Cummins 4BT

[Gordon Maney]

There was a redesign in the Cummins 6-cylinder a couple of years ago to make it quieter. Was there a corresponding change in the 4-cylinder line?

[MoparNorm]

Morning Gordon

I'm not familiar with the cylinder redesign, however the one thing that made the most difference in quieting down the Cummins was going to CRD technology, Common Rail Diesel. Part of the change was to meet 2007 emmission requirements so that diesels can continue to be sold. In CA we went two years without the Cummins H.O. for that very reason. The Jeep Liberty has a Chrysler (Detroit Diesel Division) 4 cylinder CRD made in Italy that is very similar to the Cummins CRD design, therefore I assume that the newer 4 cylinder Cummins also must have the CRD design. I'm not sure about the cylinder design, but part of the CRD technology is a high pressure fuel rail that actually pre-ignites the fuel (I have no idea how it works to quiet the motor, but the difference is dramatic), also a part of the quiet package is the relocation of the turbo, from up top to down on the side, farther away from the hood. I suppose some of our diesel gurus will chime in here soon!
MN

PS; I should add that if you are looking for a CRD 4bt it would only have been available since approx. 2003-4, it's very new if it does exist and I assume that it does since ALL diesels have to meet emission standards (low sulfur is also required starting in 2007).

[Sickcall]

I read where the Liberty diesel is rated at 165 hp. I wonder at what rpm they measure this at? The sound levels from the VW diesels are hard to tell apart from a gasser these days.

I have not keep up with the big 3 diesel comparisons but the old Cummins was always louder because it was the only one of the 3 that was direct injected into the cylinder, and did not use a precombustion chamber. It sounds as if with this new design that this has changed.

[MoparNorm]

And 295 lb ft of torque,

...at 1800 rpm, it's a good low end motor for towing and off-road.
MN

[JimmieD]

Okay, I can't resist:

Remember Maxwell Smart when he would have secret conversations with the boss? There was a clear perspex bubble that descended to hide their conversation. The physics of it was a 'white noise' generator. There random or non-random noises are generated which effect the verbal noises of sound waves within the bubble cancelling the sond except to the two speakers.

If you look into Rudolf Steinmetz's work on sineusoidal wave harmonics you'll find that waves of any type can be effected by other waves to develop common sympathetic frequencies. If you know the exact frequency you're dealing with you can feed a selected harmonic frequency to cancel or mitigate the dominance of one wave or cause a sympathy between waves.

In an internal combustion engine you have the fuel's explosion causing a sound wave, such as is perceived as spark knock under less than ideal conditions, or the exhaust note otherwise. Knowing the freequency of that wave and the fact that it travels at approximately 1,700 feet per second one may introduce a secondary wave form onto the first at the right distance and modify or mitigate that wave form.

By pre-combusting the fuel mixture in the Benz diesel's fuel rail the process creates an intake wave form that tends to cancel the fuels explosion's wave form through sine wave harmonics. It's similar to shouting at the top of your lungs during an explosion or singing along at a rock and roll concert: for all the noise you're making nobody will hear it.

[Sickcall]

Alright, don't anybody move

This entire complex is surrounded by Control agents! Agent 99, get their guns!

Yes, the "Cone of Silence". Can you hold on one minute, my shoe is ringing.

[warlock440]

I believe the Cummins splits its fuel into two seperate injections in order to quieten it down..I am not sure exactly how it works but from what I have read elsewhere it injects a percentage of the total fuel charge a few degees before the main charge..

[crike2000]

They increased the thickness of the block and also added a 2 stage injection to keep the the cylinders pressurized.

To quiet older Cummins:
1. There is a block girdle that goes between the block and the oil pan that increases the rigidity of the block. I don't know if there is one for the 4bt, but there is one for the 6bt made by cummins
2. Some of the TDR guys have bought lead fabric and glued it to the oil pan and valve cover to quiet the motor (This works)
3. Tighten the valves to the tightess factory allowance (this will lower the clatter sound)
4. Lastly there are some blankets that you can purchase that will help i think it is made by atpwrap.com (don't know much about this but that it is expensive.

