12v RPM ceiling?

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Could someone tell me at what RPM the governor starts backing off the fuel? I drive through the mountains with OD off, and the RPMs hang around the 2250 range. Is defueling taking place here? If it is, is this "lean" running hurting anything?

Thanks.

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'95 2500 SLT LB 2WD, auto 3. 54, 67,000--Westech gauges, Prime-loc, Brite box, Back-off Box, Line X, Flowmaster muffler, Borgeson steering shaft

 

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Kodiak:

Before I installed the governor spring
kit in my 96' I experienced about the
same range of "governor fuel cut-off"
as you. The RPM's on my truck would
begin to slow at about 2250 and upon
reaching 2400-2500 that was it. The
governor spring kit took care of that.
I can now "rev" up to 3400 RPM.
Apparently alot of the trucks are
set up differently. The 96' 5-speeds
have a P7100 pump that allows them to
"rev" up above 2500 RPM. I have read
some of the other posts on this and
members reported being able to get
up to 2600-2800 RPM.

As to whether or not it is "hurting
anything" that I am not sure about.


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Red '96 4x4 2500 Auto 3. 54, TST #5, Major Pump Mods, 370 injectors, Gov. Spring kit, AFC Spring kit, Banks Exhaust, Prime Loc, Cummins Chrome Kit, Pro-Torque Converter, BD Valve Body, Sendel 16" Alum Wheels w/ 33" BFGs

 

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I got these RPM warnings for the Cummins B Series engine from Fritzs` Ram page:

Destructive torsional harmonic resonance (sounds serious #ad
) occurs at 4100 RPM

Crank and rods fail at 5400 RPM (if you make it through 4100 RPM) #ad


Seriously, A few of the guys with the Gov spring kits are close to the first 4100 rpm warning.




[This message has been edited by HEMI®Dart (edited 10-31-2000). ]

 

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I believe you can turn your High Idle adjustment screw to get more rpms out of the engine. Somewhere between 3000 and 3600.
Besides checking every thing out first.
Seen this discussed in TDR also on forums, should be some info in archives.

 

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When I smash on it, and I'm empty (almost all of the time) the RPM's goes up to 3000. I dont know if the engine is turning this fast, of it's just the momentum of the needle rising fast.
When you hit it in a low gear, it rises FAST!!
I had it floored once on the interstate. I know the RPS's were up there, but I seem to remember they werent at 3000.
It was rainy and snowing, so I had other things to watch. #ad


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98 Quad cab 4X4 2500 12 valve,5 speed,3. 54 rears, 8' bed. Boost and egt gauges but basicly stock except for a "properly adjusted" AFC. Cat in the garage. Uniden HR 2510, Texas Star 1200 amp. 59,000 Mi as of 10/21/00.
NRA life member. High power/IDPA.

 

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Kodiak
As far as "lean running" goes, these diesels are not like a gas motor. As they always have wide open air intake, They control speed/power with fuel only so they always (well, sorta) are burning lean as possible. (one of the big reasons diesels are so efficient).
Larry

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1972 Chinook class C with 96/215 5spd, 4/5" exh, 4"BD, MagHytec, 85gal fuel, K&N RE0880, AutoMeter, 370's, BD gov kit, BD afc kit, www.fostertruck.com/cummins

 

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Diesels are not like gas engines... . there is no lean burn. Remember the equation Air + Fuel = POWER. There is no stoichiometric ratio of air to fuel that diesels need to run. RPM wise, the B5. 9 is governed to around 2700 rpm stock. Cummins says the engine is good for 4100 rpm. I have seen one (Auto Wurks race truck) put the tach needle pointing (no kidding) straight toward the floor. That had to be around 5000 rpm. It turned its best 1/4 mile times after that happened (and after it ran backwards for a second or so). Go figure.

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520 Rear Wheel H. P. and locomotive level torque = 15. 5 sec @ 97 mph with the rear wheels spinning in 5th gear going through the traps in the quarter mile. No slicks here, pal, no fancy auto transmission, just the truck in full street trim, 7400 lbs. of Auto Wurks Diesel/BD Performance raging, fire-breathing DIESEL POWER

 

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something to remember, anything past 2500 is past the efficiancy of our 12valves, 24 goes to around 2800. If you are pushing it hard past 2500(top speed) I hope you are paying attention to egts. I think egts' start being problems for 12valves at around 300hp and around 320hp for 24 vavles. Course ported makes more space for heat(ie fuel and power) but even there you either have to look past the egts or are only using parcial throttle. The key is even at my 590hp it peaks at 2500. By 3200 its back down to 400. To me it makes no sence to rev the p(*& out of these motors, but its nice to know you can.
On another note, when I screwed my high idle screw all the way in, then cut the head in half, I had max fueling until 3000, the governer still limited me to 3100. It hit like a brick wall.
Adam

