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Discussion Starter #1
Hey Guys,

I'm new here, I've had my Nitro for about three years now. I'm pretty happy with it, but I want more power. I consider myself a somewhat smart guy. I know a turbo Nitro 4.0L has only been done once on this forum, and the user who did it does not want to share any plans. Now, I'm no mechanic, but I have rebuilt a few air-cooled Volkswagen engines, I know how to work with metal, I am very good at soldering and electronics, and I can make models in CAD with my engineering experience. So, I am going to try and document my progress for the community as best as I can, if I am successful. This is what I know so far:

- Original turbo thread: https://www.nitroforumz.com/threads/my-turbocharged-4-0l-2011-nitro.34177/

- The 4.0L engine has a forged crankshaft: https://www.nitroforumz.com/threads/4-0l-engine-internals.25808/#post-110087

- The 3.7 likes to blow up when you add boost because the piston rings are too close to the top of the piston (or something like that). So... DON'T BOOST THEM!!!

- The 4.0L was used in other vehicles as well as the nitro, so sacrificial exhaust manifolds may be able to be purchased for cheap by buying ones from these vehicles:

https://en.wikipedia.org/wiki/Chrysler_SOHC_V6_engine#4.0

- There is a TON of room on the passenger half of the engine bay (at least in my shock edition nitro), this may be because of the diesel model, as I'm pretty sure it had a turbo, and it was mounted on that side. (Pictures confirm this)

- The nitro uses 2.5 inch exhaust tubing, has a catalytic converter coming off of each head, a center mounted muffler, and a resonator right before the exhaust tip.

So far, I have collected a decent amount of information. I am assuming (don't assume, you will make an ass out of you and me, get it? :D ) that NitrousNItro (don't want to call anyone out or cause problems here), did not want to release their work, becasue they do not want to be responsible for someone else blowing up their engine. So, straight up as a disclaimer DO THIS AT YOUR OWN RISK!!! IF MY DESIGN WORKS OR DOESN'T WORK, AND YOU DECIDE TO USE IT, I AM NOT RESPONSIBLE FOR ANY DAMAGE CAUSED TO YOU, ANOTHER PERSON, ANYONE'S PROPERTY, AND ESPECIALLY YOUR ENGINE.

Now that I got that little disclaimer out of the way, I'm not afraid to get my hands dirty. I will post more findings and progress as time goes on.
 

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Huge plans! Go for it! I would try and turbo the 3.7. Why not? It would make great YouTube videos!! As for my plans, win the Lotto and build the first HellCat Nitro!!:) Deamon Nitro.:p Hellephant Nitro!!:D The Hellephant engine is a crate motor. All you do is drop it in! :eek: With a few changes.
 

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Discussion Starter #4
Don't know how many people are watching this post... but I have made a lot of progress with my research and design. Expect some updates, explanations, diagrams, as well as a pre-experiment write up to be posted within the coming weeks. I have a lot to share with all of you.
 

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Nice that you wanna sort out everything and share it with us. When you hurry up I can do it to my 4.0 while I rebuild the engine.;)
Dont forget a intercooler!
 

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Discussion Starter #9
Alright guys, haven't posted anything in a while. I just got my nitro back from a body shop. I was actually rear ended by a drunk driver who blew a .37 on the breathalyzer (you are supposed to be unconscious at .35 I believe). I might make a thread about it with some pics lol. Sorry for the lack of posts, it's hard to take measurements and eyeball things without having the car. I should be able to now finish my experimental write up within the week.
 

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Discussion Starter #11
This is part one of my experimental write up. This just covers the theory I have behind adding extra fuel into the system to match the pressure that will also be added into the system. This is subject to change in the Future. Take note that the stock ecu may not be tuned to have an AFR of 14.7, although I will measure it once I install an AFR gauge, and put any corrections into the final write up. The next part will cover the electronics and intake side of the turbo kit. If you have no idea about anything I just said, keep reading, I will explain any terms that you may find confusing.

