Fast Efi

[Bullshark]

Jsup, let me try to chew on this for a minute, High impedance injectors don't turn on and off instantaneously. There response time is relatively slow because of their higher impedance (aka lower drive current) and their is a limited duty cycle that they can handle before they start to saturate. That may be the reason GM choose to limit duty cycle. Pulse width on the other hand is determined by the ECU fuel map at any given cell position. I think that is what TT is saying. With duty cycle left uninhibited, it would try to drive to wider pulse widths that would result in higher duty cycles at higher rpms. I drive my 36 lb. injectors to a little over 85% duty cycle at 6200 rpm. If I had a cam that would allow higher rpm, I would certainly go with larger low impedance injectors. Which I may very well do in the future. More VE to boot.
Sorry, I just can't see your point wrt the old GM crap. That old technology is just to limiting. Also, If I wanted to pay some so called tuner the type of prices they would charge to make the old stuff work I would go broke allot quicker and have nothing to show for it. I work on engine dynos and have seen the significant performance gains that the features we are talking about allow. Depending on the engine it is very significant. Sure if all I was talking about was some small grocery getter engine, I wouldn't even bother with the new stuff.

With regard to your comment that that engine simulator could recreate any engine condition, I would have to take issue. Not with all those knobs. You couldn't possibly twist all those fast enough to simulate real time transient operation. Steady state only.

I hope you weren't implying I was just buying my DFI stuff because its cool, if so, I will have to sic Turtle on you.:hunter:

I am not trying to pick a fight here, This stuff is fun for me. I just question some of your statements as not fair and accurate.

Bullshark

 

[Jsup]

Jsup, let me try to chew on this for a minute, High impedance injectors don't turn on and off instantaneously. There response time is relatively slow because of their higher impedance (aka lower drive current) and their is a limited duty cycle that they can handle before they start to saturate.

OK

That may be the reason GM choose to limit duty cycle. Pulse width on the other hand is determined by the ECU fuel map at any given cell position. I think that is what TT is saying. With duty cycle left uninhibited, it would try to drive to wider pulse widths that would result in higher duty cycles at higher rpms. I drive my 36 lb. injectors to a little over 85% duty cycle at 6200 rpm. If I had a cam that would allow higher rpm, I would certainly go with larger low impedance injectors. Which I may very well do in the future. More VE to boot.

ok, yes, I think that's what I'm saying. It's not the duty cycle left uninhibited, it's the pulse width. It becomes an issue of sizing injectors at that point.

Sorry, I just can't see your point wrt the old GM crap. That old technology is just to limiting. Also, If I wanted to pay some so called tuner the type of prices they would charge to make the old stuff work I would go broke allot quicker and have nothing to show for it. I work on engine dynos and have seen the significant performance gains that the features we are talking about allow. Depending on the engine it is very significant. Sure if all I was talking about was some small grocery getter engine, I wouldn't even bother with the new stuff.

My point is that I believe based on what I have seen to date, that the stock computer will support many applications adequately if you can find anyone to tune them anymore.

On the working on dynos part, and I'm not trying to be a prick, just wondering...

What was the comparison?

Did you go from a stock computer with a good, solid tune to a aftermarket system? If there is a way to determine that the original computer had the right tune and was set up right in the first place?

Were new injectors part of the swap?

Were the original injectors the right injectors?

How old were the original injectors?

Fuel pressure from stock to new? Was the old pressure correct? Was it tweaked?

Was the car tuned up at the same time? I have seen plugs, cap, rotor, wires totally change car's behavior.

This has nothing to do with technology, but methodology that comes to a conclusion. If the starting point is faulty, how can the conclusion support the claim? I mean there's a lot of variables to consider to say HP gains point directly to simply the aftermarket system, no?

No one is going to put in a new ECU without changing the injectors and tuning the car up, right? I mean without a proven, solid control car nothing is proven, right?