 

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I just have to ask, if efficiency is gone at 2500 rpms:
1 What turbo are you using?
2 Have you adjusted your governor to accommodate a higher curve of fuel at a higher rpm?
3 Have you installed the governor flyweight springs?
4 Did you put in a set of bigger delivery valves yet?
5 How do you measure the horsepower of your engine at such rpm levels? Dyno? GTech?
6 Have you added a high rpm cam and/or low compression pistons to your engine? Changed the cam in the injection pump?
All of the above drastically change the efficiency/power&torque curves/reliable life of your engine, &injection pump. Bolt on "level 2,3,4,5, etc" one size fits all performance does not contribute to effective, reliable power upgrades. There are things that a Bosch Diesel Injection specialist does without fancy level and number cam plates because each injection system is unique and individual and must be adjusted as per the demands of that specific unit. Sure, a set of matched, high-flow injectors makes a killing in power. That is just the resume for a high power injection pump. The high flow nozzles are there for one reason... ... to flow the fuel that the hotter pump couldn't flow through the smaller nozzles.

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520 Rear Wheel H. P. and locomotive level torque = 15. 5 sec @ 97 mph with the rear wheels spinning in 5th gear going through the traps in the quarter mile. No slicks here, pal, no fancy auto transmission, just the truck in full street trim, 7400 lbs. of Auto Wurks Diesel/BD Performance raging, fire-breathing DIESEL POWER

 

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I'll answer these questions the best I can:
#1: hx 40 16cm2.
#2: This will answer the next question and some parts of the others, my pump is IDENTICLE to the auto work trucks, sence I know you know this truck you'll also know my governor is a 4400 one.
#3: see #2
#4: see #3
#5: I have done this several ways, the last way after installing the head gasket, ported head, and BD's pulling pump was the same as the last few times I have on the dynojet 248c, in 5th gear starting at 14 to 1500 putting it to the floor until around 32 to 3400. Interesting to note at 3200 I had dropped from a peak of 590hp @ 2500 to 400hp @ 3200. Also the other ways I have done hp checks were by using ET's and MPH for 1/4 mile times, these average around 100hp more than the rear wheel dyno. I also have a Gtech and has been real consistant to the dyno.
#6: The cam is origanal 215 bumpstick that came in the truck and is surely not optimal for higher rpm's compaired to a marine 370 cam or a custom ground modle like Dave Mitchels. The cam in the pump, you might know if its different, if not ask Piers.
Piston are stockers, I did install the thickest head gasket Piers, dodge, and cummins is aware of witch is . 020 thicker to lower compression 1. 42:1 to make a final static of 15. 88:1 or slightly less considering the 131k on the shortblock.

As for the rest I have stock bosch 370 marine injector as per Joseph D's and Piers suggestion. I could have them modified to flow more but what the point? I already make 475hp and 1031ft/lbs on the motor and over 590hp and 1200ft/lbs on drugs. I don't really need more. Well not much more. LOL

 

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So, you're the one! #ad
If I may extend my hand to shake yours. I think I may have spoken to you via email. You gotta remember, there are a whole lot of postings with documented "embellished" HP figures. #ad
I make it a point to ask some questions to see who exactly is the genuine article. I don't know everyone out there yet, since I've only been doing this since Sept. I take it you're not using an EGR? #ad
I will be in more contact with you as time goes on. Too bad we're separated by so much land. Competition on the East coast is kinda lame. I have to play with Mustangs and Vettes. #ad
#ad
#ad
#ad

Chris

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1997 5sp 4X4, HX40, BD 4" Brake, Marine Compression, Custom Tuned Injection Pump, 370B Injection Nozzles, Delivery Valves, Governor & AFC Spring Kit, Psychotty Air, Water Injection, 6" Chrome Exhaust System, No Smoke Valet Switch, McLeod Dual Disc Clutch, Mag-Hytec Rear Cover, Cummins Chrome Kit, Optima Red Tops, Hadley Bully Horns, Hurst Line Loc.

 

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DieselB59, I bet the stangs & vettes make for a nice breakfast though... ...

 

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Chris, I did know who you were. I was wondering if you knew who I was. There is validation in what I said in rpm's, I've seen them. The fact is you have a valid point in cam's do have an effect on efficiency when it comes to our little diesels, my point was even as far as I am into the game, a cam change doesn't sound fun. Doesn't mean I won't change it but, 99% of these guys don't even think of going were you and I have but my point is real would doesn't worrent it. I don't even need more power than I do have now, dosn't mean I wont take it thow.
Chris its been good conversing with you, I hope what I say doesn't discurage you in the future.
Thanks.
Adam