As you all know, aftermarket performance parts for the dodge Nitro are a hard commodity to find. This includes higher flow rate injectors. I don’t even know the stock injector flow rate of the injectors in the 4.0 engine. I even checked the factory service manuals. I can calculate it online, but it is still on an estimate, and buying performance injectors for another car may not work because they not fit into the fuel rail and engine. Even if they did, we can’t tune the stock computer to take advantage of the bigger injectors. So, much like Nitrous Nitro, I have decided to go the route of adding an auxiliary injector into to the air intake. I still haven’t decided on whether or not I should put it before or after the throttle body. Nitrous Nitro mounted his before to throttle body, so why nit stick with what works.

I have derived a simple way to increase the amount of fuel going into the engine, in order to match the increased amount of air coming in from the turbo. Standard average atmospheric pressure is 14.7 psi. Coincidentally, the ideal stoichiometric air to fuel ratio is also 14.7 to 1 (14.7:1). this means that for every 14.7 pounds of air, there should be 1 pound of fuel mixed in. Let’s assume that the maximum duty cycle of the injectors at WOT (wide open throttle) is 80%, which is common for most manufacturers. Then let’s add an extra 5% onto that just to be safe, because this will affect the amount of fuel added per pound of boost. It is better to add extra fuel and run rich then it is to run lean with a turbo setup. Running rich does use more fuel and may not give the best power, but running rich keeps the engine cooler and can prevent detonation. Besides, you can always fine tune the fuel later, which is what most people do when they AFR (air fuel ratio) tune. I’m no mathematician, but I created a simple way to get an idea of what the duty cycle of the additional injector should be.

X = duty cycle required to maintain A/F ratio (AFR) at given boost pressure
Y = Standard atmospheric pressure
Z = Maximum internal stock injector duty cycle
A = Boost pressure
B = A + Y


X = ?
Y = 14.7psi
Z = 85%
A = 10psi (This is my goal, and the maximum amount of boost I want to have, set your boost controller accordingly)
B = 14.7psi + 10psi

Add the boost pressure to the atmospheric pressure to get the total pressure relative to a perfect vacuum (0 psi). This gives you variable B.

X/B = Z/Y

X/24.7psi = 85%/14.7psi

X = (24.7psi * 85%)/14.7psi

X = 2099.5/14.7psi

X = 142.823129252%

Now remember, this is an AUXILIARY injector. This means it is an EXTRA injector in the system; two are running at once. It is impossible to run something physical like this past 100% (more like 90% for fuel injectors), as that goes against the definition of a percent: a fractional value out of one hundred (100). So let’s subtract the 85% maximum safe duty cycle that we made up before from the new value we just got.

142.823129252% ≈ 142.9% (Rounded up instead of down just to be safe!)

142.9% - 85% = 57.9%

This means that our auxiliary injector should be running at roughly 57.9% at 10psi of boost. This calculation and method of fuel management is relatively primitive because it only uses boost pressure to calculate fuel needed. It is however, more advanced then simply throwing in a hobbs switch (pressure based switch, google them), setting it to a couple psi of boost, and just having it spray an extra injector at 100%. Some people have done this to there cars and gotten away with it. I would not recommend using a hobbs switch. My method should give you the chemically ideal amount of fuel to add to your engine per pound of boost. You need to do this for every pound of boost to get a crude fuel table. Luckily, I am a computer science student and wrote a python script to do this. It won’t round for you, but you can round up to the nearest tenth at the end.

This concludes part one. You are welcome to double check my work, however don’t be offended if I offer a counter argument to your suggestion, I just like to justify my method of thinking.
 

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nice theory.

To come to a know actual number for the fuel rate I would expect you start with the injector specs of our 4.0 Nitro's.
What I know, they are from bosch
Bosch Part Number:6238962391
specs .
https://www.boschautoparts.com/en/auto/fuel-injectors/port-fuel-injection?partId=62391
Bosch EV14ES fuel injector
Standard size injector
uscar port 4 hole nozzle
V spray pattern

Flow rates @ 43.5psi/3bar
22.8lb per hour
172.3G per min. (N-Heptane)
12Ohm resistance

for the enige family:
2.7 V6 EER
3.5 V6 EGF
4.0 V6 EGQ

Part#
Bosch 62391/0280158028
Chrysler 04591986AA
Volkswagen 7B0906031A

other part#
Airtex 4G1905
Bostech MP1066
GB Reman 812-12138
SMP FJ612.


