any reason not to turn it up a bit?

turf

turf

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i've got myself talked into trying to add a bit of power to my rig. im looking for some good reasons not to mess with it.

my stock setup is a 12v Cummins 5.9, Bosch p7100 pump hooked to an Allison AT545. 320,000 miles

first off, i just want to turn it up a bit. the internet says my intended modification adds 30-40 hp. no crazy hp mods, just sliding the stock fuel plate to its forward most adjustment. it looks like a fairly easy mod to do.

the truck is stock 190 hp, that would kick it up to possibly 230 hp, still under the AT545 250 hp limit.

i recently added a transmission cooler and it made a huge power difference climbing the mountain. i can maintain 45 mph or so going uphill, but it'd be nice to not block to much traffic.

From what i understand with the fuel plate, is that it is controlled by the turbo waste gate. only time its controlling the fuel flow is at full turbo boost. moving the plate forward allows more fuel to flow at full boost.

common sense says be happy with it, its gone 320,000 miles. the hp bug says it wants to make the next 100,000 more fun.

anyone else turn it up?
 
I could crank my DT-360 up easily.. but everything I read at least about the international engines is that cranking them up involves often raising the RPM... and also running the risk of excessive blow-by which would blow oil out the draft tube or run the CC pressure up and break oil seals..

also can your cooling system handle the increased horespower on hot days.. your engine will make more heat..

and finally at 320k is your engine simply tired thus not making the original HP it was designed making your bus feel doggy.. if the engine is tired.. low compression, etc cranking up the fuel is just going to mask other issues or possibly accelerate the decline of the engine...

its an easy enough mod you can try it for a short time and see if you incur any negative effects from it as far as heat, using oil, etc.. and if so chsnge it back...

-Christopher
 
turf said:
i've got myself talked into trying to add a bit of power to my rig. im looking for some good reasons not to mess with it.

my stock setup is a 12v Cummins 5.9, Bosch p7100 pump hooked to an Allison AT545. 320,000 miles

first off, i just want to turn it up a bit. the internet says my intended modification adds 30-40 hp. no crazy hp mods, just sliding the stock fuel plate to its forward most adjustment. it looks like a fairly easy mod to do.

the truck is stock 190 hp, that would kick it up to possibly 230 hp, still under the AT545 250 hp limit.

i recently added a transmission cooler and it made a huge power difference climbing the mountain. i can maintain 45 mph or so going uphill, but it'd be nice to not block to much traffic.

From what i understand with the fuel plate, is that it is controlled by the turbo waste gate. only time its controlling the fuel flow is at full turbo boost. moving the plate forward allows more fuel to flow at full boost.

common sense says be happy with it, its gone 320,000 miles. the hp bug says it wants to make the next 100,000 more fun.

anyone else turn it up?
Click to expand...


Ever make the adjustment? - im in same boat
 
The life of any engine, especially a diesel, is simply a product of how much fuel it has consumed. More power equals more fuel equals less life. Engine life should ideally be expressed in total gallons used, not hours or miles or whatever.

Also, more power equals more heat. Can your cooling system handle the extra heatload? Can the driveshaft and differential handle the extra torque? If you end up going faster, are the brakes and suspension up to it?

John
 
Last edited:
The 5.9 Cummins (like the 3.9) can be easily turned up without sacrificing durability. In fact, you can get better mpg's and endurance by bringing the HP more in line with the torque curve on an all mechanical engine with the Bosch P pump.


Check out the threads on this subject over on 4BTswaps.com. Very savvy folks there who are really into these engines. Not even any need for parts (unless you want to get crazy on HP). A screwdriver on the smoke screw and a minor advance in timing can pick up a ton of power (25 to 35%).
 