With regard to your comment that that engine simulator could recreate any engine condition, I would have to take issue. Not with all those knobs. You couldn't possibly twist all those fast enough to simulate real time transient operation. Steady state only.

Well, yeah, the simulator is good to re produce problems in tuning. My point about the simulator is that if you hook up the OBDI diagnostic tool,and read the pulse width, you can see where the limitation of the stock computer comes into play when the programming is changed.

I hope you weren't implying I was just buying my DFI stuff because its cool, if so, I will have to sic Turtle on you.:hunter:

NO NO NO not at all. Sorry, that was a knee jerk reaction from another forum. I apologize there.

I am not trying to pick a fight here, This stuff is fun for me. I just question some of your statements as not fair and accurate.

Bullshark

I'm not trying to pick a fight, sorry if it came off that way. I'm learning, and I have seen anecdotal evidence used as fact too many times on the interweb, your dyno example for example.

See my post on the previous page. I am learning about this and trying to figure out what I know, and what I don't know. I am not claiming to be right, I am reciting things that I know, and have seen, combined with opinions I was given as to why they are important.

 

[Bullshark]

One more thing, don't blink, This time next year the stuff Big_G and I are working with will be outdated. The new GM E67 ecu's will run circles around FAST and Accel, if only they would let us have access and configuration control. That will never happen, The security is getting so sophisticated that hackers will be very limited with what they can do.

 

[Jsup]

One more thing, don't blink, This time next year the stuff Big_G and I are working with will be outdated. The new GM E67 ecu's will run circles around FAST and Accel, if only they would let us have access and configuration control. That will never happen, The security is getting so sophisticated that hackers will be very limited with what they can do.

No shit, serious question....at what point could it be "all you need"

With DFI hitting the market, unless fuel delivery changes dramatically, essentially you're finding better and more effective ways to turn injectors on and off, how many different ways can there be to do that and when does it simply plateau and become just stupid?

 

[mrvette]

One more thing, don't blink, This time next year the stuff Big_G and I are working with will be outdated. The new GM E67 ecu's will run circles around FAST and Accel, if only they would let us have access and configuration control. That will never happen, The security is getting so sophisticated that hackers will be very limited with what they can do.

No shit, serious question....at what point could it be "all you need"

With DFI hitting the market, unless fuel delivery changes dramatically, essentially you're finding better and more effective ways to turn injectors on and off, how many different ways can there be to do that and when does it simply plateau and become just stupid?

That has always been my position on this....the GM stuff goes to some 500? hp, and for my more reasonable 355 roller engine on the street maybe making 400 hp on a dreamy day....i'ts good enough....I really can't see that SFI would be bringing more than the batch I have...certainly not worth the wiring hassles....

:crutches:

 

[big_G]

One more thing, don't blink, This time next year the stuff Big_G and I are working with will be outdated. The new GM E67 ecu's will run circles around FAST and Accel, if only they would let us have access and configuration control. That will never happen, The security is getting so sophisticated that hackers will be very limited with what they can do.

No shit, serious question....at what point could it be "all you need"

With DFI hitting the market, unless fuel delivery changes dramatically, essentially you're finding better and more effective ways to turn injectors on and off, how many different ways can there be to do that and when does it simply plateau and become just stupid?

The coming changes will be faster and more accurate control and to make the units more "user-friendly". Look how far the personal computer has come since 1984. Everyone wins. The capabilities and quality improves and the price comes down. Win-win all around. When I need a new tech. product, I always look at how long until I out-grow it. Then do the cost-analysis. The P.C. I am typing on here is over 6 years old, but works fine for the intended use. OTOH, I needed a new Fuel Injection system, and bought the newest product that will fill the need and future growth. Let us be thankful that we have many products to choose from to suit our needs..

 

[Bullshark]

No shit, serious question....at what point could it be "all you need"

With DFI hitting the market, unless fuel delivery changes dramatically, essentially you're finding better and more effective ways to turn injectors on and off, how many different ways can there be to do that and when does it simply plateau and become just stupid?

