always faster

Im finishing my fuel line,fuel rail and redoing some of my main harness wiring.Right now im satisfied with my setup(pretty clean) but there is some wire remaining that i didnt connect yet.One of those wire are for taking the injector duty cycle for the meth kit.

Im using Snow stage 3 digital boost controller.It use boost reference just like all kit and it also can use the injector duty cycle .

Simple questions:

-Do i really need the injector duty cycle or boost reference is just ok for meth???
-Is there any advantage to run injector duty cycle compare to boost reference again for meth??

Thank you
Eric

MVP'S ZO6

Knowing the injector duty cycle has its purpose. In short, I'd use the boost reference if I were you.

robert miller

always faster

Well thats cool and easy since my boost reference is already hooked up to my vaccum block i ll use this mode.

I already got the injectors duty cycle in my hptuner log in any driving condition so for my personnal knowledge can you elaborate on the purpose of knowing the injectors duty cycle on my boost controller.

stevieturbo

Injector duty cycle is directly related to engine load. This IS a better way to regulate meth flow compared to the very crude way of using boost only, which is in no way linked to engine load.

realcanuk

I personally get steadier A/F running the meth off the MAF, rather than the MAP. Never thought about using IDC.

stevieturbo

Likewise MAF will have a direct link to engine load so is much better than boost alone.

SteveDoten@ARH

Interesting subject, How does the meth pump get a signal from the IDC?

stevieturbo

Just tag onto an injector wire

LTstewy8

IDC and MAF are excellent ways to control meth, but don't forget that if it were a turbo car then boost would also be a good measure of engine load. S/C not so much...

I just had an idea... Could someone confirm that if meth were controlled by IDC that a fuel cut of any sort by the PCM would stop the meth pump and prevent a lean condition? That would be a plus, even if the meth takes longer than the milliseconds that the injector takes to cut flow.

stevieturbo

Boost alone is no measure of load whatsoever regardless of turbo, supercharger etc etc

But it is handy and convenient and as people will be tuning around what is injected, it isnt a big deal.

Using MAF or IDC is generally better all round as one way or another these are directly linked to actual load.

As for the question, not really sure what you're asking ? Of course if there is a fuel cut and meth flow is governed by a signal to the fuel injector, then yes if the injector receives no signal, the meth will receive no signal.

LTstewy8

I think you'll find that boost is related to load on a turbo engine

Yeah, sorry, it wasn't really a question about how it works. I just wanted to know people's opinions on that rationale.

stevieturbo

You may "think" that, but I know it isnt.

Boost is just a pressure measurement. On it's own it means very little.

Now if you combine it with rpm, then it can become the basis of a load calculation.

MVP'S ZO6

I see your point here.

LTstewy8

I can see you're not going to give up. You do have an excellent point about RPM and boost (which is yet another reason to go with IDC), but it's not all clicking for you. Forgive me for making a true statement and not clarifying all of the variables.

I could give you the academic explanantion, but I've got the perfect example right behind me in case you think engineering literature is witchcraft. I've got two 2250 kW Cat 3516C's running on separate buses behind me (diesel-electric ship) Each is running at 1800 RPM all day every day, but each has different loads on it. The port generator has around 200 kW, of load, 22 GPH of fuel flow, and roughly 2 psi boost. The the starboard generator has about 375 kW of load, 35 GPH of fuel, and roughly 5 psi boost. The correlation is easy to make. (It's a calm night out here in the Gulf of Mexico and we're not maneuvering, hence the low loads)

Now, on straight diesel ships (no electric propulsion, just a diesel, shaft, and propeller), the correlation gets a little harder to find. But picture rough seas where the propeller is popping out of the water. These diesels that are the size of your house don't change RPM very quickly, but it does turn more RPMs. So every time the prop comes out of the water, you have a huge loss of load. RPMs go up, slowly, but the real load shedding happens at the turbo, where you guessed it, boost dropped. Then the opposite happens. It goes back in the water, the RPM drops slowly, but boost does it's part to take on that increased load. Does this make sense? RPM and boost are both moving (in opposite directions) and doing their parts to make the ship go through those rough seas, but boost is doing more to adjust to the changing loads than RPM.

I stand by my statement that boost is a measure of load on a turbo engine. I'd still choose IDC for a meth controller, though.

stevieturbo

You have just explained why I am 100% correct.

Your car engine does not run at a fixed rpm. That is your other key load calculating parameter. On your boat engine you know this won't change, hence boost as a secondary works fine.

LTstewy8

Hence the second example, where RPM as a variable was introduced. Obviously you chose to ignore that part. Leave it to me to take a simple thread and end up arguing over a simple concept with a pretengineer. I suppose that I may lay claim to being 100% correct, also, since nothing I said was refuted.

stevieturbo

Well if you honestly believe there is the same load and hence demand for fuel or meth at 3000rpm with 20psi as 7000rpm at 20psi....clearly we will never agree who is right.

LTstewy8

Not once did I say anything to that degree. You're arguing nothing. I think what you've done is create a straw man fallacy.

stevieturbo

You're trying to make comparisons to almost fixed rpm static diesel engines where boost may vary slightly.

It's like comparing apples to elephants.

There is no argument. Boost alone is not a good measure of load at all simply because there are other variables that must be taken into account.

It only works in the scenario you suggest because rpm is pretty much fixed, so you already know that load parameter.
With a car engine rpm is another huge variable