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Discussion Starter · #1 ·
i've been looking at injectors and i see that there are different flow rates for different hp and tq gains. why wouldn't someone just get the largest set available?
is it because of airflow? what's the largest injector size a stock turbo can provide airflow to on a 24V engine?

what regulates teh amount of fuel to the injectors? to be more precise, how does the ecu know how much fuel to inject since there's no mass air sensor?
should i buy the nozzles or full injectors?
is there a downside to just buying nozzles, since they are cheaper?
i think i really need a book on diesel engines....
 

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the ecm regulates the amount of fuel put to motor with the MAP sensor. The MAP sensor reads boost, and the ecm gives appropriate fuel
 

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Discussion Starter · #3 ·
ah, ok, i forgot about the map sensor. what about the reasoning for choosing injector sizes; any thoughts there?
 

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well if you hiave TOO big of injectors with a stock charger then you will not be maximazing your turcks power. You will have a lot of black smoke aka unburnt fuel. The reason being is because your charger can't produce enough air to help burn all of the fuel. Bigger charger + bigger injectors = MORE POWER. (and a bunhc of other stuff, like new tranny/clutch, fuel system, ect.) But you want to have have enough air to burn the fuel, or your just wasting power.
 

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Discussion Starter · #5 ·
right, i figured that part since we need air to make power. any idea how big an injector the stock turbo is good for?
i basically want to max out teh stock turbo and leave it at that.
 

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um...i am not too sure about the max size injector for stock charger...hopefully someone else might be able to help you.
 

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Since you have an EdgeEZ and a 5spd, I am assuming you have a VP pumped truck.

It is true that the ECM manages fuel flow on these trucks, but, with an EdgeEZ and aftermarket injectors, the ECM is not going to have much to work with that it understands.

The only real measure left to work with is EGT's.

With what you have, IMO, I wouldn't go much bigger that the RV275's in Bosch, or maybe a 40 horse DDP. You just won't have enough air from the HX35 to burn the fuel. Sure, it'll smoke with bigger injectors, but you'll be loading the oil with soot, washing down the cylidners with fuel, running high EGT's, etc. You want EGT's to stay under 1200 and have smoke on hard acceleration that "blows out" when you reach steady RPM.

A BD Super B, Schwitzer S300 or Aurora 3000 are all good first step turbo upgrades that will let you run bigger injectors safely.....which lead you to a clutch and headstuds. It never ends! :)
 

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Discussion Starter · #8 ·
ok, so just a small set of upgrade inj. will max out the hx35. what's DDP stand for?
at this point, i really don't want to get into changing the turbo, i'm trying to make it very strong for mostly stock parts and leave it at that. of course that may change next year, but that's my plan right now....

what's the difference between just doing nozzles and swapping the entire injector? witht eh nozzles, don't i just take apart the stock injectors and swap the ends, then re install?
that sounds pretty easy, especially since it's much cheaper than all new injectors and if all i'm doing is a 40Hp injector, i don't want to spend all that money for full injectors.
 

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ok, so just a small set of upgrade inj. will max out the hx35. what's DDP stand for?
at this point, i really don't want to get into changing the turbo, i'm trying to make it very strong for mostly stock parts and leave it at that. of course that may change next year, but that's my plan right now....

what's the difference between just doing nozzles and swapping the entire injector? witht eh nozzles, don't i just take apart the stock injectors and swap the ends, then re install?
that sounds pretty easy, especially since it's much cheaper than all new injectors and if all i'm doing is a 40Hp injector, i don't want to spend all that money for full injectors.
Dynamite Diesel Performance
 

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Discussion Starter · #10 ·

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ive been looking at injectors a lot lately and from what shops around here are telling me is that going with just the nozzle is chancey b/c the injector life is supposed to be around 80k to 120k miles. thats coming from someone trying to sell something though. the injector nozzles are a lot cheaper and it is a DIY job. for the stock turbo ive been told not to go higher than about 60-90. you will probably be better off getting a FASS 150 gph as well. there is an article on how to do the job under the maintenence forums page on this website. looks really helpful
 

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Discussion Starter · #12 ·
cool thanks for the info. the FASS is definitely in the plans as well.
 

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Injectors is definitely a place to focus on quality, which means the best will cost you more.
 

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First, I would make sure you have a hx35. I believe most those went on the autos. You may have a hx40 (larger) and those will support much more power. Probably in the realms of 450 hp if you turn the boost up to 30 psi.

I also believe the computer works in "closed loop" for the most part, and will not drop the fuel to make up for the bigger injectors. It will just adjust the idle down. However, the computer will detect overboost and deal down the fuel unless you have a boost fooler or a chip ;) The first thing to go with a mod like this is the exhaust manifold. They are notorious for cracking/warping. It WILL warp.

READ THIS IF YOU ARE CONSIDERING TIPS:
Lots of people have trouble with their installation of tips. It is of the UTMOST importance to keep the fuel system ABSOLUTELY ABSOLUTELY clean. The tiniest microscopic little piece of grit can ruin the injection pump, and !!!plug up the ports in the injector tip!!! I think the VAST majority of the problems people have with these installs have to do with this.

