4" exhaust in '85 Ram Prospector

[driverswanted]

I've been working on a 4BTA conversion for some time now and need a question answered about the routing path for a 4" exhaust in an '85 Dodge Ram Prospector 4x4. This should be the same as a 1st generation Cummins equipped Ram. My NP208's front driveshaft output comes up the driver's side of the main driveline. I see a some space between the transfer case and the driver's side frame rail and above the transmission support cross-member. Is this where the 1st gen. 4x4's exhaust runs? If I try and pass the 4" exhaust through going above the cross member I'll be only 2" away from the transfer case.

 

[boatpuller]

1st gen exhaust runs down passenger side of drivetrain, between frame and transfercase, it gets a little tight in that area, 4" will fit but has to be just right so it doesn't rub on anything.



Caleb

 

[driverswanted]

Thanks Caleb,

So the transfer case will be ok being that close to the heat then? I can add another hanger at just forward of that point to hold position better. I have some custom cutting and welding ahead of me now. The 4BT's exhaust is at the rear cylinder, putting the case turn-down elbow within 2-3" of the firewall. Had to cut 20 degrees out of the casting to turn the elbow down quickly. Looks like I'll have to do several cuts and rewelds like that to the down pipe in order to turn it under rapidly. FUN... ... . :-laf

FYI, my project's design goal is to pull my 5k# boat down the road and also get good economy in 5th gear when not hauling. My target is 30+ mpg. Hoping the early spoolup of the HY35W will help the lack of pure h. p. . Also hoping the efficiency of the Bosch 190's will get me there. I can't get on the peak of the torque curve at 65 mph until I either get 33" tires (31. 7" now) or I find both a 3. 31 rear and front gear set. I have 3. 55's now. Right now the peak torque is going to be at about 59 mph.

Anyway the numbers add up to about 255 hp and somewhere around 450-475 lb-ft. Will be dyno-testing this spring. Hope the dyno station can handle a 4" exhaust :-laf .

 

[boatpuller]

On the first gens there is a bracket that holds the bottom of the downpipe where it crosses the bellhousing/adapter, it is bolted there to the bellhousing, the down pipe goes basically straight down and then makes a 90 to go straight back towards the hole between the transfercase and frame.





Caleb

 

[driverswanted]

Thanks,

That appears to be the same as my 2x4 '91 350. It's exhaust does a down past the cross member elevation and then an up and over, creating somewhat of a roller coaster look at that point.

The stainless exhausts offered at the good price were all post '93 style. The one I bought has the ring on the down pipe that you pull up with two 3/8" bolts. I have purchased the cast turndown elbow that allows the use of this type of exhaust. Had to cut a wedge out of the casting and reweld in order to make it turn down well before the firewall. Wondering if the Rams after '93 still used that clamp which bolts to the bellhousing. Do you know if they do?

This 4BTA could probably use one since they shake so much. I could make that. All it would take is another muffler clamp and some of the 1/8" x 1" strap I have laying around. Makes more sense having one the more I think about that tight passage beside the transfer case.

Last night I started cutting wedges out of the new down-pipe to make that sharp turn.