[Andrew Hunt]

A really sweet conversion is using a Mercedes-Benz 5 cylinder, 3.0 liter turbo diesel. I have one in a 1956 rig that weighs about 4,300 lbs with an NP 435 trans, NP 205 trans case, narrowed 14 bolt in rear and narrowed Dana 60 in front. It has lots of power and great torque. It takes off like a race horse when the turbo kicks in. The adaptation was really simple and I used the input shaft from the transmission without any modifications other than to have a custom clutch plate custom made. The pilot shaft was a perfect fit for the inside of the Mercedes pilot bearing, even though one was metric and the other in inches. The 3.0 liter turbo diesel was not offered with stick shift, so I had to use the bell housing off the Mercedes 4 cylinder 2.4 liter diesel engine, which bolted right up. This is a million mile engine that is very plentiful and a good used runner can be bought for about $1,200 to $1,500. I'd be more than happy to give some tips on this engine and re-power if anybody is interested. With Mercedes owning Chrysler now, it’s a good marriage.

[MoparNorm]

Is that the 5 cylinder diesel from the Sprinter?
As for Cummins, the ISB and/or CRD technology is what you guys are talking about, BOTH higher pressure AND pre ignition. Also the turbo was moved to the bottom of the motor, further away from the hood and more sound proofing was added. From 15 feet it sounds nearly as quiet as a gasser. BUT not my 2002, 2nd gen Cummins, I can still get people running out of the house in their pajamas, dragging their trash cans,... on trash day....ha!ha!
MN

[Gordon Maney]

Originally posted by Andrew Hunt
A really sweet conversion is using a Mercedes-Benz 5 cylinder, 3.0 liter turbo diesel. I have one in a 1956 rig that weighs about 4,300 lbs with an NP 435 trans, NP 205 trans case, narrowed 14 bolt in rear and narrowed Dana 60 in front. It has lots of power and great torque. It takes off like a race horse when the turbo kicks in. The adaptation was really simple and I used the input shaft from the transmission without any modifications other than to have a custom clutch plate custom made. The pilot shaft was a perfect fit for the inside of the Mercedes pilot bearing, even though one was metric and the other in inches. The 3.0 liter turbo diesel was not offered with stick shift, so I had to use the bell housing off the Mercedes 4 cylinder 2.4 liter diesel engine, which bolted right up. This is a million mile engine that is very plentiful and a good used runner can be bought for about $1,200 to $1,500. I'd be more than happy to give some tips on this engine and re-power if anybody is interested. With Mercedes owning Chrysler now, it’s a good marriage.

This is very interesting.... would you be willing to do an article with some photos for the magazine?

[JimmieD]

Just curious: what kind of horsepower and torque and at what RPM are we talking about with that Merc diesel?

[Andrew Hunt]

I’d be honored to do an article Gordon. I have one I’m building right now with this same engine and drive-train configuration and I could provide a very detailed “build it” article with lots of “how to” pictures that would walk the reader through the entire process, including where to find a suitable donor vehicle for the engine. If you want, I could do a whole series of articles that walk the reader through the entire process of a turn key re-power, as I finish up the rig I’m building. Just depends on what you want.

[Bill in MI]

Do it!

I'm curious as all........... well, I'm curious.

Are you running the Bosch electronic fuel injection? That's what we run on the VM 2.8L (Jeep Liberty) diesel.

[Andrew Hunt]

Bill:

This engine uses the Bosch mechanical fuel injection system and is versatile enough where you can install the engine and wire it with a simple custom harness not much different than what you have now. The biggest thing you might loose, depending on what you keep and what you throw away of the original harness is the computer that controls the Bosch fuel injection system, which will make the computer inoperable.

When Mercedes introduced the 5 cylinder turbo diesel in 1976 they didn’t just stick a turbo on their 2.4 liter 4 cylinder engine and add another cylinder; they designed and built an entirely new engine, with a computer controlled fuel delivery system that works in tandem with the need for fuel through the injectors, as the RPMs increase when the turbo kicks in. I’m not sure what not having this computer hooked up would do to the performance of the engine. It’s mechanical, so it runs off the engine and doesn’t require electronic controls to operate.

I have a Mercedes family car that has a 3.0 liter six cylinder gas engine, which is a real screamer. Its got enough get up and go that it will put you back in your seat real quick. I’ve attached a list of technical data and specs on the Mercedes 5 cylinder, 3.0 liter turbo diesel, which is a very close cousin to the 3.0 liter six cylinder gas engine in terms of power and acceleration. The engine in the Mercedes UNIMOG is also a 3.0 liter engine, but it’s a 4 cylinder. I have the technical specifications on that engine somewhere and if memory is right, I don’t believe they are much different in horsepower. If you can imagine what a UNIMOG engine swap would be like in your rig, it will give you some idea of what to expect with this engine. The biggest difference between the two is the acceleration of the 5 cylinder turbo.

Andrew