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Old 03-03-2018, 10:21 AM   #1
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Turning up the power on 4 & 6 mechanical BT's

Howdy all --- most of us would like to have a tad more grunt out of our Cummins, so I thought I'd share a couple of basic tricks. The first set of info came from one of the folks over on the 4BTswaps forum and the second is an online build post. Both of these engines can make substantially more power either with just basic tools or by spending just a few bucks. Just make sure you do NOT exceed your trannies input limit. The tunes discussed can yield and additional 70 to 100 HP and substantially increased torque without impacting durability and often yielding improved mpg's. Gotta love these all mechanical Cummins!

First is the note from 4BTswaps.com as it was written to me by one of that sites most savvy builders...

NOTE: The following was prescribed for my 130 horse Cummins 4BTAA with a Holset HX30W turbo and intercooler but is basically applicable to any mechanical 4 or 6. With just a little homework you can adapt this and dial in what you want for your motor.


"Great project. You've done several good things with the engine. Two of the areas I always recommend checking are the turbo and injectors. The third area that might warrant some attention is the injection pump. You're focusing on good work and there are some improvements in the pump that are worthwhile. If you haven't already, install a 3000 RPM governor spring. Although you won't be running that speed, it helps with gear shifts. Second, consider changing the torque plate in the pump to a #10. That one has decent manors and can provide a significant power increase when needed. Third, adjust the timing to 16 deg. No higher or you risk blowing a head gasket. That will help with power and may improve fuel mileage as well. Last thing is possibly change the fuel overflow valve in the pump. Those things have a spring that gets weaker over time and can cause a loss of power. There are aftermarket items which are vast improvements over the stock unit. All of these changes are not expensive and can be done with the pump in place. A turbo boost elbow would also be advisable to help tune the boost level to take advantage of the new power. Your 130 HP engine can quickly become 200 HP without any bad effects on the engine or sacrifice of fuel economy. You'd basically be making the engine more efficient. And of course the power can go up even further. About 250 HP would be the limits for a stock turbo and injectors. After that point you'd be looking at other mods and don't think you're looking in that direction. A solid 200 HP would feel like you had a big block gas engine in there.

Of all the changes I mentioned, the timing adjustment would probably the hardest. That one requires loosening the the nut on the pump gear and a few special tools to accomplish the job. The governor spring would be #1 in order of importance. Then the torque plate and boost elbow. The change in timing would probably be one of the last things, but can have a huge impact on performance. Changing the overflow valve can be done in a very short time. It's also the cheapest. All the changes may be done for around $300 in part cost, depending on how well you shop. Probably the most bang for the buck on a P pump engine."

The following is a link to an engine/tranny upgrade that also includes replacing an AT545 with an MT643:

https://tatumskoolie.wordpress.com/2...allison-mt643/

Have fun!
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Old 06-16-2018, 08:37 PM   #2
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?'s from a newbie

Hi,

So I'm new to a bus and a diesel and wondering where to start to learn about my engine an tranny. I bought an International, a T444E 1999. Was told it has a 7.3l turbo. And knowing that I'll be moving to Guatemala with it, I would really like learning what I can do to gain some performance and efficiency for a long roadtrip. And then once there the likelyhood is that it will be running hills. And foir the hills I need to learn what a bus can do going up and down. and ideas on driving it down hill with an automatic tranny...don't want to burn it out while its young.
So any points in the right direction for learning how to be a better driver to her would be great.
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Old 06-16-2018, 10:22 PM   #3
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Great post, I would say that the last thing the overflow valve , I prefer to do first. Get good fuel pressures then do mods.
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Old 06-25-2018, 09:48 PM   #4
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98 freightliner cummins 5.9

anyone have links to this 3k spring, torque plate, and fuel overflow valve?
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Old 06-26-2018, 10:22 PM   #5
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parts you asked about

There are many performance diesel sites that sell governor springs for the p pump p7100 cummins diesel. Google p7100 governor springs and you will find them. Things called torque plates are used when piston engines are honed, but I think you are talking a fuel plates. Again, places selling these can be found by a google search, along with the fuel return valve. The return valve is the more obscure part of the three you listed. If you are really going to mess with this stuff yourself, I think it will be in your best interest to lean about this stuff before you make any purchases. Go to a performance diesel shop and ask a lot of questions and quotes for work/parts. I am a pretty knowledgeable fellow when engine and machines are in play. The tuning on the injection pump is so important to drive ability and is so complex, I will not do this work on my own pump at this time. Hard to get very good and correct, easy to screw it up. watch a video on a p7100 rebuild..... geeze.

sorry for not giving you what you want.

william
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Old 07-04-2018, 06:37 PM   #6
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thanks, was going off original posters information for this thread.

yes there are a ton of places that sell power kits, springs, fuel plates etc, but not a lot of info unless your talking about dodge pickups. im not at the same hp as them, so figured id check in here. but ill keep googling. thanks
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Old 07-04-2018, 10:49 PM   #7
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Great engine know how over at 4BTswaps.com. They are not bus people but know Cummins extremely well.
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Old 07-05-2018, 01:10 AM   #8
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the governor springs will give you more top end. lots of folks here will say its bad for the lifespan of the motor.

start with the free stuff. tune you AFC, tighten the spring and adjust the heck out of your smoke screw. you may be happy after that.
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Old 07-05-2018, 09:27 AM   #9
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I totally agree with Turf...start with the proven enhancements that don't cost a dime and don't stress the engine as long as you don't go overboard. You may be amazed at how much torque & HP can be picked up with such simple tuning. One of the best things about all mech Cummins..
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