The ISB 3.9 4 cylinder has a max torque output of 440 ft/lbs. Can this be de-rated to 350ish ft/lbs?

Reason being I want to plonk this engine into a Land Rover Defender 110. The stock LR gas engine is 282 ft/lbs. The significant torque increase of the Cummins ISB might mean costly replacement of drivetrain,axels, axle-housing etc..

If the torque can be de-rated, will it negatively affect fuel economy?

Does the ISB 3.9 absolutely need to be paired up to the Allison 1000 transmission? I have read that the ISB communicates electronically with the Allison trans for optimal shifting. Can the ISB 3.9 communicate with other transmissions?

Thanks

 

no one replied
come on folks I need advise/help.......whelp

 

I'll try.
Why an ISB 3.9? Why not a 4BT or 4BTA? Do you already have an ISB 3.9?
I would think that cummins could reprogram the ecm for less torque if thats what you need, I don't think there is any ISB3.9 rated for 440 ft/lbs. 350ish seems to be the max. I don't know how much it would cost though.

Does the ISB 3.9 absolutely need to be paired up to the Allison 1000 transmission?
No. There are plenty of 4B's paired with a TH400 out of bread trucks and any dodge diesel auto off a 6BTA/ISB will fit, although the 727, A518, and 47RH are the easiest to get working.

What trans where you thinking of mating to it?

 

The 4bt has a reputation for being noisy and have significant vibration issues. I do not know how effective the balancer deals with the vibration.
The ISB is supposed be aN improvement in regArds to vibration,noise,fuel economy.

The cummins website (navigating from cummins.com)doesn't mention the 4cylinder isb anymore,
but this Cummins link does:

http://www.cummins.com/na/pages/en/p...trucks/isb.cfm

The ISB170 gives 170hp and 420ft/lbs. The 4bt is something like under 140ish hp & 350ish ft/lbs. I am looking for about 200-220hp. As far as torque, I would be satisfied with 360ish give or take 10ft/lbs.

I am going use my Land rover for towing quite a bit, landscaping.construcyion machinery and machine shop machinery like mills & lathes.
Currently i ahve 182 hp, I figured between 200-220 hp should give me enough zip.

If the 4bt didn't have a reputaion for vibration I would seriously consider it.

Below the spec sheet pdf for the ISB 145-170

http://www.cummins.com/na/pdf/en/pro...et/4000161.pdf

Thanks for the reply, any help is appreciated.


PS Almost forgot
I would really like to use the automatic trans found in Discoveries since its a straight drop into my defender.The factory offered the same auto on 97 defedners.

 

What do they use the 4 cylinder ISB in. I would total by a truck or van that would have this motor. Prefect motor in this day and age with the price of fuel. Great power numbers

 

Hey BrewPub, MADDOG here. I am contemplating the same swap, but I have a 97 Disco. However, my 74 ford bronco needs one first. But here is some food for thought. The 4 BT or Cummins 3.9 (Same Sh.. Different Day) were used as replacements engines on a lot of GM P-30 chassis. You know, step vans, bread trucks, Frit Lays. Some of these step vans came with auto and some with manual transmissons. You will have to shop or buy an adapter from advance adaplters, but that part is easy. I have already found several for my ford 74 Bronco. It is duable.

The 700R4 transmissions in the early to mid 80s were junk. If you have an old one use it for an anchor. However, the newer ones were a lot stronger and durable. I had one in a 1990 1/2 ton 4X4 suburban that I modified to 1 ton, 36 inch tires, and lots of extra weight and drove it to over 200K miles and had no problem what so ever. (Coming to think of it I had no problems with the whole truck what so ever). The only thing you might have to worry about is the stall speed on your converter. Remember you can really crank up the RPMs on a gas engine. The 4BT has had it at about 2400 RPM. It makes loads of torque at about 1400 to 1600 RPMs. Some automatic transmissions have a higher RPM stall speed that what some diesels redline at.

You may need vacum for shifting and cruise control. Some of these engines come with vacum pumps. But, my 1997 Gas Discovery came with an electric vacum pump for the cruise control. You wil not need vacum for brakes if you get a hydroboost master cylinder. You can get one of diesel cadillac or any older diesel blazer, suburban pick up truck.

The Tranny that you and I have on our landrovers is a great tranny - very strong and durable. It would be a great choice. There are several companies in the numerous land rover web sites that offer all kinds of adaptors for engine to tranny and tranny to engines and anything else. I do not remember which right now but e-mail me or call me and we can chat.

Do not wory about horsepower. You want torque. High horsepower engines are high RPM engines. My 5.9 24 valve Cummins makes about 750 lb all under 2700 RPM. If I drag one of the new hot high hp mustangs (I did twice) I will leave him behind to about 90 MPH. He has me by 105 MPH but by then, WHO CARES?

Torque is what moves heavy objects with ease. If your cummins 4bt does have 440 ft/lb. enjoy it, just do not take off like a bat out of hell at every stop light.

Gears and tires. You probably have 3.54 gears in your rover. These are fairly high gears. You will be making lots of low end torque. Most of it will be done up to about 2000. RPM. With my 3.54 gears at 70. I am almost at 3000 RPM - way to high for a diesel engine. But nobody makes higher gears for landrovers, like 3.42s or 3.23s. My sugestion is to get a taller tire that will put you under 2000 RPM at about 70 MPH. For that you will need a calculator.

Overall however, I will watch you closely because my 1997 Discovery is next. and I will tell you how I did with my bronco.

Regaeds,

the MADDOG

 

The ISB 170 is not exactly the same as the 4bt. In it's current state it is produced with the gear case on the rear (gears to run the injection pump and the camshaft and what not) and a built in SAE#3 adapter. I have only seen it installed in some FEDEX trucks mated to the Allison 1000 transmission. This presents some issues if you want to mate it to a dodge transmission. Talking to some folks on TDR there is an idea that you may be able to take the front mounted gear case from a 6bt (or 4bt) and install it on the front of the ISB 170. Then remove the rear gear case and install the dodge adapter to the rear of the motor. But so far no one is completely sure this is doable. You may be able to have a ring manufactuered from Phoenix castings or something of the like to mate an SAE#3 to a Dodge Housing (or any other housing if they have to manufacture it).

I don't have access to the Cummins drawings or access to a Cummins dealer (I am currently in Japan) to ask these questions. I think the ISB 170 is a great size motor. If anyone gets any info please post. I really want to put this in a Dodge Truck but need some info cleared up.

Ryan Meskimen