Jsup, your "no shit" and "well yeh" response to my points make me think you really know very little about the details of this technology. You seem to think that your tuners advise is truth without question, but when we present you with some alternative points it is dismissed as fluff. My background is EE and I too have to see validated data to substantiate any claim. Like the data you have not provided either. It would be a waist of time for either of us to post data that we would claim supports our position, because without validated detailed analysis and comparison it would not support (in my case) experience or (in your case) tuners input, and would be dismissed as :bullshit:
The bottom line is that the newer aftermarket technology offers us the flexibility to accommodate the VetteMods that we all enjoy in our hobby. The old technology does not. That flexibility offers the enhanced performance that I am referring to. If I had to limit the capability of new technology to that of the old shit so we could compare apples to apples it would be pointless.
We just finished setting up two of these for a race boat. We used the Accel Gen VII. Try doing that with your GM junkyard ECU.

:banghead:


I wish you luck with your education. My advise is listen and keep an open mind.

I'm done.

Big_G, go for it, keep us informed as you progress

Bullshark

Probably get banned for my frankness but the post racquetball beers have pumped my beer muscle.

 

[Sunshark]

Bullshark, did you con me into buying some high dollar peice of fluff? :huh:

 

[Bullshark]

Bullshark, did you con me into buying some high dollar peice of fluff? :huh:

Is that you GYopp? Welcome aboard. Some spirited dialog over here!:lol: I toned it down a little after the beer wore off. :ill:

 

[Sunshark]

yep, that would be me. BTW, the cam specs you were looking for are:

lift
.556 .556
advertised duration
285 290
[email protected]
249 252
lobe sep
110

I am running this with 1.6 rockers which would give you a lift equivelent of
.593
hope this helps with your project

Gene

 

[Jsup]

No shit, serious question....at what point could it be "all you need"

With DFI hitting the market, unless fuel delivery changes dramatically, essentially you're finding better and more effective ways to turn injectors on and off, how many different ways can there be to do that and when does it simply plateau and become just stupid?

Jsup, your "no shit" and "well yeh" response to my points make me think you really know very little about the details of this technology. You seem to think that your tuners advise is truth without question, but when we present you with some alternative points it is dismissed as fluff. My background is EE and I too have to see validated data to substantiate any claim. Like the data you have not provided either. It would be a waist of time for either of us to post data that we would claim supports our position, because without validated detailed analysis and comparison it would not support (in my case) experience or (in your case) tuners input, and would be dismissed as :bullshit:
The bottom line is that the newer aftermarket technology offers us the flexibility to accommodate the VetteMods that we all enjoy in our hobby. The old technology does not. That flexibility offers the enhanced performance that I am referring to. If I had to limit the capability of new technology to that of the old shit so we could compare apples to apples it would be pointless.
We just finished setting up two of these for a race boat. We used the Accel Gen VII. Try doing that with your GM junkyard ECU.

:banghead:


I wish you luck with your education. My advise is listen and keep an open mind.

I'm done.

Big_G, go for it, keep us informed as you progress

Bullshark

Probably get banned for my frankness but the post racquetball beers have pumped my beer muscle.

Actually, no you have me all wrong. I freely admit, I do not know much about this at all an my experience is limited.

I am not dismissing what you say as fluff. I am questioning what I have been told. BIG DIFFERENCE. I have learned a whole lot already.

LIke I said earlier the other motors I did were C3 L48s, this is my first EFI motor.

So, I do appreciate your input and insight and so you know it's not on deaf ears.....I am absorbing it and my opinion is morphing as this unfolds..

Hey, if you're ever in Jersey I'll beat you up on the raquetball court, my treat.

 

[Bullshark]

Hey, if you're ever in Jersey I'll beat you up on the raquetball court, my treat.

