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So who has bumped the power on a 6CTA cummins

DinoShepherd

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Well Ddmk18 came out today and installed my 4k springs and turned the screws and adjusted the rack travel. wow big difference. I am very pleased. all for about $80. Thanks For the help Dillon.
4k springs. I understand that the pump on our trucks does not respond exactly like the pump on the 5.9 for which these spring kits were designed. Our pumps getting less rpm than advertised on the kit.

Are you actually hitting 4K rpm? That seems high for the 8.3.

Reason on I am asking is I picked up the pacbrake 3/4K kit and wanted to know which to install.

Thanks...
 

Ddmk18

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I only run mine to about 2700 max if towing or pulling a hill. Normally I just leave it in 1-5 and let it do its thing. The reason I usually go with 4k is because I know it will have full fueling to what ever rpm I run to whether it be 2000 or 2700 I know I will have full power on tap.
 

Tornadogt

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I have never had defueling
If I understand it correctly, we have limited options on how high the engines will rev. Governor springs and valve spring float. So yes we all have Defueling, that is what the governor springs do. Without defueling (properly working Governor springs) the engines would rev until something broke, the fuel pump could not keep up with fuel supply, or the max amount of air is pulled through the turbo. All would be a bad thing.
Please correct me if I am wrong.....
 

162tcat

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The engine itself can do 3k all day long. Turbo upgrades and other supporting mods may be necessary to take full advantage if the additional power/rpm and to keep EGTs down.
 

74M35A2

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The aftermarket governor springs which are available were designed for the Bosch P7100 pump commonly found on the early Dodge Ram 5.9L mechanical diesel engines. They have been proven to fit and work in the Bosch MW pump, but will have a lower than specified result (as mentioned above, a 3k GSK nets 2400-2700 on an 8.3 MW).

The Cummins 8.3 spins a factory +3000rpm in marine applications, in power ranges up to and exceeding 400hp. This is mostly a change of air and fuel handling. Bigger IP, large air-water cooler, larger HX50 turbo, larger injectors, etc.... I believe they also use a very different harmonic damper on the crank nose.

Yes, the valve sprigs are also a limiter, yet higher rate springs are available directly from Cummins for the 8.3L. Their part number is specified in some of the aftermarket exhaust brake literature (Blue Ox, Pac Brake, etc...), as it is a required change for their product to work correctly. I think they are referenced in the aftermarket as 60lb springs.
 

MtnSnow

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I see that 74M35A2 and 162tcat have pretty much summed it up. and just to clarify I take defueling to be a reduction of fuel PRIOR to the expected rev limit.
 

profo

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Been reading all the pages a few time and want put PacBrake springs in my 8.3 but there are different kits I have read over and over and maybe missed something but does anyone have a part number of the kit used I want to make sure I get the correct one. I have done the Low fuel adjustments and my EGT's stay at around 1200 pre turbo on flat ground at 60 mph not towing anything I know the camper part has some drag but didn't think it was that much, would like to get EGT's down I tried a different Turbo from a guy who said that it was a lil bigger than the H1 but my EGT's went up even more. Thinking of putting 395 tires on it which is a lil smaller which will make my rpms higher but should drop EGT's a lil. Don't have room for intercooler cause AC condesor is there in front of radiator I am also think of water injection to bring Egt's down cause I carry 110 galions of fresh water in camper all the time. Has anyone tried this?

Thanks marty
 
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74M35A2

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Livonia, MI
Been reading all the pages a few time and want put PacBrake springs in my 8.3 but there are different kits I have read over and over and maybe missed something but does anyone have a part number of the kit used I want to make sure I get the correct one. I have done the Low fuel adjustments and my EGT's stay at around 1200 pre turbo on flat ground at 60 mph not towing anything I know the camper part has some drag but didn't think it was that much, would like to get EGT's down I tried a different Turbo from a guy who said that it was a lil bigger than the H1 but my EGT's went up even more. Thinking of putting 395 tires on it which is a lil smaller which will make my rpms higher but should drop EGT's a lil. Don't have room for intercooler cause AC condesor is there in front of radiator I am also think of water injection to bring Egt's down cause I carry 110 galions of fresh water in camper all the time. Has anyone tried this? Thanks marty
The RV guys show that a less restrictive muffler helps greatly in lowering EGT's. They seem to be the largest group of personally owned 8.3 engines, and they are always seeking more hp and mpg, so I study there. A lot of them use the Aeroturbine 4040XL muffler. Advancing injection timing is also supposed to lower EGT's, but I have yet to do that, since it is 11F outside right now. Your thermocouple or gauge may not be accurate (possibility). 1200F seems high for an otherwise stock engine. Increasing the low fuel rate should not play much part in 60mph fueling. Most guys can't get their EGT past 900F on a stock engine from what I am seeing. You do seem to have a knarly box on the back, but I doubt it adds that much loading. If changing turbos increased EGT, the one you installed likely has more backpressure on the turbine (exhaust) side. Our engines come with a Holset HX40/H1E. Next sizes up are HX50 and then HX55 if staying with Holset. Do you know the model of the turbo you installed? You would have to compare compressor maps if it is not a Holset to know which way you went.
 
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74M35A2

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I have never had defueling
Actually, you do. You have "de-fueling" every time you take off from a light. The governor controls the engine speed. The throttle is nothing more than simply a request signal for desired engine speed/power. There is a spring loaded air pressure diaphragm on the back of the injection pump that has an air line going to it, which limits fuel rack travel on take off until turbo pressure is up, this limits excessive exhaust smoke. This mechanism is called "AFC", or air-fuel control.Not that anybody is wrong, but I would call de-fueling as any action of (user) unintended fuel rack reduction. The 3 things that can reduce the fuel flow to the engine beyond what the accelerator pedal is asking for would be:1. Engine RPM (governor spring)2. Boost controlled fuel addition (take off), aka AFC. 3. Running out of fuel (ummm, I have done this more than I care to mention). Note: SS site not allowing paragraph spacing right now.
 

MtnSnow

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Well then in that sense yes I would agree I have had defueling but at the time of my original reply it wasn't about the AFC but having the system defuel prior to reaching governed speed....Anyways back to everyone's studying and interpretations :)
 

profo

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The stock turbo was a h1e I just ordered a hx50 and governor springs when I said I set the low fuel I meant low buck fuel adjustment this helped acceleration I have not messed with timing at all and have not even checked it yet I need to read more cause I am not sure how to adjust it. There is no muffler on the vehicle its a straight 4" pipe. Even before I adjusted fuel pump EGT's where at 1100 at 60 mph or under hard acceleration it will go 1300. Thanks for input will keep updated if anyone tries adjusting timing and temps go down please post.

thanks marty
 

RobertoGatos

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The stock turbo was a h1e I just ordered a hx50
Look forward to hearing what you think of that turbo. Where did you get it from? Just ordered the GSK, and a 5'' donaldson silent partner muffler so I'm thinking of the next few logical steps.
 
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