Nitrous oxide question

[Chris A]

I am pondering the use of a basic nitrous plate system on my 400. The system would be the Sniper (made by NOS I think) which is adjustable from 50 to 150 hp.

My combo is completely balanced 400 kit from hughes, 9.3 compression, roller chain, cross drilled crank, 452's with 2.14/1.81 valves bowl ported and gasket matched, hd rockers/pushrods, 223-230 duration cam at .050 w .514/.504 lift, edelbrock 750 on a performer manifold, Msd 6al with coil, stock distrib, champ. plugs, holley 80 gph (free flow) pump with 7.5 psi, pressure regulator, 7qt pan, hi volume oil/water pumps, hookers with 2 1/2" exhaust w/crossover, Tci breakaway in front of BUILT 727 w/shift kit and the stock 8 1/4" rear which will probably shoot out my rear sometime soon.

I am sure I could run 150 through this combo, it is very stout and only weak link is the 8 1/4" which will be changed to 8 3/4 soon (w/power trax locker).

Would I need an ignition retard with nitrous?? I know I would need to retard my timing but should I get a timing retard control for when the nitrous is shot off, or just retard the timing 2 degreees total?? I bought a book but It is kinda confusing as to what ignition controls I need. Also What should my timing be with this combo?? 36 total? Thanks for all the info.

[PRO]

Chris I imagine you have HD rod bolts and stock rods correct?main studs are a big plus here too but thats not to say it wont live w/o them it really depends on what the actual HP out put is.600hp is definitely a max # with stock rods and main bolts so just dont exceed that # and you'll be ok,it sounds like you may want to run 100 or 125 hp just to be safe.As far as a retard on a street car I've found it easier to use a 15* adjustable timing control mounted under the dash,MSD has 1 for your 6al.You'll want to retard timing 6-8* total when using N2O.I would like to make 1 suggestion based on my 6yr relationship w/nitrous on the street,buy a 5-8 gal. fuel cell and add a 2nd electric fuel pump and line and low fuel pressure cutout switch strictly for the supply for your gas solenoid,the reason being running both the carb and N2O gas solenoid off the same line and pump is marginal at best and not worth ruining a motor over,also run Premium in the fuel cell and HAPPY MOTORING...laughing all the way...PRO..

[This message has been edited by PRO (edited February 21, 2000).]

[Chris A]

Yes Arp bolts and stock rods with shot peen, polished beams and the works, also stock main bolts. The ignition retard you talk about is the Msd adjustable timing control I assume. I don't think I can afford an extra pump, fuel cell and line. If I stayed at 50 75 horsepower untill I add the extra cell, and used a switch with the basic system, would this work? What if I just added an red holley pump in line by my fuel tank, would this be enough for 125 horse of nitrous? I am just thinking now, havent done anything serious yet, open to suggestions, thanks for the reply.

[ROWDY]

if your only going to run off the one pump with the gas make sure you have a fuel pressure guage also at the fuel soleniod...make sure you have enough pressure for both cause if you don't kiss it goodbye...also make sure you run a colder plug but make sure it's not to cold...just check your plugs after each run.

[ROWDY]

it is highly advisably to run 2 fuel pumps

[Old hippie]

First things first...What pistons are you running? Cast, Hypereutectics, or Forged? I would advise forged pistons. Hyper-u's are good street slugs but are less forgiving than Forged pistons when you detonate the engine. They tend to be brittle where Forged pistons have a certain ammount of "ductitility or ductibility" (not sure of the term) and will absorb some detonation before ruining your engine and your (pick one) day, week, month,year, or decade. The other point or two I need to make here is #1) NEVER, NEVER, NEVER, NEVER EVER AS IN DON'T DO IT run less than 5# of fuel pressure to your n2o plate. You lean out a n2o fuel system and you will have parts carnage like you ain't never seen on a carburated engine. I've never run less than 6# on the n2o side and set the cut off switch at 5# for the n2o. One trick that I have seen but not tried is to use the push rod driven stocker type pump to supply the plate only. Some of the Carter high output push rod will put out 7psi. You could regulate that down to 6psi and run a return line to the tank. These pumps will usually dead head ok but that might make you a bit uneasy so run a bypass line back to the tank and use a small gate valve when you want to send fuel to the plate. Then run your Holly blue or whatever to supply the carb. 2) What size fuel line are you running from tank to carb? You can have all the pressure in the world but if you can't supply volume it will not do you any good. At least 3/8 and preferably 1/2 inch.
Lastly, rule of thumb on n2o systems is to retard timing 2 degrees for every 50 horse power of n2o ie...150 hp n2o system needs to have the timing retarded 6 degrees. You can adjust from there but that will get you in the ball park. Just remember, don't lean out your fuel system or else you will have a very expensive (not to mention unique) base for a coffee table. Oh yeah, when you retard your timing remember that you want to retard TOTAL TIMING, not just inital at the crank. Just because you have backed out X-ammount of timing at the crank does not mean it will be the same ammount at total.
Hope this helps. The other bro's that have responded to this thread have some very good suggestions too.


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The Old Hippie Hisself

[T748]

Chris A- Im currently running a sniper kit on my 440 dart.The motor is a '68 with original cast pistons,just fresh rings and bearings and a 234@.050 .495 comp cam solid.A torker2 with a carter 750.Now it has a demon 850.guess at compression ratio 9 to 9.5.Running pump premium through a holly black pump set to 6.5 psi.With 100 horse jets the car ran fine with my regular tune of 36 total.No problems what so ever over 2 years.swapped to the 150 jets.Got head gasket leak(no retorque style)at front of cylinder head at dowel pin on drivers side head.Fixed it,next week it was the passenger head same spot.Reread instructions on kit and backed timing out 2 degrees,no problems since.Im pretty sure that going up to 96 octane would have cured that too.I recomend a fuel gauge mounted where you can keep an eye on it.I have one on the cowl.I also have a set of fuel/air ratio gauges.Not really needed but nice to have.If your bracket racing your car a nice addition is to get an old highbeam switch mounted on the floor with the system power run through it.You can kick it in and out as needed.

[Chris A]

Ok, It sounds like the easiest thing would be to mount a 5 gallon cell in the trunk than run a red pump to a regulator, and fuel safety valve, then straight to the solenoid. I would also run a return line back to the cell and only turn the pump on when racing obviously. I am using the stock whatever fuel line that is on my 73 now. Id imagine 5/16.

I don't understand what a gate valve will do and where I can get it? Jegs/summit? Does this just close the return line from the regulator so all fuel goes to the solenoid? Also about the retard, will the MSD adjustable timing control retard the timing 6 degrees total??

Thanks
Thanks

[ROWDY]

use the secondary cell and yes it is a smart move to have the fuel safety switch...just remember that it is better to run a fat mix...basically set the carby as you normally would because the carby doesn't assist with the gas system...to fatten the fuel side of the gas system,just play with the fuel pressure but like Old Hippie said 6psi is about what you should set it to..good luck

[Old hippie]

By gate valve I am talking about a little 1/4 turn valve like a tank switching valve. Set it up as a "T" in the fuel line after the pump but before the fuel solenoid. One position sends the fuel to the plate and a 1/4 turn sends the fuel back to the tank or the cell. This is only if you decide to use the system I described. The other thought I had was why run a 5 gallon cell to supply the plate? We have got a one gallon cell on my cousins Maverick that supplies the plate only. You don't need that much storage capicity 'cause the plate dosen't use very much fuel in relation to the ammount of n2o used per run.

The Old Hippie Hisself