Your on! Looser buys the :drink: On occasion, my job gets me up to the Picatinny Arsenal. Better polish up your game

Bullshark

 

[big_G]

Looks like the dust has finally settled...lol, but I better not see any group hugs. Remember my motto: "I don't believe anything I read, and only half of what I see". I am still waiting on the EFI intake, and then the fun begins. Yea!

 

[Jsup]

Hey, if you're ever in Jersey I'll beat you up on the raquetball court, my treat.

Your on! Looser buys the :drink: On occasion, my job gets me up to the Picatinny Arsenal. Better polish up your game

Bullshark

COOL, let me know.

I'm out of service for the next month, broken finger. But offer stands!

 

[turtlevette]

Jsup, let me try to chew on this for a minute, High impedance injectors don't turn on and off instantaneously. There response time is relatively slow because of their higher impedance (aka lower drive current) and their is a limited duty cycle that they can handle before they start to saturate. That may be the reason GM choose to limit duty cycle. Pulse width on the other hand is determined by the ECU fuel map at any given cell position. I think that is what TT is saying. With duty cycle left uninhibited, it would try to drive to wider pulse widths that would result in higher duty cycles at higher rpms. I drive my 36 lb. injectors to a little over 85% duty cycle at 6200 rpm. If I had a cam that would allow higher rpm, I would certainly go with larger low impedance injectors. Which I may very well do in the future. More VE to boot.
Sorry, I just can't see your point wrt the old GM crap. That old technology is just to limiting. Also, If I wanted to pay some so called tuner the type of prices they would charge to make the old stuff work I would go broke allot quicker and have nothing to show for it. I work on engine dynos and have seen the significant performance gains that the features we are talking about allow. Depending on the engine it is very significant. Sure if all I was talking about was some small grocery getter engine, I wouldn't even bother with the new stuff.

With regard to your comment that that engine simulator could recreate any engine condition, I would have to take issue. Not with all those knobs. You couldn't possibly twist all those fast enough to simulate real time transient operation. Steady state only.

I hope you weren't implying I was just buying my DFI stuff because its cool, if so, I will have to sic Turtle on you.:hunter:

I don't know anything about this subject.

But i'm curious about the electrical profile of an injector. Is there a current inrush at turn-on that tapers off similar to any inductive device?

I'm not understanding the duty cycle thing. Do wider pulses necessarily translate into higher loading? Are you saying it can't go open and just stay open under max fuel requirements?

 

[big_G]

I think the move to low-impedance injectors (like I'm using) allows faster open/close times. I think closing (under pressure) is the tough part, especially at elevated fuel pressures.

 

[Bullshark]

Turtle, I plagiarized this of another internet site to save time. It explains the diff.

Low- 1.7 to 3.0 ohms (Peak and Hold Driver/Injectors)
These type of injectors and drivers may also be called current sensing or current limiting. They are more expensive and complex than saturated circuit drivers, and are not generally used with domestic production ECUs. They are primarily used in aftermarket high performance systems. Most high flow injectors are low resistance (2-5 ohms) and use a peak and hold driver to activate them. The Peak current is the amount required to quickly jolt the injector open, and then the lower Hold current rating is used to keep it open for as long as the ECU commands. These require the extra kick from the higher current to keep the opening and closing time of the injector stable at the higher fuel flow rate. With this type of driver, 12 volts is still delivered to the injector, but due to the its low resistance, the current in the driver circuit is high. How high? Using Ohms's Law we can calculate the current rating (12v/2 ohms = 6 amps). This is substantial current flow and a Saturated Injector cannot handle it. The drivers also come in two values; 4 amp peak/1 amp hold, and 2 amp peak/0.5 amp hold.. Even though 6 amps may be available to operate the injector, the maximum it is allowed to reach is 2 or 4 amps, depending on the driver's current limit.

