I have this hooked up already, but I am just wondering how this actually compares to a real electronic boost controller. Why is it that the ECU doesn't just read the MAP sensor and adjust the duty cycle based on that?
I wonder this because I have already experienced a fluctuation of boost during different conditions, one being temperature, which i see there is compensation for.
What I am really wondering is would it be possible for a software revision to adjust the duty cycle based on the MAP sensor reading? I am concerned about this because I will be using nitrous occasionally and I'm sure this will affect the exhaust flow signifigantly I believe boost at the same duty cycle will vary greatly on and off nitrous. If it isn't possible to do the adjustments based on the map reading, would it be possible to add a boost duty cycle table to the nitrous paramaters that would subtract whatever percentage is needed when the nitrous is activated? (I could be wrong, I'm just looking for some direction.)
Boost control
Any rev limiter works by cutting the fuel. Once this happens there is no combustion in the cylinder. At this point the presence of nitrous in the cylinder doesn't make any difference, as there is no combustion, but I think it is likely the nitrous would not get heated enough from compression alone to release the oxygen.
Hondata
I only say this because of horror stories passed down and read such as this.
"Don`t activate or have the system activated when you hit the stock rev limiter. The stock rev limiter is a fuel cutoff. If you cut fuel while you`re injecting nitrous, you`re instantly very lean. This momentary lean condition has the potential of causing internal engine damage and intake backfires."
"Ignition RPM limiter-The rev limiter is implemented by cutting the signal to the fuel injectors so the cylinders have no combustion. If you're running a dry system, which depends on the fuel injectors to provide compensating fuel for the nitrous, losing fuel this way is the ultimate disaster. An after market ignition will typically implement the rev limit by cutting off spark rather than fuel, which is a much safer implementation of the rev limit. Typically, you'd get your stock PCM programmed to set the rev limit up higher than you'll ever expect to go (like 7000RPM), and use the setting on the after market ignition as your actual rev limit."
I still think it would be a good idea if there were an option to cut the nitrous signal when boost cut is activated or better yet when any fuel cut was activated.
Another scenario would be if boost cut was activated, but all conditions for nitrous were still a go. then you have the possibility of a nitrous backfire.
To further on my first post. I have also read some scenarios where stock boosted cars like WRX's, SRT-4's etc.. on nitrous have boost spikes of 2-3 psi. and this was taken directly from a manufacturer website:
"With the injection of nitrous, a tremendous intercooling effect reduces intake charge temperatures by 75 degrees or more. Boost is usually increased as well, adding to even more power. "
So it looks like the IAT compensation for the solenoid may help reduce a boost spike.
"Don`t activate or have the system activated when you hit the stock rev limiter. The stock rev limiter is a fuel cutoff. If you cut fuel while you`re injecting nitrous, you`re instantly very lean. This momentary lean condition has the potential of causing internal engine damage and intake backfires."
"Ignition RPM limiter-The rev limiter is implemented by cutting the signal to the fuel injectors so the cylinders have no combustion. If you're running a dry system, which depends on the fuel injectors to provide compensating fuel for the nitrous, losing fuel this way is the ultimate disaster. An after market ignition will typically implement the rev limit by cutting off spark rather than fuel, which is a much safer implementation of the rev limit. Typically, you'd get your stock PCM programmed to set the rev limit up higher than you'll ever expect to go (like 7000RPM), and use the setting on the after market ignition as your actual rev limit."
I still think it would be a good idea if there were an option to cut the nitrous signal when boost cut is activated or better yet when any fuel cut was activated.
Another scenario would be if boost cut was activated, but all conditions for nitrous were still a go. then you have the possibility of a nitrous backfire.
To further on my first post. I have also read some scenarios where stock boosted cars like WRX's, SRT-4's etc.. on nitrous have boost spikes of 2-3 psi. and this was taken directly from a manufacturer website:
"With the injection of nitrous, a tremendous intercooling effect reduces intake charge temperatures by 75 degrees or more. Boost is usually increased as well, adding to even more power. "
So it looks like the IAT compensation for the solenoid may help reduce a boost spike.
