Full Size Jeep Network

Where did you source the ISB170? Are they significantly quieter? I rode in a 78 f250 that had a 4BT swap and it was loud as hell but it was straight pipe and no insulation, carpet, or sound deadening anywhere so the thing was a complete tin can. Your CJ8 is probably a similar beast. Couldn't hold a conversation in it but I feel like it would be a good bit different in a nicely built Wagoneer with sound deadening and carpet. I hope I'm not wrong.

Adventure_Wagon88 wrote:Where did you source the ISB170? Are they significantly quieter? I rode in a 78 f250 that had a 4BT swap and it was loud as hell but it was straight pipe and no insulation, carpet, or sound deadening anywhere so the thing was a complete tin can. Your CJ8 is probably a similar beast. Couldn't hold a conversation in it but I feel like it would be a good bit different in a nicely built Wagoneer with sound deadening and carpet. I hope I'm not wrong.

If one is able to maximize the power it should be fairly easy to run a much quieter exhaust. No matter what though, insulation will have to be addressed. Truck diesels are noisy, part of the industrial aspect.

Sent from my SM-N930V using Tapatalk

I've put 91,500 miles on mine in the last 2 1/2 years, over 5,000 in the last 3 weeks. 74 J-20, 4bt, p-pump, NV4500, 205, 3:73 gears, 32" tires. Hauled in some scrap loads at over 16,000 lbs gvw no issues, haul my skid steer all over with it no issues. Humpty is insulated very good, don't cheap out there if you're gonna DD it. IMO the 4bt IS the perfect engine if a diesel is what you want. Cruising at 80 MPH is easy and done often, it's at 15 to 18 lbs of boost and about 800 degrees on the pyro. Mileage is 24 to 26 pounding miles, 30 is in it driven easy.

Great info Burfurd, it's cool to hear from someone who has really broken theirs in. Is yours by any chance the one ZM Jeeps built?

Yes It is, that was a very good experience. Zack is a standup guy, a man I consider a friend.

Awesome, I talked to him on the phone the other day when ordering my floor pans from him. I plan on talking to him more as I get further down the road towards the motor swap. With your setup, what RPMS are you turning at 65-70?

At 70 it's at 1,900 +or-, empty truck 3.54s would be perfect, towing the 3.73s are perfect. I can set the cruise at 85 and run comfortably.

Was sitting in traffic the other day and thought of this thread. In front of me, on a trailer, was a freshly rebuilt 4bt. Drool.


Sent from my iPhone using Tapatalk

Bufurd wrote:At 70 it's at 1,900 +or-, empty truck 3.54s would be perfect, towing the 3.73s are perfect. I can set the cruise at 85 and run comfortably.

I'm at the same place in my HighBoy....

I just purchased a V6 eco-diesel for my jeep grand Wagoneer project.

I have to love my Dodge ram with the eco-diesel the one not in the jeep grand Wagoneer of the weight ratio is very similar.

I am going to do a Dana 60 and keep the Dana 44 and use a 6l80 transmission And an atlas transfer case.

Going into the shop in January

I put a 6BT with a NV4500 5 speed in my 1987 J20 about 8 years ago. Spent a lot of money doing it and the "cool" factor was nice but in reality it is heavy, noisy and under powered. I know you can get a lot more power out of the 6BT than I have but I'd have to dump a lot more money into it and it would still be heavy and noisy. I'm in the process now of pulling it out and installing a 401 but I'm keeping the NV4500.