Rockauto Newsletter (Cummins Diesel Mj)

[Oyaji]

True - I'd be less concerned with the longevity of the B-series engine based on it's stellar reputation.  It's an overbuilt engine to begin with and there are quite a few folks running some serious modifications on stock internals...and they have been doing so for several years and hundreds of thousands of miles.  You're economy will likely take a hit if you're in the throttle too much.  I agree that he'll likely need to gear down to achieve a balance between sustainable highway speeds and fuel economy.  The 1998-2004 VW TDIs might be a good starting point for him to look at gearing as that engine has similar HP specs (90HP and 155ft-lbs) to the B3.3.  My '02 VW TDI can do 80+MPH with no problems, although I suspect a lot of that has to do with the aerodynamics of the vehicle.

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That's good to know about the reliability and longevity of the B-series Cummins engines. In that case I agree that need not be a fear  when boosting its power.

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It will sure smoke a lot more - but in a state that doesn't care, that smoke may add a certain perverse pleasue to driving a diesel! :D  Economy will suffer in proportion to the increase of smoke - but sometimes it will no doubt be worth it just for the visual effect!.    :rotf: .

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Regarding aerodynamics - your VW TDI example not only has less frontal area but also a much lower coefficient of drag than a Comanche. You're right in your suspicion about its 80+MPH capability being tied to its aerodynamics. Gearing choice depends on power required to equal load demand, so the VW as an example isn't a good one to use in helping to choose.

[terrawombat]

Ok, I'll buy that.  Let's look at a better example:

 

http://www.4btswaps.com/forum/showthread.php?18015-2001-Jeep-WJ-Cummins-B3.3t-Swap

 

B3.3 in a lifted WJ.  Seems to be okay in stock form, but if you're going over any hills you're going to want the extra power (or lower gearing, but the author never stated if he did anything with the gearing).

[Oyaji]

Ok, I'll buy that. Let's look at a better example:

 

http://www.4btswaps.com/forum/showthread.php?18015-2001-Jeep-WJ-Cummins-B3.3t-Swap

 

B3.3 in a lifted WJ. Seems to be okay in stock form, but if you're going over any hills you're going to want the extra power (or lower gearing, but the author never stated if he did anything with the gearing).

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It is a better example, but I have trouble putting much faith in quantitative statements by that guy after I read stuff like this from him:

when asked the weight of his Grand Cherokee: "I would guess around 5700lbs" (Wiki puts the GC at 3,574 pounds - so that means he replaced the ~550 pound I-6 with a 2,700 pound I4 diesel? *lol*)

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when challenged about his fuel economy: "That was what the mpg display was showing, but based on math I have been getting about 21mpg city and highway." (Incidentally, all the electronic fuel economy readings I have seen are based on injector pulse width signal from the ECU, so I am wondering how he uses this on a mechanical injection engine that doesn't have an ECU.)

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His qualitative statements I have less trouble with, because they are based on simple observation - but I think he is mod-happy and that his ideas for mods are not sound (like doubling his power with fuel pump mods. and adding cooling with methanol injection):.

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"Now that I have her running I am going to start adjusting the fuel to see if i can get a little more power and get a little higher rpm. Right now I max out at about 2200 I know I can safely go up to 2800rpm. I am able to get on the highway and hit 75mph it just takes a minute to get to that speed."

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"Also I have a guy that rebuilds pumps and a injectors and he thinks he can hot rod my pump and get me another 80hp which should put me at 165hp, this engine is just a little underpowered for this jeep, around town its great but going up the mountains it struggles to stay over 50mph."

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"Does 70mph no problem. Only weakness thus far it going up the mountain, can keep it at 60 but that's at 2500rpm and she does start to get real hot, I'm thinking methanol injection will be a good solution to this."

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:nuts:

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He's got problems alright, but I think most of them could be corrected by regearing. 

[mpace6a]

 

Ok, I'll buy that. Let's look at a better example:

 

http://www.4btswaps.com/forum/showthread.php?18015-2001-Jeep-WJ-Cummins-B3.3t-Swap

 

B3.3 in a lifted WJ. Seems to be okay in stock form, but if you're going over any hills you're going to want the extra power (or lower gearing, but the author never stated if he did anything with the gearing).

.

