Simple upgrades without turning up fuel?

[Diesel]

So I want to boost the power of my truck just a little but I don't want to touch the pump fueling. Here is what I thought about doing:

12-16cm exhaust housing
new turbo wheel (what size/type?) while I am in there putting on the housing
muffler delete on stock exhaust
injectors with more spray pattern (please help figure out if this is worth it without turning up the pump)
pump timing (dont want to do this if it makes smoke or makes it harder to start)

Biggest thing is that I want the truck to start and run as smoke free as it does stock...basically I want to upgrade the engine the way Cummins would have.

[oldestof11]

Bigger turbo and injectors mean you HAVE to adjust the pump. However, adjustments need to be done on a person level.

Like on mine. I have stock injectors, stock turbo, 3.5" downpipe straight to a 4" then out in front of the passenger rear wheel, 4200rpm spring, and a DennyT stage 1 fuel pin. I adjusted the AFC spring up tight and not a whole lot smoke down low. With it all the way down, it smokes pretty good. I have since turned the DennyT around 180* so there is NO boost compensation. I went from a pegged 30lbs gauge down to 12 pushing it hard.

Mine starts just fine at 0* and no block warmer.

[Diesel]

Ok thanks now I understand. Maybe I'll go a piece at a time?

Like could I delete muffler and do turbo housing first?

Does anyone make a muffler delete for the stock exhaust that I can order so I dont have to go to a sleezy muffler shop?

[cmann250]

I don't have dyno sheets to prove it, but the biggest difference you'll see with deleting the muffler is sound. I don't think there's any noticable power difference. If you have the 21cm exhaust housing, anything will be better. I don't know if the gain vs dollar ratio is good, but you might look into an HX35 if you are staying with stock fueling

[Diesel]

I gotcha. I think I absolutely need to get a turbo exhaust housing even if I don't get a wheel upgrade. Sounds like I am losing out on a lot of low end power.

So first I'll get a 16cm and see what I think.

Question: what is the difference between pump timing, replacing the fuel pin, and turning up the screws?

[cmann250]

Question: what is the difference between pump timing, replacing the fuel pin, and turning up the screws?

One of the gurus: please correct me if I'm wrong. Messing with the timing (either pump-to-the-head or jumping a tooth) changes the relationship between where the piston is and when the fuel is injected. The ramp of the fuel pin controls when the fuel comes on in relationship to boost. The smoke screw (on top) controls low/no boost fuel. The fuel screw adds pressure and volume. And my understanding of the starwheel is it says where the fuel pin starts.

[PToombs]

Caleb has it mostly right. You can turn the pump towards the head 1/8th of an inch and get a noticable difference in driveability without hurting any thing. No reason to go hog wild and pushing it to the head or jumping a tooth. As for the starwheel, the higher it is the more boost it takes to move the cone and add fuel. The lower it is the less boost, and it will smoke easier down low when you get on it hard.

[Diesel]

So to turn up my timing 1/8" I literally loosen and rotate my pump? That will make it peppier than stock? I guess that sounds good to me because I don't have to turn up fuel. Why wouldn't cummins turn the timing up?

[PToombs]

Yeah, almost that simple. Don't forget to loosen the bolt at the rear bottom of the pump. I prefer to loosen the injectors lines and retighten them to prevent strain but most don't. It will lower EGT's because it's firing sooner and will pep it up a little.
Emissions my boy, emissions!

[cmann250]

As for the starwheel, the higher it is the more boost it takes to move the cone and add fuel. The lower it is the less boost, and it will smoke easier down low when you get on it hard.

The way you explained it sounds like where the starwheel is set changes the spring rate (k value if you're into Physics) of that AFC spring. That sounds to me that changing moving the star wheel up/down changes how soft/firm the spring is. I do know that you can get different AFC springs...

[PToombs]

I'm not sure it has a variable rate or not, I just know that's how it works. I hate physics, that's why I went to vocational ed.

[Diesel]

I just watched a youtube video on how to move it so that is happening soon.

Now will a fuel pin cause smoke or hard starting? Could I install a fuel pin without touching the pump settings? Are there other "emissions" settings that I need to get rid of for some MPG and power?

[cmann250]

A fuel pin won't effect starting at all. A really aggressive fuel pin could cause more smoke, but there are conservative pins out there. I have my stock pin rotated to the deep side. If you pull it out, you'll see it's on an eccentric. I'd try that to see how you like it before you buy a different pin.

You're starting down the slippery slope

[oldestof11]

The only thing that causes hard starting are: Worn injectors, worn pump, timing WAY off, too cold with out grid heaters, not enough battery to turn it over, bad fuel shutdown solenoid (FSS)

[Mark Nixon]

The only thing that causes hard starting are: Worn injectors, worn pump, timing WAY off, too cold with out grid heaters, not enough battery to turn it over, bad fuel shutdown solenoid (FSS)

.......and air in the lines, plugged filter, broken draw-straw, burned wiring.....need I go on?

The 2 single biggest power achievers, from a "no pump adjustment" standpoint, would be larger air cleaner and a tighter turbo housing and that only helps to move the air better and sooner.

Mark.