Max dry shot on stock fuel system with 28lb injectors?
12-14-2005, 09:28 PM
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I went 200 dry on the stockers with stock fuel pump.... no problems.
Your's may blow up. I did a bunch of supporting mods to the cooling system and tune to support it.
Your's may blow up. I did a bunch of supporting mods to the cooling system and tune to support it.
12-15-2005, 10:31 AM
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Originally Posted by Nitro Dave's Nitrous Outlet
Ok I have a question. What was the duty cycle on the injectors at his size. We have had cars come in with cam only maxing the duty cyle one the injectors
Dave
Dave
I've seen over 140%... they seemed just fine... fuel pressure remained good and none of the injectors died. They are still running in the car as we speak.
12-16-2005, 10:46 AM
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Originally Posted by Homeslice (tm)
I went 200 dry on the stockers with stock fuel pump.... no problems.
Your's may blow up. I did a bunch of supporting mods to the cooling system and tune to support it.
Your's may blow up. I did a bunch of supporting mods to the cooling system and tune to support it.
12-16-2005, 11:39 AM
#7
Originally Posted by Homeslice (tm)
I've seen over 140%... they seemed just fine... fuel pressure remained good and none of the injectors died. They are still running in the car as we speak.
Dave
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12-16-2005, 12:05 PM
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Injector locking must be a rare thing, but when it happens I hear it's ugly
http://photo.worldnews.com/PhotoArch...bf6-medium.jpg
http://photo.worldnews.com/PhotoArch...bf6-medium.jpg
12-16-2005, 01:46 PM
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Originally Posted by Nitro Dave's Nitrous Outlet
Wow are you serious.. We always tell anyone above 85 percent they need to start looking into some injectors. Over that you are taking a chance on them locking up. Ideal is around the 70 percent range.
Dave
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12-16-2005, 01:51 PM
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Originally Posted by wilddawg
What supporting mods did you do. share some and save this mans motor
No thermostat, water only, CTS / IAT tricker box, VERY VERY COLD PLUGS, a good handle on timing, no hot lapping, lots of cool down between runs. My engine ran very very cold... some days in the morning I'd have to pull over to let it warm up. Most fo the time it ran in the 150-160 range.
I sprayed the nitrous directly on the MAF wires from just inches away.
12-16-2005, 02:04 PM
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We have discussed this before If I remember correctly. Homeslice was sprying very close to the maf maxing everything out for about as much fuel flow as the stock stuff would spit out. Then he was pilling up on the nitrous to get the AF in line.
If all the info was accurate it seems like a basic way to test what the stock stuff can handle. And it appears...like many things with GM..its alot more than you would ever think.
Not that I would recomend to the avg user to try this. But the previous discussions where enlightening.
If your a novice user I wouldnt recomend it.
If all the info was accurate it seems like a basic way to test what the stock stuff can handle. And it appears...like many things with GM..its alot more than you would ever think.
Not that I would recomend to the avg user to try this. But the previous discussions where enlightening.
If your a novice user I wouldnt recomend it.
12-19-2005, 11:50 PM
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Originally Posted by Homeslice (tm)
I've seen over 140%... they seemed just fine... fuel pressure remained good and none of the injectors died. They are still running in the car as we speak.
140%? Isn't 100% on static?
12-19-2005, 11:57 PM
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Originally Posted by Geo.
OK dumb noobie question here:
140%? Isn't 100% on static?
140%? Isn't 100% on static?
Makes you wonder how they determine the duty cycle in the PCM code doesn't it?
12-20-2005, 12:02 AM
#14
Static just means they are no longer pulsing, but rather holding wide open. It doesn't indicate total flow capacity though, and thus reporting that they are flowing past static. It's hard on injectors to be at static for very long, however, a 1/4 run the jury is out...
Robert
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12-20-2005, 01:55 AM
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Originally Posted by Homeslice (tm)
Makes you wonder how they determine the duty cycle in the PCM code doesn't it?
Originally Posted by Robert56
Static just means they are no longer pulsing, but rather holding wide open. It doesn't indicate total flow capacity though, and thus reporting that they are flowing past static. It's hard on injectors to be at static for very long, however, a 1/4 run the jury is out...
