325/600 engine tuning for fuel economy, 3rd injector event elimination, G56 question

A

apexfd

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Jun 1, 2013
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Ill get straight to the point. Im looking for hard facts about a few things.

1. Does a smarty touch installed on a 04.5+ truck remove the 3rd injector event? Or can the smarty touch be loaded with custom tunes that can?

2. Does eliminating the 3rd injection event on the 325hp 5.9 engine actually improve anything? Lower EGT/improve MPG? Prevent meltdown?

3. Can the early G56 be modified to have the same 6th gear ratio as the later version? Or is it better to just swap the gearbox entirely?

I ask because my first project truck was a early 2004 with the 305hp engine. I put a Colt Cam stage 2 in it, 64x76mm turbine he351cw, 2nd gen manifold, and a good intake, smarty junior. That truck gets an honest to god 26mpg consistently, unloaded. My friend with a 2005 truck wants me to do a bunch of work to his 325/600 engine to make it as efficient.

Sorry if these questions have been asked already. Ive been looking for other an hour and all i can find is BS and junk on cumminsforum.

Thanks.
 
Don't know what a Smarty can and cannot do nowadays and I don't care. Get yourself a custom tune with HPTuners from someone reputable.

Yes, the third injection elimination will gain you FE.

Yes, You can pull your G56 apart and install a newer gear to obtain the newer gear ratio. Honestly, your best off just to swap the gear box.

My question to you is why? If you're that hard up to reduce engine rpm's get bigger tires.
 
The 325 engines also have a different cam profile than the 305 engines that ultimately creates in-cylinder EGR. This along with a catalytic converter in the exhaust met emissions standards for Cummins at the time.

Will you install a cam in your friends engine? If so, which one?
 
apexfd said:
Ill get straight to the point. Im looking for hard facts about a few things.

1. Does a smarty touch installed on a 04.5+ truck remove the 3rd injector event? Or can the smarty touch be loaded with custom tunes that can?

2. Does eliminating the 3rd injection event on the 325hp 5.9 engine actually improve anything? Lower EGT/improve MPG? Prevent meltdown?

3. Can the early G56 be modified to have the same 6th gear ratio as the later version? Or is it better to just swap the gearbox entirely?

I ask because my first project truck was a early 2004 with the 305hp engine. I put a Colt Cam stage 2 in it, 64x76mm turbine he351cw, 2nd gen manifold, and a good intake, smarty junior. That truck gets an honest to god 26mpg consistently, unloaded. My friend with a 2005 truck wants me to do a bunch of work to his 325/600 engine to make it as efficient.

Sorry if these questions have been asked already. Ive been looking for other an hour and all i can find is BS and junk on cumminsforum.

Thanks.
Click to expand...

The tunes that come with the touch modify the post injection event but do not remove it. The touch can be loaded with custom tunes written with UDC Pro.

Elimination of the post event can improve things, but it can also make things worse. If it is a completely stock truck (and I mean completely), then keeping a post event should be done. If not you will probably plug a CAT over time. Especially if you do a lot of low load, low rpm driving. When the engine is warmed up that is mostly where the post event works anyway.

If you are trying to improve performance. Especially with longer injection events, and higher rpms then eliminating the post injection has real benefits. With the stock fuel map, there is a lot of post injection event at high rpms and high loads. Multiple reasons for that but the end result is high egts, and wasted fuel. IMO if you plan on running an engine above 2800 rpm for any length of time, the post has to go.

As a general rule (and all general rules are false), for more power you want a short total cylinder burn, and for mileage you want the burn to last over a longer period of time, but with less injected fuel (hence the multiple injection events). The stock post injection event on an 05 is not setup to improve mileage. On later 4th gens it is.

I hope this helps.
Paul
 
Lots of really good information there. Thanks guys.

Swapping the g56 would be last on the list. Getting a healthy, efficiently running engine is first on the list.

This truck will get a Colt Can stage 2, I don't see the need to get a bullet stage 3 for a near stock truck.

Real interesting information PaulB! I didn't know that about the 4th gen injection events.
 
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