Injector/Fuel system questions

[DigitalFusion]

I think I am missing something...

The fuel injectors for the Phazer/Nytro (and viper I guess) are the same 324cc size. According to this calculator, two of these injectors at 42.7 psi are good for 98hp at 80% duty cycle on a non-FI motor. On an turbocharged motor, they drop to 82hp. Even at 100% duty cycle, they only go to 102hp.

The reason I am posting is because I have the Boondockers kit on my Phazer and was trying to figure out my boost limitations if I was to build the bottom end with rods and pistons. It doesnt appear to have any extra injectors like the MCX kit(s) that provide two more for the 140hp kit, just the Boondocker Control Box. The FPR looks completely stock (exactly the same as the stock on my 2008, right down to the markings on it).

How? Did they really sell this kit and have the control box push the injectors at 100+% duty cycle? When they released their peak dyno numbers it was 165 at 17 psi, which would be pushing the injectors to 160%???

What am I missing here?

 

[Macheater]

Well from reading your other posts it sounds like you have very little info on the boondocker kit. I'm assuming you have already contacted them? Clearly the stock injectors are not going to support double the airflow. Going with injectors large enough to supply enough fuel to support that kinda hp is gonna be problematic at lower throttle positions.

I think you need to find a way to verify the flow rate of the injectors that are supposed to be used for the turbo. If they are in fact the same as stock, then you are clearly going to have to limit the boost. It sounds like you already know that pushing the duty cycle beyond 80% is not recommended. You might be able to step up to the next size injector to push to hp level higher without suffering to much ill effect at lower throttle openings.

Without knowing much about the mcx kit, it sounds as if they took all this into account with their kit and added extra injectors where as boondocker took a different approach.

Good luck with it. I've been following your thread in the phazer section.

 

[DigitalFusion]

Well from reading your other posts it sounds like you have very little info on the boondocker kit. I'm assuming you have already contacted them? Clearly the stock injectors are not going to support double the airflow. Going with injectors large enough to supply enough fuel to support that kinda hp is gonna be problematic at lower throttle positions.

I think you need to find a way to verify the flow rate of the injectors that are supposed to be used for the turbo. If they are in fact the same as stock, then you are clearly going to have to limit the boost. It sounds like you already know that pushing the duty cycle beyond 80% is not recommended. You might be able to step up to the next size injector to push to hp level higher without suffering to much ill effect at lower throttle openings.

Without knowing much about the mcx kit, it sounds as if they took all this into account with their kit and added extra injectors where as boondocker took a different approach.

Good luck with it. I've been following your thread in the phazer section.

Thats an accurate assessment. There is zero documentation out there on this kit, even after talking to Boondocker. They said they have nothing on it except for the control box instructions, which appears to be nothing more than the instructions for the Apex control box copy-pasted with the names replaced, right down to the Octane recommendations showing compression ratios and limits for the stock fuel system being that for the Apex.

The injectors look identical to my stock 08's, There is one for sale post from ages ago selling a used boondockers phazer kit advertised as complete with everything and it didn't have injectors listed. I have private messaged several dozen people from old posts at several different forums just hoping to talk to someone who actually installed one of these. I have had zero results. Except one owner here on TY that has one that the PO installed.

There has to be an affordable option here. I can't just slap a set of 550's on it as it seems like way too big of a jump and I'd have a hell of a time getting it to idle and get it tuned. It seems like I could possibly get away with some Apex 380's, but they would have to be at 63psi at a 90% duty cycle, so I would have to have a 2:1 regulator on there with lots of dyno time in order to tune?

 

[Macheater]

At this point I think your best bet is to keep the boost reasonable to where you can get it to run well. If you can do that and keep the engine in 1 piece, then you have a platform from which to work and a point of reference from which to build. As it is, your flying blind so to speak. One other statement I would make about duty cycle is that I would not have a problem pushing the injectors to 90% or more if need be. My reasoning is that as long as it is not a racing use sled, it is only at full throttle/high rpm/max duty cycle for relatively short periods. With such a 1-off project I would proceed very slowly and carefully. Race gas to ward off any deto from leaness, eye on the afr gauge, and dyno time if possible.

I also can't say that I know much about the boondocker controller but, I would be very tempted to get a pc3 or 5 with the ignition box where you can have timing adjustability.

 

[DigitalFusion]

Yeah, I have a PCV PTI on order, and Straightline Performance chassis dyno is basically down the road from me. I just need a place to start. I'd like to avoid going to the dyno and forking out $ only to find out I am nowhere near where I need to be.

I hear what you are saying about Duty Cycle. I only know enough to be dangerous, and that knowledge comes from 15+ years ago when built my own turbo and engine management setup on the automotive side of things. I was under the impression that the 80% rule was just as much about safety (from getting too lean) as it was about injector lifespan. Plus, I assumed that since will be a dedicated "out-west" sled, I can see it being pinned to the bars for extended periods, during climbs for example?

If the stock fuel pump can support the MCX kit with its 2 extra injectors running 140hp, I should be able to run some Apex 380's without having to upgrade the pump, shouldnt I?

 

[Macheater]

My remarks about pushing the duty cycle of the current (stock???) injectors was based on initial setup and testing. Trying not to throw too many unknowns into the mix. If this is gonna be a mountain machine that strategy isn't gonna work long term. It sounds as if you have the knowledge and resources to make this work. Just proceed slowly and deliberately and it will come together. I know dyno time is expensive (I just recently spent $500 on tuning my Apex) but well worth it.
Good Luck! And keep us in the loop.

 

[DigitalFusion]

Ahh gotcha. That is good advise. I wouldnt go so far as to say I have the knowledge to make this work! Anything I learned 15+ years ago has mostly long since been forgotten!

 

[DigitalFusion]

For documentation / potential future searchers, It appears the PCV will allow values of down to -100%, so 550's shouldn't be an issue. 550's are a 58.91% increase over stock, so as a baseline a person could start there.

 

[Jakelfin]

How do you fit apex injector in phazer or nytro? Many are speaking of this change but as we know, nytro has different kind injectors with long nose/neck. Are those somehow interchangeable on is there some machining needed?

 

[Jakelfin]

I'm still trying to find out how they fit other type injectors in nytro/phazer fuel rails. What kind of injectors should fit?