Robert
Robert
Anyway I'll leave this to the experts (you guys), it just caught my eye 
Last edited by Geo.; 12-20-2005 at 02:01 AM. Reason: edit: DC calculation.
12-20-2005, 02:43 AM
#16
Originally Posted by Geo.
Yep. Maybe it is what the PCM would give if it could based on the MAF reading since you are making it so cold, but not sure if that makes sense.
This I don't get, since being held open and never closing = 100%. They don't get any more open than "wide-open" right? I thought the PCM just knows (how many ms open / ms for two revolutions) for duty cycle. Anyway I'll leave this to the experts (you guys), it just caught my eye
This I don't get, since being held open and never closing = 100%. They don't get any more open than "wide-open" right? I thought the PCM just knows (how many ms open / ms for two revolutions) for duty cycle.
Anyway I'll leave this to the experts (you guys), it just caught my eye Robert
12-20-2005, 07:30 AM
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Originally Posted by Robert56
The question should be, how much can the injector flow at static. You would think if 100% (static) was an indication how much total an injector could flow, homeslice would have blown his motor up for sure. If you think static equals max flow, where did additional fuel come from to support 200hp shot and 140%. He would have been so lean the motor would have not lasted at that power. Static is just the injectors being held open, which is not a perfect scenerio, but obviously can continue to flow fuel. Maybe we have a fueling expert that can give us all some insight on this.
Robert
Robert
Last edited by cantdrv65; 12-20-2005 at 07:36 AM.
12-20-2005, 08:40 AM
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I can tell you when injectors are tested for flow on the test bench they are operated at static for several seconds. This is done during quality control, cleaning, and matching of injectors. This is a true 100% static condition, and not PCM calculated.
If this was a danger issue it would've became well known as fact before now. Further, if the injector somehow became inconsistent due to being run at static, then flow-testing, and flow-matching of injectors on the bench would be highly unreliable. I know of no evidence whatsoever that this has happened.
All the 'evidence' (I use the term loosely) I've ever seen suggesting that running injectors past 80% can damage an engine has come from people who have damaged their engine under boost conditions. This changes the game tremendously because the fuel volume through the pump drops when injectors are firing into a boosted intake manifold. This is not something you'd want while running 8 injectors wide open. There are also those people who out of fear, run the fuel pressure much higher than neccessary not realizing that causes fuel volume to drop even more.
Without knowing more about individual cases I'd say evidence like that is inconclusive as far as blaming the injector for running static.
Every fuel injected vehicle I know of no matter the manufacturer has the PCM programmed ability to run the injectors at 100% DC. It's as simple as starting the engine up dead cold in winter and getting into the throttle. The coolant temp fuel offset alone is well more than enough % extra fuel to cover a 200-shot at normal operating temp. If someone knows of PCM code that prevents a static condition to protect the injector then I'd love to hear about it.
If this was a danger issue it would've became well known as fact before now. Further, if the injector somehow became inconsistent due to being run at static, then flow-testing, and flow-matching of injectors on the bench would be highly unreliable. I know of no evidence whatsoever that this has happened.
All the 'evidence' (I use the term loosely) I've ever seen suggesting that running injectors past 80% can damage an engine has come from people who have damaged their engine under boost conditions. This changes the game tremendously because the fuel volume through the pump drops when injectors are firing into a boosted intake manifold. This is not something you'd want while running 8 injectors wide open. There are also those people who out of fear, run the fuel pressure much higher than neccessary not realizing that causes fuel volume to drop even more.
Without knowing more about individual cases I'd say evidence like that is inconclusive as far as blaming the injector for running static.
Every fuel injected vehicle I know of no matter the manufacturer has the PCM programmed ability to run the injectors at 100% DC. It's as simple as starting the engine up dead cold in winter and getting into the throttle. The coolant temp fuel offset alone is well more than enough % extra fuel to cover a 200-shot at normal operating temp. If someone knows of PCM code that prevents a static condition to protect the injector then I'd love to hear about it.
Last edited by white2001s10; 12-20-2005 at 11:59 AM.