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Thread: 903 cummins

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    903 cummins

    I'm wanting to install the 903 cummins engine I recently purchased from the military out of a Bradley. Want to install it into a 1985 pete 359 model. However having a hard time finding an adapter plate for trans and flywheel. Also anyone know of after market high performance parts. Running into a dead end on all avenues. It is rated at 650 hp but know it's capable of over a 1000 hp. Very familiar with the engine as I use to overhaul them in the Army. I called cummins they have very little in the way of parts even listed for the engine.


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    a friend of mine had a 903 with double turbos all he could get was about 550 hp plus it blew up every 100000 miles.

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    Back in the late 70's early 80's I worked for a company that had a fleet of them in Freightliner and Ford trucks running NC to CA and the Northwest. As long as you did not run them hot they were million miler trucks, Did not like hills to well.
    That being said, they are used in a lot of boats to this day. Try some heavy-duty marine stores for parts.
    Jack

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    Quote Originally Posted by jackhartjr View Post
    Back in the late 70's early 80's I worked for a company that had a fleet of them in Freightliner and Ford trucks running NC to CA and the Northwest. As long as you did not run them hot they were million miler trucks, Did not like hills to well.
    That being said, they are used in a lot of boats to this day. Try some heavy-duty marine stores for parts.
    Jack
    Freightshakers and Two Story Falcons = Thomas Produce, Greensboro.

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    Man, the memories those 9 nothing 3's gave me.First truck was a 903 in a 1970 COE KW, 13 speed,torsion bar suspension, and as my dad said, it would out-run the word of God. LOVED the exhaust sound, hated the fuel mileage. Lots of head problems.
    I understand they are still used in foreign countries, and we used to get some parts from marine engine outfitters. Never heard of them putting out that much HP. Also lots of Steiger farm tractors in the west still use them. Check out Steiger tractor dealers. I see parts are still available for that application. Remember that engine is much heavier than a 6 cylinder, more weight on the springs.Also, we had to use a larger radiator than a regular Cummins or Cat. Do not believe your stock one will be enough cooling with that much HP.
    Not so sure I would attempt such an adventure.
    Keep us advised how it turns out. Good luck.
    Last edited by jbatmick; 01.21.2013 at 06.15 PM.

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    That Army truck in my signature had a 903 Naturally Aspirated, 300 hp, with a 5 speed and 2 speed transfer case. 5th high @3200 rpms= 42mph. 1st low @ 3200rpm = 3.5mph, but it would do that all day long.

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    I still run a VT-903 in my K100. What you've got is a VTA-903, and that 650HP is already double what I'm running, at the stock 290HP. Your VTA is running an intercooler, oil cooler, and aftercooler that my truck doesn't have, since they were military spec (I believe I just have a small oil cooling cyinder). At your power rating, air is what's holding you back, not fuel. Dual turbo setups were common on these engines to put a bit more pep in their step. If you've worked on these engines before, you probably already know how to crank up the fuel, but the major tweaks I've heard from old timers is turning the screw in the throttle shaft CCW 6 turns, replacing the AFC with an aneroid and putting a grease zerk on it then pumping it full of grease, and increasing the size of the pump gear from 3/4" to 1" or 1 1/4". I've heard that a 1" gear gives most drivers enough power to get into trouble with, but I priced one through cummins, and they wanted $1,100 for the #### thing (the fuel pump I was building only cost $700), so I passed on it. Other than that, play with the shims and springs until you get that governor up to 3600rpm, because you're going to need to run the engine over 2500rpm to get it down the road like you'd expect an engine with a 4 digit HP rating to behave. 2700rpms in my truck will get me right up to about 75mph in 8th OD, but I'd gladly trade that top end speed for a bit more pep in the lower gears. Pretty sure I'm due for a new set of injectors ($75ish reman, or $250 each through cummins), and need to set my overhead (can't seem to turn my engine over by hand since there is no room for an air hammer or breaker bar).




    Check boating forums and farm tractor forums for anyone selling off an engine, and keep it for parts. There is no aftermarket for these engines, and there isn't really an OEM market anymore. I believe cummins can still slap you together a VTA-903 from scratch at 650 HP, but it'll set you back about $130,000, or at least that's the bargain that militaries get on the engines.




    I'm not 100% sure, but I think the 1000HP rating engines were stationary motors running constant speeds. Even talking about more than 450HP out of these motors makes cummins parts reps go pale in the face. I think there is one cummins rep at their des moines location that remembers playing with the 903s, and more than one person has recommended him to me, but I can't recall his name right now. I know that TJ working the parts counter at Van Der Haags in Des Moines knows who I'm talking about, since he owns two 903's, and runs one in his 359 Pete, and has been playing with the pump and turbos for a while.
    Last edited by barroll; 01.26.2013 at 12.23 AM.

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    stay on top of the maintenance on that engine, it'll run good.

    We didn't put many hours on ours every year, but we still went in and ran overheads on them annually. Just part of the service.

    I spent 14 years pulling that engine out of bradley's in the guard.

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    Quote Originally Posted by Autocar View Post
    That Army truck in my signature had a 903 Naturally Aspirated, 300 hp, with a 5 speed and 2 speed transfer case. 5th high @3200 rpms= 42mph. 1st low @ 3200rpm = 3.5mph, but it would do that all day long.
    Built for comfort, not speed - right? Looks to be pretty tall leg lift to the first step. Thanks for the service!

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    I APPRECIATE ALL THE INFO JUST HAVING A HARD TIME FINDING A CLUTCH,PSI PLATE AND AN ADAPTER TO MOUNT A MODERN TWIN COUNTER SHAFT TRANS TO IT. I'VE COMPLETELY REBUILT THE ENGINE AND HAVE HAD IT ON A DYNO 1,003 HP AND 1600 FT LBS OF TORQUE AT 3300 RPM. EVEN THOUGHT ABOUT PUTTING IN A SET OF BOXES BUT STILL CAN'T FIND AN ADAPTER PLATE THINKING ABOUT SEEING IF A MACHINE SHOP CAN MAKE ME ONE?. OUGHT TO BE ONE &^%$ OF A MOTOR IN AN OLD PETE. FUEL MI WILL SUCK BIG TIME I'M SURE. BUT AS A PLAY TOY IT SHOULD BE REALLY FUN. GO OUT AND STOMP ME SOME SLIMY GREEN DRIPDROITS (DETROITS). ALTHOUGH I WILL HAVE TO ADMIT I DO LOVE A 2 STROKE DETROIT. JUST NOT THEM SERIES 60 JUNKERS

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