FPSS and rev limiter?
03-05-2005, 12:20 PM
#1
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FPSS and rev limiter? It seems search is down...
I have recently installed a NOS 5177 kit with a FPSS and microswitch for activation. I don't have my window switch on yet, which is why I'm asking this. Is it that bad to spray through shifts? The most my car is making on a 100 shot, I figure, is around 400rwhp. I'd think the stock 4L60E can handle that. Also, how about hitting the rev limiter? I seem to have that problem occasionally. It seems to me that if it cuts the fuel, then the FPSS would engage and thusly shutoff the nitrous.
I'm probably far off with this, but I've been wondering ever since I nailed the limiter on the gas....
I have recently installed a NOS 5177 kit with a FPSS and microswitch for activation. I don't have my window switch on yet, which is why I'm asking this. Is it that bad to spray through shifts? The most my car is making on a 100 shot, I figure, is around 400rwhp. I'd think the stock 4L60E can handle that. Also, how about hitting the rev limiter? I seem to have that problem occasionally. It seems to me that if it cuts the fuel, then the FPSS would engage and thusly shutoff the nitrous.
I'm probably far off with this, but I've been wondering ever since I nailed the limiter on the gas....
03-06-2005, 01:53 PM
#3
Your 100hp shot is really a 85hp at the wheels so your fine. I ran with out a window on an auto. Powerbrake brings rpm's up then when you nail it your about 3500rpm when to the floor. Another trick I used was to make n2o line a little longer and it can act as a window also. Set your rpm limit a little higher and adjust shift points to your needs. I did 125hp shot this way with no problems. This is all with the 5177.
03-06-2005, 01:58 PM
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Thanks for your advice.
Any thoughts on the nitrous cutting off when the rev limiter is hit because of the FPSS? It seems to me that w/o fuel there would be no fuel pressure, which would activate the FPSS and then shut down the nitrous.
Any thoughts on the nitrous cutting off when the rev limiter is hit because of the FPSS? It seems to me that w/o fuel there would be no fuel pressure, which would activate the FPSS and then shut down the nitrous.
03-06-2005, 02:12 PM
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Weird...I hit the limiter all the time. Especially at the track when I lower tire pressure.
I guess I can just set it higher, I just thought that would be bad for the motor as well. How high would you suggest? 6200, 6300?
I guess I can just set it higher, I just thought that would be bad for the motor as well. How high would you suggest? 6200, 6300?
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03-15-2005, 12:27 PM
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The fuel pressure is not cut when you hit the limiter. It partially closes the throttle and I believe pulls fuel at the injectors. So spraying on the limiter is a bad thing.
03-16-2005, 02:55 AM
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Originally Posted by Robert56
Your 100hp shot is really a 85hp at the wheels so your fine. I ran with out a window on an auto. Powerbrake brings rpm's up then when you nail it your about 3500rpm when to the floor. Another trick I used was to make n2o line a little longer and it can act as a window also. Set your rpm limit a little higher and adjust shift points to your needs. I did 125hp shot this way with no problems. This is all with the 5177.
No it isn't good to spray through your shifts unless your tranny is built to take the stress. Your FPSS is there incase fuel pressure drops and that doesn't happen when u hit the rev limiter. That is why you need a window switch.
03-16-2005, 12:12 PM
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I raised my limiter to 6300 and dropped my shift points 1 mph...just to be sure. Car still runs it up to around 6000 before it shifts on the 2-3 shift.
I only made 401rwtq on the dyno...with around 700psi in the bottle though. I think I should be fine spraying through shifts with that little of power, at least I hope.
I only made 401rwtq on the dyno...with around 700psi in the bottle though. I think I should be fine spraying through shifts with that little of power, at least I hope.
03-16-2005, 09:10 PM
#11
Originally Posted by bhz28
your 100 shot isn't an 85, it is all determined on bottle pressure. Thats why in the kit it says jets are rated at 950 psi, it is all determined by pressure, so say u wanted a little more out of your 100 shot jets, then all u have to do is let your bottle heater get the pressure higher and you will be spraying more than a 100 shot.
No it isn't good to spray through your shifts unless your tranny is built to take the stress. Your FPSS is there incase fuel pressure drops and that doesn't happen when u hit the rev limiter. That is why you need a window switch.
No it isn't good to spray through your shifts unless your tranny is built to take the stress. Your FPSS is there incase fuel pressure drops and that doesn't happen when u hit the rev limiter. That is why you need a window switch.
About spraying through your shifts, I did and no problems with smaller hits. There is a thread going about this and you would be surprised at how many do. But, it's up to each person if they want to take the chance.
03-16-2005, 11:28 PM
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Originally Posted by Robert56
For your information, the way NOS rates their 5177 jets at the crank, at 950psi, a 100hp shot is dual .033 jets, now considering the 15% driveline lose that equals 85rwhp. For NOS every .001 increase yeilds a 2.5hp gain at the flywheel and using the 15% equation you can set up your jet combo to any hp you feel comfortable using. All this info is based on the manufacturer's suggested 950psi. Telling someone to jack their bottle pressure up to get more HP is a little dangerous, imo. Some do it (myself) but you better know what your doing, espesicaly on a dry, because most are at their injector limit running the 85hp jets. Check out Nitro dave's dry kit, as it lists the rwhp at 80hp max. If you doubt me, ask him.
About spraying through your shifts, I did and no problems with smaller hits. There is a thread going about this and you would be surprised at how many do. But, it's up to each person if they want to take the chance.
About spraying through your shifts, I did and no problems with smaller hits. There is a thread going about this and you would be surprised at how many do. But, it's up to each person if they want to take the chance.
07-03-2005, 01:11 AM
#15
Say your window is set fo 3500 to 6400rpm. If your shift point drops below 6400 during shift it will automatically be back on. So, if you don't want the spray while shifting set the high end rpm off a little lower. Then it won't interfear with shift. You can also set your shift points higher with a tuner program.
