concealer404

iTrader: (3)

Roofles!

Braineack

iTrader: (62)

you can see it on a 93-94 too. It's fun.

I remember samnavy trying it on an FMU setup got frustrated from the lack of control and went to 460s and a MS1 I built for him.

it is cute.

1. You were arguing something about BEGi being the only vendor that has boost control issues. I remember reading more than a few posts about the newer FMII kit when it was first released that were shipped with boost control issues. There was relevance.
2. That's because their setup can't achieve the same power as this one at the same boost level. :P

Like Corky said, they aren't going to be shipping them at this boost level. I'm guessing they are going to ship them at 6.5psi which is still producing 190rwhp like the website claims. I mention the FM setup because it's very similar and is still as potentially dangerous out-of-the-box if the user also runs 10psi and runs out of stock injector.

I haven't talked to either, personally, since roughly 2008. I don't need pointers, I learned everything from google and copyed and pasted it all until you guys made me your leader.

No, but they have made the power, repeatedly, on different dynos. Doesn't mean everyone should swap in stock injectors and crank up the boost. But it's obvious that it can be done--they have shown us that it is possible. Doesn't mean you should do it by any stretch.

This reminds me of getting into an argument with the MS-extra developers over the ideal gas law code. Their argument was that it's the law and you can't break the law; expect that we ALL here have had issues with the MS on hot starts due to that code. they eventually changed the code cause I wouldn't stop bitching about it, along with everyone else that had issues. So yes, while the law is the law, in real life situations the law didn't seem to hold true.

I really would like to delete the Turbo Miata FAQ because more than half of it is BS.


Look.

A lot of this shitting is counterproductive. They developed a turbo system that's making output unlike any other vendor has been able to bring to the market. That's a good thing for the community.

I realize you, me, and others may not like the way BEGi goes about some of their business and some of you have legitimate gripes, and that's fine, but some of this stuff we're arguing about is really pointless.

18psi

iTrader: (76)

Ok fair enough.

cyotani

iTrader: (8)

Sig worthy material here.


EDIT: 18PSI beat me to it.

Savington

iTrader: (31)

No. Duty cycle is a mathematical calculation based on engine speed. At 7000rpm, it takes 17.142ms for an engine (any four-stroke engine) to travel through a full engine cycle. Thus, if you open the injector for 17.142ms, that's 100% duty cycle. If you increase the pulsewidth beyond 17.142ms and expect more fuel to come out of the injectors, you should not be accepting money for tuning services.

If you add pulsewidth to the injector, AND the final requested pulsewidth is under the max allowable pulsewidth for your engine speed, AND you don't see a decrease in AFRs, then you're running out of fuel pressure, not injector size.

Required fuel flow decreases and increases with horsepower/airflow, not torque.

18psi

iTrader: (76)

I wanted to touch on that too - I have never, ever, seen IDC stay flat or decrease with RPM. Ever. Even on cars that spike to 20psi and then taper to 10 at redline, the IDC at redline is always the highest. Because it's not about pressure in relation to speed as much as it is airflow in relation to speed. And unless you start closing the throttle towards redline (some newer cars actually do this), I just don't understand what Corky is getting at.

Time for Maximum Boost 2?

Braineack

iTrader: (62)

This is what I was trying to say. Keep in mind I posted that at 7am and was looking to argue for no reason.

what I should have said is that you cant increase the PW any more. You can only expect more fuel to come out at that point if you increase the fuel pressure.

What I was trying to convey is that even if you hit 100%DC, or 17ms at redline, if still haven't necessarily run out of injector.

nitrodann

18, im sure you know this but to add to your point, injector duty should decrease with HP, so if your car peaks at 6 but revs to 7500 it should decrease past 6 to hold a stable AFR.

Duty cycle is percentage of total fuel flow available per time period. 100% is injector flow rate in CC each minute.

Duty cycle follows HP while pulsewidth follows torque.

Dann

cardriverx

iTrader: (12)

I assume this is a just trying to incite an argument right? With the noise of a dyno, by the point you can hear det/pre-ignition it is already doing damage.

concealer404

iTrader: (3)

I'm more amused that watching the tailpipe is an acceptable way to detect detonation.

Chiburbian

iTrader: (1)

This may be a dumb idea but...

What if the BEGI method involved changing the moment that the injector fires, moving it forward in time? By this I mean that normally the injector fires a moment before the intake valve opens, correct? At higher engine speeds you could theoretically rely on air speeds and density to be able to pull off extra fuel from the walls of the intake if you start firing the injector earlier. Am I completely off base with this?

When running at 100% duty the injector is still turning OFF once the intake valve closes correct? If that is the case, even at 100% duty cycle there are still times during the complete revolution that the injector is not firing.

Fuel puddling, fuel on walls etc...

Maybe this is what we are missing, or am I completely misunderstanding something important?

Savington

iTrader: (31)

No. Duty cycle increases with both RPM and pulsewidth. Pulsewidth increases and decreases to match airflow requirements which closely correlate to horsepower. Torque has nothing to do with it.

Savington

iTrader: (31)

You're kind of off base, yeah. The "fuel walls" theory might be valid for a few engine cycles, but once all the fuel is pulled off the walls of the port, the engine needs to rely on the fuel delivered by the fuel injector.

The injection timing theory has a little merit to it, but not enough to get around the hard limits of injector flow and engine speed. In theory, injection timing should be set up so that the injector begins to open as soon as the intake valve closes. The idea here is to get the most homogeneous mixture possible. In reality, you tune this by adjusting injection timing without altering injector pulsewidth until the mixture is as rich as you can make it (i.e. most fuel being delivered to the cylinder and burned) and then reduce pulsewidth until your desired AFR is obtained again. At high IDCs, however, injection timing has a minimal impact on the operation of the engine, and at ~100%DC it has absolutely no impact on the operation of the engine.

Joe Perez

iTrader: (8)

It doesn't.



No.


Yes, you are completely off base. You're not even in the same stadium.






Translation:

At high loads, the injector is open for nearly the entire engine cycle, whether the intake valve is open or not. Injector timing is completely irrelevant in this context. This is inherent in the fundamental concept of high injector duty cycles.

Savington

iTrader: (31)

I just assume that with all of your posts

yes.

If you hit 100.0%DC, you have by definition run out of fuel injector. You can add fuel pressure (or reduce manifold pressure) and make the injector flow more, but then you wouldn't be at 100%IDC anymore.

Leafy

iTrader: (1)

100%IDC means the injector never closes. At 7000 rpms its takes 8.5 milliseconds to complete a revolution so an entire engine cycle takes 17.1 milliseconds. 100% IDC means that the injector is open that entire 17.1 millisecond period. Yes, this means that the fuel is just chillin in the intake runner for a large amount of time, its forming a vapor film on the walls that will evaporate when the valve opens.

Braineack

iTrader: (62)

it's not over until the block vents.

Chiburbian

iTrader: (1)

I see where my math was off. I was thinking that the 17ms was the length of the combustion sequence.

7500/1minute * 1minute/60seconds = rpm/60 = 125 revolutions per second

This means that means that each revolution revolution of the crank takes 8ms and a full cycle takes 17ms. For some reason I thought that the 17ms was how long one revolution took.

nitrodann

What.. torque is VE. This correlates with injector pulsewidth.

More air density = more fuel density = more pulsewidth per cycle = more torque

Power = work over time = fuel over time = flowrate X DC

No?

nitrodann

The message I replied to was deleted so I deleted mine for clarity.