Do it!!!!!

my bus is now fun to drive. a little more power makes a lot of difference.

the smoke screw is your friend. would still fiddle with it if it was easier to adjust and test. small adjustments make big differences. i have probably test driven 40 or so different settings between fuel plate and smoke screw. there are a lot of wrong settings, but when you start to get close... its worth it.

it all started with a heat problem. i cracked my exhaust manifold running it too hot, up a mountain. i added gauges, a trans cooler, and started tuning the AFC. Advancing the timing is something i havent taken yet, but would help with fuel economy as well.

i've got a thread here about my experiences.
http://www.skoolie.net/forums/f39/fuel-plate-17187.html

if you have the p-pump read up on it and tear into it. the hardest part is getting through the seals on the AFC. (which is easy)
 
I will re-iterate here..



one thing to remember is that most of the diesel engines will Lose durability if turning up the "smoke" also involves turning up the RPMs.. while diesels dont like to LUG, Navistar themselves on their inline 6's mentions that the DTA-360 (466 is similar but a couple hundred lower). *CAN "safely" have its RPM turned up to 3200* - the valves wont float, the pistons wont slap the heads.. but the Books indicate that Life expectency drops significantly when spinning the DT over 2900.. anything below 2900 is "long life expectency"..



while most diesels produce the most torque and HP below the high RPMs stated, the power guys like to spin em fast because the turbos spool up nice N high and pump out lots of boost.. if your engine's turbo isnt up to the task of spinning faster then dont turn up the fuel.. the more fuel you burn the more your turbo will spool.. if the turbo is waste-gated then you should have no worries.. but if its not you can over-spin your turbo and destroy it (and maybe the engine)..
-Christopher
 
i agree with Chris. i stayed away from the "governor spring adjustment" thats where you can go up and over the 2500rpms that most of us are governed at. that will get you the mph's, but at reduced engine life expectancy.

i have the 545 and only turned up as much power as i could find for free. the 545's limit is 230-250hp. i have a stock 190hp cummins, with some tweaking im shooting for an extra 20-30hp.

every time i take off in the bus, im happy i turned up the power a bit. i don't blow any smoke (now) and it makes it a fun, capable vehicle.

the fuel plate position and the smoke screw are intertwined. when you find their happy spot, it makes you smile. i rolled coal plevty of times trying out adjustments, and basically if you are rolling coal, its wrong.

the 545 isn't going to take many wheel spinning burn outs with a 500hptuned motor. you can't go crazy with hp.

i could change injectors, but why?

if you want mph's, change the ring gears. if you want power, tune the afc.
tune the afc anyway :)
 
the nemesis of the AT500 series transmissions is line pressure.. producing lots of low-rpm torque from the engine is great for MPGs and off-the-line power.. it spells disaster for the 545 and variants.. the line pressure on a 545 may not reach its spec'd full operating maximum until over 2000 RPMs.. and if you do break the drum loose against the C1 clutches, you'll never feel it.. it will just glaze those clutches and cause much faster wear..



while I have zero proof.. its my belief the AT500s were designed to be a gasoline transmission.. where you almost always stall the converter at 2000 or above and dont have the brute low end torque a diesel has..



like turf says be careful with your transmission.. esp if you get into advanciong your injection timing.. you can get gobs of torque getting the right combo of timing and fuel..



being an old hot-rodder I can hinestly say that power-adding is a total blast.. but you also Bust stuff doing it... and its worth every miniute of it.
-Christopher
 
Something I am not seeing much about here is gauges. For those of us who have the Dodge pickups first thing before any power mods are gauges. EGT especailly, fuel pressure and boost are also nice to have. But the EGT( exhaust gas temp) is important. 1200 degrees pre turbo is about max for any length of time. short bursts of 1500 are ok for about ten seconds. you can melt pistons with too much heat.
 
oh my what a mess. at least I have blown an engine that bad, some rods yea but not the whole block lifting.
 
that was an awesome video.. i saw that when they first relerased it... best part is the crank still spinning after the block flies off
 
And that was only 2000 HP. There are 5.9 sled-pullers cranking out THREE thousand these days!


Gotta love those 12v Cummins.
 
FYI, nowhere did they say it was a 5.9, claims it's a 6.7. I was waiting to see the front of the truck explode on the chassis dyno, disappointed, but a dyno room explosion is always a treat.:thumb:
 
cool video!! yea, turning up the screw make you feel like that :)
all of the above. lots of fun and can be lots of damage.
 
I'll add a few pennies of thought to the mix. For all the mechanical injected rigs out there: Certainly do hike up the power some, but nothing crazy. The 5.9 or 8.3 Cummins, Ford 6.6/7.8, IH (360, 408, 466, 530), or Cat 3208 can easily take running 2800rpm all day for years. Advance the timing will not only up the mpg, but will push the peak torque higher in the rpm range, and is a little nicer to the trans. As said a couple posts prior, get the gauges!
 
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