Grunt needs help with 903!

[JJuday]

I am a driver of a a Bradly Fighting Vehicle in Iraq and I am wondering if anyone here could help me get some more power out of the old girl. We added 6600 lbs. of armor to it and it used to do almost 55. Now it strugles with 40. We need to get to the fight in a hurry, so if anyone at all can give some advice on how to get the old hog to scream please let me know. We will soon be pulling the pack for services so that will be an oppertune time to mod. it. Thanks for the great site and advice! JJuday.



2003 SLT. Graphite, 4X4, Quad Cab, 6-Spd. Hide-Away Gooseneck Hitch. And my wife drives it everyday while I'm gone!

 

[JJuday]

Also!!!

Sorry I forgot to mention that it has a VT-903, Big Cam, V-8, Cummins.

 

[RussW1911]

I had the same PAC in the AAV's in the Marine Corps. You can have the Mech's turn up the pump, similar to a twelve valve. Thats the only way I know of being able to get more pep out of her.



Stay safe, Semper Fi Russ Wallis

 

[HBarlow]

JJuday:



I have no suggestions for increasing the power of your Bradley Fighting Vehicle but... .



I want to take this opportunity to thank you and your fellow Marines and soldiers for your service to our nation in the worldwide war against terrorism. Your countrymen back home are aware of the courage you exhibit and the sacrifices you are making and we are both proud and grateful.



Harvey Barlow,

ETCM(SS), USN, retired

 

[davemac]

Amen to that!!!

 

[GHinton]

JJuday, no tips, but just hope you and everyone on our side make it home safe and sound, mission accomplished. THANKS!

 

[JoshPeters]

If it has a pump similar to our P7100 pull the AFC cover off and slide the fuel plate forward!



I'm not sure what exactly is in it... just a suggestion. I'll see what I can find out. A friend of mine is a Mechanic in the Guard. He may know.





Josh

 

[MKoth]

I believe that the 903 uses a common rail type fuel system, with a camshaft actuated injector set-up. If that is the case you can change the orifice size of the fuel return line that comes out of the heads. The smaller the orifice, the more fuel the injectors are forced to put into the engine. Just keep a close eye on exhaust gas temps.

 

[sbentz]

903?? Wow, I am getting old.

I used to tune and repair these old boys. Simple PT fuel system, same as Small cam, Big Cam, etc... .



Really want to make it fly? Here goes:



Pull the 4 7/16" bolts holding the lower governor cover on the fuel pump. Pull the snap ring. Slide our the governor spring, and "button holder". .



There is a 1/2" diameter steel "button" that controls the fuel pressure. look at the number on it. replace it with a new one, from Cummins, 10 or 15 smaller.



Example: if it is a 25, get a 15. Worst case, if you go too small> SMOKE! One of the smallest you can find? a 5 or a 7 button. Old trucker trick. that and stiff gov spring, and watchout.



Shim up the gov spring . 125 or so for more RPM. And more fuel pressure.



Go and spin the tracks off of it...

 

[tgbol]

Restricting the return line will increase the rail pressure. The problem with that is the idle will speed up too. The dump trucks at work will plug the tank vent and idle about 1200rpm. Open the cap and it idles back down.



sbentz is correct changing the button controls the fuel delivery. Again the idle speed might need adjusting. Shimming the governor spring will giv you a few 100 more rpm. it is possible to build enough heat to make the manifolds glow orange.

 

[HoleshotHolset]

That's good info...

My brother works on the VT-903's in the Coast Guard 41' boats... and always wanted to crank one up. He's in NYC right about now, though. Probably standing somewhere with a gun.



My best friend is in Iraq right now too... . I told him to keep his head down - JJuday, you make sure to do the same thing.



Matt

 

[A Johnson]

Don't restrict the return line, do what sbentz said if anything.



I can't imaging getting more HP out of a military 903, I thought they were pumped to the nuts in the first place. I guess he could always braze the end of the button flat and lap it smooth. Yikes!!!



A Johnson







Not responsible for any 903 failures of any kind.

 

[A Johnson]

Length: 21 ft 2 in

Width: 11. 83 ft with armor tiles; 10. 75 ft without armor tiles

Height: 11. 8 ft

Weight: 50,000 lbs unloaded; 67,000 lbs combat loaded

Power train: 600 hp Cummins VTA-903T diesel engine with GM-Allison HMPT-500-3SEC hydro-mechanical automatic transmission

Cruising range: 250 miles

Road speed: 38 mph

Crew: M2A3: 9 (3 crew; 6 dismounts); M3A3: 5 (3 crew; 2 dismounts)

Armament: 25-mm M242 Bushmaster cannon

TOW II missile system

7. 62 mm M240C machine gun







Ok, it puts out 600hp and we are going to tell him how to turn it up?

What did this put out as a stock automotive application? Maybe 350-400hp @1800-2100RPM. I realize many truckers really turned these up, but think we can get him past 600HP?!! Gee I wonder what the expected life of this is in battle and full duty cycle? My guess is 2 hrs or so.



A Johnson

 

[RBratby]

the 903 in the coast guard are only 340 hp. i used to work on them when we had a 41' utb here at the station. now we had a 47' mlb and it runs detroit diesel 6v92ta. they have more power but it has to many electronics controling the engine.

 

[JJuday]

Thanks!!!

Thanks for all of the responses! Found out unfortunatly the other day that the P. T. O pump was on it's way out and it held till we were trying to get back to the F. O. B. Well she started to stumble and I thought that it was out of fuel or worse. The fuel shut off was jimmy rigged and the cobble job came loose and the pump was only engaging half way, supplying only half of the fuel. It finally broke and I couldn't get it started and had to a combat pull with another Brad. The grease monkeys fixed the problem and I am screaming down the road faster than ever now! Thanks guys. JJuday.

 

[jrjuday]

Josh: Keep your foot outta that thing, your'e making fuel prices skyrocket back here! Pretty soon I won"t be able to afford to get my minimum dailly requirement of #2 smoke!! Seriously, thouogh, glad to see you got the problem resolved. You definitely need to be able to depend on that Cummins!! Haven"t been able to link up with you or Jen lately for some reason. Be careful. Dad.