, more to the point!

the cummins 6bt was originally a marine engine anyways, but they made newer versions in the trucks that made up to 325hp i believe, although they were 24 valve versions (i don't like them as much, too many extra parts!). also you are exactly right about the EGT gauge! it's not hard to MELT your turbo! but my main point was making power without a huge increase in fuel consumption. mainly things like increasing boost and water/methanol injection etc. i'm jealous though, not only does your bus have a 5.9 with the inline pump, you've got an mt643!! your tranny could actually handle some extra power.

ah well, enough ranting about how to make monsters.
gotta rest up so i might feel better for work tomorrow.
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Old 01-11-2008, 09:21 PM   #19
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Re: Get my bus moving!


No bicycle trouble here. Just a bunch of bikes that need work. No trouble. Many of them will be cut up for Kinetic parts anyway.

Yes, it was actually a surprise to discover the MT643 under Millicent. Turns out, as a full 40-footer (84 small scholars), Millicent has a Gross Vehicle Weight Rating a little bit above 30.000 lbs. And 30.000 is the limit for the AT545. So any bus with a GVWR above 30.000 will/should have the bigger tranny.

Work tomorrow?! That reminds me -- I'm going on the road tomorrow. 15 liter Cummins, 500 HP, 18 tires. I may be gone a while.
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Old 01-11-2008, 11:49 PM   #20
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Re: Get my bus moving!

Jason,

Did you see much of a decrease in your fuel economy when you upped your rpms? I'm looking to do something similar to my 360.
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