Which motor to swap in...

[ken]

6-71's are Supercharged, gear driven.

 

[Trango]

So, let's do the math on that. Let's say that you want a 2100 redline engine.

Now, 11x20 tires increase your roadspeed just about 10%. So, you have a truck that went about 60 with a 2600 redline motor and 9x20's, and once you put on 11x20 tires, you are now going about 66.

However, if you use the stock deuce tranny and a motor with 2100 redline, you are now down to 53, even with 11x20's on. If you don't upgrade your rubber, you're looking at something on the order of 48 MPH.

Now, let's say that you wanted a 60 mph truck again... you need the following ratio OD's, at 2100RPM, for:
with 11x20 rubber: 33% overdrive
with 9x20 rubber: 47% OD

I had to search high and low to find a 31% overdrive that wasn't overkill for either the truck or the wallet.

Bottom line is that, in my opinion, you're automatically limiting yourself by going to a low-redline engine. If your goal is to go even as fast as a stock truck, LET ALONE FASTER, it's going to take moving Hell through high water on the roofrack of a VW beetle to get a tranny or truck combo capable of going 65 with a 2100 redline DD.

I'm done preaching but after spending 2 months of my free life just trying to make my deuce go faster up hills ALSO with a higher top speed, I couldn't fathom anyone intentionally making it go slower.

If anyone is interested, I have a spreadsheet to help you calculate your final speed with whatever deuce mod you want to do. hit me at racecadet@yahoo.com and I'll send it over.

Cheers
Bob

 

[rdixiemiller]

We ran a lot of Detroits in the charter boats, They screamed, leaked, and smoked. They did work well, but anyone who could afford it put in a Cat, or a Cummins. Cats and Cummins had better longevity ratings
The following designations are used with marine Detroits:
1) 6-71 (normal supercharged engine)
2) 6-71 T (turbo as well as supercharged)
3) 6-71 TI (turbo intercooled)
4) 6-71 TA (turbo aftercooled)
5) 6-71 JT (Johnson and Towers) These were really hopped up motors, some were aluminum blocks.

We ran a lot of 6-71, 6V-71, and 8V-71's. The New Florida Girl had (3) 12V71's. There were also several who had 6 and 8V-53's, as well as a few 3 and 4 cylinder 53's and 71's. 3208 Cats and 250 Cummins were the big dollar engines. One boat had 2 big MAN Mercedes V-12 engines.

 

[JasonS]

Isn't a misnomer to call the non-turbo detroits supercharged since there is no way to build any boost? There are no exhaust valves, the air just flows right thrugh the sleeves and out through the exhaust pipe. With a turbo it could have positive pressure. I think that the correct term is scavenged.

 

[Recovry4x4]

The math doesn't lie Bob! I agree whole heartedly.

 

[rdixiemiller]

You get some boost from the supercharger, but they are there mainly to keep exhaust scavenging at optimal levels. The turbo helps recover some of the huge exhaust plume from the 2 strokes. I can remember one thing, wring off the blower drive shaft and she stops quick!

 

[hot rod deuce]

id go with the cummins just because 350 Hp versions of the same block are common and cheap if you ever want to up grade. Heck i have a 350 and a 400 just laying there rottin away. If you look im sure you can find a good runner 350 HP 855 for less than 1200 bucks. that will be more then enough power and if not there are tons of aftermarket parts around.

Or i have a city transit bus with a 6-92 turbo and supercharger with alison auto for $1750

There are exhaust valves but no INTAKE valves. The air from the supercharger comes through ports in the side of the sleeve and out the valves in the top of the head. Its not like a snowmobile motor. So the air is pushing against the side of the piston until the piston gets below the port. If it can build compresion it can build boost. yeah you lose the blower and thats the end right there no air in...

 

[spicergear]

Personally, if I were gonna put another swap motor in a deuce, I'd go with a 71 Series Detroit. Not for power, not for ease, but for SOUND! They have such an awesome sound, sounds like they're really spooling up and roaring when they're actually just purring along with crank speed. Love that sound.

 

[Recovry4x4]

Tom, welcome home brother. I'm sure you will report what you can, when you can. Undersood the sworn to silence deal.
Kenny

 

[jollygreen6x6]

OK fellas, thanks for the info. All of this is extremely useful. Both motors make similar HP and torque, the Detroit will work better with the 13 speed, the Cummins has more abundant parts, and the like. Now, being that both motors will work with my application, I think that I will go with a 6-71 for 2 reasons:
One: I am making a unique vehicle here. John Deere green cab, orange snow plow, some oddly-colored crane on an old army truck. I want this to have a unique engine as well. Cummins are everywhere in trucks. Detroits are quickly dying out, and I want to preserve a special part of the trucking industry that helped build it. It's a unique motor that functions very well that is falling by the wayside, and I think it is only appropriate that one power my vehicle.
Two: I like working on trucks. I really enjoy nothing more than tearing something apart and puting it back together. I would just as well drive a truck as work on it.
There is NOTHING else I do in my spare time. Eat, sleep, and go work on "that big green, butt-fugly lawn orniment that gets in the way of mowing..." If it needs frequent work/maintainence, this is my kind of motor.
Also, for you guys calculating speed out, read the first part of my post. I am working on a 5-ton, not a deuce. The 5-tons have 6.44 gears, not 6.71.
Thanks again for all the info. You guys are AWESOME. I could have never hoped to have this many people be this willing to help out, or pour this much info into a simple engine comparison. I found this site by accident, and have yet to regret it.
Thanks again to everyone.

 

[Trango]

Chuckles, I know the feeling. After building 2 trucks in the last 10 months, I am really ready to take a break from vehicles.... but a friend suggested that we move onto building a diesel motorbike and now I can't stop contemplating it!!!!

Tom, dude, you are back! EXCELLENT! Good to have you back on board. Thanks for the help with the intake. 30 minutes ago I was at the exhaust shop with the deuce, telling them how I wanted the 3208 hooked up!

Bob

 

[rdixiemiller]

If a Detroit is what you want, then by all means have at it! It should be a fairly easy swap, the engines are similar in size. One of my buddies is getting the urge to bob down an old deuce, and he wants to use a fuel injected 300 Ford gas engine. He has found a donor deuce sans engine and tranny. I believe he is figuring on using an AOD tranny and a stock deuce T-case. Should work well, and have decent highway speed with the Fords ability to run 3000 rpm all day long. The torque curve should work nicely with deuce gears, and be lighter on the front to boot.
It's all in what you want, and what work you are willing to do.

 

[Lee Alessi]

the USMC is using a diesel kawasaki

 

[Desert Rat]

Tell me it ain't so Joe!!!!!!!!!!!!!!!!!!!!!! Someone in the pentagon is in dire need of re-examining which country PAYS their paycheck!!!!!!!!!!!!!!! MORONS!!!!!!!!

 

[cranetruck]

Don't forget that the deuce's multifuel engine is built on licence from a German design (MAN). The HIAB knuckleboom cranes used on HEMTT, FMTV and at least one deuce are made in Sweden....

 

[Desert Rat]

I hate it when truth gets in the way of a good story.........................................

 

[rdixiemiller]

Guys
The most "Made in America" vehicle in the country is a Toyota.

 

[Desert Rat]

 

[Joaquin Suave]

My choice would be a Cummins 6CTA.

 

[jasonjc]

the 1903 sprinfield rilfe of WWI fame was built on linces for gremany