You will also probably hear someone refer to a "pop test" The pop should be only minimally affected by the tip. If it popped evenly before, it most likely will do so again. But your idle may become SLIGHTLY more irregular. If it's more than slightly, something is in the tips. Your injectors are a matched set popped to the same pressure. Never swap one from a junkyard without popping them all.

Personally, I am very happy with my edge Jammers. 100 hp tips make the hx40 spool up in short order, and my fuel efficiency improved 1.5 to 2 mpg. Gotta get bigger exhaust, too. EGT's will get out of hand.
 

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Discussion Starter · #15 ·
First, I would make sure you have a hx35. I believe most those went on the autos. You may have a hx40 (larger) and those will support much more power. Probably in the realms of 450 hp if you turn the boost up to 30 psi.

I also believe the computer works in "closed loop" for the most part, and will not drop the fuel to make up for the bigger injectors. It will just adjust the idle down. However, the computer will detect overboost and deal down the fuel unless you have a boost fooler or a chip ;) The first thing to go with a mod like this is the exhaust manifold. They are notorious for cracking/warping. It WILL warp.

READ THIS IF YOU ARE CONSIDERING TIPS:
Lots of people have trouble with their installation of tips. It is of the UTMOST importance to keep the fuel system ABSOLUTELY ABSOLUTELY clean. The tiniest microscopic little piece of grit can ruin the injection pump, and !!!plug up the ports in the injector tip!!! I think the VAST majority of the problems people have with these installs have to do with this.

You will also probably hear someone refer to a "pop test" The pop should be only minimally affected by the tip. If it popped evenly before, it most likely will do so again. But your idle may become SLIGHTLY more irregular. If it's more than slightly, something is in the tips. Your injectors are a matched set popped to the same pressure. Never swap one from a junkyard without popping them all.

Personally, I am very happy with my edge Jammers. 100 hp tips make the hx40 spool up in short order, and my fuel efficiency improved 1.5 to 2 mpg. Gotta get bigger exhaust, too. EGT's will get out of hand.

i thought they all cam e with hx35's. is there an ID number on teh turbo somewhere that will positively ID it as a 35 or 40?

i plan on some sort of "chip" at some point anyway, and if/when themanifold warps, i'll just get one of those cool aftermarket ones...
for exhaust, right now i'm just running an open downpipe whicdh will eventually become a single stack.

good info on the rest of it, thanks.
 

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There should be a tag between the little metal tube and the waste gate actuator on the air side of the turbo. The hx35 is not a bad deal, either way. One is not necessarily "better" just different. The smaller turbo will be MUCH more responsive. And the power #s are from memory, so beware :) But I would imagine you could probably get 350 out of a 35. I am also not sure about which ones came with which turbo.

Basically, the way I understand it, the pump can supply the injectors, but then the lift pump cannot supply enough fuel and the turbo cannot supply enough air at the upper end of the injector spectrum. So in the least, you must drill out your banjo bolts, and perhaps turn up your boost at 100hp injectors.

An auxillary fuel pump is always a good idea because you will mount it on the frame rail where losing a prime is not an issue, but more pressure is not the way to overcome restrictions. Remove the restrictions. I would make sure to adjust the pressure down on the FASS to 10 or 12 psi to not cause problems with the injection pump.

I use a carter pump that kicks on when the pressure after the filter drops to 4psi. I think it's set at 7 psi or something (factory maximum is 10 psi, min is 5 psi)

A RELIABLE source of information regarding this sort of thing is Dodge Ram Information

I goofed, the difference is hx35 and hy35, not 35 and 40. By the way, the rule of thumb is supposed to be 10 psi of boost per 100 hp. I suspect you can go over that, but it may smoke when you stuff it.
 

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I guess I got my wish list mixed up with my reality list!:toiletcla

Anyway here's a link to the power from a hx/hy35 as well as the hx40. It verifies the 350 hp, but I am guessing that is at stock boost levels, so perhaps you could go higher.

CumminsDatabase.com :: Turbo Comparison
 

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Discussion Starter · #18 · (Edited)
thanks for the info, that's what i'm looking for. looks like i'm going to get an airdog first, as i believe in being careful and making sure the supporting mods are in place before i attempt for more power.

somewhere in there, i saw that a boost fooler was recommended if one were interested in more boost, but i thought that was only for later model cummins trucks? it said that the ecu will see the extra boost and set a cel. that's not applicable for a 99 is it?
 

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The HX-35 was installed on manuals and the HY-35 came on Autos. The big difference is the HY has less flow than the HX due to the turbine housing design. Adding a quality lift pump before ANY kind of chip is manditory or you will fry the VP-44. Installing a fuel presure guage and/or idiot light is also VERY strongly suggested. Boost and Pyro guages are a must have in order to monitor vitals and properly diagnose issues.
Boost foolers are just resistors that limit what the sensor tells the ECM allowing more fuel to flow before the electronics cut delivery. 98.5 and up to the common rails all use the same fuel delivery system so the 99 is in there.
Use a planned approach to mods... intake, turbo, exhaust, fuel, and programing or you will suffer poor performance. If you cant afford to do it all at once, then I suggest that you start with the exhaust and intake to let her breathe. Then move to the fuel system upgrades before going to chips/programers, and finnally injectors and turbo. This way you dont have a meltdown from EGT's that spike. Just my $.02
 
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