It is a better example, but I have trouble putting much faith in quantitative statements by that guy after I read stuff like this from him:

when asked the weight of his Grand Cherokee: "I would guess around 5700lbs" (Wiki puts the GC at 3,574 pounds - so that means he replaced the ~550 pound I-6 with a 2,700 pound I4 diesel? *lol*)

.

when challenged about his fuel economy: "That was what the mpg display was showing, but based on math I have been getting about 21mpg city and highway." (Incidentally, all the electronic fuel economy readings I have seen are based on injector pulse width signal from the ECU, so I am wondering how he uses this on a mechanical injection engine that doesn't have an ECU.)

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His qualitative statements I have less trouble with, because they are based on simple observation - but I think he is mod-happy and that his ideas for mods are not sound (like doubling his power with fuel pump mods. and adding cooling with methanol injection):.

.

"Now that I have her running I am going to start adjusting the fuel to see if i can get a little more power and get a little higher rpm. Right now I max out at about 2200 I know I can safely go up to 2800rpm. I am able to get on the highway and hit 75mph it just takes a minute to get to that speed."

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"Also I have a guy that rebuilds pumps and a injectors and he thinks he can hot rod my pump and get me another 80hp which should put me at 165hp, this engine is just a little underpowered for this jeep, around town its great but going up the mountains it struggles to stay over 50mph."

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"Does 70mph no problem. Only weakness thus far it going up the mountain, can keep it at 60 but that's at 2500rpm and she does start to get real hot, I'm thinking methanol injection will be a good solution to this."

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:nuts:

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He's got problems alright, but I think most of them could be corrected by regearing

The way I understand it, water/methanol injection, if done properly of course, will help with cooling and add a bit of power to the engine. How much of either, I have no clue, although the way i understand it is that you inject a water/methanol mixture into the cylinder between firing strokes to cool down the cylinder walls, keeping the engine running cooler and, to some degree keeping the air in the cylinder denser since its cooler. Makes some sense i theory, although, in my head at least, not enough to make a huge difference?

[Oyaji]

 

 

 

 

Ok, I'll buy that. Let's look at a better example:

 

http://www.4btswaps.com/forum/showthread.php?18015-2001-Jeep-WJ-Cummins-B3.3t-Swap

 

B3.3 in a lifted WJ. Seems to be okay in stock form, but if you're going over any hills you're going to want the extra power (or lower gearing, but the author never stated if he did anything with the gearing).

.

It is a better example, but I have trouble putting much faith in quantitative statements by that guy after I read stuff like this from him:

when asked the weight of his Grand Cherokee: "I would guess around 5700lbs" (Wiki puts the GC at 3,574 pounds - so that means he replaced the ~550 pound I-6 with a 2,700 pound I4 diesel? *lol*)

.

when challenged about his fuel economy: "That was what the mpg display was showing, but based on math I have been getting about 21mpg city and highway." (Incidentally, all the electronic fuel economy readings I have seen are based on injector pulse width signal from the ECU, so I am wondering how he uses this on a mechanical injection engine that doesn't have an ECU.)

.

His qualitative statements I have less trouble with, because they are based on simple observation - but I think he is mod-happy and that his ideas for mods are not sound (like doubling his power with fuel pump mods. and adding cooling with methanol injection):.

.

"Now that I have her running I am going to start adjusting the fuel to see if i can get a little more power and get a little higher rpm. Right now I max out at about 2200 I know I can safely go up to 2800rpm. I am able to get on the highway and hit 75mph it just takes a minute to get to that speed."

.

"Also I have a guy that rebuilds pumps and a injectors and he thinks he can hot rod my pump and get me another 80hp which should put me at 165hp, this engine is just a little underpowered for this jeep, around town its great but going up the mountains it struggles to stay over 50mph."

.

"Does 70mph no problem. Only weakness thus far it going up the mountain, can keep it at 60 but that's at 2500rpm and she does start to get real hot, I'm thinking methanol injection will be a good solution to this."

.

:nuts:

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He's got problems alright, but I think most of them could be corrected by regearing

The way I understand it, water/methanol injection, if done properly of course, will help with cooling and add a bit of power to the engine. How much of either, I have no clue, although the way i understand it is that you inject a water/methanol mixture into the cylinder between firing strokes to cool down the cylinder walls, keeping the engine running cooler and, to some degree keeping the air in the cylinder denser since its cooler. Makes some sense i theory, although, in my head at least, not enough to make a huge difference?

