Back to stock injectors for a short time

[diesel4life]

I like what you have to say Mike! I can't wait to get some injectors in mine! I'm going to go with DAP's 75's. Just going to be a little longer, when you need a new vp44, ball joints, brakes all around, a turbo, a manifold, and $1,800 worth of dental work all at the same time you kinda got to prioritize

I see in your sig you have a "built" trans. Not sure how far in depth you went with it but keep in mind most of the time thats going to be the weak link. For instance I recently helped a buddy install a set of 60's on his truck. His trans has a basic shift kit and new clutches and valvebody, slightly higher line pressure but retained factory replacement tc all with less than 40k miles since rebuilt. With just the injectors alone his tc slips under heavy throttle running EMPTY. He originally wanted to try my Smarty after the injector install to see if he liked the combo, no way is that going to happen until he sinks some more money into his trans. Even 75 hp injectors is probably going to give you well over 100 ft lbs of torque. More power is always funner to play with, but if your keeping the factory HY turbo and tow alot more fuel can become more problems. I intentionally stayed on the conservative side (40 HP) for truck reliability and I also wanted to retain healthy towing manners. I recently took a trip down south with a lot of 6-8% grades some which were 2 or more miles long and I was peaking at around 1100 degrees towing with my set up 275s with Smarty tweaked on level 5. I'm really not sure how much more fuel I could have been able to use before having to back out of the throttle?? As it was I used whatever I needed and the truck ran great.Theres nothing set in stone with what you can and cant run it largely depends on how you use your truck and of course your right foot.

[CTcummins24V]

The ECM meters the fuel on all 98.5+ Cummins. The ECM meters it thru the VP on 2nd gen's and thru the injector on 3rd and 4th gens, but the ECM is where it actually occurs.

I am kind of new to the diesel world...so without a box/programmer the vp44 will not supply all the wanted fuel to say a +50 hp or greater injector?

[Mopar1973Man]

I am kind of new to the diesel world...so without a box/programmer the vp44 will not supply all the wanted fuel to say a +50 hp or greater injector?

Yes it will but there is a flip side to this problem. It not the fuel that becomes a issue but the boost pressure. As you add more fuel there is more boost pressure created and so as you start to get towards 20 PSI the wastegate opens but being you got extra fuel the truck will start to pass 20 PSI anyways and ECM will limit the fuel. So the fueling box is to control boost fooling as well as adding extra timing and fuel the stock software.

[AH64ID]

I am kind of new to the diesel world...so without a box/programmer the vp44 will not supply all the wanted fuel to say a +50 hp or greater injector?

Exactly as Michael said. Injectors add additional fuel without the ECM knowing about it.

[JOHNFAK]

It's also the same with larger injectors. With 400K miles on the RV275's we won't know until you calibrate the SGII if they were worn enough to flow more fuel than the new ones or not; however, lets assume they were still +40 and the new ones are +50. If you run the SGII on the 15.5% setting with the new ones you are actually getting worse mileage than the SGII is telling you because for every gallon of fuel the ECM tells the SGII you are burning the injectors are actually flowing more fuel. Anything else is just a guess. My point is that you got better mileage with the stock sticks than the SGII told you, but the stock sticks still appear to be worse in the mileage department than the RV275's by a few points. Additionally until you calibrate the new injectors with the SGII you don't know if your mileage is going up or down, despite any increase in the SGII readings. I'm not trying to beat a dead horse, I just see this confused by a lot of people on many forums and want to make sure anyone reading it sees what actually occurs inside the ECM as you adjust fueling with injectors. This is something I deal with when tuning other peoples trucks with UDC when they have aftermarket injectors. The HPCR ECM is a lot more complicated but the base computations and operation is the same in terms of how they report fuel usage to the OBDII and overhead.

awesome ...

[Jbh97009]

I see in your sig you have a "built" trans. Not sure how far in depth you went with it but keep in mind most of the time thats going to be the weak link. For instance I recently helped a buddy install a set of 60's on his truck. His trans has a basic shift kit and new clutches and valvebody, slightly higher line pressure but retained factory replacement tc all with less than 40k miles since rebuilt. With just the injectors alone his tc slips under heavy throttle running EMPTY. He originally wanted to try my Smarty after the injector install to see if he liked the combo, no way is that going to happen until he sinks some more money into his trans. Even 75 hp injectors is probably going to give you well over 100 ft lbs of torque. More power is always funner to play with, but if your keeping the factory HY turbo and tow alot more fuel can become more problems. I intentionally stayed on the conservative side (40 HP) for truck reliability and I also wanted to retain healthy towing manners. I recently took a trip down south with a lot of 6-8% grades some which were 2 or more miles long and I was peaking at around 1100 degrees towing with my set up 275s with Smarty tweaked on level 5. I'm really not sure how much more fuel I could have been able to use before having to back out of the throttle?? As it was I used whatever I needed and the truck ran great.Theres nothing set in stone with what you can and cant run it largely depends on how you use your truck and of course your right foot.

