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Discussion Starter · #1 ·
Hey all, first post but I've been lurking for a couple months. A lot of really cool info on the site. I've searched though a most of the NOS threads and haven't seen anything that answers my questions. Basically I'm needing some suggestions for a small system to hit an index in a flat bottom drag boat.
I ran nitrous in the late 80's-early 90's... we used a NOS cheater system with a spray bar through the tunnel ram plenum. The motor was a 850 hp BBC and we only needed about 50-75 HP of nitrous to hit the 8.0 second index. We'd vary the n/f jet sizes based air/track factors and it worked really well.
Fast forward to today and we are back in boats, basically doing the same thing. We have a 588 BBC and based on what it ran on the motor, I'm guessing we'll need another 80-125 HP to hit the index.
Seems even a sportsman fogger is overkill for that small a HP. So what do you guys suggest, a small plate or what?
Does anyone still use the old school plenum spray bars? I don't seem them discussed at all. Back in the day, I liked the plenum bar set up. It was clean and jet changes were quick and easy.
Sorry for the long post and I appreciate any help.
 

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Another option would be to spray a larger amount for a shorter amount of time.
I that makes any sense.
For example if you needed 100 shot the whole time to hit an index, you could use a 175 shot with a timer and only spray it for x amount of time and then have it shut off. This might help you with tuning as well because when the weather gets better or worse you could leave it on for a tenth more or turn it off a tenth sooner and so on.
 

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Another option would be to spray a larger amount for a shorter amount of time.
I that makes any sense.
For example if you needed 100 shot the whole time to hit an index, you could use a 175 shot with a timer and only spray it for x amount of time and then have it shut off. This might help you with tuning as well because when the weather gets better or worse you could leave it on for a tenth more or turn it off a tenth sooner and so on.
2x
 

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I do the same thing to go from 10.4's to 10.0's in the heat for some Index racing I do at times. Small shot, from a .028 to a .035 jet depending on the weather. Have EFI so I add the little bit of fuel via the ECM.

I can also use a much larger jet and hit it later on down track and get the same result.

I would use a fogger if I were you and a digiset or similar timer (if rules allow) and use a "normal-sized" shot for a short amount of time. You can always manually turn it back on later if you think you need a little bit more or missed the tree and want to make a race out of it......... :)
 

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Discussion Starter · #6 ·
Yes, we are still using a tunnel ram with a pair of dominators. Hadn't really thought about using a timer, that might be a good idea. One guy I talked to is using a pretty big system and a controller. Leaves with it on at about 30%, ramps up to 80% over a few seconds, then it turns off. The problem with that is flats are pretty sensitive to how you put the HP to them. I prefer to hit the boat with all the HP we will use, then take it away so the idea of a timer seems like something to consider....
thx
 

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Fogger system and a timer is the only way to go. On a motor we did over the winter we just bought an Edelbrock fogger kit from Induction Solutions and installed it our selves, its a bit of a job but its fun. Edelbrock stuff is real nice. MSD makes a nice little digital timer for abotu $150 bucks.

You wont be dissapointed with a fogger, lots of room to grow, you can dial in each cylinder with jetting and the distribution is much better than a spray bar.
 

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Discussion Starter · #9 ·
Fogger system and a timer is the only way to go. On a motor we did over the winter we just bought an Edelbrock fogger kit from Induction Solutions and installed it our selves, its a bit of a job but its fun. Edelbrock stuff is real nice. MSD makes a nice little digital timer for abotu $150 bucks.

You wont be dissapointed with a fogger, lots of room to grow, you can dial in each cylinder with jetting and the distribution is much better than a spray bar.
Chris, I think you're giving me to much credit for knowing what I'm doing... :confused: I wanted to check out your set up last race but got busy on Sunday. Maybe if we get some time you can show me your combo with the nitrous/data logger set up next race.
On a seperate concern, was it you that was telling me your solonoids draw something like 40 amps total?? We'd have to add an alternator with that much draw...
 

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They do draw quite a bit but they are the HUGE Nitrous Pro-flow solenoids that go up to 550 hp, they make smaller solenoids that draw less. I do know the Edelbrock ones we got dont draw as hard as mine do. I wouldnt be too concerned about that, worst case scenario you run a mini alternator, they put out 60 amps, handle huge RPM and weigh nothing, Great for bracket racing.

Stop by next race, Ill help where I can.
 
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