High- 10 to 16 ohms (Saturated Circuit Drivers/Injectors)
Most domestic OE production EFI systems use an ECU with 12 volt Saturated Circuit drivers. These are very inexpensive, simple, and reliable. This type of driver works by supplying 12 volts to the injectors and the ECU turns it on and off to establish a fuel injector pulse. In general, if an injector has a high resistance specification (12-16 ohms) the ECU uses a 12 volt saturated circuit driver to control it. This means that the current flow in the driver and injector circuit stays low keeping the components nice and cool for long life. Conversely, a downfall of a Saturated Circuit driver is that it has a slower response time (and closing time) than a peak and hold type. This slower time can somewhat decrease the usable operating range of the injector energized by this driver. An injector operating on a saturated circuit driver typically has a reaction time of 2 milliseconds while a peak and hold driver typically responds in 1.5 ms.

http://www.robietherobot.com/Storm/fuelinjectorguide.htm

Bullshark

 

[69427]

I don't know anything about this subject.

But i'm curious about the electrical profile of an injector. Is there a current inrush at turn-on that tapers off similar to any inductive device? A capacitor will see an inrush of current. An inductor will experience a ramp-up of current, dependent upon its L and R value. There is a plateau peak at the end of the ramp, determined by the system voltage and system resistance.

I'm not understanding the duty cycle thing. Do wider pulses necessarily translate into higher loading? Depends on what you mean by loading. Wider pulses mean more average power dissipation in the injectors and the ECM driver transistors. Wattage means heat. Are you saying it can't go open and just stay open under max fuel requirements?

In theory, yes, you can hold the injector open forever. However, there are usually downsides. You have to hope that the fuel flow can remove the heat generated by the winding current (Twelve watts at one amp current), and the possibility of the engine going lean if the airflow increases a bit during the period that the fuel is maxed out. It's just nice having a safety margin (dutycycle-wise) to be able to increase the pulsewidth to compensate for any increased airflow.

 

[mrvette]

I think the move to low-impedance injectors (like I'm using) allows faster open/close times. I think closing (under pressure) is the tough part, especially at elevated fuel pressures.

Won't affect the close time hardly at all, unless the armature/piston/iron can be made smaller/lighter also.....intertia.....but then why not make ALL of them smaller???

I suspect my first thought stands.......

:amazed:

 

[mrvette]

I don't know anything about this subject.

But i'm curious about the electrical profile of an injector. Is there a current inrush at turn-on that tapers off similar to any inductive device? A capacitor will see an inrush of current. An inductor will experience a ramp-up of current, dependent upon its L and R value. There is a plateau peak at the end of the ramp, determined by the system voltage and system resistance.

I'm not understanding the duty cycle thing. Do wider pulses necessarily translate into higher loading? Depends on what you mean by loading. Wider pulses mean more average power dissipation in the injectors and the ECM driver transistors. Wattage means heat. Are you saying it can't go open and just stay open under max fuel requirements?

In theory, yes, you can hold the injector open forever. However, there are usually downsides. You have to hope that the fuel flow can remove the heat generated by the winding current (Twelve watts at one amp current), and the possibility of the engine going lean if the airflow increases a bit during the period that the fuel is maxed out. It's just nice having a safety margin (dutycycle-wise) to be able to increase the pulsewidth to compensate for any increased airflow. [/QUOTE]

Turtle, IF you took a resistor in series with the injector/coil, any coil, and apply voltage....looking across that resistor with a oscilloscope you will see the current go up like a ramp on a sawtooth, when the currents rise to the top of the heat is when it starts leveling off in a decreasing ramp....just like a blade on a straight saw....damn nearly the same shape....

there is a point that current will not go higher....
and therefore the VOLTAGE appearing across said series resistor will not increase all you see is a build up ramp then a straight line at some voltage level....

so when the voltage is turned off, you get a inverse inductive kick, which is what makes the spark in your ignition, that is a funcion of the power into the coil/injector...in the case of a injector...it's wasted energy....

in the case of our spark coils....it's what we need to fire the plugs...obviously....