I appreciate the info. My trans is 'built' with alto clutches, kolene steels, billet/super servos, Kevlar 2nd gear band, billet accumulator, band strut, anchor, apply lever, modded valve body or 'shift kit', billet single disc converter, double deep aluminum pan, and probably other stuff I don't even remember... I actually have a triple disc converter and billet input and flex plate too, but haven't found the drive to pull the trans again, honestly I'll probably just run what's in the trans now until the converter starts to squeal! After reading and reading about Mikes setup(s) I've kinda copied his, I run the edge comp on 5x4 all the time, and drive very easy. I'm all about the milage 99.8% of the time. I think I'll be ok with the 75's. Also, fwiw I have an hx35 not the hy, which helps, but when I get caught up with some other things, since my hx is well worn, I'm going to replace it with either a s300g, or super b, but I'm leaning towards the 300g for the 12 cm exhaust housing...

[cajflynn]

A super b is a s300g.

[JOHNFAK]

A super b is a s300g.

A modified s300g base though right .,,,

[cajflynn]

There is no difference between the two.

[Mopar1973Man]

I'm going to replace it with either a s300g, or super b, but I'm leaning towards the 300g for the 12 cm exhaust housing...

HY35W is 9cm2 HX35W is 12cm2

[ISX]

Exactly as Michael said. Injectors add additional fuel without the ECM knowing about it.

How does it calculate GPH then? How does Mike use his scangauge for instant MPG? Or is he just cheating it with a bunch of correction percentages?

[Mopar1973Man]

Not cheating if the gallons consumed and the gallons displayed match...

[ISX]

Not cheating if the gallons consumed and the gallons displayed match...

If the ECM isn't reporting it right then you have to cheat it right? I don't care about the end result...I want to know how it all works.

[Mopar1973Man]

Let's say the ECM is reporting 15.5% off from actual GPH flows (With the RV275's and Edge Comp 5x3). Then ABS computer is off by 1% on MPH.

[AH64ID]

If the ECM isn't reporting it right then you have to cheat it right? I don't care about the end result...I want to know how it all works.

It's not cheating. There probably aren't many rigs that don't use a correction factor. The ECM modulates the fuel thru the VP44, the injectors just move more than the ECM thinks (hence an increase in overhead mpg's). The scan gauge has to be calibrate anyhow, and the volume difference between stock and +50 injectors is going to be linear (at least close enough to use a fixed calibration).

[Jbh97009]

A modified s300g base though right .,,,

The super b has a 14cm exhaust housing, while most 's300g' turbos that places like dap, II, schied, cpp, htt etc sell have a 12cm exhaust, which is what I would like over the 14cm...

[Mopar1973Man]

Well I'll have to admit the +50HP injectors pull strong hauling the RV around and the EGT's are much cooler than the RV275's. I was capable of taking on most of Midvale, ID grade in 5th gear hauling along at 55-60 MPH just toward the last little bit of the summit I had to back down to 4th gear but very controllable for EGT's. I had more issues with the blowing winds and the trailer than with truck.

[AH64ID]

Well I'll have to admit the +50HP injectors pull strong hauling the RV around and the EGT's are much cooler than the RV275's. I was capable of taking on most of Midvale, ID grade in 5th gear hauling along at 55-60 MPH just toward the last little bit of the summit I had to back down to 4th gear but very controllable for EGT's. I had more issues with the blowing winds and the trailer than with truck.

You back down at 1200° correct?

Good results for sure!

- - - Updated - - -

Just under 500' in 1.4 miles makes for an 6.7% grade average with small sections up to 9%. It's a good pull for sure, I am just able to do it in 5th at 55 on a hot summer day. For an HX35 I think you are setup pretty good.

[Mopar1973Man]

You held at 1200° correct?

Good results for sure!

- - - Updated - - -

Just under 500' in 1.4 miles makes for an 6.7% grade average with small sections up to 9%. It's a good pull for sure, I am just able to do it in 5th at 55 on a hot summer day. For an HX35 I think you are setup pretty good.

Correction.

[Texas CTD]

Well I'll have to admit the +50HP injectors pull strong hauling the RV around and the EGT's are much cooler than the RV275's. I was capable of taking on most of Midvale, ID grade in 5th gear hauling along at 55-60 MPH just toward the last little bit of the summit I had to back down to 4th gear but very controllable for EGT's. I had more issues with the blowing winds and the trailer than with truck.

Comp on 5x5?