In the past I did a similar kind of project and procharged a 5.7 SBC.
There was a boost regulated Fuel pressure regulator in the fuel rail to the injectors and it was recommended that for every PSI pressure the FP should also be increased with 1psi when you use the stock injectors.

Currently there is a stock FPR build in our fuel tanks, I think that the in tank FPR, device should be deleted and a boost regulated one installed under the hood.
Then we also need make a return line to our tank because our current fuelrail has no fuel return line.

Its also possible to upgrade injector size and CC - Lb/h can be calculated on the desired boost. There are companies who can alter the ECU ,remap and change the pulse witdh of the stock injector or better upgrade to a bigger fuel rate injector.
 

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Discussion Starter #13
Dutchty, I think the fuel system should be ok, as far as I can tell from my research, most people consider this a "low boost application", and apparently upgrading the fuel pump without tuning the stock ECU can lead to poor idling. I don't have any tuners in my immediate area, the nearest one is a few hours away. Although, you do have a point, and I do agree with you in the sense that it would be better If I upgrade it. I have looked into it, but it adds a little more complication, I believe the stock fuel pump should maintain it's ideal fuel pressure. However I do have a question for you. For the info you gave me, is that 43.5psi the Nitro's stock fuel rail pressure, or is that just what those injectors are tested at?
 

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Discussion Starter #14
Also do you believe this method of calculating the fuel would be close to what is required? I am still very open to suggestions.
 

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For the info you gave me, is that 43.5psi the Nitro's stock fuel rail pressure, or is that just what those injectors are tested at?
43.5psi pressure is whats commonly on the fuel rail.

So when you increase boost with 10psi', the fuelrail pressure must be increased to about 53.5 psi when you drive at 10psi boost with stock injectors.
our stock injectors flow 22.8lb/h with 10psi fuel increase its about 25.3lb/h - 266CC/min
There are several injector calulators who calculate the fuel rate etc.like Stan Weiss.
But when your on idle at 53.5psi its way to rich for the engine. Thats why most aftermarket turbo applications use a boost oriented fuel regulator.

But also the pump must be ok to deliver this kind of volume and fuel pressure.
Our pump should cope to >55PSi without a problem but the quality of the Dodge nitro fuel pumps are not that ok.
also I don't know the fuel volume rate of the Nitro fuel pumps.
In your case at 10psiboost=> about 55psi fuel pressure: the fuel pump volume should be at least:
270CC/min x 60= 16.200cc an hour x 6 injectors = 97.200CC = about 97Liters/hour at 55psi.
Thats is not that enormous but you can upgrade every pump nowadays.
Just replace the current intank pumpmotor with a walbro one who can deliver up to 5 bar/and at least 100l/h

But coming to your engine performance when you increase to 10psi, the engine will result in about 433hp:D pending on the horsepower the injectors should be calculated.

(Don't kow it will hold 10psi with our high compression ratio) then you need an airflow of at least 280CFM. from this you can calculate your turbo setup.
 

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Discussion Starter #19
lol Dutchty, you've made me reconsider my method. I've been pondering going the FPR route, however, deleting the factory one worries me, because I can't have it throw any codes or check engine lights, I still have to pass inspection in my state (we don't have emissions testing though!). Maybe I'll try both and do two write ups! Who knows? But, since the fuel rail pressure does seem pretty high, I think that the factory fuel pump should hold up to an extra injector. I'm going to attempt to measure the duty cycle of an injector at a few different RPMs, and that should help even my math a little better. The supplementary "ecu" I plan on installing should do all of that for you, but I want to make sure it checks out first. I have a way of doing the ecu part for cheap, because I know those things cost a fortune. No spoilers though, wait for part two!
 
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