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Water/methanol Injection was used in WWII (and maybe earlier?) to reduce peak combustion temperature and increase octane rating to reduce detonation in spark ignition aircraft engines, thereby allowing higher supercharging boost pressure and drastically increasing maximum power output for brief running periods. It has sometimes been used for extreme racing applications since then.

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I know of no advantage or benefit from its use in diesel engines (nor have I ever heard of such an application either, for that matter), but maybe I am missing something.

[terrawombat]

Water/methanol injection is commonly used on diesel engines for many of the same reasons it's used on gassers.  Lowers EGTs and increases air charge density.  I've heard lavish claims that it will increase fuel economy by up to 15% but have yet to see any real-world data to back that up.

 

First time I saw one of these systems was at a tractor pull event.  Every tractor had a massive water/meth system installed.

[mpace6a]

My limited knowledge is coming from my cousin. Hes been builđing an 01 cummins for a while now. Hes getting somewhere in the high 900hp/1800ft/lbs power range with over 100psi of boost.

[Oyaji]

Water/methanol injection is commonly used on diesel engines for many of the same reasons it's used on gassers.  Lowers EGTs and increases air charge density.  I've heard lavish claims that it will increase fuel economy by up to 15% but have yet to see any real-world data to back that up.

 

First time I saw one of these systems was at a tractor pull event.  Every tractor had a massive water/meth system installed.

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Not the same as a spark ignition engine. Every singe combustion event in a compression ignition engine amounts to detonation - which is why they are so much more heavily built and why they clang and clatter so damn much. :)

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 Diesels are also an unthrottled  engine design (wide open unrestricted intake with no butterfly throttle valve to restrict intake air - they rely entirely on fuel delivery to control RPM and power settings)  that always operate with an excess of oxygen in the combustion cycle. (A side effect of that excess oxygen is high oxides of nitrogen emissions.) To boost power you definitely want to  both increase the combustion temperature (since engines turn heat into useful work, heat is a plus), and work on getting more air into the engine, as that is the hard part (getting more fuel in is the easy part - you can pump liquids far more easily than gases). To increase the intake air charge density a far better way to go about it is with supercharging and inter- and after-cooling... but I suppose once you have hit your limit and are reaching for a way to  get a bit more density and keep your engine from slagging/melting itself down, M/W injection might net you  one last benefit once all other options are exhausted. That would be very much just for specialty applications - like  your tractor pull example.

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In no way do I think it is  a good  solution for a daily driver road vehicle!

My limited knowledge is coming from my cousin. Hes been builđing an 01 cummins for a while now. Hes getting somewhere in the high 900hp/1800ft/lbs power range with over 100psi of boost.

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Wow - that is boosted nearly 7 atmospheres (6.8 bar). Most supercharging is between 7.5 and 15 psi (0.5 and 1.0 bar).

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I reckon he is a brave soul with deep pockets and tremendous faith in the amount of over-design that went into that engine. Hopefully he has a good bit of other people's experience on which to base his modifications. Regardless, he may still rather abruptly find the absolute limit by experiencing catastrophic and very expensive failure.

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No less amazing for all that!

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Just the other day my dad was telling me stories about how some local farmers have boosted the engines in their International Harvester 806 tractors (about 100 horsepower stock) all the way up to 300 horsepower, and apparently with no ill effects over many seasons of hard use. I find that  only somewhat less amazing... but I guess it just goes to show that some engines are so far over-designed that they can handle big increases. I am not sufficiently wealthy to go out seeking the bleeding edge of what is possible, so I'll leave it to them, since doing so not only affects the life of the engine but also everything else that is attached to it.                   

[terrawombat]

There are a lot of folks over on the Cummins forums that will install water/meth systems on their heavily modified rigs, but you can also find them on some rigs that have very few modifications at all.  The fellas that are towing with their Cummins trucks on a regular basis will usually look to a water/meth system to keep EGTs down when they've got 10K lbs behind them and they're going up steep grades.  Just recently I towed a 4,600lb truck on a 2,200lb trailer with my '04 Ram 2500 Cummins.  At 6,800lb I am well below the maximum towing capacity for my truck, but when I started going up some steep West Virginia roads I watched my EGT meter get into the 1100-1200F range...starting to get very close to the melting point of aluminum - granted, nothing is actually pure aluminum inside the engine, but the point is there is an inherent danger of making the exhaust combustion temperature TOO hot.