Once the ECU cuts fuel, there is very, very little fuel in the combustion chamber. Fuel will only burn from about 9 to 20 to 1 AF ratio, so once the injectors shut there is no way the fuel will burn, and therefore can not run lean as there is no combustion.
Some of the stories are based off a wet nitrous system, which will run lean at fuel cut since the ECU is not controlling fuel. However, with a wet n20 setup and an ignition cut you will wash the oil off the cylinder walls at the rev limit, which is why we don't recommened the wet setup ever.
The best thing is to cut nitrous off a few hundred rpm before the rev limiter.
The IAT sensor is too slow to respond to a rapid change in temperature. In any case, I've never noticed a boost spike when nitrous is activated. If you have a datalog which contradicts this, send it to me.
Some of the stories are based off a wet nitrous system, which will run lean at fuel cut since the ECU is not controlling fuel. However, with a wet n20 setup and an ignition cut you will wash the oil off the cylinder walls at the rev limit, which is why we don't recommened the wet setup ever.
The best thing is to cut nitrous off a few hundred rpm before the rev limiter.
The IAT sensor is too slow to respond to a rapid change in temperature. In any case, I've never noticed a boost spike when nitrous is activated. If you have a datalog which contradicts this, send it to me.
Hondata
cutting nitrous before the rev limiter is a given.
I would just feel much safer if there was an option to cut nitrous if boost cut was activated.
I will get back to you about the boost creeping. If everything goes well I assume using the engine Load condition and setting the max load just under boost cut could be effective?
I would just feel much safer if there was an option to cut nitrous if boost cut was activated.
I will get back to you about the boost creeping. If everything goes well I assume using the engine Load condition and setting the max load just under boost cut could be effective?
A fuel cut rev limiter is fine with nitrous. In any case the nitrous should be set to shutdown before the rev limiter. A boost cut will not start the injectors up again until you go to zero throttle or below 2000 rpm, in which case the nitrous will switch off.
We've explained the behaviour of nitrous, the rev limit and fuel cut the best we can. I don't believe that there is anything further to add and I don't want to get drawn into a point by point rebuttal of statements from unknown sources, which does not apply to the way we control the nitrous as a dry shot.
We've explained the behaviour of nitrous, the rev limit and fuel cut the best we can. I don't believe that there is anything further to add and I don't want to get drawn into a point by point rebuttal of statements from unknown sources, which does not apply to the way we control the nitrous as a dry shot.
Hondata
This is why I am here, to LEARN....
If you have a problem with helping people then you shouldn't be the one answering questions. I am not trying to drag this on its just so hard to get full answers on here. I would be stupid for not getting answers from multiple places and comparing.
I think it is pretty important to understand exactly how this output works and reacts to certain conditions BEFORE throwing it on there and ruining components. Because that one question that I didn't ask could spell disaster.
I hope you understand the consumers point of view when answering questions. I don't know if you are extremely tired of answering questins on here, but it always feels like there is a lack of effort. Look at my first post then look at the reply...Did that answer my question?? So I had to post again...
If you have a problem with helping people then you shouldn't be the one answering questions. I am not trying to drag this on its just so hard to get full answers on here. I would be stupid for not getting answers from multiple places and comparing.
I think it is pretty important to understand exactly how this output works and reacts to certain conditions BEFORE throwing it on there and ruining components. Because that one question that I didn't ask could spell disaster.
I hope you understand the consumers point of view when answering questions. I don't know if you are extremely tired of answering questins on here, but it always feels like there is a lack of effort. Look at my first post then look at the reply...Did that answer my question?? So I had to post again...
hitting the limit on a dry hit, then staying OFF the throttle would pose no danger, but if you immediately upshift and jump back on the throttle there's a strong chance of a nitrous backfire in the exhaust. A fuel cut only rev limit on a wet nitrous hit is dangerous period, for a wet hit you'd want ignition cut also. Pick a shift point, set the nitrous to turn off 50 rpm over the shift point, then set your rev limiter 300 rpm higher than that. If you miss a shift just quit your run.