I hope this is the right forum to post this. I'll admit I don't know much about diesels, so here's my question. I have a ’38 Plymouth coupe street rod with a Chev drive-train (350/350/Nova rear) that was in the car when I bought it. I’m planning a ground-up rebuild and I want to use a Mopar power-train. I’d love to have a hemi but they’re expensive and gas-thirsty. So…I’m thinking of using a Dodge/Cummins with appropriate automatic and probably 8¾ rear, and running it on biodiesel homemade from vegetable oil - with the cost of fuel these days, that's real attractive. And while there are plenty of Ford rods and quite a few Chevs, a Plymouth is unusual – a biodiesel one would be over the top!

I figure the car weighs around 3K lbs. It originally had a straight-6/3-speed and the 350/350 has room to spare, so I think the Dodge combo would fit. It’s a daily nice-weather driver so it needs to be reliable and economical. It’s also a hot rod so it needs to perform (I confess the testosterone kicks in for the occasional stoplight sweepstakes!) MINIMUM goals are 0 – 60 in the low-5s, ¼-mile in the low-14s at 100 mph, and 20-mpg city. I realize a diesel may cost more upfront but I think it would be as cheap/cheaper than a gas engine in the long run – I don’t plan to sell the car or rebuild it again anytime soon.

Constructive comments are welcome. Any recommendations as to which Dodge/Cummins, which automatic, mods to both, etc? Is this practical - or should I just pull out my wild hair and drop in that hemi?

 

only problem i see is finding a front suspension system thats gonna be able to hold all the weight

now you could with a 4bt cummins, and still get 400hp out of it and its alot light/smaller than the 5.9L 6cylinder cummins

good luck, i would love to see a cummins in some sorta street rod

 

if u can use the 5.9 low 5s would be a piece of cake, my 82 weights 4400 lbs. does 5.6 0 to 60 with 9 in. slicks

 

I'd be concerned about the rear end tho...kinda small for the torque of the cummins

 

i was concerned too. unless one is towning dont worry i am starting my 4th year of street and strip with chry. 9.25 aint broke it yet. i think the 8.75 will do the job. i used the 9.25 because that was what i had.

 

The 8.75 is tough and would be fine with an auto trans. A manual might sheer the pinion nut though... Hemi cars came with the 8.75 on autos and Dana 60's with manual. It's a good guide...

 

We ran GMC 292" sixes in the '30s, 40's and 50's Chevy's, but the Cummins is way longer even than that big six

The 5.9 weighs in at 930lbs, is very long, and the trucks get a Dana 80 to withstand the torque input.

330hp and 750ftlbs torque is a simple 1hr upgrade, so not many 8.5" r&p's is gonna survive more than maybe once when you let in the clutch.

That's real truck low rpm hp and torque, not imaginary hi-rpm power, requiring very large driveshaft yokes and cross&bearing sets.

Since you won't be hauling mega-weight loads, the driveshafts may not require such size, but I think anything smaller than a Dana 60 will not survive.

Definitely not, particularly if you tend to get happy feet, like I do

Mopar used them in Hemi application in the '60s, but I'd seen even some of them broken.

Good luck with your project - post it here if you run a 5.9CTD

 

exactly...the ctd willput out more than the hemi at a lower rpm, and for a longer time period.

 

Have you considered the new EFI Hemi with 6-speed or auto outta one of the new trucks - that would be one smooth street rod setup.

Air conditioned, powerful, excellent fuel mileage, no choked-up, finikey, hard-starting, hard to manage, poor driveability street-hassle.

Could probably pick up an insurance-salvage wrecked truck complete for 3500 bucks or so - section and narrow the frame, sit the body on it to get that late Dodge ride, with an all modern disk-brake drive-train.

Whaddaya think?

 

You need basically a 3' box for the cummins. Its almost 3' wide pump to turbo and 3' long and about 3' deep..This is not including the IC or the radiator.

 

You will have to do some frame reinforcing for the engine torque... Build you a ford 9" rear end with at least 31 spline shafts. You need to make sure you gear it very high (2.23-2.73 range).. Let that engine lug and use the torque instead of trying to get RPM HP out of it... push the engine back as far as you can to try and get some of the weight off the front end... don't forget you need to make sure you have enough space for the inner cooler...

I would look for a 12v engine for simplicity, but a new CR rail engine would also rock and you then have incab adjustable horsepower...

You are doing exactly what I plan on doing when I grow out of my Jeep hobby... I want to get an old 40's car and put a CTD in it and make it a highway vacation cruiser, and also be able to tow my small run about...

If you can get it to hook up, with a good auto tranny I don't see why you can't pull low 13 second 1/4's easily and have 20+ mpg...