 

Although I completely agree that water/meth systems are not a good solution for a daily driver, they are an easy add-on item for specialty applications.  When people hear they don't even have to remove a single nut or bolt on the engine and can have an increase in engine power they get all warm and fuzzy inside - kind of why nitrous oxide took off in popularity (but that also had to do with the Fast and the Furious movie).

[shelbyluvv]

The Cummins will push 40 PSI stock, right from the factory on some models. I know a lot of guys running 100 PSI+ on twin and triple turbo setups. W/M injection is used in a lot of diesel applications. You will also see NOS and Propane on the big boy drag and pulling trucks. I love owning my CTD!

 

I am also pushing 22 PSI on a 2.2 Dodge gas motor. That is followed up with a 75 shot of juice once I get into second gear. The only internal part of my rotating mass that is after market are my pistons. I was breaking ring grooves after 20 PSI.

[mpace6a]

Purely for lowering egts makes since...especially since said cousin lives in Denver.

 

there's a guy on youtube with a second gen cummins that consistently runs 9sec qtr miles. Iirc he has to use nos just to spool his turbo, which sounds like a jet engine winding up

[Oyaji]

Just because you can do something doesn't mean you should... and just because other people are doing something does not make it a good idea...

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[terrawombat]

Just because you can do something doesn't mean you should... and just because other people are doing something does not make it a good idea...

 

Agreed.  I look at W/M more as a solution in search of a problem.  There are a handful of other things that should be done prior to even considering W/M.  My response was aimed at addressing this:

 

 

I know of no advantage or benefit from its use in diesel engines (nor have I ever heard of such an application either, for that matter), but maybe I am missing something. 

[Oyaji]

 

Just because you can do something doesn't mean you should... and just because other people are doing something does not make it a good idea...

 

Agreed.  I look at W/M more as a solution in search of a problem.  There are a handful of other things that should be done prior to even considering W/M.  My response was aimed at addressing this:

 

 

>>I know of no advantage or benefit from its use in diesel engines (nor have I ever heard of such an application either, for that matter), but maybe I am missing something. 

 

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No worries, man. I wasn't addressing you (or anyone) in particular - just the idea of going overboard with mods.

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I don't mean to sell short the idea of experimentation and back-yard mods, either. Sometimes from such work are great ideas born. But just being a "me too" "I can do that too" copy-cat won't do anything but get you started on the path while emptying your pockets, since copying produces nothing new and can be extremely costly. Experience, formal education and careful study of what has come before  are ways to save a lot of cost and headache along the way.

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If you do decide to go the path of unguided self-funded experimentation, you also have to be prepared to accept a certain amount of this sort of thing among your "peers":

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:yes:

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With regard to the application comment, I was referring to production applications, not mods. Thanks for the extreme after-market apps you guys mentioned - it was good reading them.       

[GHayduke]

I'm a Cummins guy as well, running a 5.9 12 valve in my 96 5-1/4 ton truck.  You can add fuel and air to the engine and gain power & fuel economy to a point, then you get to a point where you start loosing fuel ecomomy.  I saw someone put a early Dodge Sprinter CDI engine ( 6 cyl Mercedes) in a Jeep Scrambler online.  I think the 5 or 6 banger sprinter engines might be a good candidate for a MJ or TJ swap. Not sure how tall it is, that's where the 4BT is a issue (need to lift a CJ 4 inches to fit one).  But I hear Sprinters can get 30MPG & haul quite a bit.... Might be great mileage in a Jeep. 

 

After you get used to the Torq of a diesel, you just don't get that feel from a gasser... especially with the mileage. You roll into the power slower, but boy the power!!!

My wifes Mercedes E320 CDI ( 3.2L I-6) puts down 369 ft pds of torq & still gets 34MPG when were going 70+ on the highway in no-where Missouri. EPA milage says 37 highway if your nice to it... It's a cousin to the bigger sprinter engine I believe.  Expensive technology yes, but awsome driving performance and feel.  I'd love a diesel Jeep !

 

[onlyinajeep726]

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Dear god... not this thing again hahahaha.

[mpace6a]

 

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Dear god... not this thing again hahahaha.

I still think this thing is the perfect candidate for an armored urban assault MJ! Just remove the spoiler and crap and replace any steel plating with tempered armor plating!